Gizmo

Gizmo 48V Battery Meter values

2011-10-02T13:35:00.000-07:00

While I don't use one any more a friend of mine is restoring a couple of Gizmos and I thought it might be nice to know what voltage the different marks are on the Gizmo 48V Battery Meter. Assuming each 48V meter is the same you probably can use these values. According to the Gizmo User Manual early Gizmos had a 12V meter hooked to the first battery so these values might not match. In the picture the tip of the V is where the value is to be read. The voltage where the needle first starts to move is at about 27V and where it hits the upper end of the range is about 66V. When I had lead acid batteries in my Gizmo I knew when the resting voltage was near or at the bottom of the green it was definitely time to charge! I usually charged at every opportunity I had which meant every time I got home.

Battery Balance Meter 9V Battery Replacement

2011-10-02T11:31:00.000-07:00

As it turns out I got tired of replacing the 9V battery which powers the Battery Balance Monitor volt meter. I was going through them faster than my smoke detectors were "producing" them and the place I had them installed required a zip-tie each time I replaced the battery.

I decided to see if I could find an isolated DC-DC. I have some Tyco 1/2 brick DC-DC converters which would run from pack voltage but it seemed a bit overkill to use a 150W unit to power something which draws in the mA range of current. Not being an EE I didn't have much to go by as to where to look or what kinds of parts are available. I found that Jameco Electronics had a small isolated DC-DC converter which took 9-18V input and had 9V output. I ordered this, two 3.5mm terminal blocks, a small ABS case, a PCB which fit the case, and some stand-offs to mount it.

The DC-DC said it had filtering built in but I decided to install an inductor and capacitor on both the input side and the output side to smooth out the current. I didn't find out if I need an inductor in both the positive and negative leads. I only put the inductors in the positive leads. I used two small inductors out of a dead PC power supply. The fuse holder, 1/2A fuse and 22uF capacitors came from a dead digital mulit-meter. Here is a picture of the finished board.

I didn't realize that the 3.5mm terminal blocks were not spaced correctly for mounting in the holes of the board. As it turned out they mounted diagonally just fine which actually made it easier for the wires to make the bend to go out the hole in the bottom of the case. The block on the left is for input power and the right is for output. They are connected to match the order/placement of the markings on top of the DC-DC. On the back side I used leads cut off of LEDs used in other projects. They are plenty large for the minimal currents involved and they don't flop around with road vibrations. I only had to use one insulated wire which I decided to put on the top side of the board.

I mounted the box portion of the case to the underside of the dash in the Gizmo. There is a little fiberglass tab which was unused in my Gizmo. Looking at another Gizmo I see that this tab is where the fuse block used to be mounted. I put some soft wide weatherstripping on the underside of the box, drilled holes to match the holes in the fiberglass tab and then ran a large zip-tie through the holes to mount the box. I figured that mounting in this way would lessen the sharp jarring and vibration that Gizmos get on rough roads. I then mounted the PCB to the lid of the box and drilled a small hole in the lid for the wiring. This allows me to get to the unit by merely removing the lid to the box making installation/removal much easier.

So far, this has worked flawlessly.

My parts list:

CONVERTER,DC-DC,5W,9V@0.556A 9-18Vin,REGULATED,ENCAP,FCC/CE Jameco PN:2107477
CASE,ABS SPEEDY,3.125 x2 x.875 Jameco PN: 18922
PROTOTYPE BUILDER,1.6 x2.7 Jameco PN: 105100
MOUNTING HARDWARE KIT,CIRCUIT BOARD Jameco PN: 106551
HEADER,3.5mm,TERM BLOCK,2 POS, TOP SCREW Jameco PN: 2094506
Two 50V 22uF capacitors
250V Fast Acting 0.5A fuse and holders
Two small inductors

CycleAnalyst Control Board

2011-09-08T22:56:00.000-07:00

It has been a while since I installedthe CycleAnalyst and I've received a couple of questions about how Ibuilt the control board so I figured it was time I documented it. Ihave gone through a couple of iterations so the one here is the finalversion. There really isn't much difference between the two versionsexcept that the first one had a reed relay which would turn off theCA's back light when the headlights were off where as this versiondoesn't switch the back light on and off but instead has a 1Kohm 15turn potentiometer used to adjust the back light brightness. Theother change is that I added a toggle switch to the side of the boxthe CA is in so I could turn on the CA when the key was off.

[edit: I wanted to have the CA operate without a 12V system under normal charging circumstances which is why I went the route I did. The only time I need the 12V system to work is when driving and when using the manual over ride switch. If you don't need/want to operate the CA without the 12V system a simpler solution might be to hook the CA to the switched side of the main contactor and use a SPDT relay to switch on the CA when charging or with a manual over ride.]

The CA would always seem to recordeither +0.1A or -0.1A when sitting idle which would increment ordecrement the amp-hours faster than reality so I decided to figureout a way to have the CA only come on when the key was turned on orwhen charging. Since the CA is a high resistance device it doesn'tdraw much current. I also noticed that the relays in the Zivancharger are rated at 1A at 30VDC and 0.3A at 110VDC which meant thatI could likely get by with a 10A 28VDC relay to switch the CA to apack voltage of 70VDC without any problem. I also figured that if therelay welded shut there wasn't much that could go wrong other thanthe CA not turning off. In any case, if you use a relay outside ofits ratings you do so at your own risk. I'm also blessed with a DC-DCconverter from Sure Power Industries which has a switched andunswitched outputs. As far as I can tell it is not an isolated DC-DCconverter so both input and output grounds are shared with packnegative. I hooked the coil of the relay to the switched 12V so thatwhen the key is turned on the CA is connected to the pack. So farthis has been working just as I want.

Since I don't charge with the key on Ineeded a way to turn on the CA during charging so I could see thepack SOC without having to fully charge to get to a known SOC. Thishas been handy when I have had to go farther than the round triprange of my rig. I could just charge until I knew I had enough tomake it back home. Fortunately the Zivan NG line of chargers has twoauxiliary relays, each with a NC and NO contacts. AUX1 closes the NOcontact when the equipment is switched on. AUX2 opens the NC contactat the end of charge. All I did was run a wire from B+ to the NOcontact on AUX1, a jumper wire from the C contact on AUX1 to the NCcontact on AUX2 and then from the C contact on AUX2 back to the CA.This will turn the CA on while charging and off when it is done.

Zivan NG1 relay connection

I recently had my NG3 reprogrammed withthe LiFePO4 profile with the same 69.3V saturation voltage. I alsoinstalled another 50A Anderson connector to hook this charger to forthose times I need a quick charge. The problem is that this chargeris usually mounted on my shop wall so doesn't have the wiring toautomatically turn on the CA so I installed the toggle switch to turnon the CA at any time. Since I didn't want another high voltageswitch in my dash I merely wired in +12V from the always on side ofmy DC-DC converter and ran this to the +12V input of my CA controlboard. Since I didn't want anything back feeding to the rest of the12V system I installed a diode between the key switched input and thetoggle switch. If you look by pins 1 and 2 in the picture below youcan see the diode. BTW, since the Zivan chargers are isolated I can charge with both at once for a 55A charge rate!

CA Control board

Note that there are 16 wire locations.I didn't really have to have so many but I wanted to be able todisconnect the CA without having to desolder things or disconnectthings back at the source so I took the liberty to also make the CAcontrol unit a convenient disconnect location. Here are the pin connections:

Vertical set

1 – +12V switched with key

2 – +12V manual over ride switch

3 – Speedometer input

4 – Ground from pack negative

5 – Shunt -

6 – Shunt +

7 – Out to Zivan NG1 relays from B+

8 – B+ Pack positive

Horizontal set

9 – CA Back-light

10 – CA Back-light

11 – Speedometer to CA

12 – Ground to CA

13 – Shunt - to CA

14 – Shunt + to CA

15 – In from Zivan relays

16 – B+ out to CA

Pin 1 is connected to pin 2 through thediode. Pins 7 & 8 are connected to each other as are pins 15 &16. Pins 3, 4, 5, and 6 are connected directly to pins 11, 12, 13,and 14, respectively. The wiper and one end of the 1K pot areconnected to pins 9 & 10. Apparently the CA has a constantcurrent LED driver for the back light so it is perfectly safe tocompletely short out the LEDs or connect a resistor in parallel withthem so it doesn't matter which side hooks to pin 9 and pin 10. Ifound through experimenting that about 600 ohms of resistance acrossthe LEDs would dim them to the brightness I liked for night driving.When they were full on it affected my night vision. [Grin Tech(ebikes.ca) now make a CA which has optional red back lighting whichI would definitely use if I had the choice now.] If you lookcarefully you can see where I drilled a small hole in the side of thebox so I can adjust the back-light brightness without opening up thebox.

Wired up

This is what the box looks like wiredup. Note the large zip tie on the bundle of wires. This is to providestrain relief on the connections in the box. It seems to work well.Also, if you look at the lower left corner of the picture you canjust see a zip tie going through the corner of the box. There isn'treally any where to mount more things under my dash so I suspendedthe control box from opposite corners using zip ties. The box doesn'tbounce much at all and doesn't pull on the wires.

The speedometer input comes directlyoff the wire feeding my main digital speedometer. I did have to put a22nF capacitor at the C6 position on the CA board. Note that I haveCA rev 2.2. When I would get to 48-50mph the speed would startjumping around erratically and eventually just go to 0. Changing thecapacitance of the RC filter would filter out the controller noise.When I was going over 50mph I could let off the throttle and thespeed would be rock solid. As soon as the controller was asked forpower the speed would go weird again.

Battery Pack Balance Monitor

2011-07-25T22:52:00.000-07:00

It has been 19 months since I installed my LiFePO4 battery pack made up of 40 (originally 36) Thunder Sky TS-LFP100AHA cells in a 2p20s arrangement for a nominal pack voltage of 64V and an energy capacity of 12.8kWh. From January 2010 until the end of July 2010 I ran with 18 cell pairs and top balanced the pack at 4.00vpc. At this point I received my reprogrammed charger back from Elcon set for a saturation voltage of 69.3V which, until recently, I had bumped up to 69.7V. At this point I also installed the remaining 4 cells for a total of 20 cell pairs. I also did my final top balance at this point in time since I had noted that there was very little if any balancing going on and that it wasn't the same cells which hit top voltage first. I left the Black Sheep Technology BMS boards in place but they did not do any shunt balancing since my charge was ending at 3.485vpc and the boards don't shunt until 4.00V.

With the BMS boards, however, I had no way of knowing if any cell was going high or low relative to the others. When the BMS alarm would sound all I knew was that at least one cell was low. I wanted some way to narrow down if I had a weak cell or a bad connection. Lee Hart has posted on the EVDL Library a Batt-Bridge Battery Balance Alarm. This device used resistors selected for a particular pack voltage and a series of LEDs. I emailed Lee about some alternatives to his circuit. I wanted to have some sort of meter which would deflect to show me what was going on rather than wait for a large enough voltage swing to occur to light one of the LEDs. You can read about my dialog with Lee and some other discussion on the DIYElectriccar site. What I ended up doing is ordering a 9V battery powered volt meter from eBay seller clinia. He will setup the meter to what ever specs you want. Here is a picture from his listing of the meter:

With a battery balance circuit such as this the voltage reading will be exactly half of what the difference is between the two halves. Because of this I had the meter setup to display a reading double what the input voltage was. Now I can glance at the meter and see the actual voltage difference between the most negative half of the pack and the most positive half of the pack.

The circuit is constructed by connecting a resistor between the most negative post of the battery pack, to one end of a potentiometer, and the other end of the potentiometer to another identical resistor and then to the most positive end of the pack. A volt meter is then connected between the middle post of the battery pack and the wiper on the potentiometer. The potentiometer is used to calibrate the device so that when each half of the battery pack is exactly the same voltage the meter will read zero. One of the challenges with hooking wiring up to high voltage DC in a vehicle is the potential for a short which could cause all kinds of damage, including fire. The challenge is then to find small, low amperage, high voltage fuses. Radio Shack fuses won't cut it. I then searched for name brand fuses and holders but didn't know that I wanted to have to mount them on PC boards and such. Next is to determine where and how to mount them. I then inquired Lee about using a resistor as a safety device. Since I wanted this device to draw as little power as possible I used resistors with a very high resistance. This meant that any short would cause only a very low current and wouldn't burn something. With this in mind I went about coming up with a way to mount the fuses right at the terminals so that no matter where any wire might short the current would be very low and not cause any problems. Naturally I wanted to secure things where there would be no shorts but I wanted to be safe.

In playing around with Ohm's Law, V=IR, and trying a couple of fuses I had laying around and my DMM, I determined that it really doesn't matter what resistance I use as long as it is high enough. I ended up getting 100K Ohm, 1/2 Watt, 5% resistors. Since the max my pack voltage would ever go is 80V, if I were to top balance at 4.00vpc, this means that the maximum current would be I=V/R=80V/100KOhm=0.0008A=0.8mA. This is only 0.064W so well under the resistor's rating. This is if one wire shorted between the extreme most posts which is highly unlikely to happen! For the potentiometer I picked up a 1KOhm 15 turn pot. This means that between the negative post and the most positive post would be a total of 201KOhm of resistance and with a fully charged pack at 70V (I'm really having charging end at closer to 69.3V now) the current draw of the device is under 0.35mA. This is quite acceptable and means that even if I left for a year and didn't charge that the pack would only be drained about 3Ah. Furthermore, this is evenly across the full pack so there will be no imbalance caused by the device. Perfect!

These resistors take care of protecting two wires but what about the center tap? What if it shorts to something? I played around with different resistors to see what difference they made to voltage readings. They do make some difference so I decided to go with a 10KOhm resistor on the center tap wire. This only changed the reading by about 0.01V which is acceptable to me. The most voltage the center tap could ever see was 40V so the current would be at most 4mA and 0.16W, again well under the 0.5W rating of the resistor.

For mounting I bought some double clad PC board material and cut out 25mm squares. At the moment I'm not using the BMS boards so I can use the screw mounts for them. If you have read earlier posts on the BMS boards you know I am using brass bolts with a tapped hole in the center. I drilled an off center hole for the screw to go through and then used a dremel tool to grind away a gap in the copper on both sides of the board. I used a #57 Wire Gauge drill bit to drill three holes, two for the resistor and one for the wire to attach. Below are the three boards I built. The two at the top are the most positive/negative boards with one showing the back side. The one marked with an M is for the center tap.

Terminal connections

The small unfilled hole is where I attached the wire to the board. Note that I soldered both sides of the board. I did this to provide as many path ways for conduction as I could to hopefully minimize the chance for a bad connection. I haven't done it but I probably should conformal coat the boards except for the solder pad for the screw. It was very easy to make the pad and draw the M. The copper is textured somewhat and is very ready for soldering.

The next thing to do was to decide how to connect everything. While I like the good connection achieved with soldering I didn't want such a permanent hookup since I would have to do the soldering on the vehicle or in the battery compartment. These Gizmo's don't have much extra room for things, especially after all the things I have added over the years. I decided to get a 4.5cm square PC Board from Radio Shack and mount the pot and some PCB terminals to it. The set of four terminals is for hooking up the battery connections (only 3 are used) and the double terminal is for hooking up the volt meter. This makes a simple and hopefully reliable connection point. Time will tell how well this will hold up.

Front view


Rear view

Except for the insulated jumper wire I just used the leads I cut off of the resistors to make the connections. For the wire connections from the terminals to this board I used 24 gauge aircraft wiring I got from Aircraft Spruce. The wire is tinned and rated to 600V. Most importantly the insulation is very tough. I accidentally set some on a hot soldering iron and it barely made a mark on it! The wire is rated to 150°C which explains the minor damage from touching the soldering iron.

Next came the need to mount the volt meter. Since a Gizmo dash is curved it is very difficult to mount flat meters. I also don't want big holes in the dash, especially if I change something in the future. I decided to mount this meter the same way I mounted the CycleAnalyst, by carving the back of an ABS project box to match the contour of the dash and then silicon the unit to the dash. I first needed a pattern to go by so I used some air dry clay as I did before. I used a 4"x2"x1" Radio Shack project box wrapped by a strip from a cereal box and pressed the clay onto the dash and then let it dry.

Unfortunately the dry, sunny, warm days we were supposed to get turned into cool wet days so it took a while to dry. After a couple of days I finally carved out the center and then used a hair dryer to finish the drying so I could remove it from the dash. Here is the result:

I carved the edges so I could place this inside the project box. After cutting the back off the project box I put this inside and held the sides firmly while I used my Dremel tool to cut the project box to match the contour.

While the clay was drying I took the screws which hold the lid to the project box in place and screwed them into a piece of cardboard. I sprayed them with metal etching primer and then sprayed them with a couple coats of gloss black paint. This seems to work well and the paint doesn't chip when inserting the screws. I did have to cut the screws shorter since they would have hit the dash otherwise. On the thinnest corner of the box I reinforced the screw hole by gluing in a piece of the ABS box I cut out between the screw hole cylinder and the wall of the box. Regular ABS glue for black sewer pipe works great for this. Without the reinforcement the screw mount would tend to twist and deform the edge of the box.

To mount the display I placed the box cover face down on a piece of #2 plastic scrap, scored the opening I wanted with a small tipped Xacto knife and then went to work repeatedly running the knife down the groves until I cut through the front. Working from the back makes sure that any slips don't show through on the front. The hole was then filed with a standard 8" mill file until it was smooth and the correct size to hold the bezel. This part took me about an hour to do. Here is the finished result:

The ammeter really doesn't look like it is crooked. When sitting in the seat it all does look just fine. I have the meter hooked up so that a positive display represents how low the most positive part of the pack is from the most negative part and a negative reading is the opposite. I'm still trying to decide how I want to label the meter so that my wife and any one else who drives my Gizmo will know how to interpret the reading. As you can see the front (most positive) half of the pack is 0.02V lower than the back (most negative) half. When I did my last pack balance I had to do each half separately. I believe this is why there is a difference. However, under a >1.5CA load the difference is +0.13V and when regen current is over 50A I get a -0.00 reading so I may have a poor connection or weak cell pair in the front half of the pack.

Here is a parts list:

Low Cost LCD Volt meter ($16.21)
4"x2"x1" Project Box ($3.19)
2-sided PC Board material ($4.19)
45mm square PC board ($2.19)
2 packages of 2-pin 5mm PCB Terminals ($2.39 each)
5 pack of 10KOhm resistors ($1.19)
5 pack of 100KOhm resistors ($1.19)
1KOhm 15-turn potentiometer ($3.19)
#57 Wire Gauge Drill bit ($2.89)
24 gauge wire ~ 25 feet total (~$6.00)
Air Dry clay ($???)
9-volt battery (from my smoke detector) [Note: Since I don't turn off the meter with the key the batteries were going dead too fast so I installed a 12V-9V isolated DC-DC. See the post at http://2003gizmo.blogspot.com/2011/10/battery-balance-9v-battery-replacement.html]
miscellaneous zip ties (had on hand)
a donation to Lee Hart for all his help. Have you benefited from his help? Send him a Thank you donation for the Sunrise EV2 project via paypal to leeahart_at_earthlink.net

I had the wire, clay, and zip-ties in stock and the 9V battery is from one of my smoke detectors. The meter will run on as low as 7V or so and has a very low drain. I decided it wasn't worth trying to get an isolated power supply for it. I just zip tied it to a small shelf under the dash. I put a piece of weather stripping under it to keep it from sliding out and it should be good to go for several months. The total cost to me for the materials I didn't have on hand was $33.44 excluding tax. For paying all retail pricing I'd say this isn't too bad.

Now if I have a cell going bad I'll see the voltage difference show up right away unless, of course, I have a cell in each half of the pack doing the same thing at the same time.

In my next blog post I plan on relaying the results of not doing any pack balancing for the past 11 months.

Edit: I remembered to take some pictures the other day when I was checking pack balance. Below are different views of the batt-bridge installation. The pack really looks dirty in these pics!

Main Board

Main Board and Center tap

Negative Terminal connection

Positive Terminal connection

A year with LiFePO4 batteries: What Have I Learned?

2011-01-17T23:08:00.000-08:00

One year ago today I took my first drive in my Gizmo with 36 TS-LFP100AHA installed in a 2p18s configuration. See the blog posts in January and February 2010 for my setup. In that time I have learned quite a bit about LiFePO4 batteries. Playing with them, using them, measuring them, keeping an open mind about how they operate and avoiding the "conventional wisdom" about batteries are all good things to do. Being a physics type is also good but not necessary. It just means there is a chance that you learned that you record everything even if you don't think it is useful and especially if it doesn't support your current notions about things or something you are trying to prove.

In the past year the odometer went from 8640 miles and now sits at 14139 miles: one mile short of 5500 miles.
I also saw this nice pattern of numbers on the odometer! The aluminum over the speedometer was an attempt to shield sun from hitting the display. Sometimes I can't see how fast I'm going and don't want to get a ticket. I've since removed it since the CycleAnalyst has a speed function I can use for the infrequent times I need it.

I spent $46.80 on electricity to recharge and used 993.43kWh from the wall (representing 12,365.37Ah) to travel that distance. This comes out to a conservative average of 137Wh/mile from the battery pack. I'll post about current efficiency values in another post. I see a trend and think it might be tied to pack temperature so I'll post in the summer about it.

This is a CycleAnalyst from ebikes.ca showing the total cycle count, total Ah and total Miles driven. The miles is higher than my speedometer gives. I'm assuming that the CA is more accurate because I calculated it from 10 tire rotations but I wanted to keep a consistent count from before I installed the CA and after so I only record the speedometer values. Also, the difference in the CA total of 12,544Ah and my total of 12,365Ah is due to the fact that the CA records total Ah that the batteries deliver whereas my figure is from adding up all the individual trip Ah which include regenerative braking. From this you can calculate that regenerative braking gained me 1.4% range over this time period. [edit: I just realized that 7597Ah came from back calculating for the time I did not have the CA and are based on the kWh used to charge from the wall. A more accurate representative result would be a 3.7% gain from regen.] Not a whole lot, however I have gone over three times farther on this set of brake pads than I did before I had variable regenerative braking so it is definitely a benefit. Not to mention the ability to come down steep long hills and not have brake fade and the much quicker panic stops than without.

The Cycle Count of 290 represents the total number of times I have charged the battery pack until it was full and I reset the CA. The Ah value is not always exactly at zero after a charge. It ranges from a fraction of an Ah above or below to as much as 2.5Ah above or below depending on how long the drive was and how much the battery temperature changed. I think it is also dependent some what on how closely calibrated it is to the shunt. With my 500A shunt the CA only claims accuracy to 0.1A so at the end of charge when the Zivan ramps down to near zero amps it may or may not register on the CA. The 290 cycles represent an average (mean) discharge per cycle of ~21% with a median of 13.6%. The highest discharge amount was 89.9% (179.6Ah) and the smallest was 4.34% (8.68Ah). At this rate I hope the pack will last 10 years. Even then I will probably have spent more than if I had stuck with 6V flooded Golf Cart batteries. However, the utility of the vehicle is so much better that it is hard to put a price on it. Not to mention I am getting valuable information on a $5000 pack rather than on a $20,000 pack in a full size car. (I need lots of range for what I do with my car so I would need a much larger pack even though a $6500 pack would work well in a small car.)

One thing is for sure, when the range is more than 20 miles it is much easier to drive more. There were several times where the 20 mile range of lead acid were not enough for what I needed. I remember heading out to one of my rental houses to show it to someone and getting most of the way there and realizing I had forgot the key. I had to turn around and go home to get it. Unfortunately I didn't have enough range to make the trip a second time so I had to take an ICE vehicle. With LiFePO4 and an easy 60-70 mile range meant those situations are no longer an issue. I've driven from Kelso to Battle Ground, WA to work on a rental house knowing I would be there long enough to charge enough to make the return trip.

If you read my February 2010 blog and the two comments you will see there was talk about my original ending charge of 71V or about 3.94vpc. Jack Rickard correctly pointed out that charging this high would shorten the life of my cells. On July 28, 2010 at 11,365 miles on the odometer I installed my newly reprogrammed Zivan NG1 with the #612 charging algorithm for 19 LiFePO4 cells. I did adjust the voltage trim pot up so now the ending charge is 69.6-69.7V. At the same time I installed the remaining two pairs of cells. I top balanced all the cells using my BMS boards which shunt at 4.00V. This means my pack voltage was at 80V when I was finished. My DC-DC won't come on at this voltage and neither will my Sevcon PP745 controller. I used a bank of light bulbs I built as a load to discharge batteries and brought the voltage down to below 70V. This took very little time since there is very little energy above 3.45V with this particular chemistry.

One might be wondering about the top balancing if my BMS boards don't shunt until 4.00V. After all, 69.7V/20 cells = 3.485vpc. Well, since there is so little energy above 3.45vpc (with my 18 "cell" 200Ah pack it was only enough to get me up to about 15mph from a stop) there is really nothing lost by stopping earlier in the charging curve. The Zivan is incredibly consistent in stopping at its programmed cutoff voltage. It even will shut down if for some reason it can't control the voltage. I found out quite by accident on the first pack charge I did. Being naive about the characteristics of these batteries I went to the store thinking that since the voltage hadn't risen much it would still be a while before they were full. When I got back the charger was beeping an error code which turned out to be "unable to control voltage" or some thing like that. Zivan chargers may not be too great to end user adjustment but I sure am thankful that they just plain do what they are supposed to. They are truly plug-n-play if you don't make any changes to your battery pack. Another point about the small amount of energy at the top of the voltage curve. I've watched the voltage at the end of charge. From the time the charger first starts to ramp back on the current it is only 10-15 minutes before it is putting less than 500mA. This last phase (yellow light) of the charging curve lasts for 1 hour. Even if it continuously put in 500mA (it doesn't) that would only be 0.5Ah into a 200Ah pack. It comes on periodically and draws only 40W from the wall and that drops down rather quickly to under 20W and then shuts off. I'm sure if I didn't have any parasitic loads on the battery pack that it would shut off and not come on again during the remainder of the final charging curve.

Back to top balancing: I was wondering too what would happen. If these batteries drift I should start seeing it after a few charge cycles. I started recording the voltage at the end of charge when the charger was not charging. This was during the yellow light phase of charging. I could see the wall power on my kill-a-watt meter so I knew when the charger was not putting anything into the pack. When not running the charger draws about 4W. I can also hear when the charger shuts off and turns back on because I hear a high pitched squeak which is probably the PWM of the charger coming on or turning off. Other than the first time I took cell readings the charger was off. Below is a screen capture of the spreadsheet I'm using to record the information.

The first column lists the cell number and location in the pack. Cell pairs 19 and 20 were installed after the charger was reprogrammed. They only had about 3 cycles on them before being merged into the pack. I did have a mishap with pair #19 a day or two after installing them. I missed tightening one of the bolts which held the straps between this pair and pair #20. It had worked its way up about a centimeter or so. Amazingly, there was no melted metal but one cell of the pair took several Ah to bring it up to the rest. What I think was happening was that the high currents were draining the cell but the charge currents were not getting into it very well. It is possible that since I am using brass bolts rather than the stainless steel ones supplied by TS I avoided problems. I tightened this bolt down and charged this one pair with my bench top power supply. You will see that it is one of the higher voltage pairs, though not the highest, of the set. The next columns are a date followed by High/Low. the High/Low column shows an H for the highest cell and an L for the lowest cell for that day's reading. At the bottom of this column is the difference between these two values and represents the maximum voltage range of the pack. The cell immediately below the individual voltages is the sum of the voltages, below that is the total pack voltage as given my my ExTech Instruments EX830 multimeter. This is an awesome mid-range meter, BTW. Note that the ending voltage for the first reading is 70V. I lowered the ending voltage of my charger after this to keep my DC-DC happier. The next cell in the spreadsheet is the Watt reading on the Kill-a-Watt meter, below that is the pack temperature, in degrees Celsius, by an inexpensive indoor-outdoor digital thermometer. I placed the outdoor probe between the middle rows of batteries against the case. It is held in place by a folded up piece of closed cell foam to try to get a more accurate case temperature. The temperature was generally stable by the time the charging was finished so this value likely is very close to the internal temperature of the cells. The whole box is surrounded by 3/4" hard pink insulation foam as sold by home hardware stores. The box is by no means air tight but generally there is not much wind in my carport. Finally, the last cell is the average Volts per cell value.

As you can see, the voltages don't move around very much. The high and low cells don't change much. (Note that the dates are farther apart later in the table.) As Jack Rickard and others told me I'd get bored taking these measurements and eventually quit. Well, I like data and I'm out to test out a hypothesis that has been forming in my mind for a while. I'm no longer convinced I need a cell level BMS. I think a half pack voltage comparison is enough to spot a dying cell and take care of it. Before you tune me out read on.

After watching Jay Whitacare's talk to a group of Carnegie Mellon students and professors about their EV experiments I became less convinced that the risks of a cell level BMS were lower than a string level monitoring system. See the video linked to on the ChargeCar website or on the EVTV.ME blog. When I read "Shuttle reaction" in the comments to Jack Rickard's January 9, 2011 blog it finally hit me why these batteries are so different from other chemistries. I have since read about it in other places. It was hinted at in one of the responses to an EVDL post I made asking why my efficiency from the wall numbers were so much better with LiFePO4 batteries than with lead acid. A poster mentioned a secondary reaction in lead acid that didn't participate in the storage of energy but used energy in the reaction. I believe this was the shuttle reaction which provides the self discharge of so many other batteries. Lithium ion batteries in general and LiFePO4 in particular merely move a Lithium ion from one plate to the other during charge and back on discharge. There really isn't a chemical reaction, per say, taking place to make this happen. Barring a mechanical defect in the cell there is no way for self discharge to happen! When people put BMS boards on each cell, this then becomes the discharge mechanism for the cell, not the cell it self. If you have any LiFePO4 cells in storage make sure there is nothing on the terminals. If you want just check the voltage every 6 months or so. Unless there is something on the cell allowing charge to transfer between the terminals you will be pleasantly surprised at or bored with the fact that the voltage doesn't change much if at all, even out to the thousandth of a volt.

Another source for this information is on Gold Peak Industries (Taiwan), Ltd. website. In section 3.8 of the linked pdf it states,

“There is no shuttle-based self-discharge reaction in the Lithium Ion cell like that found in the NiMH and NiCd. As the cell ages, the self-discharge eventually becomes zero. Initially the cell suffers from irreversible capacity loss. This is a reaction of the electrolyte with the the active components if the cell. It occurs more rapidly with increasing temperature and cell voltage. For this reason, cells should not be stored fully charged at temperatures approaching 60°C. Optimally they should be stored at 25°C or less and between 30-50% state of charge. The lower limit is chosen because they are often stored in packs witch circuitry that demands a small drain on the battery. When one considers the circuitry needed for li-Ion, it becomes the most important source of self-discharge.”

Note that it states that the lower limit, 30%SOC, is chosen because so many put BMS circuits on them. Leave them off means almost zero self discharge. Furthermore, as the cell ages, what ever self-discharge there may be drops to zero any way. It sounds like the cells will become less and less prone to drift apart in any particular given pack.

Another sentence in the above quote caught my eye, "Initially the cell suffers from irreversible capacity loss." This may explain why my efficiency numbers were so high right after I installed my pack. Last winter wasn't as cold as this winter but it may be that as the capacity dropped in my cells it took a little more energy to put back what I used. Another, more likely, possibility is that each time I drove I didn't put back as much energy as I took out. I didn't have an amp hour counter at the time so I have no way to support either possibility. This may cause you to wonder how I came up with my total Ah numbers for my total. What I did was average the number of Ah/kWh out of the wall for the first dozen or so charge cycles after receiving the CA and then calculated the Ah used for all previous drives. The total I arrived at, number of cycles and miles driven were then entered into the CA to give reasonably accurate lifetime pack values.

So, what about my existing BMS boards? As you can tell I haven't been using the top balancing function of them. I think Black Sheep Technology did a very good job of designing a robust board so I don't expect any failures as some people have experienced with other products. These batteries do sag significantly when cold, so that a 1.5C discharge rate was enough to get the low voltage trip, LVT, to sound my low voltage alarm even though the pack was fully charged and had less than 1Ah removed. The total pack voltage was in the range of 58V so the 2.93 LVT value leads me to believe that maybe all boards were sending the alarm and not just a few. This isn't a big issue except that I'm about to install a switch to turn off the siren I installed so I'm not bothered by it when the pack is cold. If I forget it is off I may reverse a cell without realizing it. Or, I might get complacent and merely ignore the warning as a false positive and still kill a cell. I need to either remove the boards or at least the siren and install another type of monitoring system or leave the boards and install another type of monitoring system.

I'm planning on keeping the boards and installing another monitoring system. Why would I want to do this? Well, I could be asking for trouble but I don't expect my particular BMS boards to short out and drain a cell. They could quit working and not alert me to an over voltage or under voltage condition but I don't expect that either. The most likely failure would be the three wire connecting jumper wires running from board to board. If this happens they would fail to send the appropriate signal to alert me. I'm planning on buying or building and installing a Lee Heart type Batt-Bridge circuit. The difference is that I will either install a meter with zero at the center and have the needle swing to one side or the other if the two haves of the pack don't have the same voltage or I'll have a bar of LEDs where the middle one is lit and the ones to one side or the other will light up to indicate pack imbalance. The benefit of this type of circuit is that I can see what is going on under different load conditions. It is possible that under little or no load that the pack is balanced but that under load a weak cell will drop more than the others. I can then look for this cell knowing it is in one half or the other of the pack. It would also be possible to hook up a circuit to this which would turn off the charger on a pack imbalance condition during charging in case a bad cell wasn't caught before hand.

By having both systems in place, the cell level BMS and the Batt-Bridge type circuit, I can see what system gives me the information I need first. If the Batt-Bridge doesn't warn me before the BMS then it may not be the best method. If, the BMS doesn't warn me before the Batt-Bridge then it may not be the best method. If they warn me at the same time then the Batt-Bridge is the winner because it has fewer connections to the pack, only three wires, and it cost significantly less than the BMS system. Furthermore, it has fewer points of failure. It won't drain a single cell in the case of a short and it won't heat up from shunting current and potentially lead to a fire. While I hope I don't need either one this will hopefully provide one more data point to either support or deny the "conventional wisdom."

I hope this helps someone who is trying to decide how to manage their pack of LiFePO4 batteries in their EV. Moving to Lithium is a huge step up from using lead acid. It has very different characteristics than lead acid and what you learned about lead acid or other chemistries in the past needs to be either forgotten in its entirety and relearned for LiFePO4 or you need to re-check all previous notions against data for this exciting battery technology. If someone tells you that you have to do such and such or use this or that just ask, "how do you know that? What data do you have to support that?" You will be glad you did.

[EDIT: 01-19-2011 Be sure to read the comments. Also, if you didn't go read Jack Rickard's January 9, 2011 blog be sure you do and read comment #85 posted January 19, 2011]

Rear Wheel Bearing Modification

2011-01-16T14:51:00.000-08:00

I have two Gizmos and both have the same issue with rear wheel bearings. I assume that any Gizmo with a belt drive would have the same issue. I believe that due to the tension required in the belt, the weight on the rear wheel, loads due to acceleration and regen, road shock, and the narrow R12 bearing outer surface the aluminum cannot handle the pressure. I believe that it actually cold flows slightly allowing the bearing to start to move and continually rounds out the hub. On both Gizmo hubs the inner seal was warn down to the metal support due to the bearing slopping around as the wheel turned. It also caused a lot of noise.

As a proof of concept I took a pop can and cut a strip of aluminum just long enough and wide enough to slip into the groove made by the bearing. This worked just fine for about 50 miles and showed me that the noise was caused by the bearing movement. (Ok, for you physics types like me it was actually hub movement on the bearing but relative movement none the less.) Since this worked I decided to use a harder material so I bought some brass sheet and repeated the process. On the second try I finally got the piece made to fit and everything was fine for a while. Then one day I noticed that the outer seal was working out of the hub. Later it was even further out. Finally I took the wheel off and the seal just pulled out easily. What I found was that the brass sheet was working its way out from around the bearing and pushing out the seal. Time for a different approach.

Since the inner, belt side, wheel bearing also wears out quite fast I thought I would like to install a tapered roller bearing on each side and gain an adjustable bearing, more bearing surface, a wider outer race surface, and longer bearing life at the expense of a little more friction. The problem I ran into was that I couldn't find a bearing with the dimensions I needed. The aluminum hub would have to be machined out and the aluminum may not have enough strength to keep the outer race compressed. I confirmed this with a couple of knowledgeable bearing people. I then went to Waite Specialty Machine Inc. in Longview, WA and talked to Keith Warring. Keith is an awesome guy and knows his stuff. I took in one of the hubs to show him what the issue was. I explained what I had tried and what I had found about bearing options. He suggested that a steel sleeve be inserted and that two bearings be installed on the belt side. They regularly sleeve motors and other applications where the bearing seat has rounded out too large to properly hold the bearing. For these types of applications they machine the hole just slightly smaller than the sleeve then they heat the outer piece and freeze the sleeve and insert them. When the two are at the same temperature they create an interference fit where the sleeve won't move. They also cut and faced the spacer that goes between the bearings and installed the bearings so the hub was ready to go.

Note the extra piece between the bearing outer race and the hub. The picture below shows a different angle where you can see the sleeve.

The outer bearing where the castle nut goes did not show any signs of wear. In fact, the inner wheel bearing on all three wheels seems to be the first one to go. I believe this could be due to the fact that the shaft flexes a fair amount so those bearings don't get the same road shock.

The cost of all of this was a little over $500 for two hubs. As with much machining the setup cost is quite high so doing two hubs at once was much cheaper than doing one at a time.

The other issue I've had with Gizmo bearings is that the inner seal seat, the collar on the shaft, had rusted and then wears out the seal rapidly. I was able to sand down the collar, the metal is quite soft, and install a speedy sleeve which is a stainless steel sleeve that goes over the seal race to gives a good surface for the seal to ride on. These are not cheap! One cost me over $40 but I'm sure it was less than replacing the axle or the entire rear swing arm. I'm actually suspicious that the collar that the seal rides on were damaged first by a bearing failure which would lead to premature seal failure and then dirt and water damage. Inspect those bearings and seals regularly.

Broken Belt and Proper Tension

2010-11-18T18:13:00.000-08:00

Back in April 2010 I was driving home from work and as I came to an intersection to make a right turn I noticed what looked like a self taping sheet metal screw in the middle of the lane. As any three wheeled car driver has learned it is important to remember there is a wheel in the center of your track. I remember thinking, "I hope I missed that. If I hit it just right it give me a flat tire." As I turned the corner and accelerated up over the bridge I heard a thunk, thunk, thunk sound that seemed to be in sync with the tire rotation. I thought that maybe the screw had stuck in the tire and had caused it to bulge out or something. I thought that maybe I could just make it the 2.5 miles and 450 feet increase in elevation to get home and see what was the issue. As I continued along I found that the sound was louder under load than when lightly loaded. Even then it continued to get louder the closer I got to home. I thought maybe the tire was losing air. When I got home I couldn't see any thing wrong so I jacked up the rear and turned the rear tire. Below is what I found.

A tear in the belt all the way to the middle. It looked like the center string was not severed but the rest were.
As you can see the belt lifted quite away off the pulley. I think that I was saved by the fact that the belt was on the drive pulley a short time so didn't have a chance to slide off and that the rear wheel pulley was large enough that the belt didn't slide off.

When I took the belt into the local Applied.com store to pickup a replacement W-1280 belt the man who helped me said that it was very likely that the screw I saw got caught in the belt and tore it. Click the link to go right to the catalog page with the belt the Gizmo uses. I'm fortunate enough to have one of their stores right in town. The belts are not cheap but spending $95 for a belt rather than the retail of $130 I was happy. Maybe that is why there is retail pricing. It is so you feel great getting a deal when you pay less. In addition to the belt I asked about a tension measuring tool. The one they listed was a frequency measuring device and I didn't want to spend several hundred dollars for one so I asked about one which uses belt deflection. The guy who helped me called their supply place in Portland, OR and found out they had one for about $20 so I ordered it too. The next day I picked them up and was ready to replace the belt.

For those of you who have had the rear wheel off your Gizmo it takes quite a bit to get there. The tail piece is removed, next the rear wheel, then the e-brake, next the e-brake disk off the motor, then the belt shroud. Finally the bolts holding the motor on both the brush end and drive end have to be loosened, then the tensioning screw can be backed off allowing the belt to be removed. When installing the process is reversed. The problem is that if the belt isn't tight enough it will slip and most of this long process has to be repeated. When you think you have it things go great until it rains and you find out the belt slips again. Having the tensioner eliminates all of this. If the belt is too tight it will break sooner and wear out the bearings in the motor and wheel early so it is important to have the optimum tension.

I didn't relish doing the all the geometry calculations or hoping my measurements were right so I went looking for software that would tell me the proper tension for my setup. I found that GoodYear had MaximizerPro available on their website to do just what I wanted. I discovered that I could enter the two pulley sizes I had and have it force them to the proper spacing. I believe I had to enter what the power load was so I entered 15Hp which may be low given the potential on full acceleration and the fact that electric motors can put out a much higher horse power value than they are rated at but this value seems to work. The software then showed a Drive Layout with lots of information. A screen capture of the results is below.

Even though the picture above shows all relevant information it is nice to see drawn out exactly how the tension is figured and measured. I used a piece of 1/4" by 3/4" aluminum bar as my straight edge and pressed the tension meter in the center until it read 15Lbf at a deflection of 6.2mm. Yes you read that right. I think it is strange to mix systems of measurement but that is how it is done. I don't know why they don't just use Newtons and mm but this works.

I decided to go out and get a picture of the tension tester with my iPhone 4. I've found the HDR setting on the camera to be very useful for photos like this because it brings out the shadows much better and I don't have to do much editing later.

Here is the Industrial V-Belt Tension Tester I use on my Eagle belts. The end with the rubber cap is what you grab with your hand. The other end has a small short stub which pokes slightly into the belt surface so it doesn't slip. It works just fine for my application.

Motor Cooling Blower

2010-10-03T21:01:00.000-07:00

It has been way too long since I posted something so I thought it is time to try to catch up. Since I installed the LiFePO4 battery pack I knew it would be quite easy to exceed the 1-hour rating of the motor and over heat it. I decided to figure out how to get a cooling blower mounted and then just do it!

I had to make a shroud for the brush end of the motor. I picked up a piece of SS sheet metal from a local sheet metal shop. They cut off a strip the width I needed. It was enough to make 2 or three shrouds. I use a piece of aluminum flashing to cut out a pattern since it is easy to cut. I used this to make the SS version. I had to do this twice because I had to move the hose attachment from the top to the back of the motor. There wasn't enough clearance otherwise. The person I had make the hose attachment made it a little bigger than I was expecting but then what do you expect from a non-sheet metal worker? A one-off is much harder than something that will be made by the 1000s.

I picked up a sheet of 1/4" 6061 aluminum and cut out a piece to fit the end of the motor. I included a little extension to the bottom to accommodate mounting the blower. I had to shim the plate out from the motor to clear the shaft and housing so I used a hole saw and cut out some washers from the 1/4" sheet. I then used a piece of 1/16" aluminum to shim the bottom and left bolts to compensate for the motor support under the top and right bolts. You can see the plate below with 4 holes drilled and tapped to mount the blower motor.

The shims are visible in the picture below. The black tape around the inlet is actually rubber insulation tape which sticks to itself when it is clean. I used this to make the pipe a little larger and provide a little sealing ability. It ends up that it holds extremely well. I've tried to remove the pipe and can't get it off. Maybe the rubber melted a little, I don't know.

I picked up some aluminum flex pipe from the local wood and pellet stove shop. I wanted something which would handle the heat and be able to hold its own weight in a rough environment. I cut a PVC coupling in half and, with a short piece of pipe in it, slipped it inside the outlet. This gave me the right diameter for the aluminum hose. I put some silicon around the joint and a small sheet metal screw into the PVC coupling to make sure they didn't come apart.

My next problem was to get the splash guard to clear the new addition. The splash guard material is actually some thick #2 plastic like milk jugs are made of. I figured I could heat and stretch it into the shape I needed. I stuffed some cardboard in between the plastic and aluminum hose and used a propane torch to heat and mold the plastic. When I starts to turn clear you know it is very pliable.

Here is the result.

Just enough clearance.

The next issue is how to make sure only clean dry air gets to the blower. I wanted to pull air from outside the cabin but there just wasn't enough room to do so. It ends up that while driving I can't hear the blower over the road noise so it isn't too much of an issue. I decided to get a K&N rectangular filter and install in the back wall of the tub. The filter is designed to clamp on to a pipe but I needed to attach a flexible hose. I went to a muffler shop and had them make me an adapter out of tail pipe.

A perfect fit.

The next issue was how to mount the filter. I didn't really want anything visible and I wanted to put as few holes in the tub as I could get away with. As you can see in the pictures there isn't really anything to mount the filter to.

I decided to see how well the hose clamp screw would work in keeping the filter in place. The clamp had to go around the rubber of the filter and hold it to the tail pipe adapter piece. It ends up that the fiberglass is just thin enough to make this work. After more than 3000 miles I haven't had any issues with the filter moving out of place even though it wiggles some.
I used some bilge blower hose from a boat shop to connect the filter to the blower. This provides enough flexing for the motor to move up and down with the rear suspension and I only get clean dry air through the motor.

You can see in the picture above that the hose almost touches the top of the motor mount. I later added some strap material (like duct tape without the sticky) to hold the hose up off this sharp point. Below is a bottom view.

I initially started with a toggle switch on the dash to turn on the blower. I didn't want it to run all the time unless the motor needed it. The problem with this was that it was easy to forget. I decided that I would install a thermal snap switch to turn on the blower. The problem is that it is difficult to measure the hottest place on the motor since it is inside. I decided that I would install a switch on the case and use one which turned on at a cool temperature as far as motors go. I chose one which turns on at 105 degrees F. I figure this is early enough for the type of driving that I do so the inside isn't likely at a melt-down temperature yet.

The problem with snap switches is that most cannot be sealed. The one I have can be sealed but I didn't have the right material. The problem is two fold. Apparently air pressure changes cause issues with the turn on temperature and possibly case fatigue. The second issue is that most sealants give off a corrosive gas while curing causing the contacts to corrode. The snap switch needed to be placed inside a sealed or nearly sealed box of some sort. It is difficult to find a small aluminum container of the right size. I finally cut the end off of an empty small butane cylinder. I used a socket to flatten the bottom of the bottle and presto, I have a can!

I was going to mount this to the brush end of the motor but a quick call the Jim Husted of Hi-torque Electric convinced me I needed to mount it to the side of the motor case. You can see the hole I had prepared in the 1/4" aluminum plate. Now a new issue arose. How to mount a flat bottomed can to a curved surface. I decided I could make a mount out of a scrap piece of 1/4" aluminum sheet and bolt it to the motor case. Since my motor is a 6.7" diameter motor I mounted a 7.25" saw blade on my radial arm saw. I clamped the sheet of aluminum to the deck of the saw and locked the blade at a 90 degree angle. I slowly moved the saw blade sideways on the aluminum plate, lowering it slightly with each pass until I had a deep enough curve in the plate. A little smoothing out with a dremel tool and I had my mount. It didn't fit exactly but it fit close enough for what I was using it for. I drilled and tapped two 4-40 holes in the case and put two hex cap screws through the snap switch ears, aluminum can, and mount into the motor case. I put a small rubber grommet in the side of the can and ran my wires inside to the snap switch. Aluminum tape sealed the top of the can. The only water entry point would be through the grommet but I rarely get any there. The switch should work fine for a long time. At least I can change it easily if needed.

The yellow wires run to a 12V relay which turns on the blower fan. I actually installed an on-of-on toggle switch in the dash. The up position turns on the fan bypassing the thermal switch. The middle forces the fan off. The lower position is for auto, where the thermal switch controls the blower. The problem is that I can still forget to turn the switch to auto if I have turned it off for some reason. I tried a small 12V incandescent bulb across the "auto" position but the problem is that there is enough current through the bulb to pull in the relay. I found a small LED at Radio Shack with a resistor attached for 12V use. This works. If the fan switch is in the off position the LED will light when the snap switch closes. Turning the switch to the ON or AUTO position will turn off the LED because it will no longer have a 12V difference across its leads. Now I just have to mount the LED in the dash.

Efficiency differences

2010-02-06T19:55:00.000-08:00

When I bought this Gizmo in August 2006 it came with 6 Trojan T-875 8v batteries which were 1-2 years old. One of the things I did from the beginning was to use a Kil-a-Watt meter to record the energy I pulled out of the wall. I wanted to know how much it was costing me to charger my car and to see what the efficiency was. My regular commute is 4.4 miles with an elevation change of about 450 feet, most of that is in the span of about a mile. Sometimes my Wife drives the Gizmo to work and her commute is 9 miles. I mention this because with lead acid batteries and the Zivan NG1 charger I have, every charge cycle includes an equalization phase were the batteries are gently over charged to help all of the cells reach the same state of charge. This means that with shorter drives the wasted energy is not spread out over as many miles. Furthermore, the hill climb at the end of my commute where I would routinely see 250 battery amps, a less efficient current to pull since so much energy is lost to heat, would also not be spread out over as many miles as a longer commute would give.

From August 2006 through August 26, 2009 I used the Trojan T-875 batteries. On July 29, 2009 I didn't realize the range of the pack had diminished so far and ended up reversing a cell in one of the batteries. I never was able to revive it. At that point I took the Interstate Batteries U2200UTL pack out of Gizmo #26 I purchased last summer from Galactic Pizza in Minneapolis, MN and installed it in Gizmo #31 and used them until January 18, 2010 when I installed the TS-LFP100AHA pack. (Gizmo #26 needs extensive restoration.) BTW, if you are in Minneapolis go to Galactic Pizza and get some pizza. It is excellent! Tell them that the guy from Washington who bought one of the Gizmos sent you. Besides, you will be supporting a business which uses EVs to deliver pizzas as long as weather permits.

Note that the energy values below are all as measured from the wall so include charging inefficiencies.

2006
Total Miles: 967
Total kWh: 272.81
Average miles/kWh: 3.54
Average Wh/mi: 282.1

2007
Total Miles: 2364
Total kWh: 682.15
Average miles/kWh: 3.47
Average Wh/mi: 288.6

2008
Total Miles: 497
Total kWh: 138.53
Average miles/kWh: 3.59
Average Wh/mi: 278.7
(On March 28 I sent the NORM Circuit, which reads the hall effect throttle sensor and sends the appropriate signal to the controller, to Black Sheep Technology to get a replacement built. I didn't realize at the time that I could have kept using the old one with my manual override switch until the new one arrived so I was without a Gizmo until April 2009. The new interface was worth the wait!)

2009 (8V T-875 pack)
Total Miles: 1180
Total kWh: 315.47
Average miles/kWh: 3.74
Average Wh/mi: 267.4

2009-2010 (6V U2200UTL pack)
Total Miles: 1180 (This number isn't a typo. I had to double check it, too.)
Total kWh: 294.24
Average miles/kWh: 4.01
Average Wh/mi: 249.4

2010 (TS-LFP100AHA buddy paired pack)
Total Miles: 823
Total kWh: 135.37
Average miles/kWh: 6.08
Average Wh/mi: 164.5
(January 18, 2010 through March 29, 2010)

There some interesting things I notice about the data. First 2007 showed slightly more energy use per mile than the previous year. The Gizmo came with a 30 tooth drive pulley and in August of 2007 I had to have the motor rebuilt by Jim Hustead of Hi-torque Electric in Redmond, OR. This is the Jim of White Zombie fame and the builder of the Jim-Pulse line of Warp motors. With a 30T pulley the motor was turning too slow to keep it cool. I went to the smallest pulley I could find which was a 22T pulley. This changed the gear ratio from 3:1 to 4.09:1. The motor has been much happier. I think that the build-up of carbon dust and wearing & cracking of brushes may have had something to do with the lower efficiency.

I think it is interesting that even though the T-875 pack was aging that the efficiency showed an improvement over the previous years (except for 2007). When I look at the energy used to charge after my 4.4 mile commute, however, the energy consumption was up slightly from earlier years and similar weather conditions.

When the 6V battery pack was installed I saw right away a drop in energy consumption. At first I was expecting to see the energy consumption increase because I added over 120lbs to the weight of the Gizmo. After some thought, I think the reason that the energy consumption decreased is that the significant increase in plate area meant that the 250A draws actually reduced the current per unit of plate surface area so not as much energy was lost due to resistance. This is definitely a variable one might consider when choosing a battery pack. Lighter is not necessarily going to be more efficient. Of course I only have one data point to support this hypothesis.

The biggest shock :) came when I looked at the energy use with the TS batteries. To go from a best case of 250Wh/mi with the 6V lead acid pack to a tiny 165Wh/mi is incredible! I am including all the energy I've put into the TS pack so that if I don't completely charge the pack on one charge it will be made up for when the pack gets fully charged later. I keep thinking something is wrong. I'm using the same Kil-a-Watt meter I have been using all along. Maybe I should hook a second one in series with the first to see if they both give the same results. I'm going to periodically update the data as I get more use on the pack. The only things I've come up with as to why the efficiency is so much higher is that there is very little wasted energy when charging a Lithium Ion pack. I don't equalize each time. I plan on doing that this summer to see how far out of balance the pack has gotten. I'll probably only equalize once or twice each year since the BMS will alert me to an out of balance cell. One other possibility is that with the higher voltage I went to, the controller and motor are more efficient. I really don't know how much more efficient they are but I assume a little more. On the other hand, I don't drive full throttle as much either so the switching losses would be higher, I'm guessing. Time will tell.

(edit: updated energy consumption & distance values March 31, 2010)

Performance is WAY UP!

2010-02-06T19:25:00.000-08:00

I haven't finished installing everything in the Gizmo yet. I still have a little wiring to do on the BMS warning system, I don't have an emeter type device yet, I don't have a latching relay to kill the AC to the charger if something goes wrong, and I don't have the charger installed yet since I'm still fiddling with the finish voltage trim pot. It is finishing at about 71V right now so it isn't going too high for the BMS modules on a balanced pack. [(7-25-2010) see comments below about this ending voltage.] I have 18 "cells" and the BMS modules have a HVT (High Voltage Trip) of 4.00V. When I get things finished, or nearly so, I'll go weigh it at the Airport. A friend of mine is an A&P mechanic. He has some scales he uses to calculate the weight & balance on airplanes. I will post the data along with my CG calculations for the 6V pack and the new pack. Suffice it to say, the Gizmo is much lighter than it was with the lead acid pack.

Each pack of 10 cells with connecting straps & bolts weighs 80lbs I have a total of 36 cells. With the mounting hardware I used I figure this pack weighs about 300lbs. The Interstate Batteries U2200UTL are 62lbs each so 8 of them were 496lbs and this is without the connecting cables. It looks like I was able to reduce the weight buy about 200lbs. This is lighter than with the original Trojan T-875 batteries. They are 63 lbs each so a total of 378lbs.

The 18 "cells" I went to raised the voltage I see to about 61V nominal. After a short run to drain off the top 1% of charge or so the pack sits about 61V. After a several mile run it sits at about 60V. I find that while cruising along at about 125A or so the voltage sags to about 56-57V. A 200A load (this is 1C since I'm using buddy pairs) lowers this to about 55V. This is with the batteries at 45-50°F. Maybe when things warm up they won't sag as much. Even with this, it is much better than with the lead acid batteries.

My top speed on level roads with no wind is about 42 mph. Just after I installed the pack it appeared to be about 45-48mph so maybe the batteries were still warm from being in my shop. With the higher voltage I'm seeing current readings a little lower than before. This is to be expected. When climbing my hill I now only slow to 33mph where before I slowed to 24mph on a fully charged pack. I attribute the climbing performance to a higher voltage and being 200lbs lighter.

After installing the pack I didn't get a chance to back off on the spring tension on my coil-over shocks. I definitely sat higher and it seemed that I could feel every pebble on the road. I think I only had a 1/4" travel before the rear shock was at its maximum extension. I have since reduced the tension a couple of notches but I still ride a little higher and it is still a little stiff. I'm going to reroute the wires going to the motor so that I have more travel before the motor bottoms out against the tub of the Gizmo and the lower the tension in the spring to see how that feels.

Acceleration is much better than before. I have to watch my speed-o-meter to make sure I don't get a speeding ticket now. I can easily out accelerate the other cars on the road now. I'm not drag racing them but just comparing to what the typical driver does when a light turns green. When accelerating with the lead acid pack I almost never saw 400A from the batteries. Now I can pull 400A on every acceleration if I want. I tried bumping up the maximum amperage to the armature to 500A and noticed significant increase in acceleration. I didn't leave it there, however, since I want to stay below 2C on these batteries. I need them to last several years longer than the lead acid batteries did to recoup my investment.

In short. I love having a Lithium Ion battery pack!

New Batteries are finally in!

2010-01-26T21:59:00.001-08:00

I finally have my TS-LFP100AHA batteries in my Gizmo! I still have some wiring and electronic installation to do but I'm at least driving it. I'll do another post on the performance improvements.

I had my battery box sandblasted and then I painted it with etching primer and coated it with some reasonably durable spray paint. All this time I've been trying to figure out how to mount the batteries without bolting through the bottom of the battery box. There isn't much clearance under the box and seeing the deep scratches on the bottom I felt that if I high-centered on something I could do some damage to the box and possibly the batteries as I sheared off a bolt head or something. After talking to several people I finally settled on the idea of mounting the batteries to a 3/4" sheet of exterior plywood. I made sure to get at least 7 ply so that it would be reasonably stiff. The aluminum box bottom was bowed down about a 1/2" or more and I didn't want a flexible bottom for the batteries to sit on. I put 3/4" of rigid insulation board under the plywood.

Next I needed to figure out some way to bolt the batteries to the board. I didn't want anything conductive at the top of the batteries. Someone suggested wide nylon straps over the center of each string of batteries but I couldn't come up with a way to attach the straps and then a way of tightening them. I tried building a frame around each set with holes to bolt through to the plywood but then I didn't have enough room to fit all the batteries in. I finally ended up with a 3/4" strip of aluminum between each row of batteries and a 3/4" angle aluminum on the ends. the holes you see in the plywood are for some 1/4" x 20 cap head bolts. I installed some Tee nuts in the plywood for the bolts to go into. You can also see the 3/4" angle aluminum I used on each side of the board to hold it down. I put three bolts through each side of the box and through the angle aluminum to hold things in place.

I did several test fits of the batteries to make sure everything was going to fit. Below you can see one of the middle bars. This one is 1/8" thick because I couldn't get 1/4" x 3/4" aluminum bar stock. I finally ordered some from McMaster-Carr because I didn't like how flimsy the 1/8" bar was.
When I test fit the batteries I still had about a 1/4" at each end of the box. I needed a way to make sure that the 3/4" angle aluminum end pieces didn't slip off the narrow ledge of the batteries so I made some 1" x 2" x 3/4" shims and attached them to the angle aluminum at each bolt location. As it turned out I had to use 1/8" on the other side of the box. In the picture below you can also see one piece of the 3/4" insulation installed under the hold down strip.
After thinking about the fact that aluminum conducts heat quite well I decided to look for something else for the shims. I found that McMaster-Carr had some 1/4" ABS plastic so I ordered a 2' piece and replaced the shims as shown below.

Because of voltage limitations I could not fill the whole box with 40 cells. I decided to start with 18 buddy pairs which left a hole. Below is what I did to keep the ends of the hold down straps from slipping off the battery slot edge. I used some aluminum pipe for spacers.

Here is a picture between the batteries. They are tightly packed together and don't seem to move at all when I try to move them out of place. I'll be checking them regularly to make sure the hold down method is working. If it doesn't work, I can use some threaded rod and get some non-conductive rigid material to hold the batteries from the top edge.
Here are the batteries in the battery box before I installed 3/4" insulation around the edges.

Battery straps installed. Notice the orange 1 gauge cable to the front set of 8 cells. I turned around the front set so that the positive end of the pack wasn't against the front edge of the box. The front set of cells is not easily accessible through the battery access hole in the tub of the Gizmo. Since I had to use a cable any way it was an easy thing to do. If you look closely at some of the bolts you will see a little hole in them. This is a tapped hole which the BMS modules will attach with.

The Black Sheep Technology BMS modules are installed and I'm giving the pack the first charge as a pack. Earlier I charged all the cells up to 4.00V with a bench top power supply and then put a load on them until the first BMS module gave a low voltage trip. I then disconnected the batteries and measured their voltages to 3 decimal places and ranked them based on voltage. I paired the highest voltage with the lowest, then the next highest with the next lowest and so on until I had my 18 buddy pairs. I'll check them again in a year or so. While this isn't the best way to measure capacity it is what I had. I used several 500W shop lights and a bank of ceramic base light bases as my load. 100Ah is a lot of energy to dissipate! It took quite a while.
If you look carefully at the photo below and compare it to the one above you will see that I moved a couple of BMS modules in the second row from the back. This is the second row from the bottom of the picture above and second row from the top of the picture below. The reason is that I wanted to get the whole pack to the same SOC and my Zivan NG1 wasn't working too well for that since it wanted to see a 48V pack of lead acid batteries. I used my bench top power supplies to charge two parts of the pack and I didn't know if there would be an issue with both hooked together in series. They are supposed to be able to be put in series or parallel but I accidentally hooked up my battery pack backwards and burned out the series parallel circuitry in my dual power supply unit :(. It will be going in for repair soon. By moving a couple of BMS modules I can now split my pack at the 8 pair mark without having to remove any BMS modules. Two bolts out, remove the connecting strap and I'm done. In the photo below you can see the BMS interconnecting wires. I still have to hook up the +12V, fuse, and HVT and LVT test buttons at one end of the string and the HVT, OK, LVT circuitry to the other end. The small black wire coming in from the top center of the photo goes to the "outdoor" probe of a digital thermometer to measure pack temperature. The blue-green foam piece in the center of the pack is holding the probe against the second row of batteries. The black and red wires which join and trail off the bottom of the picture are to my volt meter. I've been playing around with the voltage trim pot on my Zivan NG1. So far I have it so that it is charging less than 0.5A when the pack hits 71V. I want to stop sooner, however since this is 3.944vpc. If I turn the voltage down sooner then my pack doesn't get fully charged. I may send in the charger to get it reprogrammed.
BTW, the picture above is of the battery pack installed in the Gizmo. That is why you cannot see the front row of batteries.

Coming up...

Performance comparison
weight change
efficiency differences

Cleaning the Battery Posts

2009-12-27T19:40:00.000-08:00

Since aluminum oxide is quite non-conductive I decided to clean all of the battery posts on my new TS-LFP100AHA batteries. You can see the surface oxidation on each of the battery posts in the sample photo below. The post on the left is the negative post, and on the right is the positive.Even though copper oxide is relatively conductive I decided to clean it as well. I preparation to do the cleaning I had ordered a stainless steel wire brush, fine single cut file, and a bottoming spiral M8x1.25 tap for the post threads. I first used the wire brush to clean off each post. I could have stopped there but I wanted to make sure I had a smooth surface for the copper straps to rest against. I put a thin layer of NOALOX on each post and then used my file to smooth off the top of each post. The NOALOX helped keep the aluminum from sticking to hard in the file grooves and also put a thin layer back immediately on the aluminum to minimize oxidation. Using the fine turned out to be a good thing. I found a battery where the center post didn't stick above the nut which holds the post in place. I found the nut on each post significantly looser than on other batteries. I'm glad I discovered this since I wouldn't want the post to allow air inside and/or work loose.

After filing the tops and putting a coat of NOALOX on each post. I then put NOALOX in each hole using a cotton swab. I followed this with the tap then a cotton swab again to get any filings out of the hole followed by NOALOX again. This may have been overkill but I did find that there was a significant amount of inconsistency in the threads. I don't think it would have made a difference in getting the bolts to work but I wanted good conduction to the bolts. I'm using a BMS from Black-Sheep Technology which mounts on top of a brass bolt with a tapped hole for a screw which holds the BMS module. I have the BMS version for the TS-LFP90AHA which has the same post spacing as the 100AH battery. The brass bolt makes sure I get good conduction to the BMS module and having the screw in the bolt makes sure I don't over stress the pcb.

Right now I have the batteries hooked up in two separate parallel strings getting their initial 4.2v charge as required by the TS documentation. I have one string hooked up to my bench top lab power supply and the other set hooked up to a 4.2V smart charger. I initially did a bulk charge up to around 4 vpc using my Zivan NG-1. So far I have pulled well over 14KWh from the wall. [edit: I do not recommend charging any LiFePO4 cell to 4.2V. Even TS has lowered their max voltage to 4.0V. It shortens their life and there is very little energy above 3.45v any way. I'm now only charging to 3.485vpc. See my January 2011 blogs.]

Now I'm working on a way to mount the batteries in the Gizmo battery box. The lead acid batteries were not bolted down, nor was the battery box. It just sat in the Gizmo frame. I don't want the Li batteries bouncing up and breaking a BMS board or something if I hit a big bump.

Lithium Batteries Finally Arrived!

2009-12-24T18:34:00.000-08:00

Thanks to the hard work of EV Components I finally have 40 TS-LFP100AHA cells for use in the Gizmo. I placed the order in September 2009 but due to several circumstances out of their control the shipment didn't arrive until now. Fortunately they were able to find a shipper who would ship to Seattle and customs didn't take a full month like it did on earlier shipments. Dave Kois, of EV Components was kind enough to let me drive up to pick them up today. I arrived while the truck was still unloading. They sure have their work cut out for them. Look at all those boxes of cells!

While unloading the forklift ran out of propane so they had to run fill the tank. They are anxious to get an electric forklift so this doesn't happen and also so they don't have to breath the fumes. Below is another picture. You can see the brand new Toyota RAV4 that Dave is converting.

Below are pictures of my cells in my 2000 Honda Insight. It was definitely over gross. I'm glad I'm not that heavy of a person. There wasn't much spring travel left.
The box in the back is the battery box out of the Gizmo. I took it out and had it sand blasted. The bottom and corners were badly eaten by battery acid. It will last much longer with Li batteries in it. I'm going to paint it black inside and out. I'm also planning on plugging the drain holes so that water doesn't get in from the bottom. I still need to put in a splash guard in front of the box so the batteries stay clean and dry. Last time I had the batteries out I put baking soda on the bottom of the box. When I pulled them out the entire bottom was wet with baking soda crystals on the sides of most of the batteries. I determined that most of the water entered from the two front drain holes which are right where the tires would splash water on the box.

Well, I'm off to get my batteries ready to install. I still have several things to do.

Primer and paint the battery box
drill mounting holes in the battery box to match up with some threaded holes in the frame of the Gizmo so the box doesn't bounce around. Even 500lbs of batteries would bounce on some of the bumps I've hit.
clean off the battery posts and coat with NOALOX. I'm going to use a very fine file for this with NOALOX on the file so the aluminum won't have time to oxidize.
Run an M8x1.25 bottoming tap down each hole to clean the threads. I'll use NOALOX here too. The BMS I'm planning on using will mount to the top of brass bolts which hold the connecting straps so I want good conductivity through the bolts.
connect the batteries up in parallel and give them their 4.2V initial charge. I have a lab power supply I can use. I also picked up a 4.2V Chinoz Smart Charger from EV Components to do this.
Rebundle the batteries in the arrangement I need to buddy pair them.
finalize my mounting design and mount the the batteries to the battery box.
It may not matter much but I'm going to put NOALOX on the ends of all of the connecting straps. They are four layers laminated with some shrink wrap. See the picture below.

I have several other things to do but I'll post about them later.

Battery failure ==> new pack

2009-11-15T21:14:00.000-08:00

This summer my wife drove to work and back and then drove back to near work again to meet me at a store. Unfortunately there was no charging done in between trips. Normally this double trip would not have been a problem. I've gone 20 miles on a charge in the summer before with no problem. Apparently my range has decreased significantly. On my way home my PakTrakr gave me a message that battery #2 needed to be charged. I should have turned around and gone back to the Cowlitz PUD building where there are some EV charge plugs and plugged in for a while. Instead I tried to nurse the Gizmo home but I had one bridge to climb up and over and then 450 feet of elevation to gain on top of that. Well, one cell in battery #2 doesn't bubble on equalize anymore. I think I reversed the cell climbing the hill. Fortunately, my son and I picked up Gizmo #26 in Minneapolis, MN this summer. It had an aging pack of 6V flooded batteries which I've installed for now. I have a pack of TS-LFP100AHA on order from evcomponents.com. They are supposed to arrive the end of November 2009. I hope to have them installed durning my Christmas break.

While I had the batteries out I discovered a couple of things. First, the bottom of the aluminum battery boxes were badly etched from battery acid. I recommend that if you have metal battery boxes that you check them regularly for potential structural problems. Also, the battery box from the Gizmo I picked up in MN had cracked welds on all four corners. The Gizmo had been used as a pizza delivery vehicle so it has significantly more miles than Gizmo #31 does but it is another structural item to check.

I can SEE!

2009-04-29T22:37:00.001-07:00

Wow! I just got back from a 10 mile run on rural winding roads and a short jaunt through town. The new headlight is much better than the old sealed beam. High beam is actually brighter than low beam now and I can light up the whole road if needed. I don't think I'll be getting many near misses with the elk which like to frequent my property. I can stand not having the adrenaline rush of nearly hitting one. With the old headlight It was difficult to see far enough ahead for comfort. Now, that is not a problem. This headlight mod is well worth the work it took. If any one wants to build one send me an email. I'll find out how much the guy who built the fiberglass cup wants to build you one too. I can give you measurements of my mounting plate if you want.

Splash Guards in place

2009-04-24T19:30:00.000-07:00

I finally have the splash guards in place. Below is the right side. I split it into two pieces since this side has the new Gizmo Interface and I still need to get to it easily for programming as testing continues. It is a little difficult to get the splash guard out from around the front shock. The material is pushed up under the lip of the tub so no water will be able to get on the wiring from above. I'm hoping not too much enters from the front.
Here is the rear splash guard. The original one was not much wider than the fender. Carl Watkins of NEVCO said that when they had Gizmos come in for service they would widen this splash guard to protect the motor more. This one is bolted to the lip of the tub and zip-tied at the bottom. I also pushed the material up as high as I could since the hinge holes are exposed and water just runs down the back of the Gizmo and through these points.
Here is a close-up of the right hinge hole. You can see the plastic through the chip in the fiberglass.
The right side splash guard is one piece. I don't think I'll have to get access to this wiring as often as the other side. It wraps around the back corner a little ways. I'm trying to keep spray from getting on the terminal block mounted on the gold colored aluminum mount just visible through the plastic.In addition to this I bought some silicon spray from the Napa store and sprayed the controller and wiring. The spray insulates and helps keep water from sitting on things. I hope the controller will stay cleaner than when I had battery terminal spray on it. That stuff was a dirt magnet and the controller looked terrible. I feel much better about driving in the rain now.

Gizmo Interface update.

2009-04-23T20:49:00.000-07:00

As with any new item there is a testing and tweaking phase, then add a feature and do more testing and tweaking. The Gizmo Interface is coming along nicely. Variable regen is working on demand and the other basic functions work too.

Currently, while driving forward, I can press the activate regen button and vary the regen current with the throttle trigger. Unfortunately the controller only has a regen range of 50% of the max setting to the max setting. I wish it had a high and low setting so I could get a wider range of regen. I ran it with 250A max regen for a while but the low end was a little too agressive. I lowered the max to 200A which makes the low end more useable but I don't get the agressiveness I like at the high end.

I can also get regen if I pull the throttle while pulling on the brake. This is useful when doing a panic stop and you forget to hit the activate regen button.

I found a controller setting where the regen voltage can be changed. At first I thought this was an input voltage that the controller read to adjust the regen amount. In testing I discovered that this is the voltage in the armature (I think it is the difference in voltage but I'm not sure) at which point regen stops. I lowered this from 2.00V to 0.50V and now I get regen down to about 4mph. At these speeds the motor is spinning too slow to charge the batteries and it actually is a drain on the batteries. The batteries supply more current than generated at around 10mph but I'm trying to save the brake pads, not extend range. While I don't have a way to test it, regen probably comes out a wash as far as extending range goes. However, making the brake pads last an extra 500+ miles would be a great thing. As I expected, the motor doesn't get a chance to cool down during the coasting to a stop phase so it tends to warm up a bit. I'll probably add a blower to the motor to compensate for this. My 2 mile 400 foot elevation climb (most of this is in 1 mile) tends to heat things up quite a bit. I regularly see 250+A out of the battery. I'll have to check the armature current some time to see what it is.

The actual setting which controlls the regen amount is the Footbrake setting. I set this to come on at a voltage a little higher than the acceleration voltage and be at max just below the maximum voltage the throttle trigger sends out.

Next up: My new splash pannels. (Thanks goes to Fred in FL with Gizmo #30.)

Headlight is in!

2009-04-21T19:43:00.000-07:00

I finally have a working adjustable headlight in my Gizmo! I did discover, however, that adjusting a Gizmo headlight is a bit different since the nose drops a fair bit when I sit in it compared to when it is empty. I finally just went out and drove it and then would stop and adjust the headlight and then drive some more. This headlight has a relatively sharp cutoff line so if it is aimed too low you can't see very far down the road.

This particular headlight has a 5W bulb in it too. I wired this small light to come on when the key is turned on and wired an ON-ON switch in the dash to turn on the headlight. The down position has the headlight off with the 5W light on. The up position turns off the 5W light and turns on the headlight. I guess you could say I have a running light mode.

As I talked about in my previous blog this mount has been a bit of a process. My goal was to build a unit which could be easily added to any Gizmo without having to do body work. Other than the less than careful extraction of the original fiberglass plug mold, I accomplished my goal.

Here are several pictures of the itterations I went through to get to the final product. I didn't take a picture of the original plastic sign material prototype. The next step was to see what it would be like to create a plastic mold of the headlight hole. I lined the hole with plastic wrap and filled it with wax. I supported a stick in the center of the wax to aid in pulling the plug out when it cooled. Here is the final carved result.

Next, I made a 1 inch thick model because I was thinking I would make the mount out of UHMW plastic.

Finally, the fiberglass cup idea was done. Below is an aluminum prototype plate made out of some damaged door kick-plate aluminum. I actually mounted the headlight and assiociated hardware to this plate. This showed that I would either have to carve the final aluminum plate thin around the mount holes and/or carve the plastic stops down on the plastic nuts. I ended up doing both. On this plate the top nut bent out the top of the hole and bent in the bottom.

Here is the fiberglas cup and final aluminum mounting plate. You can see the grinding marks above and below the top hole and to the sides of the side square hole. The eyebolts were mounted to the plate to hold them square and inplace while I used JB weld to glue them to the cup.

Here is the cup with the eyebolts cemented in place. If this doesn't work I will build another cup with the area where the screws go built up. I'll grind notches in the back side and install some blind nuts to bolt the front plate to this cup. You can see two screw holes beside the wire hole in the center of the cup. As it turned out, it was difficult to hold the nuts in place while the screws were tightened from inside the nose of the Gizmo and then install the headlight adjusting cup. If I have to take the unit out I'll be installing blind nuts in these holes.
Here is the finished unit with the aluminum plate painted. I didn't want to see it from the front.Here is the unit with the adjusting cup in place.
In this bottom view you can see that the adjusting cup is offset to the left side. This is to accomodate the adjusting screw on the right.

Here is the unit installed and ready for the headlight. You can see the damaged and partially repaiared portion of the nose.Here it is, ready for use!
If you have a Gizmo and want a similar unit send me an email. I can find out how much the guy who built the cup for me would charge to build you one too. I don't plan on making a kit out of this. I can give you a list of parts and dimensions I used to help you out, however.

Progress on the Adjustable Headlight Mount

2009-04-18T21:10:00.000-07:00

The headlight which came in my Gizmo was mounted in a specially shaped hole in the nose of the vehicle. The method was both inexpensive and made for a clean looking finish. There are three problems I had with the setup as it came. One was that water would collect under the headlight so I had to remember to swish it out before opening the hatch. The hole needed a slight down hill slope to it to drain water. The second issue was that the headlight was hard to aim. It was mounted with velcro at the back of the hole. I was able to get it close most of the time. Fortunately the beam was wide enough that when the aim was off it wasn't too bad to drive. The third thing had nothing to do with the design of the vehicle. It was the fact that the headlight was designed for a 4-headlight system. There is nothing wrong with this except that the wattage of the high beam element was lower than that of the low beam element. Turning on high beam meant that the road got harder to see even though the aim was higher. Initially I looked for a replacement sealedbeam headlight which was for a two headlight system and found that my '97 S-10 pickup had the right headlight. I was going to buy one and the plug that matched it (it has one angled pin like this |_\ whereas the existing headligh had a pin pattern like |_|) but I decided to see if I could come up with a way to have the standard aiming mechanism that a car has. I wanted to do as little body work on the Gizmo as possible. I gave up on making a standard size headlight mount and went with a smaller headlight. I found a Hella Headlamp upgrade in the 150mm rectangular size which included the mounting frame. I purchased it from Susquehanna MotorSports at www.rallylights.com. They were most helpful and were willing to go measure the size of the headlight for me to see if it would fit. The only modification I had to make was file off the tip of the upper adjusting screw slot.

Below is a photo of the headlight hole. The velcro is visible in the hole. The dust is because the Gizmo has been sitting waiting for the replacement Gizmo Interface board.

Here is the back of the headlight. The piece of velcro on the bottom of the headlight came off because it was in water so much.
Once I had the replacement headlight I had to figure out how to mount it. I tried a wax mold of the hole as a pattern but that was a little difficult. I also carved a 1 inch thick piece of wax to try since I could get some UHMW plastic in that thickness but I was concerned about the heat generated by the headlight. At least the wax setup gave me a proof of concept item so I knew the headlight would fit. Finally, one of the members of our EV club, www.lceva.org said that he did fiberglass work and could make a mold for a cup which would fit the hole. I could then mount the headlight mount to that and slip the whole unit into the hole. So, that is what we are doing. Below is the first step, building a plug the shape of the original hole.
Unfortunately there was a weak spot at the top of the hole in the Gizmo which cracked when removing the plug so I still will have to do some repair work on it. After the plug was made, a mold was made and then the cup which is going into the Gizmo. Below is the inside of the nearly finished cup and the aluminum plate I had available for the headlight mount.
Here is the back side of the cup and the aluminum plate. I'm planning on epoxying the four eyebolts into the cup. I mounted them to the aluminum plate to keep them square with the plate. I don't have any room to bolt from the outside of the cup so I hope the epoxy will hold the stainless steel eyebolts. I'm trying to decide between using some Plastic Steel Epoly and some Permatex Epoxy Metal Filler. I may go with the metal filler since it is supposed to handle a 2 inch gap without support. Only the tips of the eyebolts will be close to the fiberglass cup.

The two pieces as they will go together.Here are the two pieces as they will look when assembled.The two square holes hold the nylon "nuts" for the adjusting screws and the two holes in the lower left corner are for the tension spring. I went to a recking yard and got the screws and spring out of about a 1990 GM pickup. There is a whole list of vehicles from 1986 through 2002 which used the 150mm rectangular headlamp.

Finally on the road! (Day light only.)

2009-04-12T10:02:00.000-07:00

I finally got the Gizmo going enough to test drive it on the road beside my house. The programming of the new Gizmo interface is still being worked on. I tested things with the rear wheel jacked up and the front wheels blocked. Naturally, when the programmer is on the east side of the country and I'm on the other, I have the be the eyes, ears, and hands of the programmer. The strange thing was that the only way I could get the rear wheel to turn was to have regen on and enabled then pull the throttle trigger. A quick phone call and an email later and things started working like expected. We needed to get things to the point that it would be safe to drive while the other things, like regen settings and such, were figured out. I have to program the settings in the controller and give feedback to Ron on the tweaks needed in the interface.

I drove the Gizmo to the April 7, 2009 LCEVA meeting and then trailered it home since I don't have a working headlight yet. I'm still working on the new mount. Hopefully it will be a drop-in retrofit for other Gizmos.

We decided that it would be best and cheaper if I bought the programming interface to hook to my laptop and the Gizmo interface so that we wouldn't be sending boards back and forth across the country just for programming. The programming interface has now paid for itself in savings of shipping costs.

Here is a picture of the board:
This was the dryest location it would fit in. The old one was in the splash of the front right tire. The contactor is on the left and the DC-DC is on the right. I still need to bundle the wiring a little differently but this was good enough for some road testing.

In the next photo you see the cover over the Gizmo interface and that I have mounted the fuse block on the top cover. The fuse block used to be under the rear tail piece and would get water on and through it any time it rained, which is quite often here. This location should be much better since I'll install some splash guard plastic over the entire side when I'm done.

In addition to replacing the old Norm interface with the new Gizmo Interface, I replaced the old two wire speedometer pickup with a three wire version. The old one picked up too much interference when regen was activated and it also frequently gave spurious readings when it got wet. With this new one I actually can get a reading of 1mph. I rarely saw that with the old sensor. The sensor and mount can be purchased from Black Sheep Technology in the Gizmo Parts section.
The wiper relay used to be mounted under the tail peice beside the fuse block. Since I needed to add another relay I decided to move the wiper relay to the same location. The photo below is of the left side of the Gizmo. The spring and rod are for the mechanical emergency brake. I also wanted to get rid of the stack of ground wires going to the negative post of the battery so I installed a terminal block and connected the ground to each post. The gold sheet metal is actually an aluminum kick plate from the front door of one of my rental houses. The tenant's dog literally chewed one edge of it so they had to replace it. I kept it in case I needed some aluminum sheet. Well, here it is, at least part of it. I used two C-clamps and some pieces of wood to make a metal bender. A block of cedar and a hammer were used to make the bends clean. The lower right corner is bolted to the frame using an existing threaded hole. I zip-tied the other side and will probably just silicon the top edge so I don't have to drill more holes in the fiberglas tub. Even without anything holding the top edge, it doesn't rattle.

The relay on the right has a diode across the coil. It is inside the black heat-shrink tubing. I need to add a diode to the wiper relay and the high-beam relay. When the coil in the relay is de-energized the decay of the magnetic field causes a spike in the voltage. The diode shorts this out. I discovered that the headlight relay was wired wrong so that the headlight low-beam was on when the coil was energized and off when it wasn't. I'm wondering if the spike produced every time the headlight was turne on and any time the wiper was run along with any other transients may have been part of the cause for the old Norm circuit failing. It had no "surge protection" in it.

Original Regen Circuit

2009-03-01T00:06:00.000-08:00

My Gizmo came with a regen system in place. Various methods had been tried on this Gizmo including a pressure transducer on the brake line. What the end result was, was a single setting for regen which was activated by the brake light circuit. There is a toggle switch on the dash which was used to enable or disable regen. The difficulty in using this regen mode is anticipating when to lightly put the brake on so as not to stop too soon or too late. Right now I am in the process of installing a replacement "Norm circuit" on my Gizmo. This circuit read the hall effect sensor in the throttle handle and would change the state of the FS1 line (pin 4 on controller connector B) based on the state of the trigger. FS1 would be shorted to ground (FS1 closed) when the throttle trigger was pulled and then FS1 would be opened when the throttle was released. For regen to work FS1 has to be in an open state. When my original circuit became intermittent I decided to find a replacement. Ron Anderson of Black Sheep Technology was commissioned to build a replacement circuit. The new circuit will include variable regen, amoung other things. The purpose of this post is to document the original regen circuit. I will post about the new circuit when I get it installed and operational. Right now I'm rewiring. In a week or two I'll be testing out the programming of the new circuit.

Note that pin 11 on Controller Connector B is an analogue input used for regen with a voltage range of 3.5-0V. I don't understand why this input is from 3.5-0V when pin 10 (torque/speed command pin) has a range of 0-5V but that is what the controller manual says. Oh, the controller I'm talking about is a Sevcon SepEx PP745. Below is the circuit diagram for the original regen setup.

Drive cutout issues

2009-02-22T00:22:00.000-08:00

I have Gizmo #31. This Gizmo has a D&D SepEx motor and Sevcon PowerPak controller.

Through trouble shooting intermittent drive cutout issues over the past couple of years I believe I have an understand of how the NORM circuit works on this vehicle. This vehicle also has circuitry installed to enable constant regen when the brake light comes on. The NORM circuit affects this too.

My NORM circuit has 5 wires attached to it. The pink wire is attached to the switched +12V line of the DC-DC converter. The White wire is connected to battery pack negative. The blue wire is connected to pin 4 on the controller connector B and is called the FS1 line according to the controller manual. In conjunction with the NORM circuit is a hall effect device in the right hand control handle to provide feedback based on throttle trigger position. One wire is labeled "-" (black wire on my rig) and is connected to the white wire on the NORM circuit (battery pack negative). On the opposite side of the hall effect device is another wire labeled "+" (pink wire on my rig). This wire is connected to the yellow wire on the NORM circuit. The NORM circuit has a voltage regulator which puts out a +5v on this yellow wire. In the center of the hall effect device, between the + and - wires, is a third wire (orange wire on my rig) which connects to pin 10 on controller connector B. This line is an analogue input from 0-5V and is what the controller reads as torque request. In addition to connecting to pin 10 on the controller the center wire from the hall effect device also connects to the orange wire on the NORM circuit. This is necessary because the NORM circuit needs to know when throttle input is requested so it can control the state of the FS1 line. The schematic is below:On power-up the NORM circuit must have FS1 in an open state so that the Controller will boot up without giving a sequence fault. If FS1 is closed (shorted to battery pack negative) then the controller will sequence fault as a safety precaution. When the throttle trigger is pulled it sends a portion of the 5v coming from the NORM circuit out to pin 10 on the controller. On my rig this ranges from 0.82-4.24v as seen by the controller. When the controller sees a voltage greater than its lower threshold it knows that torque is requested but it won't do anything if FS1 is open. This is why the NORM Circuit must have a connection to the output of the hall effect device. The NORM Circuit monitors the voltage from the hall effect device and when a voltage greater than the lower threshold is seen the NORM circuit closes the FS1 line and drive will commence. Provided of course a direction is selected and no other fault conditions exist. When the throttle trigger is released the NORM circuit opens FS1. On my rig regen is enabled by the brake light. Regen, however, is disabled if FS1 is closed. This is why FS1 must be open when no throttle input is selected. If I didn't have regen FS1 could remain closed after the controller boots up and I wouldn't notice.

I don't know what kind of mechanism is used to close FS1 but it seems to be what has caused nearly all of my drive cutout problems. I have had the following drive related issues:

1) No drive on power-up because FS1 was closed, this caused a controller sequence fault.

2) No drive after power-up because FS1 remained open even when drive was requested. If I held the throttle in for 5 seconds-5 minutes sometimes drive would start to work. This usually happened if the sun had been shining on the vehicle for a while but eventually it didn't matter.

3) Similar to #2 but would happen while driving but only if the throttle was released.

4) Drive would cut out while moving and throttle still pressed because FS1 would open.

5) Regen would start to work then cut out or just wouldn't work at all.

6) Regen would pulse on and off, usually at speeds below 25 or so but sometimes at all speeds.

I believe that all of these issues in my case have to do with the NORM circuit not properly handling the state of FS1. To deal with these issues I installed a SPDT switch in the FS2 line as shown in the schematic. The common side of the switch is connected to the FS1 line (pin 4 on controller connector B). One side of the switch is connected to the blue wire on the NORM circuit. The other side of the switch is connected to battery pack negative. I chose an on-off-on style of switch so I have some options. For normal operation the switch is set to connect the blue wire to FS1. If on power-up the controller gives a sequence fault (2 blinks) I switch the switch to the off position momentarily to clear the sequence fault then back to normal operation. If the NORM circuit is just not closing FS1 I switch the switch to short FS1 to battery pack negative and I can then drive. This is how I deal with items 1-4 above.

To deal with items 5 & 6 regen I switch the switch to the off position and regen works just great. No pulsing and it never cuts out until the speed is too slow, of course.

The problem with this is that the switch has to be switched back to one of the on positions for drive to work. This is a bit of a hassle but it sure beats being stranded.

Right now Ron Anderson of Black Sheep Technology www.black-sheep.us is working on a replacement unit. We hope to integrate regen into the unit too so that others can easily add regen if they have the same controller setup as I do.

Hopefully this helps. Feel free to contact me if you have any questions.

3W LED vs Incandescent Tail Lights

2007-10-07T00:09:00.000-07:00

There was a discussion on the EVDL a while back about the 3W LED tail light brightness as compared to the regular tail light. The led bulbs were purchased from Super Bright LEDs. The picture shows three different bulb arrangements each with the brake off then on.

Picture
1 - 3W led tail
2 - 3W led tail, led brake, 3rd
3 - 10W regular tail
4 - 10W regular tail, led brake, 3rd
5 - 5W regular tail
6 - 5W regular tail, 10W brake, 3rd

The pictures were taken with a Canon EOS-20D, EFS 17-85mm lens at the 85mm mark, manual mode with 1/6" at F32, ISO800, white balance on shade. The camera was about 50 feet from the tail light. It is difficult to see the real brightness difference between the lights. In the day light the 5W incandescent is not very noticeable. The 10W is better but the 3W led is very intense and quite noticeable. The leds also clearly come on quicker. The Gizmo has a smart blink unit which blinks the brake lights several times when the brake is applied. The leds are more obvious since they come on and shut off a few ms faster than the other lights. The "3rd" brake light is not what came standard on the Gizmo. The original led 3rd light was almost not noticeable in the day light since it had a narrow beam width and was aimed upward a little. Even when I re-aimed it it was not very noticeable. The current 3rd light is one for a pickup shell top.

If any one has any suggestions on how to take more accurate night pictures of such a small point of light let me know.

Just arrived

2007-09-21T19:10:00.000-07:00

Here is my Gizmo right after I got it home in August 2006.