New Rear Springs

The 'air spring' helpers were not getting it done; just too much weight back there.

Even inflated to 180% of the recommended limit, the rear sagged.

So I ordered some heavy duty springs with a 3 inch lift from Rovertym (now RTE Welding.)

Aren't they pretty?


Before the batteries are re-installed, it rides much higher in the rear, a little like a hot rod.

Charger - Mark I

The charger is at a point where I can put it in the car. I etched a circuit board to hold the smaller components.


The larger ones - inductors, capacitors, and rectifiers - are mounted wherever they could be fit.


A computer power supply is used to drive the control circuitry.

It has a wooden enclosure sized to fit on the left front fender.


I know it ain't pretty, but it's working.

More Assembly

On top of the motor mount bridge is space to mount the UMOC motor controller and the high voltage junction box. The 'anti-vibration' mounts are slices of silicone from a tube that cured before I could finish using it.



The batteries in the lower rear box are being connected. 14ga wire is run to each battery. Initially I thought of using twenty 12V chargers, but now the wires are used to sense and record each battery's voltage.

These East Penn batteries keep peeing all over everything. In a failed attempt to control the acid, I cut up kitchen sponge/towels, soaked them in a baking soda solution, and placed the around all the filler holes. Later they all disintegrated.



It looks better when covered up.




Then the upper rear rack was installed and populated.

Motor to Transmission plate

The machine shop, Mobile Hydraulics of White River, finally finished the motor coupling and transmission mounting plate.



The design took some time to get right. The basic design idea came from Ross Cunniff. Below is a profile view of the spacing involved.

The face of the motor had no mounting holes, and it was not flat.

After machining the face flat, the material was not thick enough to support threaded holes, so the spacing collar was bolted to the motor face from the inside.


The coupling uses a taper-lock design that squeezes onto the splined shaft of the motor. This allows adjustments to the position of the flywheel and clutch on the transmission input shaft, though it means pulling the motor to access the screws. Good measurements allowed me to get it right the first time.



The motor is suspended from a bridge which is bolted to the original motor mounts on the frame. The shop machined slots in the bridge and the motor's mounting plate to adjust the exact mounting position of the motor.

Charger - First Steps

The parts for the charger arrived a few days ago. I have let the magic smoke out of some of them, but I made some progress.

The diode I chose (STTH6004W) comes in a DO-247 package. While it is rated to 60A, the terminal legs are rather small, and did not last long when soldered to 14ga stranded wire.

I lost some IGBTs when I thought the varistor across would protect them. Or the fuses would help, but nope - IGBT goes bang!

However I can push 10A through a string of 4 batteries.

Charger - The Beginning

What to do about charging the batteries? As I am using 12V lead-acid, I could buy a commercial charger for each one. I have one of the Samlex 1215A chargers and it is a solid piece of work. They run about $120, and as I plan to have 20 batteries, that's about $2400. A benefit of this approach (example here) is that each battery is charged individually to the correct voltage for as long or short a time as necessary. And with good whole pack (high voltage) chargers running over $2000, the costs of this plan seem reasonable.
Reasonable even more so because I do not know how many batteries I will have in the end. As I understand it, the whole pack chargers are programmed at the factory with the charge parameters (voltage and current) for your pack. So if I decide I want to up it to 23 batteries, I would need to send the charger back (from Africa) to be reprogrammed. On the other hand, if I switch to lithium, I would need a new charging system anyway. (Though it may be possible to sell a bunch of 12V chargers....)
Searching around for ideas and information, I came across this thread started by Simon Rafferty, where he shares his design for a programmable buck charger. (There is now a thread about a 10kW 60A DIY charger!) I could understand it, and I figured I could risk a few hundred dollars in parts to learn whether or not I could build one. So today I ordered parts from digikey.com, coilws.com, allelectronics.com, and from a few ebay sellers.
I already have Atmel ATmegas for control and LCDs for display. It's the power components with which I am not familiar, primarily the inductors but also the IGBTs.
Waiting for parts....