Throttle test

I did the first test of the throttle control of the motor and drive. Everything went well; the drive was flexible enough to account for the idiosyncracies of the ebay special throttle position sensor I am using. More good news, the motor drive will fit in the engine compartment, freeing up more space in the back, and simplifying the wiring. I am running off mains power here, but it was a good feeling sitting in my car and revving the electric motor.

Battery box

I have started a sheet metal box to hold the battery. This will be welded in place of the spare tire and gas tank. I need 100 cells, give or take, and the squarest pack I could make with about that number turned out to be 7 cells wide and 14 cells long, giving 98 cells. I started with a pristine sheet of 16 gauge steel:
Which got a little less pristine as I taught myself sheet metal fabrication:

The finger brake at TechShop wasn't big enough to bend all four sides of the box, so I had to do some old fashioned whacking it with a hammer and a dolly to get a nice fold on the last two sides. I won't show any closeups of the hammer marks.

Next, remove the gas tank. I'm going to try to find a new home for this, as it is in good shape.



Next, I had to grit my teeth and cut a bloody great hole in the bottom of my car. Not an easy thing to do with a classic car with decent sheet metal.



The hole will be bigger in the end, but I don't want to get too excited about cutting and end up getting rid of some metal that would help hold the box in later.

Test fit!


Astute readers will notice the complete lack of welds. Unfortunately, Saturday is welding class day at TechShop. so I wasn't able to get a welder all day. I need to weld some separators between the rows of cells as well.

Mmmm, toast!

I needed a way to discharge the battery pack during my BMS tests, so I headed down to my local K-mapart to pick up a space heater. It's spring here in Califoria, though so there weren't any. I figured a nice Toast-R-Oven uses lots of electricity too, and I can make toast with it later. It's pretty funny to go to the store to find something that uses the most electricity.

One Logger per Child

I got one of the xo laptops from the One Laptop per Child project while they were having their give one get one promotion. It's really a neat device, but I haven't had much time to play with it. It really makes a good datalogger, though. I can hook it up to the battery pack and collect data on charge/discharge cycles while using my grownup laptop for grownup things.

The BMS finally works

It's been three months, but I finally have a working battery management system. Here I'm testing it with 24 cells in series and the Manzanita charger. I deliberately discharged one of the cells, and the system is bringing it back in balance as it charges the whole pack. It's been a lot of work, but this system should give the best life possible to my pack.

I'm sure there will be some fiddling with the control algorithms, but at least the hardware is done.

What a thousand boards looks like

The production run of BMS boards arrived today. Richard Hatfield of Lightning Motors went in with me on an order of 1000 to bring costs down.

Beginnings of a battery pack

I've finally entered the home stretch with the BMS system, and have 3 final prototypes installed on cells for testing. Cat for scale.