Kermit comes home

Kermit left his home of the past 15 months at TechShop, and made the 10 mile trip back to my house in Mountain View this evening. It was a little bit nervewracking setting out on the open road for the first time, but we made it without assistance from AAA. I set the maximum current to the motor at 30 amps, and limited the maximum RPM to about 3600, so I definitely didn't set any speed records. It was a trick accelerating from a stop through certain traffic lights before they turned yellow again, and I'm sure I irritated more than one other driver. Accelerating from 0-5 mph was very difficult, with torque not picking up until the car got going a bit. Once rolling, though, it felt peppy, at least compared with the stodgy original acceleration.

I need to fiddle with the voltage, current and frequency parameters a bit until I get acceptable performance. Mostly, I wanted to be assured of getting home without overheating my motor, which was no problem. I could hold my hand on the motor once I got home.

It feels really good to have come this far. Even though the car is by no means done, it is a usable means of transport at this point, and I will be driving it to work and dragging groceries home.

I'll keep updating this space with further news as Kermit rolls on.

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.