I'm planning to have my car running at the Mini Nationals in Hamilton on the 25th of October. This isn't going to be an easy task as there is a lot to do. F40 Motorsport are working on my motor-gearbox adapter plate. It's not cheap, but they say they can have it done in time. My first cardboard template for the rear battery box didn't work out so well, now I've replenished my cardboard supply I can try again.
I likely won't have time to mount all my cells, but there is a bigger problem, I don't have a BMS. The only safe way to charge without a BMS is in parallel or, better, cell by cell. I need about 30 cells to reach the minimum voltage of my inverter. If the cells are half charged from the factory, then I need about 20*30=600Ah. I've got a 3A bench supply, which will do this in 200 hours, or almost 10 straight days if I connected them all in parallel.
I think I will have to see how well the PFC-30 goes into a 3v cell, they say it's safe into a short circuit so this shouldn't be a problem.
In preparation for this task, I finished the charging part of my battery test bench. You can see below the partial first charge of cell 1939. I wasn't able to make the watchdog timer in my LabJack U3 work, and without that I don't trust it enough to leave unattended. The power supply is limited to 4.2V which is safe in theory, but I would like to watch at least the first charge.
The current jumps around because I fiddled with the voltage limit on the power supply a couple of times. Also, the current appears to be quite strongly dependant on the voltage, but that is because the power supply's voltage regulator is separated from the cell by a quite high resistance shunt. I'll replace this with a much lower resistance shortly -- it made sense when I was trying the system out on AAA cells, but now I'm measuring amps, not milliamps.