Ed came over and helped me make a temporary battery box for the rear seat. This lets me evaluate performance with 40 more cells, for a total of 76. Knowing how well the car performs at higher voltage with a larger battery lets me decide how hard I need to work to squeeze cells under the bonnet. The intention is still to retain 4 seats in the car, this box is just an experiment.
Building this battery box was harder than it sounds. The seat base is full of curves so the bottom of the box needs a strong base, and holding the cells down with their dangerous high voltage terminals very close to the edges is not trivial. I'll post a picture of the lid which was key to holding the cells down shortly. The box is made of wood which is more flammable than I would like, restraint will be achieved with ratchet tied downs attached to the seat belt anchors.
In other news, the new cable connecting the inverter to the motor has resolved my inverter instability. I'll blog more about this cable soon.