Controller Cooling Fans

During the auto-tune of the controller to the motor, the controller heat sink got to almost 60 degrees C. Clearly it was time to fit the cooling fans to the controller that had been broken off in the decommissioning from whatever factory it came from.

This is how it arrived from Germany a year and a half ago. The fans did not arrive with it so it wasn't shipping damage. The seller sent over two fans later but one wasn't the correct one. They should both be 5.6W but one was a 2.8W. I pinched a 5.6W off my other controller.






I removed some useless plastic that was the old clip-in fan mounting and added a 3 'L' brackets.

Then I made up a plate to mount the fans and added two stainless steel filters. I reversed the fans to pull air through the filters.

My fan plate is square but notice how it doesn't fit up the side of the controller due to the controller being a bit "out of square". It's just the metalwork that secures the heat sink fins to the plastic work (the heat sink is fine). I think it's better to leave well enough alone rather than strip it down and straighten it. The other controller should be the one I end up using and it's case is in way better condition.

Hopefully this should make it easy to keep clean. A vacuum once every few months. I couldn't test the fans so I'll just have to wait until I get the controller hot again.

Battery Pack Balancing

After around 9 months of storage of my battery packs, and following the controller auto-tuning saga mentioned previously, I began the task of balancing up the cells within each of the packs. The charger and BMS within the packs handles balancing after charging but it is less stressful on the packs to do it with an external current source. I charged each pack normally then when the BMS cut out due to a cell going to 3.9 volts (usually at a pack voltage of between 54 and 55 volts), a little external device switched to a 180mA current source. This is the same amount of current that the BMS can bypass across each cell pair. It took somewhere between 24 and 50 hours to get the packs to 58.3 volts. It took from 21st January to 12th February to balance the 12 packs. I did some work on the dashboard (yet to be blogged) during this time.

My device in the piece of black heat shrink dangling below the pack being charged.