Living in San Diego I didn’t expect to have to deal with cold batteries. Turns out the CALBs do not like getting under 45F – they really can’t produce the current I need to drive the car – setting off the miniBMS alarm.
I’m working with a machinist to come up with some insulation for the rear pack, and adding some heating to the packs. Simplest solution is to use plant seedling mats – they heat up whenever the temp drops below 74F. However, I couldn’t use mats due to the criss-cross of support beams. Solution: use soil heating cable. The cable I bought has a built-in thermostat and can cover up to 10 square feet. So now, all I’ll have to do is plug in the car each night – something I already do. 🙂
So when you design your pack, make sure you add in the heating lines for cold weather, as well as the necessary insulation.