Just a quick update to show the new active BMS boards as well as the battery module heating boards. The heating serves two purposes. Of course, one of those is to heat the modules in really cold weather. Performance is affected when temperatures drop substantially. With the vehicle usually plugged in, it’s easy and effective to provide some amount of heating to counteract the performance degradation effects. These customized heater boards are able to provide about 120 W of heating. The other purpose though is to aid in high-power balancing of the battery cells. There is a string of heating elements (power resistors) that is switched on to an individual battery cell. This is our own patent-pending technology that serves the purpose of both heating and high-power cell balancing. Our custom active balancing boards have cell-by-cell active balancing. But in addition, there is this additional ~20 W per cell for passive balancing. Typical passive balancing systems are not even a couple watts. This combined active/passive balancing system allows us to very aggressively perform a patented technology that we license which gives a substantial improvement in battery pack life.
Custom heater boards on the pack baseplate 
Battery modules with their accompanying heater and active balancing boards