Fox ESS ECS4000 Battery CM4000 | Master battery module with built-in BMS | Capacity 3.975kWhThe CM4000 is the controller module in the modular ECS4000 battery system. It comes paired with CS4000 slave modules to form high voltage battery stacks. Features The FOX ECS CM4000, as part of the scalable ECS4000 lineup, offers: Modular scalability: Build systems from ~4 kWh up to ~28 kWh High performance LiFePO chemistry: Long life, safe, stable Efficient & certified: >95% round trip efficiency, UL IP65 rated Plug and play: Easy installation with