May 30, 2017
The use of large-scale battery arrays for backup and carry-through energy storage is getting increasing attention, as evidenced by Tesla Motors' recent announcement of their Powerwall system for homes and offices. The batteries in these systems are continually charged from the power-line grid or other source, and then deliver AC-line power back to the user via a DC/AC inverter.
Using batteries for power backup is not new, with many systems spanning basic 120/240Vac and several hundred watts for short-term desktop-PC backup, to thousands of watts for specialty vehicles, such as ships, hybrid cars, or all-electric vehicles, up to hundreds of kilowatts for grid-scale telecom and data-center backup (see Figure 1). Yet while advances in battery chemistry and technology get much of the attention, an equally critical part of a viable battery-based installation is its battery management system (BMS).