A second life for used electric vehicle (EV) batteries has been granted by engineers from Toyota Motor Corporation and JERA, the largest power generation company in Japan. The 485 kW/1,260 kWh Sweep Energy Storage System is now operational and is connected to the consumer electrical power grid.

The system incorporates a sweep function developed by Toyota researchers to enable use of reclaimed automotive batteries to their full capacity regardless of their level of deterioration. The sweep device controls energy discharge by switching electricity flow on and off through series-connected batteries in microseconds. This capability also supports direct AC output from the batteries and eliminates the need for a power conditioner by reusing onboard inverters, thereby reducing costs and preventing power loss when converting from AC to DC.

The project partners plan to deliver 100,000 kWh of supplied electricity in the mid-2020s by putting reclaimed lithium-ion, nickel metal-hydride and lead-acid batteries back to work in Sweep Energy Storage Systems connected to the Chubu Electric Power Grid Co. power distribution system from a facility at JERA’s Yokkaichi Thermal Power Station. JERA is also collaborating with Sumitomo Chemical to advance a low environmental impact process for recycling lithium-ion batteries for EVs.