California Energy Storage Showcase

UC San Diego and BMW are giving new life to used electric vehicle batteries by storing up to 108kW of electricity for a few hours inside each battery.

The University of California, San Diego (UC San Diego) remains San Diego Gas & Electric’s biggest demand response customer, regularly shedding 6 MW to 10 MW when called upon. To continue to meet this demand, UC San Diego is expanding their energy storage capabilities. They have collaborated with German carmaker BMW and are testing the "second-life" for electric vehicles (EV) batteries. When batteries lose 20 percent of their charge capacity, they are no longer suitable for vehicle use. The UCSan Diego project repurposes used mini-E EV batteries for stationary energy storage (approximately 108 kW of power capacity and 2-3 hours of energy storage). The system will be integrated with a solar photovoltaic system and possibly fast EV Direct Current charging. Secondary use for EV batteries reduces their up-front cost and benefits consumers and utilities by avoiding electricity demand-charges and integrating variable and intermittent renewable energy. Although the batteries used in EVs usually only have a vehicle lifetime of 8-10 years, they still have significant capacity left for alternative uses. Demonstration of this technology will help to prove the feasibility of using second-life EV batteries for stationary energy storage. If the project demonstrates that used batteries from EVs have a viable second use, the overall cost of owning an electric vehicle could be offset.

See more information about the BMW Energy Storage System.

project photo project photo project photo

Photos courtesy of UC San Diego.



Demonstrating the value of energy storage to provide:

  • Reliability
  • Renewable integration
  • Valuing second-life EV batteries for the potential to reduce the upfront cost of purchasing an EV.

Type of Technology

Reused EV battery first serves as a mobile automotive application and then is redeployed into the secondary post-automotive market for stationary energy storage.

Quick Facts

  • Power Capacity Rating: 100 kW
  • Energy Capacity Rating: 160 kWh
  • Type of Energy Storage: Second life electric vehicle batteries (Li-ion)

Key Developers and Partners

  • UC San Diego
  • BMW
  • U.S. Department of Energy

Energy Commission Funding



Project construction has been completed, the system commissioned and it is operational.


Location of New life for Electric Vehicle Batteries Project in California