General Motors and grid equipment supplier ABB this week showed an early version of an energy storage system using battery packs from the Chevy Volt electric car.
The two companies are partnering to build a prototype which they say can be used either for large-scale grid storage or backup power for consumers. They estimate that 33 repurposed Volt battery packs could supply 50 U.S. homes for four hours during an outage or brownout.
Batteries lose their storage capacity over time, but used car batteries are still viable for grid storage. GM estimates that once used car batteries have 70 percent of their initial charge, they can still be suitable for grid storage.
Finding a viable method to repurpose used EV batteries after seven to 10 years of driving isn't just a question of consumer convenience and driving range. Because batteries are the most expensive component of electric cars, car companies and battery makers are trying to find ways to draw more money from that asset with grid storage.
"As we grow our battery systems expertise, we need to assure we're optimizing the development of our battery systems with secondary use in mind from the start," Micky Bly, GM's executive director of global electrical systems, said in a statement.
GM and ABB plan to build a prototype storage system able to deliver 25 kilowatts, which is the power consumption of about five U.S. homes or a small retail or industrial business. These units will be designed to store 50 kilowatt-hours of energy.
ABB said that its existing inverter products can be used to feed power to the grid at off-peak times, which would let utilities use the battery packs to cut peak power load. The company intends to test the batteries for backup power as well.
The next step in the partnership, which was first announced last year, is to build a battery system that's connected directly to a local grid distribution loop, the companies said.
The partnership intends to demonstrate that it's technically feasible to build energy storage systems with used auto batteries, but the business models for recuperating and servicing end products still have not been worked out.