First Chevrolet Volt battery pack built at Brownstown Township plant, January 2010Enlarge Photo
The engineers behind its development will be the first to tell you that most packs will last quite a bit longer than that. But even the most carefully treated Volt battery pack will still have a finite lifespan in an automobile.
Still, when the pack's energy capacity has fallen to 80 percent or less of its original 16 kilowatt-hours--meaning it's no longer serviceable for use on the road--it can still be repurposed for other uses.
One such application is being developed by power grid systems developer ABB Group, who envisions using retired Volt battery packs to store energy for later addition to the power grid.
ABB’s plan calls for five or more Volt battery packs to be assembled into an energy storage unit, much like an oversized battery backup. General Motors showed off a prototype at an ABB facility in Raleigh, N.C., during the Plug-In 2011 conference this week.
Ideally, these units would use either wind or solar power to maintain a full battery charge, but in the event of a blackout could feed power back to the grid. The units would also provide supplemental power for peak demand periods.
2011 Chevrolet Volt outside Detroit-Hamtramck assembly plantEnlarge Photo
Repurposing the battery packs would keep them out of landfills, promoting whole-car recycling, although any substantial supply of used packs out of junked Volts would be many years in the future.
Some utility industry observers remain skeptical that electric utilities will want to purchase arrays of used battery packs with varying energy capacities, and unknown histories, duty cycles, and usages.
Many feel that utilities instead may purchase new automotive-scale lithium-ion cells and rack them for energy storage. Southern California Edison is already testing a prototype of such a unit, which allows erratic and unpredictable renewable energy--wind or solar--to be stored and fed into the grid at times of maximum demand.
To show how serious GM is about this, the company has appointed Pablo Valencia to the newly created position of senior manager, battery lifecycle management. Valencia and his team are tasked with ensuring that vehicle battery packs have a life beyond their intended design, providing both environmental and societal benefits for years to come.