A second-life battery is an EV traction pack that has retired from vehicle service, typically at 70 to 80 percent of its original capacity, and been redeployed as stationary energy storage. A stationary battery does not care about range, so a pack too tired for a car can work for years on the grid.
In service today
- Redwood Materials runs a 12 megawatt microgrid in Nevada on retired GM packs and commissioned a 7.2 megawatt-hour system at a GM plant in June 2026, with roughly 10,000 more packs set aside.
- B2U Storage Solutions, based in Lancaster, California, has 24 megawatt-hours of retired GM packs bidding into the Texas market for under $200 per kilowatt-hour.
- Second-life packs are a small share of grid storage today. Repurposing follows UL 1974; the packs are eventually recycled for materials.
Why it matters for parking
The car that charged in a garage this decade may be holding up the grid next decade. Inside an enclosed structure, a second-life system is subject to the same NFPA 855 and fire-marshal review as any battery energy storage system. Sources: IEEE Spectrum; Redwood Materials; B2U.