More than 700 batteries that used to sit inside electric cars are now doing something completely different. They’re storing power for the Texas grid, built entirely from what the industry calls second-life EV batteries: packs pulled from cars that can no longer handle daily driving, but still have plenty of life left for less demanding work.
The site, called Bexar Martinez, sits just outside San Antonio inside CPS Energy’s service territory. Built by B2U Storage Solutions, it went live on September 26 and can store 28 megawatt-hours of electricity, enough to help thousands of homes through the hours the grid needs it most. It’s the company’s second project like this in Texas, feeding straight into ERCOT, the state’s main grid operator.
Why This Matters on a 105-Degree Day
Picture Elena, a home health aide who drives across San Antonio’s south side every afternoon checking on older patients. When ERCOT issues a conservation alert during a July heat wave, she worries about her patients’ window units cutting out, and her own apartment losing power before her overnight shift. Batteries like these exist for exactly that moment. They soak up extra solar power during the day and release it in the evening, when air conditioners run hardest and the grid strains the most.
San Antonio sits in one of ERCOT’s fastest-growing pockets, with new data centers and factories pulling more electricity every year. More local storage means fewer close calls. Fewer close calls means families like Elena’s patients spend less time worrying about the power cutting out mid-shift.
The Money Side of Second-Life EV Batteries
Reusing old batteries instead of buying new ones isn’t just greener. It’s cheaper, and that matters if your electric bill has crept up the last few summers. B2U says its second-life systems cost as much as 40 percent less to build than comparable new battery projects, with the same reliability. Lower construction costs for grid storage tend to filter down into what utilities pay for backup power, one of the quieter ingredients in your monthly bill.
“Bexar Martinez proves that second-life batteries can deliver reliable, cost-effective grid services at scale,” says Freeman Hall, B2U’s CEO.
The project also qualifies for a domestic content bonus under the federal Investment Tax Credit, another reason this storage keeps getting cheaper. Utility Dive reports B2U already runs more than 100 megawatt-hours of these systems, with 50-plus more coming to ERCOT within six months.
Good for the Planet, Too
Every EV battery that gets a second job is one less battery mined and built from scratch. B2U’s team put it simply: every battery they redeploy keeps valuable materials in service longer. Multiply that across hundreds of packs, and you’re looking at real savings in raw materials and manufacturing energy.
There’s a fun twist coming, too. B2U struck a deal with Waymo this year to take batteries from its self-driving fleet as those cars retire. The robotaxi dropping someone off downtown today could end up powering San Antonio homes a decade from now.
This isn’t Texas’s first attempt to shore up its grid with batteries. Record battery storage growth statewide has already started showing up as fewer outages instead of just bigger numbers on a spreadsheet.
Keep an eye on ERCOT’s grid alerts next summer. If San Antonio gets through triple-digit heat with fewer conservation warnings, batteries built from cars already sitting in driveways deserve part of the credit.