Your Depleted EV Battery Pack Could Power the Grid after Sunset

reuse ev car battery packs to power the grid
Reused EV Batteries Could Power the GridMark Vaughn
  • A company called B2U has developed a system to use depleted EV car batteries to store electricity from solar panels to power the grid when the sun sets.

  • The depleted batteries can be used in that capacity for over five years.

  • After their grid duty, the batteries can be recycled into new battery packs.

Batteries in electric cars will eventually hold less electricity. That’s just battery physics. It’s why, much to your chagrin, your cell phone battery doesn’t last forever. But what to do with batteries after their acceptable life in cars has dwindled? Reuse them.

After several years of duty making an EV go down the road, the capacity of the car’s battery pack to hold a charge drops. It’s like your gas tank gets smaller but it still holds gas. When the capacity of an EV battery to hold a charge, known as the battery’s State of Health, drops to anywhere between 60% to 80% of what it was originally, it’s not time to send the battery to the recycler—it’s time to send it to the reuser. A reuser is like a useful, and increasingly critical, stop before the recycler.

reused ev car battery packs to power the grid
The solar panels and batteries at B2U.Mark Vaughn

A company called B2U, in the Southern California high desert city of Lancaster, is a reuser. B2U has a sprawling facility outside of town that takes depleted EV batteries from Nissan Leafs, Honda’s Clarity, and General Motors and even Tesla batteries, racks them together, and connects them to its big array of solar panels. The solar panels charge the battery packs all day. Then, when the sun goes down and the solar panels can no longer power the electric grid, the old Nissan Leaf batteries discharge their stored electricity onto the grid and B2U sells the electricity to the local utility.


Those reused EV battery packs can keep the grid operating cleanly for more than five years, at which time they will be shipped to a recycler and made into new batteries. It’s another use for the batteries in their lifecycle that can help keep the grid running on renewable energy—and reduce the amount of non-renewable energy—required to keep everyone’s lights on and air conditioners running.

B2U has been in business since 2019. In addition to their facility in Lancaster, they are finalizing another one in the remote Cayuma area of SoCal near another solar array. Eventually, all solar farms could—and probably should—have battery storage attached to them.

Reuse of car batteries on a large scale like this is fairly new, but it can be done efficiently and with minimal environmental impact.

“We’re enabling that reuse,” said Freeman Hill, CEO of B2U. “We think the industry needs to treat reuse as a very important segment that needs attention and obviously needs to build itself up. We’ve got this stack of advantages: We think that our system, which we’ve got some patents on, and the software, which is hard to replicate, and then frankly, our particular use case, deploying a lot of batteries in large scale stationary storage, which is also hard to replicate.”

The B2U facility in Lancaster has 1300 batteries that once powered Leafs, Claritys, and a few other manufacturers’ EVs. The supply of depleted car batteries is relatively small right now but is doubling every two years, Hill said. As more of the world’s car fleet goes electric, the supply of semi-depleted batteries will grow.

reuse ev car battery packs to power the grid
B2U’s solar panels are adjusted every seven minutes to make sure they’re aimed right at the sun. Mark Vaughn

At B2U, the batteries remain in the same packaging they had when they rode in the cars, and they’re stacked in 56 temperature-controlled “cabinets” that look a little like smaller versions of shipping containers. Inside each cabinet are efficiently arranged racks of batteries.

B2U has worked with the carmakers to pair the battery’s software with its own proprietary software to monitor every battery in every cabinet and control its state of charge and the rate at which it both charges and discharges electricity. If a cell heats up, it is automatically shut down, both for efficiency and safety.

“We’re deploying a lot of EV batteries in second-life stationary storage applications,” Hill said. “We’re showcasing a patented technology. It enables us to take the pack and its casing out of the vehicle and then in a plug-and-play fashion, put it into our cabinet enclosures.”

Carmakers are still just trying to get people to buy electric cars and have only started to think about what happens at the end of those EVs’ lives, Hill said.

“A lot of the OEMs are still in this discovery phase, if you will: ‘How are we going to deal with all these batteries?’ They’re still dealing with the transformation on the front end and trying to sell a lot of EVs. But on the back end, there’s a stream of these things now reaching end of life.”

There’s a lot more to it than just plugging in a Leaf pack. In its four years, B2U has sorted out how to transfer the electric battery storage from powering a car to powering a grid.

“So much of this is software and digital,” said Hill. “It’s the intersection of software, digital, and obviously, the physical infrastructure to support this.”

OEMs have learned to trust B2U, Hill said.

“Our strategy is developing that direct relationship with the auto OEMs. That relationship leads to trust, because they see that we’re doing things the right way—all the right permits, all the right safety precautions.”

Battery management on a cellular level reassures OEMs that the liability of such usage is safe.

“We’re managing each battery in real time, all the time. We have great safety mitigation and risk mitigation here. And that’s what gets them comfortable very quickly. (They see) that reuse makes sense.”

Hill quoted a McKinsey study that said passenger vehicle batteries alone could supply 200 gigawatt hours a year of capacity in newly available batteries. An average house might use two to three kilowatts. A gigawatt hour would be a million kilowatt hours.

“So we’re talking about 500,000 homes that could be supplied from a gigawatt hour. 200 gigawatt hours is 100 million homes.”

There are about 125 million households in America, according to The B2U solar array in Lancaster is only three megawatts, with 28 megawatt hours of storage capacity. So there is enormous room for growth as more EV batteries become available. And they will become available.

“By the second half of this decade we’ll have a real problem with all the batteries that are becoming available, all of which are going to have to be recycled. And then the question that we’re trying to help the industry answer is, ‘Should we reuse these batteries or some healthy portion of them before we recycle them? That’s what we’re trying to demonstrate. The economics are very compelling.”