Understanding the Mechanics of Electric Vehicle Battery Exchange Systems

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Though electric vehicle (EV) battery tech is improving, the time it takes to charge an electric car is still viewed as an obstacle to mainstream adoption. To address that concern, some companies built a system that swaps out the battery pack in your EV for a charged one.

So how does it work, and can it really solve the problem of long charge times? We’ll explore that here.

How Electric Car Battery Swapping Works

Charging an EV’s battery can take hours , and even fast charging can take around 30 minutes—much longer than an average gas fillup . Battery swapping attempts to solve that problem with a system that changes out the battery pack in your EV for one that’s already charged.

The process is supposed to take much less time than even the fastest EV charging options—around ten minutes. According to Ample , a startup specializing in this technology, stations can be set up in an area about the size of a couple of parking spaces. They’re autonomous and keep several batteries charging at a constant rate, which avoids sucking large amounts of power the way fast-charging stations have to.

The components to build each station are shipped, tested, and assembled on-site. In theory, an EV would drive into one of these stations and automatically have its battery pack replaced with one that was fully charged and ready to go in a few minutes.

Companies in China are already doing it, according to Bloomberg . Their stations operate in much the same way as Ample’s do, completing a swap in as little as a few minutes. Nio , one of the largest EV companies in China, has hundreds of swapping stations in use at the time of writing.

If an EV battery swapping system were adopted en masse, it could make EV charging infrastructure much easier to roll out. That coupled with the short time it takes to change a battery would eliminate barriers to entry around charging that hold many people back when it comes to buying an EV -–not being able to charge the battery at home , for example.

What About EVs Not Designed for Battery Swapping?

To swap out the battery pack quickly, some EVs, like the ones Nio manufactures, are built with a modular battery that’s designed for quick removal. For EVs already in circulation, however, a different approach is needed.

Khaled Hassounah, Ample’s co-founder, describes modular battery swapping in an interview with Ars Technica:

“Typically, you have the high-current connector, you have the big bolts that are holding most of the weight, and all that needs taking out. In our case, we’re just removing modules in protective buckets, but the big structural piece that connects to the cooling and the high power and all that always stays in the car.”

Hassounah says his company has designed several “plates” that interface with different models of EV currently being sold; frames that fit the specifications of EVs like a Tesla or Leaf that can accept Ample’s modular batteries. Battery packs broken down into multiple LEGO-like blocks of cells are then swapped in and out of that frame. Drivers can choose how many of those modular blocks to add to their car, and what kind of modular blocks get used will depend on the EV’s make and model.

You can see a (highly stylized) breakdown of that in action in Ample’s video .

Potential Disadvantages of EV Battery Swapping

While the concept of simply swapping out the battery in an electric car seems good on its face, it’s challenging to execute. Companies like Tesla have tried it in the past , ultimately deciding to focus on their Supercharger network instead.

The main problem with this approach is getting people to trust that the batteries they get won’t be defective. Why give up their battery, which they’ve always been able to monitor and maintain , for another one that’s been used by someone else? What if that battery has a limited charge capacity, or has a problem and catches fire ?

The solution to that approach seems to be companies owning the batteries and leasing them to drivers, providing the swap stations as a service that people pay for. If something happens to the battery, the company would assume responsibility and presumably exchange the bad battery for a new one.

Battery swap startups also claim that swapping makes it easier to monitor EV batteries for defects and repair them before problems become serious. Since they’re constantly being charged at their stations, the company could theoretically monitor them for problems as they rotated through.

There’s also the issue of how the battery pack “talks” to the onboard systems in the car. Would a battery manufactured by a different company really work as well as OEM? Ample claims its batteries can, and the success of the technology in China seems to indicate it can work, as long as manufacturers work together with the companies building this technology.

Whether battery swapping in EVs will see mass adoption isn’t certain. Improvements in battery technology within the next few years might render the idea obsolete if they can charge quickly enough. However, if adopted at scale, it could solve the charging problem and push EVs farther into the mainstream.

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Understanding the Mechanics of Electric Vehicle Battery Exchange Systems