The Dream of Swappable EV Batteries Is Alive in Trucking

Battery swaps used to be the future. To solve the unsolvable problem of long recharging times for electric vehicles, some innovators at the dawn of this EV age imagined roadside stops where drivers would trade their depleted battery for a fully charged one in a matter of minutes, then be on their merry way.

That vision didn’t work out for passenger EVs — the industry chose DC fast charging instead. If the startup Revoy has its way, however, this kind of idea might be exactly the thing that helps the trucking industry surmount its huge hurdles to using electric power.

Revoy’s creation is, essentially, a bonus battery pack on wheels that turns an ordinary semi into an EV for as long as the battery lasts. The rolling module carries a 525 kilowatt-hour lithium iron phosphate battery pack attaches to the back of the truck; then, the trailer full of cargo attaches to the module. The pack offers a typical truck 250 miles of electric driving. Founder Ian Rust told me that’s just enough energy to reach the next Revoy station, where the trucker could swap their depleted module for a fresh one. And if the battery hits zero charge, that's no problem because the truck reverts to its diesel engine. It’s a little like a plug-in hybrid vehicle, if the PHEV towed its battery pack like an Airstream and could drop it off at will.

“If you run out of battery with us, there's basically no range anxiety,” Rust said. “And we do it intentionally on our routes, run it down to as close to zero as possible before we hit the next Revoy swapping station. That way you can get the maximum value of the battery without having to worry about range.”

To start, a trucker in a normal, everyday semi pulls up to a Revoy station and drops their trailer. A worker attaches a fully charged Revoy unit to the truck and trailer—all in five minutes or less, Revoy promises. Once in place, the unit interfaces seamlessly with the truck’s drivetrain and controls.

“It basically takes over as the cruise control on the vehicle,” he said. “So the driver gets it up to speed, takes their foot off the gas, and then we actually become the primary powertrain on the vehicle. You really only have to burn diesel for the little bit that is getting onto the highway and then getting off the highway, and you get really extreme MPGs with that.”

The Revoy model is going through its real-world paces as we speak. Rust’s startup has partnered with Ryder trucking, whose drivers are powering their semis with Revoy EVs at battery-swap stops along a stretch of Interstate 30 in Texas and Arkansas, a major highway for auto parts and other supplies coming from Mexico. Rust hopes the next Revoy corridor will go into Washington State, where the ample hydropower could help supply clean energy to all those swappable batteries. Happily, he said, Revoy can expand piecemeal like this because its approach negates the chicken-and-egg problem of needing a whole nation of EV chargers to make the vehicles themselves viable. Once a truck leaves a Revoy corridor, it’s just a diesel-powered truck again.

Early data from the Ryder pilot shows that the EV unit slashed how much diesel fuel a truck needs to make it down the designated corridor. “This is a way we can reduce a path to reduce the emissions of our fleet without having to buy anything — and without having to have to worry about how much utilization we're going to have to get,” Mike Plasencia, group director of New Product Strategy at Ryder, told me.

Trucking represents one of the biggest opportunities for cutting the carbon emissions of the transportation sector. It’s also one of the most challenging. Heatmap has covered the problem of oversized SUV and pickup truck EVs, which need larger, more expensive batteries to propel them. The trucking problem is that issue on steroids: A semi can tow up to 80,000 pounds down an American highway.

There are companies building true EV semi trucks despite this tall order — Tesla’s has been road-testing one while hauling Pepsi around, and trucking mainstays like Peterbilt are trying their hand as well. Although the EV model that works for everyday cars — a built-in battery that requires recharging after a couple hundred miles — can work for short-haul trucks that move freight around a city, it is a difficult fit for long-haul trucking where a driver must cover vast distances on a strict timetable. That’s exactly where Revoy is trying to break in.

"We are really focused on long haul,” he told me. “The reason for that is, it's the bigger market. One of the big misconceptions in trucking is that it's dominated by short haul. It's very much the opposite. And it's the bigger emission source, it's the bigger fuel user."

Rust has a background in robotics and devised the Revoy system as a potential solution to both the high cost of EV semis and to the huge chunks of time lost to fueling during long-distance driving. Another part of the pitch is that the Revoy unit is more than a battery. By employing the regenerative braking common in EVs, the Revoy provides a redundancy beyond air brakes for slowing a big semi—that way, if the air brakes fail, a trucker has a better option than the runaway truck lane. The setup also provides power and active steering to the Revoy’s axle, which Rust told me makes the big rig easier to maneuver.

Plasencia agrees. “The feedback from the drivers has been positive,” he said. “You get feedback messages like, it felt like I was driving a car, or like I wasn't carrying anything.”

As it tries to expand to more trucking corridors across the nation, Revoy may face an uphill battle in trying to sell truckers and trucking companies on an entirely new way to think about electrifying their fleets. But Rust has one ace up his sleeve: With Revoy, they get to keep their trucks — no need to buy new ones.