A Battery On Wheels Turns A Diesel Semi Electric Without Touching The Engine

Revoy, a San Francisco startup, has introduced a swappable electric trailer for diesel trucks, which can cut emissions by 85 percent. The 575 kWh plug-in module is available to fleet operators with a per-mile subscription model. This innovative solution turns existing diesel semis into hybrids without replacing the truck, reducing fuel use and emissions. The electric dolly measures 13 feet long and weighs 22,000 lbs, with a lithium-iron-phosphate battery that feeds an electrically driven axle. When the truck driver hits the throttle, the system engages the electric motor to shoulder the heavy lifting, keeping the diesel engine from straining. Under braking, the motor flips to regenerative mode, topping up the battery while helping slow the truck. The dolly also runs active safety systems, including rollover, flipping, and jackknifing protection, as well as blind-spot detection and automatic reversing. With the add-on fitted, a standard semi can cover over 200 to 250 miles on electric power alone, resulting in significant fuel savings and reduced emissions. The company claims average fuel economy can climb from 6 to 8 MPG to 20 to 35 MPG, and touch 40 MPG on short-haul runs. Revoy has secured regulatory approval and completed a yearlong pilot with freight company Ryder System Inc. The company is now launching its first commercial operation in Oregon, with plans to scale production and have dozens of units running US shipping routes by late 2027. Revoy has raised $27 million in its latest funding round, pushing total funding to $41 million, which will be used to develop a cheaper second-generation dolly.