Revoy's Battery‑Powered ‘Backpack’ Converts Diesel Semis to Hybrids

Revoy, a San‑Francisco startup founded in 2020 by CEO Peter Reinhardt and CTO Ian Rust (formerly of Cruise), has developed a battery‑powered “backpack” – also called a “dolly” – that can be attached between a tractor’s fifth wheel and a trailer. The unit is about 4 m long, weighs roughly 9,979 kg and houses a 575 kWh lithium‑iron‑phosphate battery that powers an electric axle. When the driver accelerates, the system supplies electric torque, reducing diesel engine load; during braking the motor operates regeneratively, recharging the battery. The device also includes active safety features such as rollover protection, blind‑spot detection and automatic reverse.

According to Revoy, a standard semi‑trailer equipped with the backpack can travel 322–402 km on electric power alone and achieve fuel consumption far below typical diesel levels, especially on shorter routes. The company says the solution lets fleets extend the life of existing trucks without the high cost of fully electric rigs. The technology is still in development, with no firm rollout timeline disclosed.