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Electrified trailer cuts fuel consumption in semi-trucks by 36.3%

Range Energy makes truck trailers, with a clever connection to any standard tractor cab, loaded with electric powertrains to turn any semi into an efficient hybrid. They also let you push entire trailers around by hand at the depot in "shopping cart mode."

Range's 53-foot (16-m) RA-01 trailer packs its own 200-kWh battery, as well as an 800-volt e-axle powertrain that can put up to 14,000 Nm (10,326 lb-ft) of torque, at up to 350 kW (469 hp), through the rear wheels. The same battery also feeds a rear liftgate and powered landing gear.

It works with any electric or diesel-powered cab and is perfectly suitable for fleet operations, without any modification to the trucks. It takes its cues from a smart kingpin, which basically senses the acceleration and braking loads that the tractor is putting on the trailer, and uses its electric motors to help out.

https://newatlas.com/automotive/range-energy-electrified-trailer/