What is Regenerative Braking?

Regenerative braking is an application in electric vehicles that captures the energy produced by the friction of braking and applies it back to the vehicle. This recovered power can increase the miles a vehicle can cover or power onboard auxiliary units. Regenerative braking also increases braking efficiency and reduces noise and CO2 emissions.

Possible applications for regenerative braking in electric trailers are a focus of researchers who are exploring its potential to increase energy efficiency.

How Does Regenerative Braking Work?  

Regenerative braking harnesses the energy from the vehicle’s electric motor when braking, storing the energy in batteries or capacitors to be used by the vehicle again. This supplements the vehicle’s range, allowing it to go further with less fuel.

The amount of power stored in the battery is variable depending on the number of stops, the speed before braking, and even the type of terrain traveled. If you’ve ever wondered why hybrid and electric cars get better mileage or range in the city than they do on the highway, regenerative braking is your answer.

Potential Application in Electric Trailers

There are manufacturers who have developed or incorporated regenerative braking into their trailers already. We talked to several key manufacturers within the trailer industry to understand more about the complex questions surrounding regenerative braking and trailers.

“An electric motor is required to capture energy regeneratively. On a trailer, the primary opportunities to capture that energy would be from an e-axle or in-hub wheel motors,” says Matt Gold, director of sales for Hyliion. “These would act as supplementary trailer brakes and would capture electrical energy when the trailer brakes engage. A battery pack would be required to store this captured energy.”

This energy, he notes, could be sent back to the axle to provide additional power to the wheels, or to supply supplementary power to electric auxiliary loads such as PTO equipment, lift gates, or refrigerated trailers.

“The basic components needed to capture braking energy are a generator, an inverter, and batteries,” notes Steve Hubbard, engineering leader for electrification technology at Thermo King. “There are numerous examples of e-axles in electric cars and trucks that perform this function, and this technology can certainly be extended to trailers.”

Trailer component manufacturer ConMet has developed an in-wheel motor system capable of capturing and storing regenerative braking energy. “Trailers are an active part of the vehicle system whether they are connected to a tractor or not. To date, fleets have seen significant passive efficiency gains from trailer aerodynamics and light-weighting. Regenerative braking on trailers introduces a more active role of efficiency gains on the system,” says Caleb Lander, electrification product manager at ConMet.

Regenerative Braking Powers Progress

While universal application of regenerative braking in trailers won’t happen overnight—there are technological hurdles that are actively being examined—it’s a promising route to increasing the efficiency and practicality of electric trailers.

As electric vehicles gain more ground in North America, electric trailers are an enticing road to explore. Regenerative braking will help power the industry’s progress toward that development. Improved energy efficiency gives any fleet an edge, and for drivers crisscrossing the continent on 18 wheels, regenerative brakes will be good for the long haul.