Braking to Accelerate the Future

Tales of truck electrification are sweeping the industry. Fleets are beginning to understand the pros and cons of running electric vehicles (EVs), and as charging infrastructure spreads, EV comfort level grows.

With a $2 trillion infrastructure bill, the Biden Administration plans to build half a million new EV charging stations across the U.S.—four times the number of the nation’s gas stations. With this growth, manufacturers are making room for new electric trucks in their assembly lines.

Fleets running electric trucks are putting boots to the ground to discover which routes and applications are best suited for these vehicles, and the industry is getting closer to understanding how running an electric tractor affects the role of the trailer behind it.

Where Does the Electric Truck Battery Go?

Oftentimes, electric truck batteries are found near the outside edges of the underside of a tractor, and the center space contains the electric motor. This doesn’t leave empty space under the hood, though—here, manufacturers house much of the wiring and other electronics needed to run the electrified powertrain.

Although there is significant weight associated with electric truck batteries, it is mostly offset by removing the diesel engine.

One of the most exciting prospects for the future of electric trailers is a “bi-directional power transfer,” according to Colby White, Great Dane electrification product manager.

“If the trailer has excess energy or capacity in the battery, it could potentially extend the range of the tractor. Conversely, if the trailer’s battery is running low and the refrigeration system still needs to run, it could be possible for the tractor to give up some of its power to the trailer,” White says.

Today’s trailers don’t yet have this capability, but White says trailer manufacturers like Great Dane are studying the sophisticated technologies needed to facilitate this kind of interface between the tractor and trailer.

The Forefront of Electrified Technology

During the 2022 Technology and Maintenance Council (TMC) annual meeting, Great Dane displayed a ConMet eHub in-wheel electrification system connected to a Great Dane Everest trailer. The technology lowers emissions and creates a more carbon-friendly footprint through regenerative braking.

“In-wheel electric motor solutions, such as the PreSet Plus eHub system, transform kinetic energy into useable power creating a truly zero-emission vehicle when combined with an electric tractor,” says Marc Trahand, vice president and general manager for ConMet eMobility. “Energy that would otherwise go wasted as heat from friction produced by braking is captured at the wheel end and used to power auxiliary systems, such as an electric TRU, or charge the system battery.”

Trahand says this unique energy harvesting method eliminates the need for diesel engines inside the TRU without creating an additional strain on the tractor’s battery. This allows fleets to reduce fuel costs and direct emissions, as TRUs can emit up to twice the amount of NOx and 500 times the number of particles as modern diesel truck engines.

Bring on the Benefits

Electrifying the trailer using technology like ConMet’s PreSet Plus eHub system can potentially provide a host of benefits beyond simply saving on fuel costs.

For example, opting for an electric TRU also gains fleets increased access to noise restricted and low-emission areas, says Marc Trahand. When paired with an electric tractor, these benefits are even greater, enabling a quiet, zero-emission, fully electric truck, and trailer.

Additionally, Trahand says, because regenerative braking generates power on the road, it’s possible to reduce TRU battery capacity, and therefore shed some weight from the vehicle.

“The ability to charge the trailer’s battery enroute also reduces the need for shore power and charging stations when at the depot or making long delivery stops. The trailer’s battery can be quickly filled with the energy regenerated at the wheel end, which can be up to 156kW from a single braking event.”

Trahand says ConMet’s system is capable of sending energy back to the wheel ends, powering the in-wheel motors, and providing propulsion assist to the trailer. This could become a significant potential benefit for an electric tractor, as this lightens its load while simultaneously extending tractor battery range.

Did you know? The average traditional diesel-fueled reefer will burn .8 gallons of diesel per hour, while an eTRU averages only 8.1 kilowatts of electricity per hour. Using the average diesel and electricity costs from November 2019, this equals a savings of $1.36 per hour per vehicle.

The lightweight, modular, electrifed wheel end captures wasted braking energy and repurposes it as electricity to provide robust, decentralized propulsion, and auxiliary power for a myriad of commercial vehicle applications.

WATCH: Crawl Under a Great Dane trailer to See a ConMet PreSet Plus eHub