Braking to Accelerate the Future

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 discovering 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.

ARCHITECTURE OF ELECTRIC TRUCKS AND TRAILERS

An important variable in accessing heavy-duty EV adoption is added weight. Although there is significant weight associated with EV batteries, it is mostly offset by removing the diesel engines and fuel tanks from both tractors and refrigerated trailers. Additionally, the industry is making meaningful advancements in battery science and electric vehicle architecture every day, for both the truck and trailer.

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.

One of the most exciting prospects for the future of electric trucks is a possible “bi-directional power transfer” with refrigerated trailers that are equipped with a battery power source, according to Colby White, Great Dane electrification product manager.

“If the trailer battery has excess energy or capacity, 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 TRAILER TECHNOLOGY

During the 2022 Technology and Maintenance Council (TMC) annual meeting, Great Dane displayed a Carrier Vector eCool system powered by ConMet eMobility on a Great Dane Everest trailer. Click here to watch a tour of the trailer.

This technology utilizes ConMet’s eHub system, an in-wheel electric motor solution, that provides electric power to a Carrier Vector TRU. This 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 adds, “this unique energy harvesting method eliminates the need for diesel engines inside the TRU. This allows fleets to reduce fuel costs and direct emissions, helping fleets make meaningful progress toward achieving their own environmental goals.”

BRING ON THE BENEFITS

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

“For example, opting for an electric TRU allows fleets to have access to noise restricted and low-emission areas,” comments Marc Trahand. “When paired with an electric tractor, these benefits are even greater, enabling a quiet, zero-emission, fully electric tractor-trailer.”

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

Trahand adds, “future generations of ConMet’s system will be capable of sending energy back to the wheel ends, powering the in-wheel motors, and providing propulsion assist to the trail“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.”er. 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 Vector eCool system powered by ConMet eMobility is currently making regular deliveries and is in normal operations with multiple fleets, realizing significant cost savings and making progress toward achieving fleet sustainability goals.

For example, one national foodservice delivery fleet is projected to save almost $30,000* in reduced maintenance and fuel costs, as well as decrease direct carbon emissions by 46,800 pounds each year per Vector eCool equipped trailer.

*Assumes TRU uses .87 gallons of fuel per hour, 300 operational days per year, and $6.75/gallon diesel price

ConMet eMobility’s PreSet Plus® eHub System (Pictured)
The lightweight, modular, electrified wheel end captures kinetic energy and repurposes it as electricity to provide auxiliary power for a myriad of commercial vehicle applications.