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Truck Tech: Power booster edition

More powerful battery systems will help curb emissions

For decades, a 12-volt battery system was just fine for running accessories on a commercial truck. Then came auxiliary power units to help with nighttime idling. With the dawn of electric and autonomous trucks — and stricter pollution regulations — get ready for 48-volt battery systems. 

Powering up to 48-volt systems

We write a lot in this space about electric trucks and the high-voltage power systems that power them. There’s a lot of other power needs under the hood of a Class 8 commercial truck. And the industry is working on ways to meet those increased demands.

Enter the 48-volt battery system.

Most carmakers equip one or two passenger vehicle systems with them. Often they are used in mild-hybrid applications — gasoline engines with an electric boost to power regenerative braking and provide a kick in torque during acceleration. An electric motor replaces the belt starter generator.

But 48-volt systems are still in development for big rigs. Several prototypes in the Department of Energy’s SuperTruck 2 program will have them. Commercial application is probably a few years away.

Ben Karrer, an Eaton Corp. technology development manager, explained what is coming and why it is necessary. The power management company last month introduced a family of 48-volt DC-DC converters for diesel-powered commercial vehicles that can power accessories such as antilock brakes and lighting. 

Eaton engineer with blue 48-volt power system
Vik Yeranosian, senior engineer at Eaton’s eMobility business, with an Eaton 48-volt DC-DC converter for diesel commercial vehicles. (Photo: Eaton Corp.)

“In the commercial vehicle space we see three uses for 48 volt, but the biggest one by far right now is in upgrading the emissions systems,” he told me. 

The California Air Resources Board comes first in 2024, mandating reductions in smog-forming oxides of nitrogen. The U.S. Environmental Protection Agency is finalizing a 90% reduction in NOx compared to current levels for 2027. And Europe is expected to follow suit with its yet-to-be-written Euro 7 regulations.

48 volt-systems to the rescue

“A 48-volt system plays in the active heating portion where you would put an electric resistive heater inside of the [diesel] aftertreatment system,” Karrer said. That would quickly generate 2.5 to 10 kilowatts of electric power to help meet ultra-low NOx requirements by keeping the heat on the catalyst even when the engine isn’t working as hard.

Karrer detailed two other uses for 48-volt systems. One is a mild hybrid system that would use regen braking like in passenger vehicles to send power back to an energy storage system, which could be a battery or group of batteries. The accumulated energy could be used to power electric accessories like air conditioning when the truck is parked for the night and the driver is resting.

Most trucks today have an auxiliary power unit (APU) that powers the AC. But APUs are fairly expensive and get their power from diesel or a 12-volt electric system. “An integrated solution would be more efficient, better packaging, better performance,” Karrer said.

The third use for a 48-volt system is autonomous trucking.

Autonomous driving systems require a lot of electric power for the sensors, computation and steering and braking actuation. All need redundant systems because there is no driver to take over in an emergency.

“Your average truck going around today needs 1 to 2 kilowatts of electric power to drive all the headlamps and ECUs [electronic control systems]. Level 4 autonomous systems need 5 to 10 kilowatts in some cases,” Karrer said.

Half as good as a 48-volt system?

In some cases, a 24-volt system meets the growing needs, but Karrer sees the industry mostly skipping that step, especially if it is designed for heating the aftertreatment system and for hybrid power.

A 15-liter diesel engine in a Class 8 truck always tested the 12-volt system in especially cold starting conditions. That’s not the case with a 48-volt system, like Eaton is applying in Paccar Inc.’s SuperTruck 2 prototype.

“Asking an industry that has been pretty happy with 12-volt electrical systems to move to something new in a world where they also have a lot of people devoted to high-voltage electric system integration and development for battery electric and high-voltage hybrid systems is really a draw on the resources.

“The OEMs have everybody who could spell electric is working on their battery electric vehicle programs,” Karrer said. “And you have teams that are not particularly adept or skilled at generation of new electric architectures who are having to step into this 48-volt space. So it’s a challenge.”

Twice as nice

Volvo Trucks North America is upgrading its I-Shift advanced automated manual transmission to offer a dual power takeoff (PTO) that is more efficient, functional and saves money. The new dual PTO allows I-Shift to incorporate independent drives separated by the vehicle’s centerline. That creates space to install two independently clutched pumps that are easier to install and service separately or at the same time. 

“Leveraging the new capabilities of a dual PTO in Volvo’s I-Shift transmission increases the truck’s operational versatility, a customer can haul portland cement one day and aggregate material the next,” said Andy Hanson, VTNA product marketing manager.  

The I-Shift transmission comes in 12-, 13- and 14-speed configurations. It is also available with an overdrive gear and crawler gears.

A green and gray transmission dual power takeoff unit
Volvo’s transmission PTO T4X-J2X (PTRD-D3), a transmission-mounted clutch dependent power takeoff (PTO) with two independently clutched rearward-facing DIN connections. (Photo: Volvo Trucks North America)

Best of the rest …

Semi tough

Bloomberg reports that Daimler Truck Holding AG sees an easing of the prolonged semiconductor shortage. Karin Radstrom, the head of the company’s Mercedes truck brand, said that after months of factory outages because of supply chain disruptions, the situation is improving. “It’s better, it’s not perfect, but it’s better than last year,” Radstrom told the news service. “I try to not celebrate too early, we’re still monitoring the situation closely.”

Charging simplicity

Heliox will supply Paccar Parts with mobile 25kW and 50kW chargers to Kenworth and Peterbilt dealers and customers building electric truck fleets. The mobile chargers are lightweight, transportable and often use existing infrastructure. That makes them convenient for newcomers to avoid creating on-site infrastructure. 

Safety assessment

Locomation filed a Voluntary Safety Self Assessment with the Department of Transportation outlining how its human-in-the-loop autonomous convoying system is safe for pre-deployment testing on public roads and complies with federal and state regulations. The report covers Locomation’s on-road testing of its Autonomous Relay Convoy prototype systems with a safety driver and test engineer in both vehicles

Expanded electric training

Volvo Trucks North America and sibling Mack Trucks have opened a new facility in Tinley Park, Illinois, to train technicians that will work on VNR Electric and Mack LR Electric trucks in Volvo and Mack dealerships in the central states. The 14,865-square-foot facility outside Chicago is newer, larger and more modern compared with the previous site based in Joliet, Illinois.

Sweet finish

Is there a better use for a refrigerated trailer than to carry ice cream? We don’t think so either. Great Dane, a Savannah, Georgia, trailer maker for 122 years, recently supplied a newly designed refrigerated body to Leopold’s Ice Cream, another Savannah institution. The Great Dane Johnson reach-in refrigerated truck body provides Leopold’s with more refrigerated capacity for deliveries. Sweet!

A white Leopold's ice cream truck with a refrigeration unit from Great Dane.
Great Dane’s newly designed refrigerated body for Leopold’s Ice Cream. (Photo: Great Dane)

That’s it for this week. Thanks for reading. Click here to get Truck Tech delivered via email on Fridays.


Alan Adler

Alan Adler is an award-winning journalist who worked for The Associated Press and the Detroit Free Press. He also spent two decades in domestic and international media relations and executive communications with General Motors.