Electric trucking is slowly becoming more mainstream, but battery-powered big rigs are probably not for everybody, at least not yet. Tesla and Mercedes-Benz have proved that you can squeeze over 400 miles of range out of an electric truck, but some companies and drivers might still see that figure as an inconvenience.

That's why Germany's Mahle has come up with a solution to make electric trucking a little more palatable to more people: add a diesel engine. The company's new range extender system packs everything into a single enclosure that can be easily fitted into the same space that's being used by a couple of battery modules on an electric truck tractor.

The all-in-one enclosure has a compact diesel engine, a generator that powers the high-voltage battery, and everything else that's needed to keep moving, including a fuel tank, an AdBlue tank, an exhaust gas treatment system, and a cooling system. That's a lot of complexity added to a vehicle that was designed from the get-go to be much simpler than a combustion truck, but Mahle says it's worth it.

By taking out roughly a third of the battery capacity, the rear axle load can be reduced by roughly 881 pounds (400 kilograms), while the total vehicle weight can be reduced by about 1,322 lbs (600 kg). This means the truck can carry heavier loads, while the total range of the vehicle can exceed 500 miles (800 km), with the battery providing about 250 miles and the range extender powering the remaining 250 miles.

The generator itself doesn't have any physical connection to the driven wheels, and instead sends between 110 kilowatts and 130 kilowatts to the electric drive system. It doesn't use any rare earth elements, which makes it quite environmentally friendly, too. And because the diesel engine used by Mahle can be powered by biofuels like HVO100 biodiesel, carbon dioxide emissions are "virtually zero," according to the company.

However, under real-world conditions, where conventional fuel is being used, Mahle claims a truck that uses its range extender emits about 80% less CO2 compared to a conventional diesel truck.

"Our range extender is the key to disconnecting the market ramp-up of battery-electric trucks from the inadequate pace of infrastructure development," said Marco Warth, Vice President, Mahle Corporate Research and Advanced Engineering. "If the charging station is busy, or alternative routes are called for as a result of weather conditions or congestion, and infrastructure reaches its limits, other fleets can be stranded. An e-truck with a range extender just carries on. Operational availability is maintained, even under peak conditions."

The company's new plug-and-play range extender will be unveiled next month at the IAA Transportation show in Hanover, which runs between September 15 and 20.