Inner cities’ appetite for goods is insatiable, which means that delivering them an inescapable inconvenience. So making trucks cleaner and quieter – with the advent of Euro 6 – has broadly been well received. However, the announcement by Daimler a few weeks ago that it is now running a fully electric prototype 26 tonne rigid chassis is really exciting. At long last electric power is moving up and away from vans and light trucks.
Daimler’s foray into electric power for light commercials is well known. Its Fuso brand has been the standard bearer in the shape of the Canter Eco Hybrid, which has now been in production for several years. An all-electric version (Canter E-Cell) was unveiled at the 2010 Hanover show, and trials in Portugal (where it is built), and later Stuttgart, have progressed ever since. These vehicles are now on their third generation pre-production trials – including with parcels and logistics giant Hermes – so inevitably closer to series production, now promised at the end of 2017.
Battery technology has improved the while, and based on a six-tonne chassis, Daimler reckons that a three-tonne body/payload allowance can be expected. But in the grand scheme of getting goods delivered into cities, such weights remain small beer. Stand on any central London street corner in the small hours and you’ll see that the trucks doing the heavy lifting are 18- and 26-tonne rigids. So July’s news of heavier weight electrics was always going to grab more attention.
Step back a moment: at a Hanover show 12 years ago, a concept truck in the shape of an Axor hybrid 44 tonne tractor was on show. It was a half-hearted affair, with too many unanswered questions and it subsequently slipped into obscurity. But it’s now apparent that Mercedes-Benz’s development engineers had not given up hope of bringing full electric motion to heavy trucks.
Why now? At Daimler’s Untertürkheim test track, Dr Wolfgang Bernhard (who head up Mercedes’ truck and bus) conceded that when, a decade ago, the battery of a 25-tonner consumed a third of its tare weight, he had been sceptical. But that was then and this is now. “The time is now right for electric trucks, because two factors have come together,” he explained. “Technology has made great progress and the market is emerging.”
So, while electric power is still not a serious prospect for long-haul, an all-electric 25 tonne truck is entirely realistic, he said, stepping aside to allow a three-axle electric Antos to sweep silently onto the podium. And behind the wheel of this Urban e-truck was Sven Ennerst, head of truck product engineering and global procurement. It was pure theatre. And when electric trucks make the move to this weight, it’s time for even the most ardent naysayers to start taking note.
So how has Mercedes done it? Full details are to be revealed at the IAA Hanover show, in September, but the basics are already clear. The development vehicle is a 6x2 rear-steer Antos 26 tonne chassis. Most of what you would expect to see between and beside the chassis rails has gone. No diesel engine, no radiator, no gearbox, no prop shaft, no differential, no after treatment, exhaust or AdBlue. No diesel tanks. So the tare weight has already been considerably reduced.
“The standard truck components that remain are proven designs and we have added the latest battery technology, based on developments in our passenger car division,” said Ennerst. That still means Lithium-ion cells, but plenty of them. With a design referred to as crash-proof, three packs of batteries – comprising 90 modules and 1,080 high-energy cells – lie neatly between the rails. At 2.5 tonnes, they give the vehicle an impressively stable centre of gravity but the scales remain tipped against it – because this is all 1.7 tonnes more than a diesel equivalent drivetrain.
However, Daimler designers claim a real margin of just 700kg, leaving a 12,800kg payload. How? Because they factor in a one tonne allowance in light of EU Commission proposals to allow an increase in gvw for trucks with alternative drives. Time will tell, particularly when Brexit gets into gear. It might not be wise not to count on that for UK fleets – although the government should be just as anxious as the EU to encourage electric trucks.
Either way, the innovation is impressive and a 212kWh pack has a claimed range of 200km. The electrically-powered rear axle is based on ZF’s AVE 130 11.5 tonne portal axle, already used in Mercedes hybrid and fuel-cell buses, and has its motors close to the wheel hubs to minimise weight. That axle has been reconfigured for the Urban e-Truck with the new housing raised for a ground clearance of more than 200mm. Super single tyres are also used because of the frame width and positioning of the drive motors – again with the bonus of weight saving over twins.
Thereafter there’s a list of unfamiliar components, including an HV (high voltage) control unit, HV junction box and fuses, HV distribution unit, three inverters and an HV air compressor and steering pumps. Braking is regenerative and efforts to provide intelligent battery management are claimed to have contributed to the extended range.
Why an all-electric 26-tonner now?
Mercedes trucks’ chief Dr Wolfgang Bernhard says three major factors have influenced the German giant’s decision to run with the Urban e-Truck. First, online trade is increasing at 5—7% a year, and in the next decade is forecast to be responsible for 20% of deliveries, with most of those in cities. Secondly, regulations on cleaner and quieter trucks will only get more stringent. And thirdly, fleets are becoming increasingly image conscious, so their need to brandish green credentials can’t be ignored.
All true, but while this truck’s silent operation is a boon for night-time deliveries, there could be a day-time issues. Cyclists and pedestrians already have safety problems interacting with heavy trucks in cities: a near silently approaching 26 tonner, with only tyre noise to warn of its presence against the urban cacophony, might prove an unacceptable risk.
That however, will not be difficult to overcome. The overwhelming impression is of a well thought through concept. We are witnessing the arrival of the first fully-electric proper electric truck. What about a production date? “During the next decade,” we are told. That will be here before you know it. There’s no doubting that Damiler has just dramatically raised the bar on gross weights that will tolerate pure electric power.
