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It almost seemed like it was E-cars with range Extender a dying species. But technology is coming back to the streets - more versatile and innovative than ever before.
Electric cars with internal combustion engines as a range buffer came into fashion at the beginning of the decade. They showed a way out of the dilemma that arose from the batteries, which were very expensive at the time: In the early electric cars, traction batteries and thus the range were small, but the range fear was great thanks to the lack of charging infrastructure. E-cars with range extender technology, including the Opel Ampera and the identical Chevrolet Volt, as well as the Fisker Karma and BMWs i3, were able to take this fear away at a moderate cost.
In contrast to the currently very successful plug-in hybrids, the additionally built-in gasoline engine did not serve as a drive source, but as a power generator for the electric drive. The combustion engine and the electric motor do not have a mechanical connection. In practice, this bridging technology was already on the brink of extinction, because with the production stops of Volt and i3 with range extenders, this type disappeared from the market in 2019. But meanwhile there are signs of a renaissance of the special double heart technology, which among other things could help make a breakthrough in special niches of e-mobility and could further lower the prices for e-cars in general.
Combustion to supply electricity
The Geely subsidiary LEVC, for example, relies on this special mix of electric drive and gasoline engine with the VN5 van launched in Germany in the summer. In addition to an electric motor on the rear axle, there is also a 1,5-liter three-cylinder in the front that has no mechanical connection to the wheels. Its job is to provide power should the traction battery run out of power. At 31 kWh it is compact. With a fully charged battery, the e-van offers a correspondingly emission-free radius of up to 122 kilometers in city traffic.
The VN5 does not have a range problem, however, because the range extender motor can provide power for almost 400 more kilometers with the fuel supply. As the official total range, LEVC specifies 489 kilometers for the VN62.000, which costs just over 5 euros. Its particular advantage is obvious: it is the first e-delivery van that can cover long distances despite a small battery. LEVC also wants to offer the technology this year in a mobile home version called the e-Camper at prices from 73.000 euros.
With the help of the range extender principle, the German motorhome group Knaus Tabbert also wants to make electric campers marketable. What this could look like was shown at the end of August at the Caravan in Düsseldorf with the near-series “Knaus e-Power Drive”. This is a motorhome based on Ducato, the diesel of which replaces an electric motor with up to 180 kW / 245 PS. This can accelerate the fully equipped motorhome to a top speed of 140 km / h and a continuous speed of 120 km / h.
However, the traction battery only offers 35 kWh, which limits the range to around 90 kilometers. A small combustion engine therefore functions as a high-voltage generator that continuously charges the battery while driving. The vehicle in which the electric motor drives the front wheels therefore drives exclusively and without limitation electrically until the next refueling stop. While a light and efficient Wankel engine was installed in the concept presented, Knaus Tabbert is planning to use a 1,0-liter four-cylinder gasoline engine for the series version.
Range extenders have little power
The start-up Fering comes again from Great Britain and wants to bring an electrically powered off-roader with a huge range of even 2022 kilometers on track in 7.000 with the Pioneer. The off-road vehicle has all-wheel drive, with which several electric motors should enable a gradeability of up to 60 percent. The maximum speed of the Pioneer, however, is only 125 km / h. At 80 kilometers, the range is also modest thanks to the small battery.
In addition, a 0,8-liter three-cylinder diesel with 70 kW / 95 PS is on board, which acts as a generator for the electric drive. With a correspondingly large tank, this should provide up to 7.000 kilometers of additional range, which allows the Pioneer to be used long-term far away from any charging infrastructure. A climate-neutral operation at the same time would be possible if the combustion engine is fed with biodiesel. This solution can offer advantages, especially in terms of weight, because the Pioneer should only weigh 1,5 tons. Despite the mini battery, the off-roader is not particularly cheap with a price of around 175.000 euros.
The focus of the range extender concept Zero Vibration Generator (ZVG) by the automotive supplier Obrist is particularly on lowering the costs of electric cars. The technology installed in a Tesla Model 3 for demonstration purposes, among other things, combines a 100 kW / 136 PS electric motor in the rear with a traction battery of just 17,3 kWh. This is significantly smaller than the 52 kWh or 82 kWh batteries used by Tesla. Wherever the Frunk is located in the Tesla, Obrist has therefore also installed a heavily encapsulated one-liter two-cylinder gasoline engine, which is not physically connected to the drive, but drives a generator that in turn supplies electricity to the electric drive.
Thanks to the balancing compound and the encapsulation, the two-cylinder should not be acoustically perceptible to the occupants. At the back of the Tesla there is a 30-liter tank, which is enough for long tours, because the fuel consumption of the system should be between 2,5 and 4,5 liters per 100 kilometers.
Does a hybrid have to meet the emissions standard?
In addition to a 40 kW generator for gasoline operation, Obrist has developed a 45 kW equivalent for e-fuels such as methanol. The eco-fuel for this variant could be obtained from climate-neutral hydrogen, which would have a neutral carbon footprint. In principle, the hybrid drive system should meet the limits of the upcoming Euro 7 emissions standard despite the combustion unit. More important, however: the CO2 backpack of the electric drive would be small thanks to the rightsizing battery, and the vehicle weight would also be significantly less than that of the production model 3. In addition, lower acquisition costs would be feasible with the ZVG solution thanks to the significantly smaller battery. According to Obrist, a production vehicle at the price level of a conventional gasoline model would be realistic. However, it remains to be seen whether the Obrist solution will be used in a production model. It could be so far in 2025.
For more reach
Even beyond the niche, the range extender could play a bigger role again in the future. At least in the summer of 2022, the car manufacturer Mazda wants to launch a hybrid version of its MX-30 electric car, in which a Wankel engine produces electricity as a generator while driving. In this way, the overall range of the crossover should increase significantly. However, at the expense of the purely electric drive, because the traction battery will be smaller than the current MX-30.
The Japanese approach is both unusual and consistent: the petrol engine uses a rotary engine, a rather exotic design that has a long tradition at Mazda. The rotary piston engine should be particularly suitable for use in part-time electric vehicles due to its small footprint and smooth running. In terms of price, the variant with the serial plug-in hybrid drive will be in a similar range to the purely battery-powered model.