Range extender

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The AC Propulsion genset trailer , built for the AC Tzero sports car prototype, a trailer with tank, Honda motorcycle engine, generator

As a range extender (Engl. Range Extender ), additional units in an electric vehicle refers to the range of increase of the vehicle. The most commonly used range extenders are internal combustion engines that drive a generator , which in turn supplies the accumulator (battery) and electric motor with electricity. Additional batteries, which are carried as a battery trailer, are less common. Just as unusual, but on offer e.g. B. on the roof rack, are fuel cells operated with hydrogen or methanol as in fuel cell vehicles , whereby the use is limited by the lack of filling stations.

Problem

Due to the limited battery capacity, electric vehicles usually do not reach as long a range as vehicles with a combustion engine (a Tesla Model S, for example, covers a maximum of 500 km; as of 2016). In the case of an electric car, the problem is that the vehicle is only ready for use again after a longer charging time (at fast charging stations, 80% charging is usually possible in approx. 30 minutes; at less connected stations, several hours are sometimes necessary; compared to the faster refueling process of around 3– 5 min for conventional vehicles). With a range extender, the time in which the vehicle can be used continuously (i.e. the time between charging or refueling cycles) is increased, and thus the range is increased. In addition, a combustion range extender can be quickly refueled conventionally at the petrol station.

Range extenders are thus an antidote to so-called range anxiety, the driver's fear that the range of his vehicle might not be sufficient.

classification

The use of an internal combustion engine generator system as a range extender leads to a serial hybrid drive . In this constellation, the mechanical energy of the combustion engine is not used directly, but first converted into electrical and then into mechanical energy. This results in a loss of efficiency, but the internal combustion engine can be operated at its optimal operating point and a gearbox is not required. The same applies to the use of a fuel cell.

In the case of a vehicle with a parallel hybrid drive, the internal combustion engine also provides propulsion; this structure is usually not referred to as "electric drive with range extender", but rather as a hybrid drive. A hybrid system is the power-split hybrid system , which can work both as a serial hybrid and mechanically connect the combustion engine for propulsion. If the vehicle is a plug-in hybrid , the battery can also be charged via the mains. Otherwise, all of the energy used for the drive is generated by the combustion engine - the electric motor and the battery only serve as a buffer system (e.g. for braking force recovery). Emission-free operation is then not possible and the systems are referred to as hybrid drives, but not as range extenders.

Series vehicles with range extenders

The BMW i3 is one of the first electric vehicles to be optionally available with a range extender. A two-cylinder in-line engine is used as such. The same engine has been used in a more powerful version since 2012 in the BMW C 650 GT and BMW C 600 Sport scooters. If necessary, the range extender charges the accumulator via a generator and, with its 9 liter tank, extends the range by around 120–150 km. The range extender can be started manually or it starts automatically when the charge level of the accumulator falls below a certain threshold. The system serves to extend the range and maintain mobility. The system is explicitly not intended as a replacement for charging the battery at a charging station and is only used to maintain the charge. The range extender is an optional extra and, with 28 kW, is significantly less powerful than the 125 kW of the electric motor (model series from 2013).

The Opel Ampera , identical in construction to the Chevrolet Volt , is sometimes referred to as an electric vehicle with a range extender, and sometimes as a plug-in hybrid . It can be driven up to maximum speed in pure electric mode, but has a very limited range of up to approx. 60 km. The four-cylinder gasoline engine with 1.4 l displacement optionally provides electrical power for driving and battery charging (serial operation), at higher speeds it is mechanically coupled to the drive train when the range extender operation is activated (parallel operation). Details are described under Voltec drive .

Prototype with range extender

Single cylinder - engine with generator swissauto as a range extender for a hybrid vehicle; presented at the IAA 2011
  • The automotive supplier KSPG operates a range extender for electric vehicles developed jointly with FEV GmbH in trial operation. The test vehicle is based on a FIAT 500. In order to achieve as little noise and vibration as possible, vibration compensation is used. The unit consists of a two-cylinder gasoline engine in a V arrangement, with the exception of the fuel tank and the radiator, all components are pre-assembled as a ready-to-install module.
  • The FEV (a development company in Aachen) builds in their FIAT-500-based electric vehicle prototype since 2008 a range extender module, the 20  kW can generate electric power and thus while driving extends the reach, but at a reduced speed. A Wankel engine is used for acoustic and installation space-specific reasons .
  • In the Jaguar C-X75 study from 2010, micro gas turbines are used in the rear of the vehicle to generate electricity.
  • Even Audi continued in 2012 announced A1 e-Tron to a Wankel engine as a range extender. However, its launch has been postponed indefinitely.
  • MAHLE Powertrain has developed a compact, flexible and, at the same time, cost-optimized range extender that has a maximum output of up to 30 kW. This has already been successfully installed in an Audi A1 demonstration vehicle.

Drive replacement concepts instead of extending the range

  • In the Opel Twin prototype (1992), the entire electric drive module could be exchanged for a conventional drive module with a combustion engine.
  • Mindset AG pursued another concept of not always having to transport the internal combustion engine to extend the range , which wanted to make the internal combustion engine easily removable. However, development was largely stopped in 2009.

Concepts for electric drives with long ranges that do not require a combustion engine

  • The company Better Place aimed to expand an exchange infrastructure for accumulators starting in Israel and Denmark. To this end, Renault has developed and marketed some vehicles up to series production. In May 2013, however, the company filed for bankruptcy in Israel in order to initiate an orderly liquidation after previous funding talks had failed.
  • A relatively long electric range thanks to a large traction battery on board the car and quick charging stations at charging stations, especially on the main traffic routes, should reduce the deployment scenarios and the need for a range extender.

literature

  • Chapter 1.2. Range extender. In: Helmut Tschöke (Ed.): The electrification of the drive train. Springer Vieweg, Wiesbaden 2015, ISBN 978-3-658-04643-9 , pp. 9-17

Individual evidence

  1. ↑ Cora Werwitzke: Fuel cell range extender for Nissan e-NV200. In: electrive.net. August 24, 2017. Retrieved March 2, 2019 .
  2. ^ Roland Matthé, Ulrich Eberle: The Voltec system-Energy storage and electric propulsion: Abstract. In: Lithium-Ion Batteries: Advances and Applications. January 9, 2014, pp. 151–176 , accessed on March 2, 2019 (English).
  3. ↑ Metall magazine , September 2013 issue.
  4. ↑ Electric vehicle development: plug-in with and without range extender. (pdf, 943 kB) In: FEV-Spectrum December 39 , 2008, p. 3 , accessed on March 2, 2019 .
  5. ↑ Tom Grünweg: Audi A1 E-Tron: Fickleness in the electric car. In: Spiegel Online . November 11, 2010, accessed March 2, 2019 .
  6. ↑ Richard Backhaus: Mahle puts range extender prototype on the road. In: ATZ online. June 21, 2012, archived from the original on June 24, 2012 ; accessed on March 2, 2019 . Mahle range extenders. In: MAHLE.com. Archived from the original on January 28, 2013 ; accessed on March 2, 2019 . Mahle Range Extender Vehicle. In: MAHLE-Powertrain.com. Archived from the original on October 13, 2013 ; accessed on March 2, 2019 (English, on your hybrid car ambitions).
  7. ↑ Semi-annual report 2009. (pdf) Spirt Avert AG , September 22, 2009, archived from the original on October 2, 2017 ; Retrieved on March 2, 2019 (especially p. 8, chapter “Continuation”). Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Ueli Kneubühler: Financial difficulties: power struggles shake mindset. In: Zisch Neue Luzerner Zeitung online . February 16, 2010, archived from the original on February 21, 2010 ; accessed on May 10, 2015 . Electric cars: Mindset writes deep red numbers. (No longer available online.) In: Luzerner Zeitung. April 1, 2010, formerly in the original ; accessed on March 2, 2019 .  ( Page no longer available , search in web archives ) @1@ 2Template: Webachiv / IABot / www.spirtavert.com

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