Range Extender - or how to get home safely

With the promotion and continuous development of electrical cars a new technical concept became fashionable - the Range Extender. It has been born out of necessity. If it's not economical to build large batteries and the more power you want to store in batteries the heavier the battery becomes then maybe here's a case to install some auxiliary power in a car - the Range Extender was born. Basically it's a gasoline or diesel powered small engine that loads the battery. With this approach the range that with only battery operated cars is pretty narrow can be extended, hence the name. Interestingly people were remembering engine types for this purpose that are not used broadly otherwise, i.e. Wankel engines or Stirling motors. The objectives for a range extender engine are quite different to what you would usually have for the engine in a car. It needs to be as small and light as possible and should be operated only at the optimal point to deliver high output at low fuel consumption.
The concept makes a lot of sense, but it also makes the car more complex and expensive to build. And it means you have to fill up your car with two sources of energy, electricity and gasoline/diesel. But given the usual driving patterns where people use their car for maybe 10-20 km per day and only rarely do long range trips, adding a Range Extender to an electrical car actually may be a good compromise after all. Also you could see the Full Hybrid car as a car that maximizes the Range Extender approach.