Electricity is generally something which you need to use just as soon as it’s generated – so something that is very transient. But the existence of batteries is fortunate indeed, because without them a pedelec would be impossible.
Because it’s hard for people to visualize electrical current, and because the processes within a battery are very hard indeed for most people to picture, batteries have always been a little mysterious. Yet according to several historians, there were electrical energy storage devices even in Mesopotamia at the time of the Parthian culture. In 1936, researcher Wilhelm König unearthed a container near Baghdad which by all appearances seemed to be for storing electrical energy.
This means that batteries have been used by humans for well over 2000 years, although they were rediscovered for the modern age only in 1790 by the Italian doctor Luigi Galvani. A fully functional battery from this more recent past was first built in 1800 by Alessandro Volta. The first electric vehicles all used lead-acid batteries, which were impossible to seal completely. If an accident happened to the vehicle, this could lead to the battery acid escaping, as happened for example with the first commercial electric bike from Philips in 1932.
In the ‘80s of last century nickel chemistry emerged, which enabled the production of rolled round cells based on Nickel-Cadmium. These proved to be very robust and long-lived. So for the first time electric bikes practical for everyday use could be manufactured – even though the range with a battery weighing around 4 kg was seldom more than 20 km. Today it is possible, since the introduction to pedelecs in 2002 of lithium battery technology, to create batteries of the same basic weight and volume which deliver six to eight times the amount of energy. And development is ongoing – it could well be the case that in the next ten years a further improvement by the same factor will be achieved.
There are always promoters of bikes or batteries who make sky- high claims of their battery technology. They claim, for example, that their batteries will last for eight years. Such claims should in general not be given much credence, in so far as they are not matched by corresponding terms in the warranty. It is also often stated that one or other chemistry is exceptionally safe. But ten years of battery testing at BATSO have determined that there is no direct connection between battery safety and cell chemistry. Rather, the following factors play a role at the whole system level: cell chemistry, plus mechanical, thermal and electrical construction of the battery pack.
Currently, most battery packs are removable. But especially in the Netherlands there are a good number of pedelecs with a battery permanently mounted inside the frame. It could well be that this solution will catch on in the longer term, as long as the infrastructure is there to support it.
For example via the possible future availability of a lockable charging cable infrastructure – see:
Copy and picture: Hannes Neupert
Translation: Peter Eland, prepared within the EU GoPedelec! project: GoPedelec! Handbook (German version), Go Pedelec! Handbook in Czech, Dutch, English, Hungarian, and Italian
Online release: Angela Budde
5 November 2012