GM goes electric - The battery effect

With E-Flex cars being purely battery-driven, GM is inevitably eager to protect its investment in such technology.

It is well known that rival manufacturers are investigating battery technology, and as a result GM has signed exclusive development deals with two battery companies.

'Whoever has an advantage in batteries will lead the business,' says Weber. 'The battery will be what differentiates the cars, and that is why we are committed to leading with this project and pioneering the market.'

Cells are currently being assessed in GM's labs, and they will be fitted into test vehicles early next year.

Tests will take at least two summers and two winters, however, because temperature fluctuations are among the main hurdles engineers must overcome.

For example, estimates suggest that even a 3% fluctuation in temperature between one end of a battery and the other will reduce its performance and lifespan.

Fears about the weight of the battery have been allayed, however, because regenerative braking systems that charge batteries by using the heat produced when slowing down are actually more effective in heavier vehicles.