One battery is transforming chemical energy in electricity and is made of several accumulators linked in series or in parrallel. New types of batteries have been developped for the use of electrical vehicles. Some more advanced accumulators have been designed but still have some inconveniences: small autonomy, high price, available space issues or related to environmental issues.

You can see on the pictures below the battery evolution over the last few years.

The selection of a battery should be done upon the following criteria, starting from the most important :
- Energy / weight ;
- Charge (Number of cycles) ;
- Life time, price ;
- Maintenance ;
- Voltage, size (depending on the application) ;
- Recyclable.

The lead batteries are the first to have been developped. The investment cost is limited, but its charcateritics are limited . The complete charging requires around 6 hours. That's why some vehicles are fitted with removable pack of batteries allowing to inter-change them quickly. For the go-karts, it is possible to do partial discharge - charge. In such case, the charging time is equivalent to the discharge time.

The Nickel-Cadnium batteries use more modern technology. The autonomy and life time are higher but the cost is more important. The also withstand power of charge 3 time higher than normal batteries. The charge / discharge time rate is therefore more interesting.

The batteries can be mounted in parallel or in series.