User:Matt B./Work in progress

Rechargeable battery Rechargeable batteries are batteries with a reversible reaction such that their stored chemical energy can be fully restored through the application of electrical energy. They are also called storage batteries, secondary cells, and, in British usage, accumulators (whose abbreviation accu, or akku from the German akkumulator, has a more widespread use). Their designs and chemical formulations are widely varied to serve many diverse markets and uses. Some types of rechargeable batteries are susceptible to damage due to reverse charging if they are fully discharged; other types need to be fully discharged occasionally in order to maintain the capacity for deep discharge. There are fully integrated battery chargers, often called smart chargers, which regulate a safe charging voltage and current for each chemistry. Attempting to recharge non-rechargeable batteries (or storage batteries in an unsafe manner) may lead to a battery explosion.

Recharging
The energy used to recharge rechargeable batteries mostly comes from mains electricity using an adapter unit. Recharging from solar panels is also attractive. Recharging from the 12V battery of a car is also possible. Use of a hand generator is also possible, but it is not clear if such devices are commercially made.

For uses like radios and torches, rechargeable batteries may be replaced by clockwork mechanisms or dynamos.

Reverse charging
Reverse charging is when a rechargeable battery is recharged with its polarity reversed. Reverse charging can occur under a number of circumstances. The two most important being:


 * When a battery is incorrectly inserted into a charger
 * When multiple batteries are used in series in a device. When one battery completely discharges ahead of the rest, the other batteries in series may force the discharged battery to discharge to below zero voltage.

Reverse charging may lead to explosion, leakage, damage to the battery and/or to the device or charger. Old and new batteries and batteries of varying types or brands should not be mixed in the same circuit.