A rechargeable battery is an electrochemical energy storage medium. Unlike regular batteries, these can be recharged for a certain number of charging cycles and convert electrical energy reversibly into chemical energy. Rechargeable batteries are available with various capacities (denoted as milliampere hour or mAh) and types. Not every rechargeable battery can be used in every device – you need to follow the manufacturer's specifications. Depending on the battery type, there are different recharging methods. The charging process is controlled by a charge regulator, which means that you can't use just any charger either.