Rechargeable batteries are rechargeable batteries that are limited in number of times and are used with chargers. The market generally sell 5th, 7th, but there are 1th. The advantages of rechargeable batteries are economic, environmental protection, electric power, suitable for high-power, long time to use electrical appliances (such as Walkman, electric toys, etc.). Rechargeable battery voltage than the same type of disposable battery low, AA battery (5th number charge) is 1.2 volts, 9V rechargeable battery is actually 8.4 volts. Now the general charge can be about 1000 times. Up to February 2012 only five kinds: nickel cadmium, nickel hydride, lithium ions, lead storage, lithium iron.