I was told there is a life span for all rechargeable batteries. Some of them can charge up to 5000 times or more before you need to replace them, others lesser. You probably need to talk with the person who sold you the batteries. The battery life is about the number of times you recharge, e.g. an original mobile phone battery will probably last between 1 1/2 to 2 years, after which, the charge may last only about between half a day to 1 day at most on standby.