The life of a rechargeable battery operating under normal conditions is
generally between 500 to 800 charge-discharge cycles. This translates into one
and a half to three years of battery life for the average user. As your
rechargeable battery begins to die, you will notice a decline in the running
time of the battery. When your two hour battery is only supplying you with an
hour's worth of use, it's time for a new one.