Long service life is the advantage of the rechargeable battery, for it can be recharged for more than 1000 times. It is economical for frequent use even though it is more expensive than primary batteries, and its load capacity is more powerful than most of primary batteries. Generally a Ni-MH battery is not recommended to use in cameras because its discharge voltage is almost constant and it is difficult to predict when the discharge ends, while rechargeable Li-ion batteries can provide camera longer service time, higher load, higher energy density, voltage decrease in discharge with discharge deeply going.