Self-discharge is the rate at which a battery, without a load (i.e., not in use), will lose its charge. For many batteries, self-discharge rate increases as the battery ages. It also depends on the chemistry of the battery and the temperature.

 

Typical self discharge rates for common rechargeable cells are:

 

Lithium 2–3% per month

Lead acid 4–6% per month

Nickel cadmium 15–20% per month

Nickel metal hydride 30% per month