Rechargeable batteries lose their charge sitting in the camera. Ni-MH batteries lose between 1% - 4% of their charge a day. Since many cameras start reporting a low battery at 80% of full charge, the batteries could be reported low in as little as ten days. This number will vary greatly depending upon the age of the battery, temperature, and camera.

Memory effect was a problem with older Ni-Cd batteries. This problem has been reduced with newer batteries and chargers, though how you use your batteries may also impact performance. Ni-MH batteries do not have this problem, nor do the Li-Ion batteries.