Battery memory
From The Glossary of Digital Photography
The tendency for the performance of a rechargeable battery to deteriorate over time with use. This is believed by many to be caused by a failure to discharge a battery completely before recharging, which disables the battery from holding the same amount of charge. Although this was true with older types of batteries, modern batteries suffer from a phenomenon known as voltage depression, which is often incorrectly called battery memory. Improper charging, rather than improper discharging, usually causes this phenomenon. Voltage depression is also usually confined to NiCad batteries, not Li-Ion or NiMH.
