How to charge and discharge laptop batteries to extend their lifetime

A laptop battery can be charged 300-1000 times. The actual number depends on the way it has been treated. In the last post of this series, I outlined the influence that the temperature has on a battery’s lifespan. Today, I will explain how a battery should be charged and discharged with care.

Fully discharge a new battery and then re-charge it. This calibrates the battery.

Calibrate the battery every 30 charges, i.e., fully discharge it and charge afterwards.

Avoid frequent full discharges. In contrast to NiCd (Nickel-cadmium) and NiMh (Nickel-metal hydride) batteries, Li-ion (Lithium-ion) batteries show no memory effect. That is, it will do no harm to the battery if it is re-charged before it is empty. Full discharges will strain the battery.

Avoid total discharges. Total discharges, i.e., to the cut-off point, can destroy battery cells. Not all cells in a laptop have the same voltage. Your laptop’s battery gauge only displays the state of the whole battery. If a cell goes below a certain voltage it will be destroyed. Therefore, it is safer to stop working when your battery level reaches 20%. The low battery level can be configured under Vista in the advanced power settings applet. Vista will warn you when the battery reaches the low battery level.