How Should Lithium Batteries Be Stored Long-Term? What Self-Discharge Rate Is Normal?

Lithium batteries slowly lose charge even when switched off. Proper storage protects capacity and prevents deep discharge, which can permanently damage a cell.

Storage Conditions

Store cells in a dry, cool environment at around 20-25 °C, away from direct sunlight and corrosive materials. Heat dramatically speeds both self-discharge and calendar aging.

Recommended State of Charge

Around 40%-60% state of charge is the widely accepted storage level. Storing a fully charged cell raises internal stress, while storing a fully drained cell risks falling below the safe lower voltage.

What Self-Discharge Is Normal

A normal lithium cell typically loses a few percent per month at room temperature; a higher rate suggests aging, internal shorts or a protection circuit that is drawing current. As a rule of thumb, check stored packs every three to six months and top them up to roughly 50% if the voltage has drifted low.

Do not leave stored packs near metal objects or with exposed terminals, because even a small continuous drain can eventually pull a cell below its safe lower limit.