Rechargeable cells self-discharge slowly whether the tool is used or not, and a tool stored flat is worse off than one stored partly charged.
Self-discharge is normal and no manufacturer on this site publishes a rate for it.
The practical consequence for an infrequently used tool: give it a partial charge before storing rather than putting it away empty, and expect to charge it before use after a long gap.
The alternative that avoids the problem entirely is a replaceable cell. Five of the twelve nose and ear trimmers here run on a single AA or AAA, which is exactly why that format suits a tool used a few times a year: there is no cell sitting in the machine losing capacity between uses. The other five on that shelf are USB rechargeable and have the problem this page is about.
For a clipper used twice a year, the mains option matters more than the battery — several here run plugged in.
Check your own manual before you follow anything here. Temperatures, water ratings and supply voltages differ from model to model, and the maker’s own figures take precedence over anything written on this site. A supply of the wrong voltage is a failure rather than a slow charge, and the figure is printed on the tool — not inferred from a connector that happens to fit.
Last reviewed August 22, 2026