IEC 62133 (portable battery safety)

IEC 62133-2 sets safety requirements and tests for portable lithium-ion cells and batteries, covering reasonably foreseeable misuse such as overcharge, external short circuit, crushing and thermal abuse. It is distinct from UN 38.3: UN 38.3 concerns transport, while IEC 62133 concerns safe use. Product safety standards such as IEC 62368-1 often call on it for batteries inside equipment, and test labs and retailers commonly ask for certificates for the cells and packs used.

Where it bites: certification attaches to specific cells and pack constructions, so changing cell supplier usually means new testing, and undocumented low-cost cells create both safety and certification problems.