The 1S 18650 Li-ion Lithium Battery BMS Charger Protection Board for 3.7V battery ensures safe and reliable charging by providing overcharge, over-discharge, overcurrent, and short-circuit protection. Designed for single-cell 18650 lithium-ion batteries, it maintains battery health and extends lifespan. Compact and efficient, it is ideal for DIY battery packs, power banks, and small electronic projects.