Daly Lifepo4 4S 12V 100A Battery Management System Circuit is an 4 Cell in Series 12V circuit power tool mostly used for solar lighting. It is designed for lithium Batteries for charging, Protection from overcharge, and Over-discharge. The battery protection board, as the name suggests battery protection board is mainly rechargeable and protects the integrated circuit board. Lithium batteries (rechargeable type) so need protection, is determined by their own characteristics. As the Orange lithium battery, its material determines itself can not be overcharge, over-discharge, overcurrent, short circuit, and ultra-high temperature charge and discharge, so lithium battery lithium components will always follow A protective plate with a sampling resistor, and a current fuse.