This product uses a 5-cell lithium battery-specific IC as a processor to detect each battery's voltage, charge and discharge current, and ambient temperature in real time. Realize battery overcharge, over discharge, discharge overcurrent and other protection functions; It has protection functions such as short circuit, over-current and temperature protection; The circuit board is of , and the copper hardware and thickened terminals are ; It does not generate heat during long-term use and is commonly used in for lithium-electric angle grinder battery packs. Charging voltage: 19/21V Single charge voltage: 3.8/4.25V Continuous discharge current: 8-30A Overcharge single cell detection voltage: 3.85-4.25V Overcharge protection delay: 1S Overcharge single cell recovery voltage: 3.75-4.13V Overcharge protection release delay: 1mS Over discharge single cell detection voltage: 2-2.8V Specification:C:OLT-MT5S90A Colour:As Shown Material:PCB Package Contents: 1 x Battery protection board Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.