2 pcs Battery Charger Protection Board:1 pcs 3S & 1 pcs 4S1: The successful start of the drill requires three 15C-20C power battery, or six 10C-15C power battery (ordinary 18650 can not start the drill!!).2: strictly according to map wiring 0V, 4.2V, 8.4V, 12.6V, do not deliberately short circuit.3: When the load of the brush motor is used, try to connect a non-polar capacitor (withstand voltage above 25V, capacity 10uF-100uF) to the motor's positive and negative terminals to prevent the reverse spike from the motor. Break the MOS tube.4: 3 groups of batteries in series, please ensure that the voltage of each group of batteries, if not the same, please fill each battery separately and then use in series. The The Discharge test, the voltage drop faster battery that group is poor battery.4 strings Battery Charger Protection Board:Type: Voltage RegulatorModel Number: 40AApplication: Alarm4 string 16.8V 40A lithium battery protection board (comes with recovery function-AUTO Recovery)Scope: Nominal voltage of 3.6V, 3.7V lithium battery (including 18650,26650, polymer lithium battery)Charging voltage: 16.8V - 18.1VContinuous discharge current (upper limit): 40AContinuous charge current (upper limit): 20AEqualization version: suitable for starting current below 80A, power 135W below the drill.size:Product Size:46 x 60 x 3.4mm (balanced version)3 strings Battery Charger Protection Board:Model Number: 3S 40A Li-ion Lithium Battery Charger Protection BoardBalanced version: suitable for starting current below 80A, power 170W below the drill.3S 12.6V 40A lithium battery protection boardScope: Nominal voltage of 3.6V, 3.7V lithium battery (including 18650,26650, polymer lithium battery)Product Size: 42 x 60 x 3.4mmCharging voltage: 12.6V - 13.6VContinuous discharge current (upper limit): 40A (if the cooling environment is not good, please reduce the load current use)Continuous charge current (upper limit): 20AColor: greenMaterial: PC + metalPackage Contents:1 x 4 strings Battery Charger Protection Board1 x 3 strings Battery Charger Protection BoardOnly the above package content, other products are not included.Note: Light shooting 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.