Lithium Battery Charger Protection Board BMS 4S 30A 14.8V

A Battery Management System (BMS) for a 4S battery pack. With this circuit you can safely make a battery pack of 4 series Li-ion/Li-Po batteries (cells). The circuit protects the battery pack against short circuits, overvoltage and undervoltage. In addition, the circuit ensures that the batteries are charged evenly (balance function). The circuit is supplied with protection connecting wires.

Specifications:

• Charging voltage: 16.8V
• Maximum charging current: 30A*
• Maximum continuous discharge current: 30A*
• Short circuit protection: 75 ± 5A
• Overcharge protection voltage (per cell/battery):  4.25 ± 0.05V
• Discharge protection voltage (per cell/battery): 2.55 ± 0.08V
• Balance function: Yes
• Dimensions: 56x45x8mm (without connection wires)

*Note: These are the maximum currents of the BMS circuit. Connected batteries may not be able to handle this current!

Pin description (See the images for the connection diagram):

• B-: Min cell/battery 1
• B1: Plus cell/battery 1, min cell/battery 2
• B2: Plus cell/battery 2, min cell/battery 3
• B3: Plus cell/battery 3, min cell/battery 4
• B+: Plus cell/battery 4
• P+: Plus output battery pack
• P-: Min output battery pack

Use the P+ and P connections to charge and discharge the battery pack.

Notes:

• For first time to use this BMS, you have to contact (P-) to (B-)
• Strictly according to the diagram wiring: 0V(B-) 3.7V(B1) 7.4V(B2) 11.1V(B3) 14.8(B+), Do not deliberately short circuit.
• After the wire is connected, it needs to charge the batteries first, then have output.
• 4 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 Discharge test, the voltage drop faster battery that group is a poor battery.
• Do not mix the good battery and the battery.
• It will be better the capacity of the battery internal resistance is closer.

Caution: Making a Li-ion/Li-Po battery pack requires knowledge. Only make the package if you know what you are doing. Incorrectly connecting the batteries and the BMS can cause the batteries to catch fire, or even explode.