BMS 3S Protection Circuit with Balancing Function

A Battery Management System (BMS) for a 3S battery pack. With this circuit, you can safely assemble a battery pack from 3 series-connected Li-ion/Li-Po batteries (cells). The circuit protects the battery pack against short circuits, overvoltage, and undervoltage. Additionally, the circuit ensures that the batteries are charged evenly (balance function).

Specifications:

Charging voltage: 12.6V
Maximum charging current: 25A*
Maximum continuous discharge current: 25A*
Short circuit protection: 45 ± 5A
Overcharge protection voltage (per cell/battery): 4.28 ± 0.05V
Discharge protection voltage (per cell/battery): 2.55 ± 0.08V
Balance function: Yes
Dimensions: 56x45x2.6mm
*Note: These are the maximum ratings of the BMS circuit. The connected batteries may not be able to handle this current!

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

B-: Negative cell/battery 1
B1: Positive cell/battery 1, negative cell/battery 2
B2: Positive cell/battery 2, negative cell/battery 3
B+: Positive cell/battery 3
P+: Positive output battery pack
P-: Negative output battery pack
Use the P+ and P- terminals to charge and discharge the battery pack.

Note: Assembling a Li-ion/Li-Po battery pack requires expertise. Only assemble the pack if you know what you are doing. Incorrectly connecting the batteries and the BMS circuit can cause the batteries to catch fire or even explode.

Dimensions
Length: 6cm
Width: 4.1cm
Height: 0.31cm