2S 8A Battery Management Systems (BMS)

BMS For Two Battery Strings And 8A Max Current

BMS often ship in locked state: no output voltage is available at the output pins. Locked state is also entered whenever over-current protection was triggered. To unlock the BMS, connect it to a charger. If you did not add a dedicated charger board, apply the appropriate charging voltage to its output terminal.

When connecting batteries to your BMS, make sure to use wires with sufficient diameter for the anticipated high currents.

When designing battery packs, use batteries of same type and same state of charge only. It is recommended you fully charge all batteries before connecting. All batteries must have the same voltage (voltage difference less than 0.05V). Do not mix batteries from different vendors, types, capacity, or age.


LiIon LiPo

For currents up to 8A, one of the commonly used boards exists in a simple unbalanced and a balanced version.


The unbalanced version is smaller and more suitable when space is scarce. If you plan to charge the batteries through the BMS, you should still aim to use the balanced version.

The terminals are accessible both from top and bottom.


The balanced version is different only when you charge the batteries: now the balanced board monitors each individual battery cell and can adjust the charge individually to ensure that all cells are fully charged.

The terminals are accessible both from top and bottom.


Connect the batteries like this:

  • First battery string to B- (-) and BM (+)
  • Second battery string to BM (-) and B+ (+)

The output voltage is available at P+ and P-.


Protection Threshold
Over-Charge >4.3V
Over-Discharge <2.5V
Over-Current 15A
Short Circuit yes,resettable
Continuous Current 8A
Size 41x16x3.5mm


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(content created Mar 22, 2024)