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.
5A
Rectangular
For currents up to 5A, you can use a very small BMS:
The connectors are located on the back:
Circular
The same logic is also available in a circular form factor:
The connectors are located on the back:
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-.
Specs
| Protection | Threshold |
|---|---|
| Over-Charge | >4.28V |
| Over-Discharge | <2.9V |
| Over-Current | 7A |
| Short Circuit | yes,resettable |
| Continuous Current | 5A |
Occasionally, this BMS is marked as HX-2S-01.
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(content created Mar 22, 2024)