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.
5A
For currents up to 10A, you can use a variant of a BMS that was originally designed for 2S configurations.
The 1S and the 2S version of this board look very similar. Make sure you check the number of solder pads on the front side. The 2S version has five main solder pads. The 1S version has just three.
Connection
This board is small and rugged but the solder pads are poorly marked, and since there are only three solder pads, one serves as common + both for the battery and the output voltage.
Battery
When you look very closely and carefully, two solder pads are marked B+ and B- on the front side. The B- pad is also available on the backside (the B+ pad is not).
Connect the battery to B+ and B-.
Output Voltage
The output voltage is available at the solder pad marked C- (which is also available on the backside) and the same B+ pad that was already used to connect the battery. Both battery and output voltage share the pad B+.
Specs
| Protection | Threshold |
|---|---|
| Continuous Current | 10A |
| Overcurrent Protection | 60A, delay max. 1.5s |
| Overcharge Protection | 4.25V, recovery <4.18V |
| Discharge Protection | <2.8V, recovery >3V |
| Short-Circuit Protection | yes, 300us delay, release by load disconnect |
| Charging Current | 25A |
While you theoretically could charge your battery through this BMS, its current limiting functionality is useless for most battery types: the current is limited to 25A. Most power supplies you may use for charging cannot exceed this limit even if they wanted. And many simple 1-cell batteries cannot handle a charging current of 25A (for a 2.500mA cell this is a 10C charging). Always check the battery specs or better yet use an additional dedicated charger board.
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(content created Mar 26, 2024 - last updated Mar 28, 2024)