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 5A, there are a few commonly available choices available.
While the vendors claim that these boards can sustain a continuous current of 5A, given the small size of the boards, you should either stay below 3A or add additional heat sinks.
Sleeve-Connectors
This board comes with long metal sleeves that can be soldered or spot-welded right onto 18650 batteries (but can be used with other LiIon or LiPo batteries as well):
Connection
Its long metal sleeves are designed to be fitted to 18650 LiIon Cells using spot welding but you can shorten the connector terminals and solder them to LiPo as well.
On the backside, there are two terminals marked B+ and B- that are identical to the metal sleeves and go to the battery.
The output voltage is available at the terminals P+ and P- in the middle of the backside.
Specs
| Protection | Threshold | Release | Delay |
|---|---|---|---|
| Over-Charge | >4.3V | <4.1V | 70ms |
| Over-Discharge | <2.4V | >3.0V | 35ms |
| Over-Current | 6A |
Regular Connectors
This board is based on the DW01 chip and three 8205A MosFET:
All solder pads are located on the backside:
Connection
Connect the battery to B+ and B-. Output voltage is available at P+ and P-.
Specs
| Protection | Threshold |
|---|---|
| Continuous Current | 5A |
| Maximum Current | 6A |
| Overcurrent Detection | 7.5A |
| Over-Charge | >4.25V (release at <4.23V) |
| Over-Discharge | <2.45V |
| Size | 35x7.4x2.2mm |
Charging
When you charge your battery through this BMS, the charging voltage is 4.2V.
It is always recommended for charging to use an additional dedicated charger board that limits the charging current to the levels appropriate for your particular battery.
These simple BMS are not designed to be chargers. They do limit the charging current, but there is no way for you to adjust the current. It is typically a fairly high current that may be significantly too high for many battery types.
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(content created Mar 24, 2024)