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.
This BMS is designed for high currents. Use copper 3mm2 copper wires to connect the batteries.
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.
60A
For currents up to 60A, here is a rugged and balanced BMS:
There is a similar board available for currents up to 40A. Make sure you check the markings on the board. These BMS are designed for tool batteries (i.e. a drill) that draw a high initial current. The continuous current is typically much lower and should not exceed 30A. Make sure you connect batteries with the appropriate current capabilities. Typically batteries with 20C or more discharge current are required.
[!NOTE]
A heat sink may be required with continuous currents exceeding 30A.
Connections
Connect the batteries like this:
- First battery string to 0V (-) and 4.2V (+)
- Second battery string to 4.2V (-) and 8.4V (+)
- Third battery string to 8.4V (-) and 12.6V (+)
The output voltage is available at the terminals marked + and - at the port labelled Discharge.
All terminals are also available at the bottom:
Specs
| Protection | Threshold |
|---|---|
| Continuous current | 60A |
| Over-Charge | >4.20V |
| Over-Discharge | <3.0V |
| Over-Current | 125A |
| Short Circuit | yes,resettable |
| Continuous Current | 20A |
| Size | 62x41x3.4mm |
The vendor claims this BMS has a short circuit protection. At the same time the vendor warns to deliberately short circuit the BMS. Due to the high currents, it is likely that the BMS can be damaged by a prolonged short circuit due to excessive heat.
Charging
This BMS has dedicated charging terminals marked as Charge. Charging voltage needs to be 12.6-13.6V. The BMS limits the charging current to 20A.
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(content created Mar 28, 2024)