18650 Lithium Lifepo4 Battery BMS Li Ion Battery Board 8S 9S 10S 40A BMS

Working process of protective board

1. How to activate the protective board

When the protection board P+ and P- have no output in the protection state, you can short-circuit B+ and B- to activate the protection board. At this time, Dout and Cout will be at low level (the two ports of the protection IC are high-level protection, low-level Normal) state to turn on these two switches.

2. Charging

P+ and P- are connected to the positive and negative poles of the charger respectively. The charging current passes through the two MOS to charge the battery. At this time, the VDD and VSS of the protection IC are both the power supply terminal and the cell voltage detection terminal (through R1).

As the charging As the process proceeds, the voltage of the battery core continues to increase. When it reaches the protection voltage of the battery core (overcharge protection voltage), COUT will output a high level at this time to turn off the corresponding MOS switch, 

and the charging circuit will also be turned off. after overcharge protection, the cell voltage will drop. When it drops to the IC voltage threshold (overcharge protection recovery voltage), Cout returns to a low level and turns on the MOS tube.

3. Discharge

Similarly, when the battery is discharging, the VDD and VSS of the IC will also detect the cell voltage. When the cell voltage drops to the IC threshold (over-discharge protection voltage), Dout will randomly output a high level to turn off the corresponding MOS tube. off, 

the discharge circuit is disconnected, and after over-discharge protection, the cell voltage will rise. When it rises to the threshold voltage (over-discharge protection recovery voltage), Dout returns to low level and opens the MOS switch.

4. Overcurrent and short circuit

When the main circuit current is too large during the discharge process, due to the internal resistance of the MOS saturated conduction, a voltage drop will occur at both ends of the MOS tube when the current flows between B- and P-,

protecting the V- and VSS of the IC. (via R2) will detect the voltage at both ends at any time. When the voltage rises to the detection threshold of the protection IC (usually 0.15V, discharge detection overcurrent voltage),

Dout will immediately output a high level to turn off the corresponding MOS tube, and the discharge circuit is disconnected.

This protection board supports 8S-10S
Different string number selections can be achieved by changing part A.
8S: Connect the "8S" position with a 1K resistor;
The "10S" position is left blank.
9S: Leave the "8S" position blank;
The "10S" position is left blank.
10S: Connect the "10S" position with a 1K resistor;
The "8S" position is left blank.

Wiring precautions:
1. Installing the protective board requires a certain amount of technical electronic knowledge.
2. When wiring, first connect the B- wire at the soldering pad position to the total negative terminal of the battery (the B- wire should be soldered to a short and thick wire) and solder the wired terminal to the battery pack first, and then insert the protective plate.
3. The connection between the battery terminal B- and the protection board terminal B- should be short and thick, otherwise it will cause the protection board to charge and discharge in advance and malfunction.

4. You need to use thick wires when wiring P+/P-. Wires that are too thin and too long will burn the board!