Electrical – How over-discharge protection function works on this circuit


How this circuit to protect so call "over discharge"? since there's no output + and – terminals on the board and this case the load should connect directly to B+ and B- without any protection for discharging.
enter image description here

Best Answer

That board looks like a DW01 IC based board. Let's look at the DW01 datasheet.

It has these diagrams:

enter image description here

Note that the BATT+ and BATT- connections in this schematic correspond to the terminals marked P+ and P- on your PCB!

Also note that the IC detects Overdischarge by monitoring the voltage of the battery using the botton left comparator in the Functional Block diagram.

If the battery's voltage gets too low, the DW01 will switch off the two MOSFETs (M1 and M2) to open the connection to BATT- (= P- on your board) to stop the discharging.