Understanding the LED boards

White board

The most simple design. This board consists of 5 LED's with series limiting resistors and a pushbutton that triggers them.

It is connected to the BMS board through a 7 pin connector, and after reverse engineering it, the proposed schematic is:

The LED's are always set to +3.3 V on their anode, and that means they must be triggered LOW through the microcontroller pins (LED 1, ..., LED 5). Also, the pushbutton topology is uncompleted. It's been understood that PB pin must trigger the turn on, however, a pull-down resistor lacks in the design. We assume that it is on the BMS board side, so we must consider it on future designs.

Green board

For those BH batteries that have the green indicator, the circuit is more complex and some modifications must be considered in our board.

The working principle: the LED's are driven from the micro-controller through the MOSFET's. This time, opposite to the white indicator, we have a GND wire.

Thus, the connection is simple. we must attach the yellow wire (GND) to one of the internal ground pins of our circuit, and the rest go as usual. 

Other schematic is depicted below. This one  shows the interconnection between the BH board and this indicator.

Finally, the circuit should remain like the one in the photograph below: