Product Introduction:
1>. Power Consumption: all lamps on 42mA; single lamp on 4mA
2>. Measurement Range: universal 2.4-20V batteries
3>. Color: Green
4>. Display Way: multi-lamp bar display or single lamp dot display
5>. PCB Size: 45*14mm
6>. Adaptive for lithium batteries, lead acid batteries and other batteries which need display electricitiy quantity.
7>. Power display adjustable; support single lithium battery 1S-4S (4.2V-16.8V); lead acid battery 6-12V; Ni-MH 3.6-18V; nickel-cadmuum battery 3.6-18V.
8>. Display Way Introduction: display battery upper/lower limit voltage, and it can be divided into 10 gears; every lamp on represents display 10%; 10 lamps on represents display 0-100%; and it can be also changed into single lamp display,that means only one lamp is on.

Lithium Battery:
After single lithium battery discharges, its voltage is 3V, when fully charged, it is 4.2 V
1S-->3V (the first lamp) to 4.2V (the tenth lamp)
2S-->6V (the first lamp) to 8.4V (the tenth lamp)
3S-->9V (the first lamp) to 12.6V (the tenth lamp)
4S-->12V (the first lamp) to 16.8V (the tenth lamp)
other parallel voltage so on

Lead Acid Battery:
Lead acid battery usually is 6V or 12V battery
6V--> 4.8V (the first lamp) to 6.75V (the tenth lamp)
12V--> 9.6V (the first lamp) to 13.5V (the tenth lamp)

Adjustment Way:
Necessary Equipment: Adjustable stabilivolt power; Screwdriver
Take single lithium battery 3.7V as an example, 3V is undervoltage low port; 4.2V is full power high port
1>. Adjust adjustable power to voltage high port 4.2V, then connect with this board ; and there may be
  2 results: one result is not on, another result is all on or several on; then adjust 503 potentiometer slowly until LED is all on; if it is not on or several on, please counter clockwise adjust; if all on, please clockwise adjust.
2>. Adjust adjustable power to voltage low port 3V, then adjust 502 potentiometer until there is a LED on; if it is not on, please adjust it clockwise; if there is all on or several on, please adjust it counter clockwise.

If there is no high-precise adjustable power, then charge the battery to full power that is high port voltage; when the battery discharges completely that is low port voltage; connect with the board and adjust it again.

Notice:
1>. Please operate according to above instructions;first adjust high port then adjust low port.
2>. Red wire connects with positive, black wire connects with negative. Please don't connect it reversely; the maximum limit voltage is 20V, please use anti-static bonding pad.

Finished Product Picture:

Tested by ICStation's Outstanding Partner learnelectronics:

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(The language in the video is English)