Capacity indicator for Li-Ion batteries

As you can see from the title of this project, this time I want to present you a indicator circuit version made with the well-known LM3914; I present a small electronic circuit, designed with SMD and THD components, easy to assemble. With this electronic circuit you can build a tester for batteries Li-Ion, with nominal voltages of 3.6V (such as those in phones), 7.2V or 12V. Depending on its nominal voltage, the battery to be tested is connected to the GND terminals and 3.6V (J3), 7.2V (J2) and 12V (J1) respectively. On a bargraph or individual LEDs are displayed,

in percent, if the battery under test is fully charged (100%, means all LEDs are light up) or discharged (with 10% of rated capacity, only one LED is bright). To calibrate the circuit, on the input pin (Sig 5) and the reference pin (Rhi 6), of LM3914, must be measured, with a charged battery, 1.25V, and on reference pin (Rlo 4), 1.135V. The current through the LEDs is about a few mA.

Have fun with it !