Star finder battery indicator circuit

This circuit is used in star finders. Its function is to detect the battery voltage and estimate the remaining battery power. When the remaining power is about one third, the indicator light will light up. The detection accuracy is 0.1V.

The core component U1 is a very common IC with a reference voltage source and an error amplifier output. The battery voltage is divided by R1 and R2 and added to the input of U1. Taking three lithium batteries in series as an example, when the remaining power is about one-third, the voltage will drop to 10.8V. The potential of the output end of U1 is pulled up by R3, and the indicator LED1 lights up. C1 and C2 are vibration and noise elimination capacitors respectively.