Battery Level Plus HD

Introduction
Today we will make a battery power monitoring system which can detect the power of two lithium batteries. To detect Arduino power supply, the Adeept Proto Shield R3 Board is needed. Do not take the Arduino UNO R3 IO port.
Components
– 1 * Adeept UNO R3 Board(Arduino UNO R3 Board)
– 1 * Adeept Proto Shield R3 Board
– 4 * Resistance(10KΩ)
– 1 * Resistance(2KΩ)
– 1 * Resistance(27KΩ)
– 1 * Resistance(36KΩ)
– 3 * Resistance(3KΩ)
– 1 * Resistance(33KΩ)
– 2 * Resistance(18KΩ)
– 4 * LED
– 1 * Wires
– 1 * TL431
– 1 * LM324
– 2 * 18650 Battery
– 1 * Electric iron

Schematic diagram

After welding :

Circuit test

Full grid electricity （about：Vin>7.6V）：

After a period of time, the power dropped to three cells（about：7.6V>Vin>7.1V）.

After a period of time, the power dropped to two cells（about：7.1V>Vin>6.5V）.

After a period of time, the power dropped to one cells（about：6.5V>Vin>6V）.

After a period of time, the power dropped to zero cells（about：Vin<6V）.