LED VoltMeter Circuit

A Simple LED Voltmeter to Monitor the charge level in Lead Acid Battery or Tubular battery. The terminal voltage of the battery is indicated through a four level LED indicators. The nominal terminal voltage of a Lead Acid battery is 13. 8 volts and that of a Tubular battery is 14. 8 volts when fully charged. The LED voltmeter uses four Zener
LED VoltMeter Circuit - schematic

diodes to light the LEDs at the precise breakdown voltage of the Zener diodes. Usually the Zener diode requires 1. 6 volts in excess than its prescribed value to reach the breakdown threshold level. When the battery holds 13. 6 volts or more, all the Zener breakdown and all LEDs light up. When the battery is discharged below 10. 6 volts, all the LEDs remain dark. So depending on the terminal voltage of the battery, LEDs light up one by one or turns off.

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