Lead Acid Battery Meter with LM339 Circuirs >>

In the circuit below, a quad potential unitage comparator (LM339) is employed as a straightforward chart meter to point the charge condition of a twelve volt, lead acid battery. A five potential unit reference voltage is connected to every of the (+) inputs of the four comparators and therefore the (-) inputs area unit connected to sequent points on a resistor. The LEDs can illuminate once the voltage at the negative (-) input exceeds the reference voltage. activity is done by adjusting the 2K potentiometer so all four LEDs illuminate once the battery voltage is twelve.7 volts, indicating full charge with no load on the battery. At 11.7 volts, the LEDs ought to be off indicating a dead battery. every junction rectifier represents AN approximate twenty fifth amendment responsible condition or three hundred millivolts, so three LEDs indicate seventy fifth, two LEDs indicate five hundredth, etc. the particular voltages can depend upon temperature conditions and battery sort, wet cell, gel cell etc. Electronics Circuit Application