Battery Charger

Lead Acid Battery Charger Schematic Circuit Diagram

The IC LM 317 is used in this lead-acid battery charger circuit. The IC here ensures that the battery receives the proper charging voltage. 1/10 of a battery’s Ah value must be charged. This fact has influenced the design of this charging circuit. Q1, R1, R4, and R5 control the charging current for the battery. The charging current can be adjusted using the potentiometer R5. The current via R1 grows when the battery is charged. This affects Q1’s conduction. Because Q1’s collector is connected to the IC LM 317’s adjust pin, the voltage at the LM 317’s output rises. The charging current is reduced after the battery is fully charged, and this mode is known as trickle charging.

Lead-Acid Battery Charger Schematic Circuit Diagram:

PCB Layout:

3D Diagram:

Components of Lead Acid Battery Charger Circuit

  • 7815
  • Rectifier Bridge
  • 1 (5W), 1K x 2, 1.2K, 1.5K x 2, 10K resistors
  • 1N4007, x 3, 1N4732A diodes (Zener)
  • NPN Transistor 2SD882
  • 4 x LEDs
  • 50KΩ Potentiometer
  • 12 Volt Relay

Component Description


The 7815 is a linear voltage regulator from the 78XX series. You might have used 7805 and 7812, which provide 5V and 12V regulated voltages, respectively. The 7815 Voltage Regulator, on the other hand, generates a steady regulated voltage of 15V.

Lead Acid Battery

Gaston Plante invented the lead-acid battery in 1859, and it is a rechargeable battery. The key advantages of a lead battery are that it dissipates relatively little energy (if it dissipates less energy, it can run for a long time with great efficiency), it can deliver strong surge currents, and it is inexpensive.

How to Recharge a Lead Acid Battery?

To charge a battery from AC we need a step-down transformer, a rectifier, a filtering circuit, and a regulator to maintain the constant voltage. Then we can give the regulated voltage to the battery to charge it. Think if you have only DC voltage and charge the lead acid battery, we can do it by giving that DC voltage to a DC-DC voltage regulator and some extra circuitry before giving it to the lead acid battery. A car battery is also a lead-acid battery.


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