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Home » 6V To12V Lead Acid Battery Charger Circuit

6V To12V Lead Acid Battery Charger Circuit

Last updated on 24 December 2025 by Admin-Lavi Leave a Comment

This article for 6V To12V Lead Acid Battery Charger Circuit explains about a dual voltage battery charger circuit.

Lead acid battery needs correct voltage for proper charging.

This charger circuit gives correct charging for both batteries.

LM317 IC is the main part of the circuit and it gives stable charging voltage.

Battery voltage is selected using a simple switch.

The circuit design is simple and reliable and is good for DIY electronics projects.

Circuit Working:

6V To12V Lead Acid Battery Charger Circuit Diagram

Parts List:

Components TypePartsQuantity
Resistors220Ω, 2.2k, 1.8k1 each
CapacitorsElectrolytic 2200uF 25V2
Electrolytic 47uF 25V1
SemiconductorsIC LM3171
Schottky Diode MBR15452
Bridge Diode 1N54024
Switch ON / OFF Switch1
ON / OFF Closed Switch1
Fuse1A, 2A Fuse2
Transformer 15V 2A, 220V AC1

AC mains supply is given to the transformer and transformer reduces the voltage to 15V AC.

Bridge rectifier converts AC to DC.

Capacitors smooth the DC and reduce ripple.

Filtered DC goes to LM317 input pin and this LM317 controls charging voltage using resistors.

Switch selects 6V or 12V mode.

Diodes stop reverse current and protect the circuit.

Fuse gives overload protection.

Battery starts charging when connected.

How to Build:

To build a 6V To12V Lead Acid Battery Charger Circuit follow the below connection steps:

  • Assemble all parts according to the circuit diagram.
  • Connect transformer primary to AC mains through switch S1 and fuse F1.
  • Connect transformer secondary 15VAC to bridge rectifier input.
  • Connect bridge rectifier AC terminals to transformer secondary.
  • Connect bridge rectifier positive to capacitors and LM317 input.
  • Connect bridge rectifier negative to ground line.
  • Connect capacitor C1 and C2 positive pins to rectifier positive.
  • Connect capacitor negative pins to ground.
  • Connect LM317 adjust pin to resistors R1, R2 and R3.
  • Connect LM317 output pin to diode D5, fuse F2 and battery positive.
  • Connect LM317 input pin to filtered DC from C1 and C2.
  • Connect diode D5 in series with battery positive.
  • Connect diode D6 across output and ground for protection.

Conclusion:

This 6V To12V Lead Acid Battery Charger Circuit is simple and reliable.

It can charge both 6V and 12V lead acid batteries.

LM317 gives stable and safe output voltage.

Circuit is easy to assemble and is with low cost.

Suitable for beginners and DIY electronics projects.

Proper heat sink is required for LM317.

References:

Can I charge two 6 V batteries with a 12 V battery charger?

Filed Under: Battery Charger Circuits

About Admin-Lavi

Lavi is a B.Tech electronics engineer with a passion for designing new electronic circuits. Do you have questions regarding the circuit diagrams presented on this blog? Feel free to comment and solve your queries with quick replies

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