Wiring Schematic Diagram

This car battery charger circuit is drawn to charge 12V batteries ONLY. It is fully automatic and will charge at a rate up to about 4A until the battery voltage reaches a preset point at which it will switch to a very low current float charge. If the battery voltage drops again the charger will begin charging until the voltage once again reaches the cut off point. In this way it can be left connected to a battery indefinitely to maintain full charge without causing damage.

The red LED will turn on, when charging is complete and charging circuit will deactivated. This circuit used only for 12 V battery. When wiring up the circuit, Certain emphasis should be taken. They are hose supplying current to the battery being charged and the connections of the transformer to the circuit board. To prevent heat build-up and voltage-drop when current flows through the circuit, the connections of the transformer to the circuit board should be made with cables having a large cross-sectional area

R1= 1Kohms    D1 = 1N4001                 T1 = 15V/5A Transformer
R2= 1.2Kohms  D2 = 6.8V 0.5W zener        LD1= Green LED
R3= 470 ohms  TR1= 4.7Kohms trimmer       LD2= Red LED
R4= 470 ohms  Q1 = BTY79/similar 6A SCR   M1 = 5A DC Ampere meter
R5= 10K ohms  Q2 = C106D SCR              S1 = On-Off Switch
C1= 10uF/25V  GR1= 6A Bridge Rectifier    F  = 5A Fuse