The bc548 transistor is working as a switch which will disconnect the ground of the lm317t from the solar cell when the battery become full charge.
Solar panel 12v battery charger circuit diagram.
Solar panel 20v 1 amp.
Before delving into the following concepts you can probably try this super easy solar battery charger which will ensure safe and guaranteed charging of a small 12v 7 ah battery through a small solar panel.
Circuit diagram of solar panel battery charger step 6 from below you can see the soldered connections how they run along the copper tracks.
One 555 timer ic is used for detecting the voltage level and relay is used to disconnect the ac input.
The following solar panel wiring diagram shows that a 12v 120w pv panel is connected to the solar charge controller panel negative terminal of panel to the negative terminal of mppt charge controller and vice versa for positive terminal.
1n4007 diodes 3nos.
12v battery charger with auto cut off circuit diagram.
Ic 7812 1no.
That looks cool isn t it.
7808 voltage regulator is used for constant supply to the operation of the circuit to cut at a required fixed voltage.
I have added in the brown wire as brown line the diode as a blue line i have also added in the ve ve makers for the battery.