12v Battery Charger circuit with Overcharge Protection
This 12-battery charger circuit provides an Automatic cut-off facility when the battery gets fully charged. Before the use of this circuit, you need to adjust the Cut off-voltage range for the auto cut. This adjustment is done by the moving 10k preset and for testing of output voltage auto cut range, a multimeter is connected to the output terminals that go to the battery. This voltage range can be set by using any 13v or 14v DC supply that connects the terminals which go to the battery. And move the preset till the green led ON. Once the auto-cut voltage is set, the circuit is ready to use.
One terminal of Input AC power to the Transformer is connected through 12 V Relay. When Battery needs charge then the Red Led glow, When the Charge level goes to about above 12v or 13v then the Red LED will OFF and the Green LED will Glow. And Input Power to the Transformer of the charger is also Disconnected by the Relay.
12v battery charger with auto cut-off circuit diagram
One 555 timer ic is used for detecting the voltage level and Relay is used to disconnect the AC input. 7808 voltage regulator is used for constant supply to the operation of the circuit to cut at a required fixed voltage.
This 12v battery charger Automatic cut circuit after a full charge and provides 6 Ampere high current and this can use for a big-size Lead-acid Battery up to 100 AH. If you want to more high current then replace the transformer with 10A and use a 10A10 Diode. You can use a readymade 12v 10 A Bridge Rectifier which is available in the market.
6A8 or 6A10- 4 pc
1N4007 – 1
7808 ic – 1 pc
555 timer ic – 1 pc
1000uf 50v – 1pc
1000uf 25v – 1pc
100nf (104) – 1 pc
10K – 1
5k – 1
470 Ω – 2
Relay 12v 6 A – 1
Preset 10k – 1 pc
LED 1 pc – Green
LED 1 pc- RED
Transistor BC547 -1 pc
10 amp battery charger circuit diagram
Connect positive output wire on NC through Common pin of Relay
This circuit has a maximum current capacity of 1 A only.