This battery charger circuit provides the Automatic cut off the 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 10k preset, and a multimeter connected with the output terminals that go to the battery.
This voltage range can be set by using any 4v to 15v DC supply which 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.
Parts List for automatic Battery Charger
- Transistor BC547 or use any NPN transistor
- D1 Red LED, D2 Green LED, D3 IN5408 or according to Output current, D4 IN4007
- Resistor R1 1k, R2 10k, R3 for 3.7-volt battery 220 ohms, 6volt-470 ohms, 12V 1k
- VR1 10k
- Relay for 3.7-volt battery 5V, 6volt- 5V or 6V, 12V -12V