Battery Charger Circuit Diagram Using Photo Voltaic

This is the circuit diagram of a rechargeable battery charger using solar cell/PV as a DC power source . This circuit can charge three types of rechargeable batteries: Lead Acid, NiCad and Lithium Ion. Lead acid batteries are generally used in emergency lights and UPS. The PV module or solar cell explained in this article is capable of producing 5 watts of power. In full sunlight, the solar cell outputs 16.5V. It can provide 300-350mA of current .

How does the circuit work?

The working of the circuit is very simple. The output of the solar panel is powered through a diode 1N5402 (D1) which acts as a polarity protector and protects the solar panel. An ammeter is connected in series between the diode D1 and the fuse to measure the current flowing during battery charging. As shown in Figure #1, we have used an analog multimeter with 500mA range . Diode D2 is used to prevent reverse polarity in case the lead acid battery is connected incorrectly. In case of wrong polarity, the fuse will blow.

To charge the lead-acid battery, switch S1 to the "on" position and use connector "A". After connecting the battery, the solar panel starts charging through diode D1, multimeter and fuse. Please note that pulsating DC is the best choice for charging lead-acid batteries. If you use this circuit to charge lead-acid batteries, replace the ordinary pulsating DC charger once a week. Keep checking the water level of the lead-acid battery. Pure DC voltage usually causes sulfur to deposit on the lead-acid battery plates.

To charge the Ni-Cd batteries, switch the switches S1 and S3 to the "on" position and use the connector "B". The voltage regulator IC 7806 (IC1) is wired as a constant current source and its output is taken from the middle terminal (usually grounded). Using this circuit, a constant current goes into the Ni-Cd batteries for charging. A total of four 1.2V batteries are used here. The resistor R2 limits the charging current.

To charge Li-Ion battery (used in mobile phones ), switch switches S1 and S2 to the "on" position and use connector "C". Voltage regulator IC7805 (IC2) provides 5V voltage for charging Li-Ion battery. Using this circuit, you can charge 3.6V Li-Ion battery very easily. Resistor R3 limits the charging current. The circuit for a small LED based lamp is shown . It is simple and low cost. Six 10mm white LEDs (LED2 to LED7) are used here. Just connect them in parallel and drive them directly from a 3.6V DC power supply. You can use a pencil type NiCad battery or a rechargeable battery as the power source.

The circuit was assembled on a general purpose PCB and enclosed in a small box. RCA sockets were installed on the front panel of the box and RCA plugs were connected with cables for connecting the battery and LED based light to the charger.

Using this circuit, you can save money on your electricity bill by switching to an alternative power source.