Build Your 5W Solar Charger & LED Lamp Circuit

Description

Energy costs can be reduced by transitioning to alternative energy sources. The photovoltaic module or solar panel described here is capable of delivering a power of 5 watts. At maximum sunlight exposure, the solar panel outputs 16.5V and provides a current of 300-350 mA. It can be utilized to charge various battery types: lead acid, Ni-Cd and Li-ion. Lead-acid batteries are frequently utilized in emergency lighting systems and uninterruptible power supplies. The operation of the circuit is straightforward.

The output of the solar panel is fed via diode 1N5402 (D1), which acts as a polarity protector and safeguards the solar panel. An ammeter is connected in series between diode D1 and a fuse to measure the current during battery charging. As depicted in Fig. 1, an analogue multimeter in a 500mA range has been employed. Diode D2 is incorporated for reverse polarity protection in the event of an incorrect lead-acid battery connection.

Charger Circuit Diagram:

If an incorrect polarity is connected, the fuse will trip. For charging a lead-acid battery, shift switch S1 to the ‘on’ position and use connector ‘A.’ Following battery connection, charging initiates from the solar panel via diode D1, ammeter, and fuse. Pulsating DC is considered optimal for charging lead-acid batteries. If this circuit is used to charge a lead-acid battery, a standard pulsating DC charger should be substituted weekly.

The water level of the lead-acid battery should be regularly monitored. Pure DC voltage can lead to the deposition of sulphur on the plates of lead-acid batteries. For charging Ni-Cd cells, shift switches S1 and S3 must be set to ‘on’ and connector ‘B’ must be used. Regulator IC 7806 (IC1) is configured as a constant-current source, with its output taken from the middle terminal (normally grounded). This circuit provides a constant current for charging Ni-Cd cells.

Small LED Lamp Circuit Diagram:

A total of four 1.2V cells are employed within this circuit. Resistor R2 limits the charging current. For charging a Li-ion battery (utilized in mobile phones), shift switches S1 and S2 must be set to ‘on’ and connector ‘C’ must be used. Regulator IC 7805 (IC2) delivers 5V for charging the Li-ion battery. This circuit facilitates the easy charging of a 3.6V Li-ion cell. Resistor R3 limits the charging current. Fig. 2 illustrates the circuit for a small LED-based lamp. It is simple and inexpensive.

Six 10mm white LEDs (LED2 through LED7) are utilized within the circuit. They are connected in parallel and are driven directly by a 3.6V DC source. Either pencil-type Ni-Cd batteries or rechargeable batteries can be used as the power source. The circuit should be assembled on a general-purpose PCB and enclosed within a small box. An RCA socket must be mounted on the front panel of the box, and an RCA plug should be wired with a cable for connecting the battery and LED-based lamp to the charger.