Let’s build a small solar AA battery charger circuit savings. In an era of expensive energy better. In an era that energy is more expensive every day. Alternative energy is a good solution, to solve immediate problems, or renewable energy to do the work well. Solar energy is an alternative that we can use another kind. For this project, we use it to charge a small battery, we must first understand the working principle of the circuit before.
How it works.
Battery charger with solar cells consists of three parts are…
1. The solar cell panels are used to change a sunlight energy to electrical energy into direct current. Normally we would put solar panels are connected to each other. Until the voltage level as needed. Which, has the principle same battery, is sunlight cell series to increase the current. And this current production, depending on the geographic location, temperature and the amount of sunlight each day is important.
2. The charger controls the voltage in this project. We use the dc booster circuit to rises voltage from solar cell panels up to charge a battery.
3. The battery is backup electrical energy of solar cells in needs time.
Photos complete circuit as Figure 1, the heart of the increase voltage circuit is IC1 in TL497 is a DC to DC converter circuit types. There is resistor R1 between VCC and pin 13 that limit current working of circuit. And the capacitor C3 is determined value of switch frequency in working of 50KHz
We can adjust the output voltage as needed by potentiometer VR1. The output voltage that change be controlled by compared circuit inside IC1
Characteristics of working overall is This circuit will increase the size of the input voltage of 5 volt solar panels. (Normal the voltage 3-5volt, current 100mA) To output the voltage maximum 12-15 volt at current 30-70 mA. To provide sufficient the voltage to flow into the battery charging. The specifications of the IC can be up to 15 volt input voltage and maximum output current 470-500mA.
Building and circuit assemblies.
We prepare PCB size is shown in Figure 2 above. Then solder a resistor and IC on the PCB. Equipment is high, the coil L1 and capacitor according down.
R1______1 ohm Resistor 1/2W
R1______4.7K Resistor 1/2W
R1______1.2K Resistor 1/2W
C1______100uF 16 volt Electrolytic
C2______0.1uF 50V Ceramic
C3______220pF 50V Ceramic
C4______1000uF 25 volt Electrolytic
Testing and deployed.
We bring solar cell panels place in sunlight location, then measure an output voltage with the DC volt meter. Which we can adjust output voltage by charging the resistance of VR1. When less sunlight, will have output DC voltage about 15 Volt (the maximum resistance of VR1) In the case of the midday sun, for example during the day, We measure an output voltage, while load is not connected. will have maximum voltage 18-20 volt.
Using to charge the battery,
– The output voltage should not be too much. We adjust VR1 until the voltage of battery with less than full power for about 1 volt. Because solar panel in this project is small. So suitable for charging the voltage to the nickel cadmium battery NiCd. or Nickel Metal Hydride AA or AAA size NiHM only.
For example, in the case of a fully charged battery, nickel metal hydride. Which has the voltage at 1.2 volt pack of 4 pcs., So we adjust VR1 until the the voltage is 6 volt.
– The charging time, Battery charging time depends on the capacity of the battery. (MA h). If there is a large capacity, it will take longer. We can be calculated from : The capacity of the battery divided by the charging current as the battery 500 mAh. When it is charged with 50mA current, it takes about 10Hour etc. However, the current from the solar cell will be uneven, depending on the intensity of the light. May take longer for about 12 hours.
If everything is normal. We plan to install on the box or the angle the sun. As a prototype. With each other’s ideas.
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