Picture of Solar Powered AA Battery Charger
Rechargable batteries are a great invention, but if you dont have an outlet nearby to charge them, they are usless. So I designed a solar powered battery charger, which allows you enough power to charge a single AA battery wherever the sun may shine.

I chose to do this project in two steps:
First I set it up to test that I generated the needed voltage (3-7).
Then I set it up to finalize, by using wire instead of alligator clips, this made it both look better and was easier to work with (8-10)

People have told me that 1 volt is not enough to charge a battery. I looked a rechargable battery and it said "charge: 1-2 volts." I would also like to add that I switched the tester to 2.5 volts and the meter moved to 50%. This tells me I do not only generate 1 volt, but 1.25 volts give or take...
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Step 1: Materials

Picture of Materials
Here is a list of the Materials you will need to recreate the Battery charger I have made,
-Light socket attached to wood (with outlet plug)
-100 watt bulb
-Hot glue gun
-Two solar panels
-Three alligator clips
-Rechargeable AA battery
-Voltage tester
-Battery holder

Once you gather your equipment, I suggest plugging in your Hot Glue Gun, so it is available to you once needed (Step 4)

Step 2: Step One

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Take your wire and cut off two pieces that are about 4 to 5 inches long each. Once you have them cut, connect the wires to the battery holder, one wire to the postivie side, and the other to the negative side.

Step 3: Step Two

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Connect one alligator clip to the negative on the Voltage tester, and the other alligator clip to the positive.

Step 4: Step Three

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Set the Voltage tester to 1 volt (DC). Rechargeable AA batteries need 1-2 volts for them to charge, this will allow you to see that you generate at least 1 volt.

*Make sure that the voltage is on DC and NOT AC*

Step 5: Step Four

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Take your Glue Gun and glue the two solar panels together, try to match them up so that the negative of on panel is adjacent to the positive of the other solar panel.

*See picture two if you find this confusing.*

Step 6: Step Five

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Connect the negative of one panel to the positive of the other panel, and then connect the remaining positive to the positive on the voltage tester, and the remaining negative to the negative on the voltage tester.

Step 7: Step Six

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Plug in and turn on the light. Test that the voltage given off by the solar panels gives you at least one Volt; this is enough to charge the AA battery.

*Once you have done this, you can remove the alligator clips from the tester and solar panels.*

Step 8: Step Seven

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Connect ONE of the postives on one solar panel to the negative on the other solar panel using wire.

*Only connect ONE positive to ONE negative.*

Step 9: Step Eight

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You should have one positive and one negative remaing, connect the negative on the battery holder to the remaining negative on the panel. Then connect the remainging (positive) wire on the battery holder to the positive on the remaining panel.

Step 10: Step Nine

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Now glue your solar panels and your battery holder to the wooden board.

Congratulations, you have made your own solar powered battery charger!
Just make sure that unless you have sunlight and are charging a battery, do not have the Battery in the holder. Otherwise it may lose its charge.
Could this be expanded for more than one battery say like up to 10 of them?

You could charge more batteries, but they would have to be in parallel...HOWEVER it would take much longer to charge all ten of them with the current setup of the solar array...which means that you would have to add more solar panels to the array.

go and get a 12v solar panel (13x30cm approx) and a diode and then you can charge up to 10 at a time(only in direct sun) 500mah 180 min 600mah 200min 700mah 230min 800mah 270min 1000mah 370min+ 1300mah 430min 1700mah 500min 2000mah 630min 1.2ah drill battery(9.6or12v) 6-7hours

You should add a blocking diode between the solar array and the battery to prevent the battery from discharging in low light or when there is no light. Nice project nevertheless!

Schmidty162 years ago
how do u know when the battery is charged
degen S.3 years ago
Hey i just had two questions.
1. When the battery is charged will it over charge and kill the battery.
2. How many volts does both of your solar panels make.
please reply i really want to make this

808create5 years ago
Does this, or any of these solar battery chargers, work on (3.6v/3.7v) lithium-ions? With or without PCBs? Thx
DIY Dave6 years ago
Do the solar panels have built in diodes?
12V6 years ago
if you add a diode it will prevent battery from draining and going flat.
tecneeq 12V6 years ago
Indeed, a simple diode would improve this a lot.
nickandcody6 years ago
what is this it needs more work
Tornado916 years ago
This project doesn't need diode??
oops!! also different sizes aaa-d?
lemonie6 years ago
1V is not enough to charge this type of cell, you need something more like 1.5V. Have you tested this and found it to work? L
even more to overcome internal resistance
No load my NiMH's are giving me 1.38V, so I'd say you need to be able to manage1.5V at least. Next time they need a charge I'll see what the charger is giving them. L
trialex6 years ago
No diode to prevent back flow? When your battery is charged AND the solar panel is in the dark, the battery will actually start discharging INTO the solar cell. Just put a simple diode like a 1N4001 between the +ve terminal of the solar cell and the +ve terminal of the battery - the cathode (white stripe end) of the diode towrds the battery.