How to Make Your Own Solar Powered Flashlight
You can build a simple solar powered flashlight with a new or recycled clear plastic container and a few other new components. A solar flashlight consists of two main parts, the lighting module and the charging module. The lighting consists of a series of small LED bulbs connected to a rechargeable battery. The charging part involves charging the battery from a solar cell. This simple prototype can save you the expense of a lifetime of flashlight batteries.
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Things You'll Need
- Pliers
- Precision screw driver
- Wire cutter
- Drill
- Multi meter (measures voltage/current)
- Soldering iron
- Transparent plastic container with lid
- 6 LED lights with capacity of 15mA current each
- Wires
- Double stick tape
- Resistor with a 27 ohm to 33 ohm capacity
- Diode, model No. IN4001 or one comparable
- Solar cell, 5v with a current of about 70mA in full sunlight=.35 watts of power
- Nicad/Nimh rechargeable battery, 3.9v
- 1 horizontal terminal block
- 2 vertical terminal blocks
- Switch
Instructions
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1
Make a small hole about 1/16 of an inch in the top of the removable lid of a transparent plastic container small enough to be hand-held.
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2
Gently push the wire from the solar cell from outside of the lid to the inside of the lid.
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3
Tape the back and borders of the solar cell to the outside of the plastic lid with durable double stick tape. Put extra tape around the inside of the lid where the wire comes in to seal off any existing gaps to prevent dirt and water from getting into the container.
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4
Drill two small holes and install a small switch on the exterior of the plastic lid to control the on/off power of the flashlight. The switch should be on the outside of the lid and its wires on the inside so that they can be attached to the positive terminal of the battery.
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5
Tape a horizontal terminal block to the battery. Tape two additional vertical terminals to the horizontal terminal, one on each side.
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6
Strip the wire from one vertical terminal and wrap it around the negative terminal of the battery. Strip the wire from the other vertical terminal and wrap it around the positive wire to the switch and also the positive battery terminal. (This controls the on/off power of the flashlight.)
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7
Strip the wire on the white bar on the IN4001 diode (or one with similar capacity) and wrap it around the negative terminal of the battery. Strip the wire on the other side of the diode and wrap it around the positive outlet of the solar cell.
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8
Wire the LED lights parallel to each other by stripping the wires of the LED lights and wrapping one side around the negative battery terminal and the other side around the positive battery terminal.
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9
Screw the plastic lid with the solar cell and switch on the outside to its corresponding transparent container which encases the LED lights, diode and battery which completes the construction of your solar powered flashlight. Direct the lid of the flashlight with the solar cell towards optimum ultraviolet rays to initially charge your new flashlight, which should take a maximum of 4 hours of direct sunlight.
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Tips & Warnings
This prototype is not waterproof so you might want to seal off any gaps in construction with a silicone sealant.
This prototype does not control overcharging of the battery which is a common cause of battery damage, therefore you need to estimate when the charge is complete which should not take more than 4 hours, and remove it from the charger.
