Earth4energy how to make homemade solar battery charger

Rechargeable batteries make good economic and environmental sense. In the same way that you wouldn’t throw away the glass every time you had a drink, so it doesn’t make sense to dispose of batteries when others are available that perform the same task many times over.

It gets even better than that when you realize that you don’t have to use any mains electricity at all to recharge your batteries—you can use the power of the sun! Solar battery chargers like this model are commercially available, which can be obtained from the Centre for Alternative Technology, U.K.

You will need:
AA battery holder
9 V battery clip (you might need this to connect to your battery holder)
8 × solar cells 0.5V, 20 to 50 mA in full sun
1N5818 Schottky diode

The circuit here will recharge a pair of AA batteries quite happily when left in the sun. This circuit is a very simple design which doesn’t provide any regulation, so you will need to make sure that you disconnect your batteries when they are recharged.

The Schottky diode prevents the batteries’ charge from flowing back through the solar cells when no charge is present. Schottky diodes have the advantage of not sapping too much of the power from our solar cells—maximizing the amount that is delivered to the batteries.

Construction is fairly simple. There are a wide array of cases available that are suitable for housing such a project. If you can get a housing with an integral battery holder you will find it will make neat work of housing the project.

House the cells in such a manner that they are shaded and protected from the sun. If the cells get too hot their electrolyte leaks—damaging the cell and making a mess.

If you want to learn more solar projects you can do for your own home, Earth4Energy offers step-by-step video tutorials any non-engineer can easily follow.