With old batteries and a few simple components, I can build my own solar phone charger. This allows me to harness the power of the sun to charge my devices, reducing my dependence on the grid. A solar charger is also useful for emergency preparedness and for powering devices off-grid. In this article, I will walk through the full process of assembling a DIY solar phone charger from start to finish using reused materials.

Gathering the Necessary Components

To build the solar charger, I will need to gather a few key components:

Old Batteries

The repurposed batteries will act as the energy storage for the solar charger. I can use any rechargeable batteries - old AA or AAA batteries work well. Lithium-ion batteries from an old laptop would also work. I need at least 3 batteries in decent condition to store enough energy.

Solar Panel

I need a small 5V solar panel that can connect to the batteries via USB. These are inexpensive and commonly available online or at electronics stores. The solar panel converts sunlight into electricity.

Charge Controller

A charge controller manages the power from the solar panel to the battery bank, preventing overcharging. I can find these for under $10 online.


I'll also need various connecting wires and cables like jumper cables to connect all the components. Having a soldering iron and solder can be useful too.

Box (Optional)

For housing the charger, I can reuse any plastic food container or project box. Making compartments inside will help organize the components.

Assembling the Charger

With all my materials gathered, I can now put together the solar phone charger:

Connecting the Batteries

First, I need to connect my 3 reused batteries together in parallel using jumper cables. This combines their voltages into one battery bank that can store more power. The positive terminal of each battery connects to the next, and the negative terminals all connect together.

Wiring the Charge Controller

Next, I connect my charge controller to the battery bank's positive and negative using cables. My solar panel will also plug into the charge controller. This manages the energy flow.

Adding Solar Panel

Then, I plug my 5V USB solar panel into the charge controller using the included cables. Positioning the solar panel in direct sunlight will allow it to start charging the batteries.

Connecting Charging Port

Finally, I take a short USB cable and connect from the charge controller's USB output port to a 5V USB charging port that I can plug my phone into.

Optional: Housing in Container

For a nice package, I can place my wired components safely inside a plastic food container or project box, feeding the cables through holes or notches cut in the sides.

Using and Maintaining the Solar Charger

Now I have a DIY solar phone charger! Here are some tips for using and maintaining it:

Placing it in Direct Sunlight

For best performance, I need to ensure the solar panel gets maximum sunlight throughout the day. Placing it in a south-facing position works well if in the northern hemisphere.

Keeping Batteries Charged

The solar panel will keep the batteries topped off each day, but I should check the charge level occasionally. I may need to supplement with charging via a wall outlet to keep the batteries conditioned.

Replacing Old Batteries

Every 1-2 years, I should plan to replace my reused batteries, as their capacity will degrade over time. Reusing batteries again keeps waste out of landfills.

Checking Wire Connections

It's good to check the wire connections every so often to ensure they are still tight and corrosion-free. Loose connections can cause power loss.

With proper care, my DIY solar phone charger should provide years of reliable off-grid power from the sun! Let me know if you end up building one too using this guide. I'm happy to help troubleshoot any issues with your own project.