How to make portable Solar Mobile battery charger

I was planning for 10 days trekking with my friends. We were unknown about the route. I had already downloaded the google map on my smartphone. Also, I plan to carry power bank with me. But I thought for a while, it was 10 days trekking with no electricity and charger. Also, with the continuous use of GPS, the battery drains too quickly.

There were no other options. So, decided to build portable solar mobile battery charger so that whenever I found the sunlight, I instantly charge my smartphone and can continue my trekking journey successfully. Not only for trekking, I found it was very useful in other places as well like if you have power cut for longer time. So, let’s start:

Step 1: Collection of necessary equipment

Soldering Iron

Soldering wire

Multimeter

Minus screw driver

12v regulated DC supply source

Step 2: Calibration of Buck Regulator

In above figure, it’s a clear view of Buck regulator. It has labeled input pin and output pin but it doesn’t mean that it will work if you directly connect the solar panel. Remember that it’s a 12v regulator so, don’t use it without calibration.

Can you see the blue resistive trimmer with screw over it? That is used for calibration. Connect the 12v DC supply to input pin of buck regulator. Connect multimeter to the output pin of buck regulator. Make sure your multimeter is in DC voltage measuring mode. Keep rotating the screw on the blue resistive trimmer with screw driver until you see 5.5v dc on the multimeter.

Step 3: Preparing USB female socket

You can see there are four wire in the USB female socket but we have only two output pin on the buck regulator. Therefore, we will connect red wire of USB female socket to “+ve” output pin of buck regulator and other three wires (black, white and green) to the “-ve” output pin of buck regulator.

Step 4: Soldering Solar panel and USB female connector

Solder the wire of solar panel to the input pin of buck regulator. Red wire for positive and black wire for negative pin of buck regulator.

The final ready product is given below:

Testing and Conclusion:

We have successfully built a portable solar mobile charger. Now, keep the solar panel facing towards the sun. Connect the data cable of mobile to female USB port and to the smartphone. You can see the charging status on your smartphone.

Caution: Buck Regulator is a device to step down the DC voltage. Here we are using 12v solar panel. If we don’t maintain the proper charging voltage of the regulator, then it could harm the mobile. The battery can get damaged. Also, make sure you are charging the mobile with enough sunlight. Don’t allow any shadow on the solar panel in order to charge your mobile smoothly.