Portable Mobile Charger (Solar) From Scrap

Introduction: Portable Mobile Charger (Solar) From Scrap

Have you ever wanted to make a portable mobile charger so that you can get a little extra charge? In this instructable I'm going to convert old scrap to convert it to a mobile charger that gives long charges and can be powered via solar-panels, this gives you all the power to keep your mobile, camera and flashlight running.

Well here is how it goes you can build a travel charger from old laptops, AC chargers or maybe using a custom circuit. This is a easy way to go Eco Friendly and reuse old stuff.

I have written this instructable as I made the project, so that I don't miss out anything.

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Step 1: Tools and Components

Like always let's start with getting all the tools and components required. Well most of it is ripped out of old junk, anyways here is the list.


  • For custom circuit
  • LM7805 IC
  • USB Input Pin
  • 2x 0.33uf Capacitor
  • Solar Panel (if necessary)
  • A case to hold all this in

Step 2: Battery

Well let's start with the battery, I used the batteries from an old laptop, its motherboard was fried. So I removed the batteries, it had eight Li-ion cells. Out of the eight I had 3 working fine with a voltage of 3.9V each and 1 with a voltage of off 3.4v. A lot of stuff can be made from an old laptop like a external monitor and other stuff.

The cells are 3.7V rated and I got a 4.1V after charging them up. I created a battery pack by joining the batteries in series and with a lot of tape. I got approximately 15 volts from the pack.

Step 3: Voltage Regulator From an Old Mobile Charger

Well 15V connected to your mobile would fry it up. The perfect voltage would be 5v.

How Do I get a 5v?

It's simple all you need is a voltage regulator. I'm doing a lot of recycling in this project, so it's basically not how you make but how you get.

I had an old USB mobile charger in my house, I don't use them because I use the tiny ones now. I ripped open once and found a transformer out of which I had made a joule thief once. The charger circuit was divided into two parts and both of them was connected using the transformer. Here's what I did I put a 12v at where the pins of the transformer used to be and got a 5v from the USB also gave me a 5v at 15v. So I got myself a voltage regulator.

Step 4: Voltage Regulator From a Car Mobile Charger

This is another place I found a 5v regulator. It was not much of a find as I knew it was in there. All I had of the charger was as you can see in the picture, I'm not sure what happened to the pins anyways when you open it, you would find a PCB like the one in the picture. You should attach the battery pack, to where the car battery power goes on the charger PCB.

Since this is basically a voltage regulator you would a very steady 5V.

Step 5: Voltage Regulator Custom Circuit

If you can't find scrap boards around but still want to make the regulator, this one is for you.

Follow the circuit above to build the voltage regulator, if you want a detailed description check out my previous instructable. In this circuit the LM7805 does all the voltage regulation and the capacitor stabilize the output.

The terminals go as follows when you hold the printed side of the IC facing towards you and the legs facing downwards-

  • The pin towards your left is input
  • The pin in the center is ground
  • The pin towards your right is the output

You could add a LED at the output to know that the circuit is running.

Step 6: Case

Once you have found your voltage regulator, it's time to find a case to get all of this in. I got mine at a local hardware store which cost about 0.5$. The case is transparent and fits the battery in just fine with enough space to also fit the voltage regulator.

Step 7: Finishing

After you have the case and the voltage regulator you may want to solder the voltage regulator to the battery pack. Where you solder is different in different cases of how you made it.

Now when you are done you don't have to worry about your batteries running low, because you would always have this additional battery pack.

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    5 Discussions


    6 years ago

    Use a lm2670 instead


    6 years ago

    You could make a 2-2 array of battery. So you will be getting 7.2 volt from it and you have 5600 mah approximately. Also, a 7805 has only <28% efficiency so it does not suitable for battery packs or efficiency-critical appliances.


    6 years ago

    How do we charge the batteries?


    Reply 6 years ago on Introduction

    To charge the batteries connect it to a solar panel or use a USB charger to charge the individual cells like I did