In this instructables, I'm going to show you how to make your own power bank. I fitted it in a case of another (smaller) power bank, because it had the right size.

For the power bank we're going to make, we need a separate charger to charge the battery.

! Attention !

This project uses LiPo batteries. You need to be carefull with charging/decharging these batteries, because the can explode when not handled with care!

Lets get started!

Step 1: Changing the Little Power Bank

In the first step we're going to change the small power bank, so the 12V to 5V converter fits in.

First open up the power bank. The lit is held in place with clips. Just pry it open.

After that you need to remove the 1 cell battery with charge circuit. Now take a knife/dremel and make the hole in the front larger so 2 USB ports will fit in later. I also needed to remove some standoffs in the case itself.

Now the case is ready to be refitted!

Step 2: Electronics

For converting the 12V from the 3S lipo battery, I used this small usb converter because it fits in the case.

First I needed to remove the USB socket, because it was a little to high. I then added the socket again with some wire.
After that, I soldered some short wires to the battery connector. And screwed them in place.

Now It's time to make a hole for the battery plug in the back of the case. I used a drill to make a hole a little smaller than it should be and used a file to make it fit snugly.

It's time to insert the electronics in the case. I fitted them in and then used some hot glue to secure them in place.

That's it! Close the case and you are ready to go!