Hello! In this Instructable I will show you how I built myself a universal portable USB charger. I am soon attending a weekend festival with camping and I realized that my crappy chinese "10000mAh" USB power pack won't last that long. I have my phone (Galaxy S4), a GoPro and my friends will also want to stay charged. As I fly RC multirotors, I have a handful of various LiPol batteries - so why not use them as a power source?
This charger can be powered by pretty much any source from about 7V up to 30V and can deliver 3A USB charge current. I am powering it from 3S (11.1V) LiPo's, but it should also run from 2S (7.4V) LiPo's, car batteries (both 12V and 24V) and even solar panels.
The parts are readily available and I believe you can build this under $10.
Let's get started!
Step 1: Parts list
Here are (almost all) parts that I used in this project.
- Project box (This is from my local electronics store, they are based in Czech and Slovak Republic)
- Universal PCB
- 3x USB type A sockets
- 10Kohm resistor
- 33Kohm resistor
- DC-DC step-down converter
- LED voltage display
Not on the photo, I also used a 2-pin screw terminal and 2-pin male and female PCB headers.
I used a XT-60 connector for the main power connection, which is commonly used with RC LiPol batteries. However you can use anything else instead to fit your needs.
You will need a soldering iron, solder, files or sandpaper, hot glue gun and a dremel tool, along with basic tools (screwdrivers etc.).
You will also need a digital multimeter.
A USB voltage-current meter is very helpful for testing your charger.
Step 2: Initial planning
I started by cutting the PCB roughly in half and making a cutout in it, so that it will fit nicely around the central standoff. Then I freely placed most of the components inside to get an idea on the overall layout.
As the 3 USB sockets are the main feature of the entire device, I placed them first onto the PCB. They slightly extend the edge of the PCB.
The last picture is the connection diagram.