This is the best power bank you have ever seen!
And now you can make your own. Here are all the electrical details and a housing exsample. I suggest you use your own ideas on the housing part, but feel free to copy mine.
This power bank has 4 usb high current outputs 10A in total current! True 30.000mAh capacity from 1S1P LiPo Battery. And... it can be charged in only 1h! Charge all of your usb devices from just one source.
Watch the video that incluides all specifications and and some instructions how it was made.
Step 1: Parts
To start making it you will need:
-DC step up modules
-Small parts (usb connectors, wires, fuse, bananna sockets,...)
Step 2: Battery
First of all of chourse the battery. The part that powers the whole power bank.
If you want it powerfull, than it must be big. This project is for single cell lithium battery. I used a cell from Kokam. I went for 30.000mAh. You may go for more, or less capacity depending what you want. Kokam cells may be difficult to find and expensive, but don't worry. If you can't get such a cell just connect more small cells in parallel to gain capacity. The voltage stays the same. So all the cheap cells that are used for rc models and toys are OK! Just connect them as shown on the photo. 18650 cells will also do the job!
Don't forget to add a fuse. I used a 40A fuse since my current on fast charging is 30A. If you do not plan to charge it so fast use a smaller fuse.
Step 3: BMS
Lithium batteries must never be over charged or over discharged. To
protect them form both use a simple 1S BMS board that you can find on ebay cheap. Just find a bms that can hold enough current. Mine is 10A. Connect as shown on photo.
Step 4: Charger
There are 2 charging options, fast and slow. You may want to have only one of them, but i wanted both.
The first and slow one allows you to use any wall micro usb charger to charge the power bank slowly. For this you need to add a charging board that will lower the voltage to 4.2v and charge the cell. (find on ebay: 1s lithium battery charging module TP4056). Charging current will be limited by the wall charger's output current in this case (usually up to 2.1A). This module can handle also 3A, so it will charge with 3A if the wall charger will provide such current. Connect it as shown on the photo.
If you have an external lithium battery charger you can add a fast charge port. So just add 2 4mm bananna sockets and connect them as shown on the photo. Now your charging limit is the external charger's current limit. I am using a Reaktor 30A charger so I can charge the power bank in only 1h.
Caution! On the photo the bananna sockets for fast charge are connected after the BMS Board. Do so, if your external charger will not charge with more than 10A. If you have an external charger that can charge with more than 10A connect the bananna sockets right after the fuse on + and - of the battery before the BMS. That's how my power bank is connected. Do this only if you know what you are doing. Unprottected charging may cause fire!
Step 5: Switch
Add a rocker switch to turn the power bank on and off.
It is used only for the output pard (DC modules and led display), so you can charge the power bank when it is off.
Step 6: DC Step Up Modules
DC step up modules will rise the cell's voltage to 5V. That's what you need to charge your usb devices.
Find them on ebay, I used 2 5A LM2587 ones.
Caution! Before connecting them to your power bank follow the procedure on my photo. You need to set their output voltage to 5-5.3V otherwise you can damage the devices you are gonna connect to the power bank.
Step 7: Final Connections
When your DC step up modules are all set up to the right voldage connect them as shown on the photo. Add as many usb uot ports as you like, but 2 per 5A DC module are just fine to let all your devices to be fast charged.
Add a voltage display, so you will know how much power it is left in the power bank. Find it on ebay and connect it as shown.
Finally add the out usb connectors and you are done! Except the housing.
Step 8: Housing
Here is another video that includes all the previous instructions with footage to help you make it.
It took me quite a while to make such a housing. I designed it as a 3D model in Autodesk Inventor. I found someone to water cut it from alluminum. I milled the front plate, sent it to the chemical cataforesis painting, and finnaly engraved and assembled it. This housing fits the battery i used. So I suggest you make your housing from any material you like and shape it so all the parts and your battery will fit inside. My first idea was to make it from wood, but i changed my mind to make it metal :)
Happy charging! :)