The Ultimate Power Bank





Introduction: The Ultimate Power Bank

Epilog Challenge 9

This is an entry in the
Epilog Challenge 9

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:
-BMS module
-Charging module
-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! :)



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    This is a very cool project, but there was one thing about it that bugs me. You said it's a true 30000mah power bank, but if it has to step up the voltage from 3.7 to 5, you lose a bit more than 20% of the amp hour rating. That's over 6000mah, and around 2 full charges on your phone. It's one of the reasons I tend to use 7.2v batteries, less loss in the step-down process.
    Also, the step-up isn't 100% efficient, so your final useable rating is going to be closer to 20000mah. Not insubstantial, but not 30000mah either.

    You are right. What I meant is that the
    cell itself is a true capacity and high-quality cell, not like the Chinese power
    banks that often have fake capacity cells in their specifications.

    Probably should include a fuse on those banana terminals since they connect directly to the battery. Aside from that, great project!

    There is a fuse. Thanks.

    Ah, I see it now. Great project!

    You can't overheat this cell. It can handle 500A discharge current. And in this project the max current is 30A (only on fast charge).

    It could if the fuse burnt out and you didn't realize it because my computer fried because I didn't check that the fuse was burnt out because I forgot to check it every 2 months like I was supposed 2.

    Correct me if I'm wrong, but wouldn't this lead to unblanced cells? Shouldn't these be ran in series to insure all the cells have the same charge / discharge? As well wouldn't this make it more efficient and allow efficient 5/12/20vdc USB PD?

    When you connect them in series it ups the voltage but does nothing to the run time, and you can connect them in parrallel as long as you ensure they have exactly the same, or extremly close voltages.