Hello again guys!
Nowadays we live in a world surrounded by the latest multimedia devices. Ipads, mobile phones and smartwatches are on top on the leading industry now. However, those things need a lot power to run during the whole day as we use them nonstop and Im sure none of us enjoy seeing the 10% mark on the battery. So lets make something to juice up our pretty electronic devices.
In this instructables we will be making our very own personal powerbank for, in this case, a special gift.
Here are the specs:
- 2 USB outputs
- Up to 2,1A. output.
- Total Cost less than 25€
- Capacity of more than 13500mAh.
- Easily Expandable.
- Cool looking blue backlight LCD screen (to show battery status)
- Lightweight for its size.
Note: This is a "simple" powerbank, it is meant to be portable and cheap. If you are looking for a bigger portable source, check UPS and other greater battery arrangements. So dont expect to light up a 100w LED with this.
Step 1: The Basics About Powerbanks
The working principle of a powerbank is very simple and is shown in the diagram.
When looking at a powerbank, the first thing see is the Input&output ports. Normally, the micro usb is for the charging the internal battery. The female usb is the 5v output, ready to plug in your device.
Inside the powerbank, we find a battery and circuitry. The concept is simple, we charge the internal battery, we disconnect and anywhere on the go, we will be squeezing the battery to power up whichever device we have connected it to.
In terms of electronics, there is a circuit to charge and control the internal battery, then we usually have some kind of battery status display. And to end up, the boost circuit which steps up the voltage of the battery (around 3.7v) to stable 5v.
Step 2: Materials Needed
To build a fully funtional powerbank we need various different things. To start, we need something to storage our precious portable energy, they are called batteries or more accurate, cells. Then we must find a way to safely charge those cells. A TP4056 with built in protection circuit will be key to do the job. Inmediatly, we notice that we have 4.2v in the cells and, as we all know, the electronics of nowadays works with 5v. To solve the voltage differential gap there, we just use a Step up converter (Boost module), set it to 5v and solder a usb at the terminals of the converter.
And there you have it, a 2 boards diy powerbank. But, what if we could get those boards integrated in one? Well my friends out there, that's exactly what we will do.
So the list of what we will need is the following:
- The main board. (Look for "power bank circuit board" on Aliexpress) This is the one I used
- Our cells, those can be lipos salvaged from old battery phones or Li-ion 18650 cells. The cuantity is up to you, more cells means more capacity, and therefore will increase the cost. (I reccommend more than 3 when it comes to decent powerbanks). When working with batteries, always ensure the have a good capacity.(Mines got 3400mAh. each)
- Some 2mm. Acrylic, aka plexiglas, of course you could use other materials, like wood, but we wouldnt able to see the photos.
- Four M3 30mm. bolts and 12 M3 nuts.
- A push button and some thin wire to connect it
- About 4cm of wire (Be a bit generous with the thickness of the wire)
- If working with lipos, you can always wrap them in some glossy finish material.
Step 3: Making the Battery Pack (with Lipos)
Well, there is not very much to go in detail in this step and the following.
Just solder the lipos in parallel.(Positive to positive and negative to negative) This way, we are increasing the capacity.
If you dont want to see the battery specs and others, wrap the finished lipo in some kind of thin heat resistant material.
Step 4: Making the Battery Pack (with 18650s)
With Li-ion cells, the connections stays the same as with lipos. All in parallel.(+ to +, - to -)
You may find sticking the solder to the ends of the cells quite difficult. If so, fine sandpaper and not touching it with bare fingers will help (solder doesnt like finger oil)
Step 5: The Acrylic Work (cutting the Acrylic)
As we have to make 4 identical rectangular of plexiglass, the best way i found was to use a template. Simply lay down the battery and circuit and measure, then draw the needed cutting lines. Also to help making perfect 90º angles, I used graph paper. Once that is done, transfer the necessary lines and mark the holes for drilling with a permanent tracer onto the acrylic.
The following thing is to cut the acrylic. Be as much precise as possible here, as it will lead to a good final result.
Step 6: The Acrylic Work (The Case)
If we have made precise cuts in the previous step, assembly will be very straightforward.
Start by clamping firmingly 2 pieces and drilling the holes. First I used 2mm. drill bit and then moved to a 3mm. drill bit. Once done, make sure the bolt can go through and tight with a nut. Repeat the process with the other 2 pieces and assemble the case with the neccesary nuts.
Step 7: Ensure Everything Fits
Time to see if everything fits tight. I had to modify sides of the circuit with a dremel bit to make it sit.
Step 8: Sharpening the Edges
To do this, use fine sandpaper. Using a sharpy cuter or knife, I was able to give a very clean edge to the acrylic.
Step 9: The Acrylic Work (Laser Engraving)
This was just for some extra detail. I ordered to the local maker store a laser engrave on the top acrylic. This is quite optional.
Step 10: Soldering External Push Button & Wiring
Now grab your soldering iron and some wire. Connect the positive end of the battery to B+ on the board. Do the same with the negative side. Then we will have to extend the button as where it is standing won't be accesible soon. To do this, simply solder two thin wires from the button board to our external button. Now ensure everything lits and the button works.
Note: there is no need to remove the leftover button on the board.
Step 11: Final Assembly
Ok, final step. Step of no return.
Start by placing the photos between the 2 layers of acrylic of the bottom. Insert 2 nuts on each bolt and place the battery and the circuit. Use some hot glue to make sure the button stays in place, you can hot glue the battery and circuit if you want. Now the top acrylic, again place the photos between the layers of acrylic and add the final nut to each bolt. Tight everything up and it is DONE! :D
Step 12: The Result
The 5v DC supply available via the USB sockets can be used to charge your mobile phone using your data cable. Almost all mobile phones require 5v DC input to charge-up. And when you are not using your power-bank you can charge its internal battery with your usual mobile charger only.
Press the button once to turn on the powerbank, press twice rapidly to light the Led and do a long press (2 seconds) to shut it down.
I hope it has inspired you to make something ,or at least, you've learned something new :).Have a good one!
Aaand yeah, I think that is all! Any question, feel free to ask. Leave a comment below if you want :D
-"Simplicity is the ultimate sophistication"
- Leonardo da Vinci