A powerbank is a portable device that can supply power from its built-in batteries through a USB port. They usually recharge with USB power supply. Technically, a powerbank consists of rechargeable Lithium-ion (Usually 18650 cells) or Lithium-Polymer batteries installed in a protective casing, guided by a printed circuit board (PCB) which provides various protective and safety measures. Due to its general purpose, powerbanks have gained popularity over the years, and today, we are going to make our own with just a 3d printer, some cells, and a circuit.
The materials and tools we will be using are very inexpensive although having a 3d printer is not very common (either cheap; yet)
These are the things required for the proyect:
- A 3d printer, or at least access to one
- Some filament for the printer (I used PLA as I don't have ABS). The color is up to you.
- The charging circuitry. There exist many of these on amazon/amazon but I used this exact model Battery charger PCB.
- Some 18650 Lithium-ion cells. Can be easily found on broken laptops and other electronic devices. You can purchase them through aliexpress/amazon too.
- A small sheet of 2mm acrilic.
- Access to a normal printer to print the photos we will be later mounting as decoration. Here is where you free your imagination.
- 4- M3 bolts lenght 10mm.
A soldering iron, some fine sandpaper and some cables will be needed too.
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Step 1: How Powerbanks Work
I wont go into details about how powerbanks work as there exist already very good instructables out there covering this topic(PowerBanks-How-It-Works/) You should also check out my other instructable about making powerbanks (Make-Your-Own-Custom-Powerbank-Gift/). At a glance, a powerbank is just a simply set of lithium cells connected to a charger circuit which has mainly one input for recharging the cells and usually two outputs to connect your devices (see images).
Step 2: 3D Printing the Case
Well this step is just about setting the printer parameters and waiting for the case to come out the printer :)
My printe settings were:
- 0.1mm layer heigh
- Black PLA
- 200º C
- 50º Hot bed
- infill 20% (I would print with 30% next time) honeycomb
- Fan 80%
- No support material
You can also (and should) tweak the settings to your specific printer.
Step 3: Modding the Circuit
As the led on the circuit doesnt fit well, we will need to relocate it. To do so, just take out the led and solder two cables accordingly to the polarity.
Once done, go ahead and install the pcb to the case previously printed. (It shouldnt be too loose, in that case use some hot glue or something similar. And remember, "Where it fits, it sits".
Step 4: Making the 1S 3p Battery
Well, there is not very much to go in detail in this step.
Just solder the cells in parallel.(Positive to positive and negative to negative) This way, we are increasing the capacity while maintaining the nominal 3.7v cell.
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 doesn't like finger oil). And always try to make the solder as fast as possible to avoid stressing the battery.
ALWAYS BE VERY CAREFUL WHEN WORKING WITH LITHIUM BASED CELLS
Lithium-ion batteries (Li-ion, Li-POs, LiFePo, etc...) are very
dangerous when mistreated. Always manipulate them safely and never discharge them below 3v, or charge them higher than 4.2v. Also dont short its lead or make any physical damage. Mistreating a battery will always cost you a lot! SO PLEASE TREAT THEM CAREFULLY!
Step 5: Acrilyc Cover
The Window cover where the photos are consists of two 2mm. thick transparent acrilic sheets. The photos are in the gap between the two layers. To make them, I cut the acrilic to the size of the enclousure but 1mm larger so I could remove the excess slowly ultil it fit nicely. And reapeater the process for both layers.
Step 6: Drilling the The Holes for the Screws
Again pretty easy, place the acrilic on its place and with a pen, mark the holes. Then use a 3mm drill bit to open the holes. Use a 5mm drill bit for the led hole. Always try not to scratch the surface of the acrilic if you remove the protective film.
Step 7: Conecting the Battery
In this step is fairly easy, just conect the negative lead of the battery with a cable to the negative of the circuit (it should be in the corner of the pcb and marked with the - sign). Don't connect the positive lead just yet as it would be inconvenient for the next step. You should only solder a cable to the positive lead of the battery and leave it unconnected. (Will be conected after installing the led)
Step 8: Conecting the LED and Routing the Cables
More soldering work here!
Extend the cable from the led and conect it back again to the pcb (Note the polarity of the led). Then hide the extension cable under the battery as shown in the image. Finally, you can proceed to conect the + of the battery to the circuit and the pcb should light up blue.
Ensure everything works correctly and then glue the led to the acrilyc with some resin or hot glue (I used epoxy)
Step 9: Adding the Images to the Acrylic Cover
This is the step where you can customize the powerbank to your likes. You can use a full size photo, or make a collage, possibilities are endless! The gap between the acrilic sheets is where the photos will lay.
If you opt for a collage(or small photos like my case), drop some glue on the back of the photo to make sure it doesnt move while you are working or in the future.
Once done, put the acrilic on its place and secure it with M3 srews (use M3 nuts if needed). Don't overtight the screws as it can lead to cracks on the acrilic.
Step 10: Final
I am very happy with the results, however there are some things that can be improved. As a general use powerbanks it does the job with its 10800mAh and 2.1A output, more than enought to recharge a mobile phone more than 2-3 times. Its quite small, but handy and useful, and most important, it can be decorated with your own photos. Great for gifts, no doubt! and a good conversation starter between friends!
I would really like to print the enclousure with ABS, as it can be treated with alcohol to give it a claner and glossy finish, thus making it look more impressive.
If any question or trouble making this proyect, feel free to ask in the comments below. Ideas would be appreciated too :)
"Sometimes magic is just spending more time on something than anyone would reasonably expect"