Introduction: DIY Wireless Charging Power Bank

Picture of DIY Wireless Charging Power Bank

As Phones get smarter and come packed with a heavier processor, it gives us a great performance, but the only down side to this is the battery life. While in intensive use the Phones may provide only a few hours of battery life, fortunately there is a wide range of power banks which are capable of charging your phone three to five times.

But when it comes to wireless charging, there are only a few power banks that offer that and are relatively quite expensive, so in this instructable I'm going to show you how to build your own Wireless charging power bank, that can charge your phone and other wearable devices.

You can also video a video on how to build this project.


Step 1: Tools and Components

Picture of Tools and Components

Here is a list of the components and tools required, the list is simple and all you need is -

Tools Required

  • Soldering Iron
  • Multimeter (Optional)
  • 3D Printer (Optional)

Step 2: Li-ion Batteries

Picture of Li-ion Batteries

The main component in this project is the batteries, I have used the 18650 batteries which I salvaged from an old laptop battery pack, there are usually 6 of these in a battery pack and for this project you will need four. The batteries which I found were rated at 2200mAH and I am using three of them in parallel which would give me 6600mAH.

I soldered wires directly to all the batteries and connected them in parallel, i.e positive to positive and negative to negative. In the end, I left out some extra wire to connect to the Boost converter.

Note - If you have a hard time soldering the batteries use a sand paper to rough out both the terminals this will make soldering a lot easier.

Step 3: Boost Converter

Picture of Boost Converter

After you have connected all the batteries in parallel you should be able to measure a voltage of about 3.7V. But a phone requires 5V to charge it, to step up the voltage from 3.7 to 5V we can use a Boost converter. For this project we will be using the XL6009 boost converter, which you can purchase one at a hardware store or on EBay.

The positive terminals of the batteries should be connected the positive input terminal of the Boost converter and the negative input to the negative input terminal of the Boost converter. Once the connection is complete, use a multimeter to measure the output voltage and vary the on board pot until you have 5V across the output terminals.

Step 4: Wireless Charging

Picture of Wireless Charging

For the wireless charging part of the project I'm using one circuit which I bought from EBay. Make sure the one you purchase has a feature, that turns on the coil only when a mobile phone or any wireless charging device is placed on it. I connected mine to an Oscilloscope and notice that the circuit Which I had sent a sine wave with a peak to peak voltage of about 16V and at a frequency of 205kHz when a mobile is placed on the coil and when there is no mobile on the coil it sends a short sine wave every few seconds to check for the phone.

This saves the battery rather than continuously generating a sine wave, furthermore the circuit has a coil with a ferrite back this improves the efficiency of the overall circuit and charges when a mobile phone is placed on the opposite side of the ferrite plate.

Step 5: USB Port

Picture of USB Port

I also needed a USB output port to charge devices without wireless charging, the USB port is connected in parallel to the wireless charging circuit and hence gets the same 5V. The positive terminal is connected to the VCC pin of the USB port which is the right most pin when the USB port output is facing towards you. The opposite end is the GND port which needs to be connected to the negative terminal of the boost converter output.

At this stage your USB circuit is done, plug in your phone cable and give it a try. If your phone is charging slowly then you can enable fast charge by soldering the middle two pins of the USB port together, this will enable your phone to charge much faster.

Step 6: Li-ion Battery Charger

Picture of Li-ion Battery Charger

Now its time to check all the components are working fine test out the wireless charging by placing a phone on it and the USB port by plunging a phone to it. If everything works fine now it is time to add the part of the circuit which charges the Li-ion battery. There are a variety of charging circuits online, but the most common one is the TP4056 based charging circuit which features overcharging protection and has LEDs which indicate when the batteries are charging and when it is complete. This circuit charges the Li-ion batteries by connecting an 5v source to the micro USB port of the device, so any standard mobile phone charger should be able to charge the power bank. I de-soldered the onboard LEDs of the circuit and soldered the regular 3mm LEDs to the terminals which I will later plug into the 3D printed case.

Step 7: 3D Printed Case

Picture of 3D Printed Case

Now that the complete circuit is completed it is time to put it in an enclosure, I designed an enclosure in fusion 360 which I later printed using an ultimaker 3D printer. The files can be found in the link below and the printer settings I used are as follows.

  • Printer - Ultimaker 2+
  • Infill - 20%
  • Filament - PLA
  • Layer Height - 0.1mm

3D Printing Files - https://www.thingiverse.com/thing:2699169

Step 8: Finishing

Picture of Finishing

After printing the case put all the components together, make sure you are covering any uninsulated wire terminals using electrical tape and use hot glue to hold the components in place. After placing all the components in the case you should have a power bank that looks like the one in the image.

Now you have a power bank ready to be used and you don't have to worry about charging your phone or wearables anymore, you can plug it into this to get the extra few charges.

Comments

dwleo (author)2017-12-29

Excellent!

My vote is yours!

What are the details on the induction coil?

keithstanley (author)2017-12-10

Nice!!!! A great instructable!! What watch is the BTW?

MortenS15 (author)keithstanley2017-12-15

Looks like a Motorola Moto360

Dragonite123 (author)2017-12-11

Just buy a wireless charging power bank. It's cheaper and better. DIY Is never a good idea. Why DIY when you can buy?

MortenS15 (author)Dragonite1232017-12-15

Because it is a lot more fun - and a lot more learning possibility.

rammy2203 (author)2017-12-13

Nice, detailed project you have my Vote.

The_Catster (author)2017-12-11

Didn't Adafruit make the same exact thing?

https://learn.adafruit.com/portable-qi-charger/overview

particleguy (author)The_Catster2017-12-12

The Adafruit's version costs about $60 and I can get a decent power bank at that cost. Whereas this seams to cost around only $10, if I were going to build a wireless power bank I would go with this one, I would make a few changes, but still the better option.

LokiDarkFIre (author)The_Catster2017-12-12

Its the same as that

LokiDarkFIre (author)2017-12-12

Even when there is no load, the circuit will use little amount of current, eventually it will drain all the battery juice.
Add a switch for turning On and Off
Its incomplete

DonnH1 (author)2017-12-10

I have had problems, in the past, directly soldering wires to any rechargeable batteries. The heat often causes damage to the cells. I see commercial battery pack rebuilders use a small spot welder. Just wondered if anyone else has had problems like that? By the way I do like the idea of the project but unfortunately I don't have a spot welder for batteries. There are plans for those on the internet. Another project. :-)

dennisbsu (author)DonnH12017-12-11

Use a fine grit sandpaper to lightly shine the surface before soldering. Applying a small bit of flux to the surface allows the solder to flow faster, thereby using less heat (that can damage the batteries). Use a rosin core solder. Be careful not to breathe the fumes from the flux!

webgeeks (author)dennisbsu2017-12-12

I agree, I also had suggested using a sand paper in the ible, I don't have a spot soldering kit and have been sanding and soldering it for a long time and I have not busted any battery yet. I would suggest using a lower temperature while soldering.

NoelA11 (author)DonnH12017-12-10

i have salvaged 18650 batteries from cordless tool batteries, and mannged to retain some of the tabs that are spot welded and using thes it made soldering a little easier. alternitivly there are many instructibles on building spot welders from MOT salvaged from microwaves.

RigoC (author)DonnH12017-12-10

You may be using the wrong kind of solder or soldering iron. The only hint I can give you here is wait until your iron is at the right temp before you place it on the battery so it can be done quickly. If all else fails, buy a case for it that has wires. They cost about $2 bucks on eBay.

jeff.verive (author)2017-12-10

Overall I like the project, but I have to advise against soldering directly to the batteries or tabs. Lithium batteries store a LOT of energy, and when they fail they are capable of reaching very high temperatures. Some of these batteries can easily be damaged by soldering heat. If somebody is interested in doing this project, I recommend that they buy the 18650 batteries with tabs and use appropriate connectors.

webgeeks (author)jeff.verive2017-12-12

Using a sand paper to rough out the surfaces and using lower temperatures while soldering, will reduce the risk of damaging the batteries. I also had suggested it in the instructables to use a sand paper.

leprasmurf (author)2017-12-11

Very nice build, I like the 3d printed case.

I do believe, however, that the TP4056 is a single cell charger and does not work properly for multiple cells.


"The TP4056 is a complete constant-current/constant-voltage linear charger for single cell
lithium-ion batteries"

src: https://dlnmh9ip6v2uc.cloudfront.net/datasheets/Pr...

Other references seem to agree
https://electronics.stackexchange.com/questions/10...

https://www.reddit.com/r/arduino/comments/4iomxp/c...

https://learn.adafruit.com/multi-cell-lipo-chargin...

webgeeks (author)leprasmurf2017-12-12

The TP4056 is designed for single cell charging because it is capable of providing 4.2V at 1000mA, but when you put a bunch of cells in parallel it would require the same 4.2V, but would charge slower at 1000mA, all the references you provided are for using the circuit in series, which I would agree the TP4056 is not meant for, because you would need higher voltage chargers for that, but this project as you see connects the batteries in parallel.

The references you provided, also agree on charging the batteries in parallel would be a better option then in parallel.

https://electronics.stackexchange.com/questions/10...

"That being said, there are a few workarounds. One is to have the batteries in series for operation and parallel for charging, and use either one or two single cell chargers."

https://www.reddit.com/r/arduino/comments/4iomxp/can_i_use_tp4056_with_18650_to_obtain_rechargable/

"The best option is probably to run the cells in parallel with a 1 cell protection board, and boost the voltage up to >7V..."

RichardQ1 (author)2017-12-11

What is the part/model details for the inductance coil? Where can we get that? RIchard

EdM63 (author)2017-12-11

very nice

MattP40 (author)2017-12-10

Cool article. One question - rather than boosting the voltage, was adding a fourth battery an option?

tm3 (author)MattP402017-12-10

the 3 batteries are in parallel. Each is 3.7V at 2200mAh. This gives 3.7V at 6600mAh, so a larger capacity and not a higher voltage. To increase the voltage with the same capacity would require 3 extra batteries not 1. Also, how would you charge the extra batteries from a 5V USB input? This current solution is the most elegant and compact.

The Life Hacker (author)tm32017-12-10

Adafruit makes a product, the PowerBoost 1000C. Price: $19.95, gets power through microUSB. https://www.adafruit.com/product/2465

tm3 (author)The Life Hacker2017-12-10

Yes, a very nice module that still only takes a 3.7V LiPo battery and not the 7.4V that was being suggested. Does anyone produce a battery charging circuit that runs on both series and parallel connected batteries that is cheap? The circuitry involved would be too complex for series and parallel operation. There is also the issue of parallel battery seesaw drain when connecting multiple batteries in parallel. There should be a 3 pole switch to disconnect each battery when not in use or they will self discharge.

The battery seesaw effect is when the very minute difference in terminal voltage causes the higher battery to discharge into the smaller and overshoot the terminal voltage, then the cycle reverses to the new higher voltage until all batteries discharge.

RigoC (author)The Life Hacker2017-12-10

You can get that module WAY cheaper than that. They start at $5 at this little store call Amazon.com. :P

MattP40 (author)tm32017-12-10

Ahh I see, thanks. A) I didn't notice the batteries were 3.7v each and B) I didn't know enough about electronics to know that adding batteries in parallel kept the same voltage

webgeeks (author)MattP402017-12-10

I had planed to add a fourth battery in parallel to the pack, but the pack was too big to carry around so I choose to stick with three instead. But even if I had to add the fourth battery I would still connect in parralel and add a boost converter.

maddog571998 (author)2017-12-08

I think that your power bank is very cheap to build.I want to charge my smart phone.Is it necessary to have a built in wireless charging feature?

If you do not need the wireless charging function you can buy a powerbank pcb on ebay for very cheap. These include li ion charging, protection, usb out and sometimes a screen too!

RigoC (author)Overlord79872017-12-10

Seriously. They start at like $1. I've seen them at the dollar store for $1.25 I assume they only have 500mA charge at most.

MikeM144 (author)2017-12-10

Totally awesome and well thought out project.


When I see things like I soooooo wish I had, or knew someone who had a 3d printer lol


Might give it a stab though it would just be a less "pretty" housing :)

Cheers for sharing


One question though, is there any reason you couldn't use the protected batteries rather than the unprotected cells normally found in laptop packs?

RigoC (author)MikeM1442017-12-10

You get get a solar christmas light set that uses lithium batteries. I buy mine after Christmas when they are 50% to 75% off. You just have to open them up and the components. Make sure they are using Lithium Batteries, not nicads or nimh. If you add the usb, it can charge via USB or solar. :)

DavidG809 (author)2017-12-10

Love the project. Just one slightly off topic question

In every instructable that involves Li-ion batts (that I’ve seen) calls for soldering then together
My question is. If you gave a 3D printer why not print a “AA” style pack (scaled up to li-ion size of course) so that the batts use a terminal instead bypassing The soldering?

Sorry if I’m missing something still learning the way of things (grin)

TimC34 (author)2017-12-10

What is the part number for the coil?

RobertC2 (author)2017-12-10

Nice!
One question: What is the 4th 18650 cell used for? Parts list says 4, text says 4, pics show 3...

Abhijit Borah (author)2017-12-10

Please may I have a link to the 'wireless charging part'. Thank you.

mechrekt (author)2017-12-10

The circuit needs a switch ?

juaspo (author)2017-12-10

Hi and great idea, will definitly build me one of these.

And also I wanted to point out that you are using a boost converter and not a buck converter since you are increasing the voltage from 3.7V to 5V. A buck converter reduces voltages.

webgeeks (author)juaspo2017-12-10

Hey, thanks for letting me know, may have gotten it mixed up in my mind.

yosuko (author)2017-12-08

great idea you have my vote

webgeeks (author)yosuko2017-12-08

Thank You, I appreciate it

alby21europa (author)2017-12-08

Nice job,but i think the qi charger are to match closed to battery....

hot temperature during charge time can make explosion.... (qi charger have 70/80 °C on work).....

maybe a second or separate enclosure are best solution.....

Kirand1 (author)2017-12-08

Very nice!

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