Cellphone Charger




About: Hello All drop me a message.

As the functions of cell phones increased astronomically, so their power requirements. Nowadays a clever :) phone which is purchased new can hardly stand working for 1-2 days and their endurance even decreases as the battery inside wears down as it gets older. So many people are buying and using battery power packs.

I've also bought one from ebay, it has 4x4200 mAh Li-ion battery power inside and even a led ligh to be used as a torch. It is able to charge my phone 4 times from zero to full. I'm using it especially in our 3-4 days bicycle tours, it is very useful.

Then my girlfriend saw the thing and wanted one for herself for daily use :)

I've thought of ordering one more from ebay but it takes 2 months for ebay orders to arrive via slow chinese post. And the customer asked for a much smaller one. So I thought making one by using a single Li-ion battery could be a much better and faster way. I had batteries, charging and usb power supply modules lying around which I'd bough on ebay some time ago so no new purchase was necessary.

So, lets start

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1: Design Research

I started with researching the market for available products as inspiration. There are many products of similar kind on the market, on the internet you can find hundreds, maybe thousands of different products.

So i've looked at the ones already designed and built, being sold on ebay. Saw that lots of them are very similar to each other. When the quick search is complete, I did some sketches and decided on a boxy rectangular shape, with rounded corners. I've planned that my charger will have two main body parts that will lock-shut on eachother without the need of screws.

Step 2: Parts Used

I've had all the parts lying around as I always purchase 10 electronic parts (sometimes more) when I need one. That makes future projects much easier. And here are they and their ebay links.


Battery charging modules

Usb power regulator module (I've used the 0.9-5v to 5v 600mA type)

I don't have a link for the switch but I've added two close-up photo of it with its dimensions, one similar in size and shape should do the job.

Also ripped off the battery contacts of an old electronic toy and used in my product.

Step 3: Electrical Connections and Testing

As the usb power regulator draws around 15ma current even while not supplying any current, it became necessary to use an on-off switch. I've also used the switch as a commutator between the charger and power regulator. While charging, the power output module will be disconnected and while outputting power, the charging module will be disconnected. As the charging module doesn'r draw any power from the battery, it will remain connected in power off mode.

Step 4: Industrial Design Engineering: Internal Placement of the Parts

For this step, I've modeled all internal parts and electronic modules as solidsorks parts.

I did the internal placement to find the optimum case shape and dimensions before continuing the 3d modeling of my design. I did some modifications to the design according to the needs arised during this placement process. I've used solidworks' assembly mode for this purpose.

Step 5: Industrial Design Engineering: the 3d Modeling

The modeling of the product case is straightforward, in summary it starts with a rectangular prism. Turns into required form step by step, then it is cut into required parts, added internal details and thats it. I've just selected several of the modeling steps on which a visible difference is done, in fact there are a little bir more than this :D

There are 3 parts at the final work, upper body, lower body and the internal support part.

No screwing is required internally or externally including the electronic cards. The parts locks on each other securing themselves very firmly. The internal support part divides the main interior space into two; battery space and the electronics space. While it counters the mechanic force applied by the battery & spring, it also applies support to the power&charging modules, holding them in place when the plugs are being inserted.

As i said, the case locks up itself, I mean really locks up. So the builder should be sure the device works properly before closing the case or it might be a little difficult (:) to open it back up.

Step 6: 3D Printing

I did the printing with an UP Printer.

it took around 5 hours and used up 40grams of ABS filament.

I've used a semi transparent filament for the leds on electronic modules to be seen from the outside, I didn't open holes for the leds.

Step 7: Assembly

The assembly is not difficult, I first inserted the modules to their places and first cut several wires into required lengths; 3 pieces of wire are cut in approx 3-4cm length and one is cut in approx 7-8cm length. Then followerd the steps below.

These steps are in fact just the translation of the circuit schematic above, if you can already read it, then you may skip the steps and continue building the circuit by using the schematic.

-> solder the 3 wires to the terminals of the switch.

-> solder the other end of the wire on the mid pin of the switch to the + pole of the battery.

-> negative pole of the battery, negative input of the power regulator circuit, negative output of the battery charging circuit are all connected to each other by the long wire. ( see pics)

-> connect the remaining pins of the switch to the positive terminals of the two circuit boards via the remaining two 3cm long wires.

I did the last step in a way that when the switch also shows the direction of power transfer. For instance if it is pushed towards the inside of the product-battery, that means the product is in charge mode, you can charge it by using any usb adapter or a pc usb port. When the switch direction is to the outside of the product, namely to usb sockets' direction, that means the product is in power output mode and you can charge your phone.

in power output mode, a red light turns on and stays on as long as the battery stands.

in charge store mode, there are two lights, a blue and a red led. Red means charging, blue means charging is complete.

Step 8: Testing

After connecting everything up, I loaded it with an usb adapter to full and tested charging with two phones. It charged one to full and the next to %47 percent. Not bad. you can use a higher capacity battery if you like to charge both of the cellphones to full. :)

Step 9: Happy Customer

I've given it to my girlfriend. She doesn't seem much impressed and asked if it is possible to paint it, then asked whether that thing has a light too :D

I plan to make an additional led light part which will be inserted to the usb port when necessary and I guess there is also a small paintjob is waiting in the near future. Maybe I should leave the painting to her.

Comments are welcome.

Bicycle Contest

Participated in the
Bicycle Contest

3D Printing Contest

Participated in the
3D Printing Contest

Apocalypse Preparedness Contest

Participated in the
Apocalypse Preparedness Contest

Be the First to Share


    • CNC Contest

      CNC Contest
    • Make it Move

      Make it Move
    • Teacher Contest

      Teacher Contest

    57 Discussions


    4 years ago on Introduction

    this is the capacity test for the ultrafire batteries,

    the one tested just managed to output 900mAh capacity.

    not good.


    4 years ago on Step 9

    Love the idea. That said, I have used those Ultrafire batteries, and their performance is very dissapointing. I didn't know how bad they were till I tore apart a couple of old laptop batteries that would no longer hold a charge. I found, inside, 8 nice 18650 batteries. I checked all and found only two were bad, the rest easily charged up to 4.3 volts. I put one in my flashlight that was going through the Ultrafire batteries very quickly and found nearly six times the power. Well they last about six times longer before recharge then those dang Ultrafire batteries. The brand in that old laptop battery was Samsung, and all those that checked good seem to have that sort of power. Not bad for something that was destine for the landfill.

    2 replies

    You are welcome, I ordered one of those empty cases from some guy on Ebay, it came in yestreday, and as expected, it was in pieces but after looking things over, and a bit of mearsurment, I found there was no room to solder wire from cell to cell. Then I recalled having an old IBM laptop that I had parted out in the back room. So a quick trip to the back room and I had a nice old laptop battery to tear down. This one had a 12-2006 date on the inside, I checked all the cells, and all were over 3.2 volts meaning they were holding a good charge. Funny nobody told me that old machine had a good battery. So I cut the strap that hold the cells, this battery had 3 groups of 4 cells each. I soldered the leads from the first set, and cut apart the others from that set, they fit nicely inside the case. After finishing the build procedure, just a matter of screwing in a couple of small screws to hold the circuit board in, pressing on some preglued parts I was set to go. After a night of charging, I now have a nice 4cell power bank holding 4 Panasonic 18650 cells 2150 mps each. It took a 100% charge, and I used it to charge my iPhone this morning, took care of the job very nicely and only went down a couple of percent, then charged my smartwatch which was down to 3% only took about six minutes to come up to 100% on the watch. TO try it, I hooked it to a 1amp wall wart and after a half hour it was back up to 100%. I was so very pleased, I ordered a couple more of those cases so I have a place for the other 8 cells left from the IBM. (it was a 12 cell).


    4 years ago on Step 2

    I think this module would suit you better https://www.fasttech.com/products/1424/10004229/1323311-hp-0161-0-8a-diy-single-usb-mobile-power-supply

    It has quiescent current 100uA. Your module has 15mA instead. It is compact. It has discharge voltage: 2.8-3.0 V so you can use the battery without protection.

    Also your battery is very fake. It has real capacity ~600mAh instead 4800mAh. Better choice is Sanyo 2600 https://www.fasttech.com/products/0/10001901/1136603-authentic-sanyo-ur18650fm-18650-2600mah-3-7v

    But your 3D printing box design of is very cool.

    2 replies

    Reply 4 years ago on Step 2

    Real batteries are difficult to find online if you want to try to get them cheaper. Most reputable brand name batteries, are faked and the fakes vastly outnumber the real ones on eBay or other cheap sites.

    As far as the Quiescent Current.. I can't find much information about the quiescent current of these USB 5v step up regulator module.. But I guess i will take your word for it for now,.. I can't be bothered checking it at the moment.

    I don't have that exact charger module in the Instructable, I have a version with inbuilt protection. It's pretty much just as cheap..
    Like this one ( http://www.ebay.com.au/itm/5V-Micro-USB-1A-18650-... )

    (That is eBay australia,.. Although i am sure you could find ones like that on other eBays...)


    Reply 4 years ago on Introduction

    Thanks for the module recomendation. It is much better than the modules i've used. And small too, it may even fit in my design maybe with minimum modification if not none. As fortunately the battery sizes are the same, the other builders can go for using a better brand easily, I'll try the samsungs next time.


    4 years ago on Introduction

    Anyone who doesnt have access to 3D printing but is still interested in a stick like this, you can buy various dimensions of square pvc tubing, and square plastic end caps. Holes and cutouts can be easily cut into the end caps with a utility knife and the components hot glued in place.

    I put all my components in one end cap, then cut a square of plastic from a spare end cap to put behind the parts. Then I put the battery contact on that plastic, then the battery, then the other end cap with another battery contact inside it. My components are basically in a brick of hot glue with the endcap on one side (with ports and switch visible), and the battery contact on the other side. I can't get to it easily if it breaks, but it is an easy solution for not having custom enclosures. I have been using it for a year now with no issues, and if I had to replace the endcap/circuit/switch brick it would cost me only a few dollars.


    4 years ago

    great instructable! I like that you included the 3d design and printing part.
    One recommendation though, as a long time powerbank user I advice you to stay away from any cell with the name 'fire' 'trust' or 'ultra' in it. They are all very bad and will die a lot of times. if you order more than one of these, there is a great chance that one or two are not working at all. Most of the time the advertised capacity is only half of that in real world use.
    I advice your to look for the samsung Li-ion cells, I mainly use the purple 3200 mAh ones and usually they last very long under heavy use. 2 of these charge my 1500 mAh battery at least 3 times and usually stop charging halfway the 4th time.

    3 replies

    Reply 4 years ago on Introduction

    Indeed there's a lot of fakes on eBay.
    Lately I used these 2600 mAh's from Samsung as there's quite a lot of people that tested these exact cells. In the tests it's clear that the capacity is spot-on or at least very close or a little more than 2600 mAh. I've been using these for quite a few months now and the capacity is still the same as in the beginning.

    These are the ones I'm talking about: http://www.ebay.nl/itm/351326751364?var=6204621683...

    I also read a lot of good stories on LG Li-ion cells. I might try these as well as soon as I find a supplier that sells genuine ones.


    Reply 4 years ago on Introduction

    thanks, I pretty much bought the first battery i saw on ebay. Next time I'll try the samsung 18650's.


    Reply 4 years ago on Introduction

    most cells on ebay are copy and fake you have to be carefull with ebay i tend to by old laptop batterys for cheap and take them from that


    2 years ago

    what kind of batteries are those, it's a dead link, is there a way to add more batteries for greater life?


    4 years ago on Step 3

    Hello there!

    Many thanks for a great project! I hope you can also help me with some questions.

    Do you know of a 'UPS-style' USB-LiPo-USB charger? I mean chips and schematics for something to add a battery power module to a 5V device which does not have it initially. Most project I've found to this moment separate charging from spending charge - and I try to find a solution.


    4 years ago

    how did you get the 3D modeling so precise? I'm doing something quite similar to what you've got here with my robo3d printer, but I'm having problems making my measurements precise enough in my SW model...

    I am just a little off, & I don't want to make a million iterations.

    Do I need to just go but some calipers, or what?

    1 reply

    Reply 4 years ago on Introduction

    This one was printed only once, I was lucky to have a minor mistake only(due to a bigger smd capacitor which I've omitted to include in my 3d model), which i was able to fix by chipping off a hole at a plastic part to enlarge the space a bit for the smd cap. You should have a caliper for sure. Without it you can not achieve the necessary precision.

    the seabass

    4 years ago

    very interesting ?going to try this at school soon(but to be honest I would much rather go buy a power bank?)