Repurposing a Cell Phone - the Making of a Rechargeable Battery Pack.




About: I like to modify things, make things, and modify the things i make. im no math whiz or someone with perfect grammar, but i am good at making things. at my school ive taken the welding, machining, mechanics ...

Long story short, I was in need of a 3-5v battery pack that was lightweight, lasted a decent amount of time, and wasn't too big.
So I looked around for something, I had plenty of rechargeable batteries that suited my needs, but none that had dedicated chargers for them.
And then I came across my old cell phone. Unfortunately when I was removing the battery contacts I pulled a pad off the board. And there were no traces nearby to solder the wire to.
So, being the person I am, I grabbed another cell phone and made what you see here.
I made this battery pack and charger with intention of using it in my fursuit, but you can use it for pretty much anything you choose to.

Was it at all necessary to do all this work? Probably not, but I wanted it to look good since I'd be using it a fair bit.
Read on to see what I did.

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Step 1: Tools and Materials

This stuff pretty much depends on how you want to do it, meaning you might not use the same tools (or materials) as me.

Some basic tools you will most likely need:
-00 or 000 Philips screwdriver (Or the appropriate screwdriver to disassemble your cell phone)
-Soldering iron and solder
-Scissors or wire cutters
-Marker or pen/pencil (I used a wet erase marker)

And any other tools that will make your build easier for you.

Some basic materials:
-Cell phone with its battery and charger
-Glue (I used hot melt glue and a glue gun)
-3 pin connector (Female, two of these)
-3 pin connector (Male)
-Enclosure of some sort (I used the enclosure from an old battery pack)
-N/O SPST switch (Just a regular pushbutton, optional)

And you can use whatever else you want to make the finished product look nicer.

Got everything? Let's build!

Step 2: Disassembly and Preparation

This step is fairly simple.

First off, take a look at your phone. From the powered down state, plug it in. Does the phone have a charging state LED?
If it does, great!
If it doesn't, you unfortunately have a little bit more work ahead of you.

Now, take apart your cell phone. CAREFULLY.
I can't give you specific instructions but I'm sure someone on the internet has some written up.

Skip this next part if your phone has a charging state LED (Or read on anyways, you might like what you hear)

Alright, so if your phone does not have a charging state LED, you'll need to use the screen as well, so you know when it's time to take the battery off the charger. You might want to use the LCD anyways, that's completely fine.
Again, CAREFULLY disassemble the LCD portion of the phone. Once you have the display free, continue on.

Ok, so now you have your phone apart. Take note of everything, there will be parts of the phone you will not need for this project. Things like the camera, memory card, SIM card, etc. that are not required for the phone to charge the battery can be used for something else.

Now take the parts and reassemble them outside the shell of the phone. Be careful with this stuff, its very easy to break and that is the last thing you want to do.
Plug in the wall charger.
Hold the battery against the contacts (Make sure its the right way) and plug in the charging cord.
Does the phone start charging? Good. Move on.
If it doesn't, see whats wrong, and fix the issue if you can.

Next, lets look at the female connector.
It will probably have 2 wires coming out of it, this is why you need another connector.
On the back of the connector, there are tabs that hold the contacts in the plastic housing. Lift up the tab for one of the contacts and pull the wire out. Then slide that same contact (And attached wire) into the other connector, so you have all 3 slots filled. Twist the 3 wires together and you are ready to go to the next step.

Step 3: Start Building!

You made sure you found an enclosure the proper size to fit the parts in, right?
You did? Great!

This is also pretty easy. Lay out the parts and determine how they will fit in the enclosure. Mark all the holes that need to be cut, and cut them. This is when you will want to determine how the battery will sit when it is connected. I chose to make a spot in my case for the battery to rest in.
Once you figure that out, make sure you cut a hole for the charging plug, and get all the other parts laid out. If your phone has a charge indicator LED, make sure you make that easy to see, either by drilling a hole for the light to shine through or by making some sort of diffuser to get the light to shine elsewhere.

Don't put it all together yet, you aren't done here.
Take the 3 pin female connector and cut the wires to the desired length. Then strip them and solder them onto the battery contacts. Keep it simple, and solder the wires so the connector has the same pinout as the battery contacts. (Battery contact #1 is connector contact #1, and so forth)

This next part is optional, I chose to do it because my phone has keypad LED's that shine through the white case, and pressing a button turns them on for 30 seconds. It looked pretty cool so I soldered a SPST switch in place of one of the keypad buttons. (I chose the "END" key)

Before you put it together, ensure that everything still works the way it should.

Now just put the phone together into the case how you want it.
Right now you can also choose to add something to the case to make it look nicer. I lined the inset area with some thin foam so it looked a little more appealing.

Step 4: The Battery

This is the last thing you need to worry about.

Since the case on my battery was a little oddly shaped, I chose to remove the battery and circuitry from the case to make it more modular. It is not necessary, but it does make it look nicer.

After I separated the battery and the case, I soldered the male 3 pin connector in place of the old 3 pin connector. Not all batteries have connectors, if yours doesn't, solder the male connector onto the pads the connector in the phone made contact with.

The reason I chose to use the 3 pin connectors is because they are easy to find and provide a strong, reliable connection.
After you solder the male connector onto the battery, make sure you mark the battery somehow so you don't plug it in backwards.

If you took the case off your battery you might want to prevent shorts, so cover the battery with something. You could use almost anything for that, tape, epoxy, whatever have you. So long as the battery is protected against shorts it is ok.
I chose to use more thin foam to cover my battery. Once you cover the battery, remark it to prevent any confusion.

Step 5: You're Done!

Now plug in the battery, plug in the charger, and admire your handiwork.

Should you have any issues, go back and double check everything.

Now that your battery pack and charger is done, you can use it in whatever you need to.
I made mine to use in my fursuit head, but by all means there's no limit to what you can use the battery pack for.

I included pictures of it in use as well, so you can see why I needed something small.

Any questions? Feel free to ask in the comments section!



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    17 Discussions


    5 years ago on Introduction

    Do you have anything protecting the lipo battery? I just finished making my own from a 1000 mah ipod battery and two 800mah RC batteries. If the aluminum "balloon" surrounding the lithium were to break, your ear would catch fire. I don't think people at the conventions would be too apreciative of that kind of attention. By the way, do you remember me?

    7 replies

    Reply 5 years ago on Introduction

    I left the protection circuitry on the battery, and simply soldered the header onto that. I can't foresee myself using it long enough to fully drain it before I can recharge it though.

    I feel as though I should remember you, but my memory isn't so hot sometimes ^^'


    Reply 5 years ago on Introduction

    I've become involved in the RC hobby and have lipo batteries that weigh 3 lbs and put out 11.1v with 5000mah for my multicopter. They have taught me how to rewire the connectors on the batteries, and a battery should ALWAYS have the female plug. You don't want to find out last minute that the protection circuit doesn't work when you bump the pins into something metal.

    As for remembering me, do you remember AM?


    Reply 5 years ago on Introduction

    AM.. AcidMods?

    as for the battery, my level of concern is rather low. I typically handle my batteries with some level of care and it usually has the contacts plugged into something, even if it is just a plug to cover them.

    i suppose i probably should have put the female header on the battery, but i was a bit too lazy to do that, since i had no female headers at the time. so soldering the male header seemed like the ideal path.


    Reply 5 years ago on Introduction

    You are correct about it being acidmods. We talked a few times in the shoutbox. As for the batteries, I said the same thing about my lipos and had male deans connectors on all of them until I had my first fire. Since then, I have switched all of my connectors to prevent the same mistake. The risks of a lipo fire are higher for me though. I drive my erevo almost every day and fly my planes and helis several times a week.


    Reply 5 years ago on Introduction

    did you go by the same username there? it seems familiar. I havent been as active there as i once was since i got my car and whatnot, i still modify things but they're just small things and not really consoles of any sort.

    I haven't got any hobby grade RC's since i can't afford them, but i do know some people who do and can. lipos can pack a punch, so i can see how fires could start.


    Reply 5 years ago on Introduction

    I went by RyanF on AM. I strayed away when I got into the RC hobby (funny story about that) but recently started coming back to it.

    If you wanted to get into hobby grade RC's, you can get a used traxxas slash or mini erevo. They go pretty cheap, aren't very big like my erevo, and only need 1 battery. They also have some decent speed too. I've also heard good things about the losi micro T.


    Reply 5 years ago on Introduction

    i might eventually get into the RC stuff, but first i need to find employment somewhere so i can pay for the gas and plates on my car.


    Reply 5 years ago on Step 3

    indeed it does, and it does with this phone too. i just chose it because pushing the end key momentarily wouldnt execute any commands or anything like that. i usually just plug the charger in and go from there, but if you wanted to turn the phone on and then charge the battery, that works too.


    7 years ago on Introduction

    Where did you find my last sprint flip phone?!?
    And why didn't you convert the other 3 batteries while you were at it?

    Guess I'll have to do it myself.
    Since you've had the circuit board out already.... think it'd fit inside an altoids tin? I know it's narrow enough, but not sure about the length.


    6 replies

    Reply 7 years ago on Introduction

    So, now I have a de-cased and re-cased cellphone cum battery charger.
    And a second "project" phone.

    Now, what to DO with it?

    My first instinct say to make a flashlight out of it, and send the high-brightness light beaming out of the antenna hole. Maybe even the worlds bulkiest laser pointer?
    What do YOU think?


    Reply 7 years ago on Introduction

    ive found that the LED backlight assemblies are really cool and versatile things.
    what i would do if you wanted a small compact flashlight, is take the backlight, rewire the LEDs in parallel and add a small resistor and switch, after removing the LCD. the backlights give off generous light and are really compact.


    Reply 7 years ago on Introduction

    im not sure if it would fit in an altoids tin, to be honest ive never had one of them before.
    i believe it should fit, but dont take my word for it. if you know how long an altoids tin is i can measure the circuit board from the phone for you.


    Reply 7 years ago on Introduction

    Sure as Shootin, it fits like a dream.

    Dark Chocolate altoids mint tin = 3.5"x2.125"x0.75" opening.
    samsung SPH-A660 = 4.25"x1.825"x1" (With antenna removed, only 3.325" long)

    basic decasing of the cell phone leaves plenty of room.


    Reply 7 years ago on Introduction

    Dissassembly was super simple(as always .

    #1: a fine screwdriver : remove 5 screwes. 1 by antenna, 4 under battery

    #2 : Spudge open the case halves.( I was completely unsafe and used a

    pocket knife. fingernails would work. it's just 2 TINY plastic clips)

    #3 : disconnect screen cable(just pry it off. easy) #4 : flip phone over, and watch circuit board fall out.

    Notes on MY version...

    By removing JUST the antenna, the entire phone body will fit into the altoids tin(lid closes, and 99% latches. remove the screen for more space than you know what to do with). This means, I don't have to de-case the battery or solder AT ALL, if I don't want to :-)

    I have a SECOND, fully functional phone identicle to the first(warranty return that the company didn't want returned) and 2 additional batteries. This can be shelled for a project, or left as-is to be used as a 3-batttery 911 car-phone.

    Notes on YOUR version :-)

    There is a 0.25" rare earth magnet in the screen bezel.

    It was there to tell the phone if the screen was open or shut.

    You can use this to your advantage ;-)

    Most every flip phone uses this technique.

    I THINK most slider phones do as well.

    Might be a good way to control power to the screen and/or keyboard leds.


    Reply 7 years ago on Introduction

    good to hear it worked out for you as well :3
    i didnt worry about the magnet too much since the LEDs turn off after 30 seconds anyways, so i figured id leave it as is.

    feel free to PM me pics so i can add them to the 'ible if you want :)