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