DIY: Galaxy S3 Wireless Charging

When Samsung's Galaxy S3 phone was announced it was announced with a wireless charger accessory too. The phone launched months ago but there is still no news on the wireless charger. Reading posts on the XDA Developers forums, some people made their own wireless chargers by using the charging elements from a Palm Pre and the Palm Touchstone charger. I decided to make my own from reading various posts and seeing various videos on the subject and decided to make a DIY guide to consolidate all of the info so you can make your own.

What you need:

-Palm Pre Touchstone Battery Cover (Palm Pixi works as well, but the contacts on the induction coil will be reversed)
-Palm Touchstone Charging Dock (Getting the charging dock bundle with the USB cable and wall charger is recommended as the Touchstone Charging Dock does not work with some wall chargers and the dock has a hole that specifically fits the Palm USB cable)
-Thin Wire (I used wire from another USB cable)
- Soldering Iron, Solder

- Wire strippers/Knife

- Multimeter

One drawback to doing my method is that I used wires which created a small bulge on the battery cover. Another method would be to use copper tape or wires that are thinner than ones from a USB cable

What to do:

First make sure everything works. If you don't have an actual Palm Pre/Pixi, you can make sure it works with a multimeter. Place the cover on the dock (magnets from the dock will align with metal discs on the battery cover) and set your multimeter to check for voltage. If it shows a voltage value of around 5V then the dock and battery cover work.

As can be seen from the picture above the multimeter is set to 20V (as the charger will output around 5V) and a probe is placed on each of the golden terminals. From the picture, the bottom terminal is positive (red) while the top is negative (black). If your multimeter shows a negative value, then switch the two probes and it will show a positive voltage and the terminal where the red probe is will be the positive terminal.

 Then you will have to remove the coil from the Palm Pre battery cover. The coil, circuit, and metal discs are attached by a sticker, so just peel the whole thing off and you'll end up with what's shown below.

Now you need to solder the wires to the terminals. I got some wire from a spare USB cable I had. To make soldering easier, I first applied a small amount of solder onto the wire then placed the wire onto the terminal and just touched the solder I originally had from the wire with my iron. It immediately stuck onto the terminal without mess and without a huge bulge. Remember which colour wire is which. In my case, the white wire is positive and the green is negative.

Next, you can check with your multimeter to make sure that you did not short your wires when soldering them to the terminal. Set your multimeter to check for resistance and connect a probe to each of the wires. If there is a value then there is a connection between the two wires which will short out and could damage your  device. You will have to resolder your wires making sure the wires/solder don't touch the other terminal. If your multimeter is blank or shows a 1, like mine, then there is no connection and you are good to continue.

You can test the voltage again if you like by doing the same as was described above when testing the cover and dock.

When it is all working and there are no shorts, we will start working on the connection from the coil to the phone. On the other end of each wire, apply a big glob of solder to it, as shown in the blurry-ish picture below.

This will allow the wires to touch the two wireless charging ports on the back of your phone. You can now connect the wires to the back of your phone. As can be see from the picture, the bottom port/port closest to the microSD slot is for the negative wire while the top port/port closest to the camera is for the positive wire. If the globs of solder you put on the wire is too big, trim it down with a knife or cutter. To ensure the wires connecting to the phone's charging ports stay in place, use a piece of tape to hold them down. The battery cover will also help hold them down when it is put back in place.

You can now attach the coil to the battery cover temporarily to make sure everything works. I find it is better to attach the coil to the back of the phone not on the battery cover when you want to make it more permanent as it is more convenient to not have wires attached to the battery cover in case you need to remove it to swap sims/microSDs/batteries. The adhesive should still be sticky and just stick to the battery cover. Ensure that your connections are correct and then you can place the battery cover on the charging dock. If you have a stock rom there will be a popup indicating you are charging wirelessly.

Now that it works, you can attach the coil to your phone more permanently. Remove the coil from the battery cover and use tape to attach it to the back of your phone. I placed a thin sheet of plastic over the coil so that the adhesive does not stick back on to the battery cover.

Now you can test the charger again and make sure it is not interfering with the phone's NFC. If it is, then move the coil lower on the phone. In the picture above, the metal discs were removed as I wanted to put my phone in a case. Putting it in the case with the metal discs in its original positions resulted in a very weak attraction of the disks to the magnetic dock making it very loose. I'll talk about a method to improve on this below. If you choose not to use a case or choose to use a bumper case, leave the metal discs in their original position, close up the cover and you are done. If the battery cover does not close completely or there is too big of a bulge then you can go back and reduce the bulge on your solder points or try an aftermarket battery cover like the one I have above. With the new cover there is no significant bulge.

If you want to use a non bumper case then you can remove the metal discs from the original positions and place it outside of the battery cover. To align them, place the pieces of tape on the sides of the dock as shown below, then place the metal discs on top. The magnets will position the discs.

Now just place your phone with your battery cover attached on top of the tape, approximating where your coil is. You will end up with below.

You can now place a case on your phone and it will have better grip. One warning though is that if the case is too thick then the phone will not be able to charge completely. I used a TPU case and it would charge, but when it reached 100%, but not saying fully charged, the phone would keep disconnecting and reconnecting to the wireless charger. This will probably damage your phone in the long run so it is not recommended. A thinner case might work, or you can drill 2 holes in your battery cover and wire the charging coil outside on the battery cover. In the end, I chose to use a bumper which simplified the build.

This is the end of my guide to installing a wireless charger in the Galaxy S3. Feel free to leave me comments or questions regarding the guide and installing your own charger.