Updated: Wireless Car Charger for Smartphone

Update: I decided I want a more professional feel for the device. I created a 3D printed attachment that holds the electronics.

Are you tired of multiple power cords laying around your car? Constantly plugging my phone in was getting to me so instead of hassling with cords, I re-purposed a Qi charging pad and a GPS mounting bracket to fit my needs. The only other product on the market that is similar is a nokia charger at $94 with some reviews that complain about defects in the design. This is a super easy Instructable that should only take around 40 minutes to build and about $45 in material cost. 

Bill of materials:

• Your choice of wireless charger and matching induction coil. 

           (I picked up a Qi charging pad and a slim fit coil for $34 on ebay)

• Mounting bracket or holder for your phone. A garmin 200 series bracket fits perfectly around a galaxy s4 with a slim case. $6 (or print your own for a specific fit)

• Used mouse pad or rubber to protect the electronic circuits $0 if you have a spare
• Cigarette charger if you don't have one already. ~$3 from China

Tools:
Screw driver
X-acto knife
Hot glue gun
Scissors
Credit card
3D printer (optional)

Step 1: Gathering the Goods

First, you will need to get the wireless charge and circuit coil out of the packaged case. This specific charger has 4 small screws hidden under the rubber feet of the device. Inside you will notice three main components: a circuit board with input power plug, a coil for the transmission of power via induction and possibly a weight to give the device a little extra weight. To remove the glued coil from the weight, I slipped a credit card under the surface to avoid bending the coil. The weight is actually used for a more reliable transmission of power between the coils. I noticed a much quicker connection time when the lead weight was behind the transmit coil. Then remove the two screws holding down the PCB. The whole charging circuit should now be accessible. 

Step 2: Assembling the New Charger

Once the circuit is free, its time to protect it from any stray wire or lose coins. I chose to use an old mouse pad rubber backing for a nonslip surface that would give it a little extra grip. The coil needs to have the least amount of material between it and the phone transceiver for the power induction to work. You could add a small amount of material between the coil and the phone but I like the look of the exposed coil. Next, slip the coil over the GPS holder so that it lines up with receiver coil on the back of the phone case. Its good to get a close estimate of the position so that the coils between the circuit and phone line up.  Hot glue the coil to the backing and tuck the circuit board under holder. The final photo shows the clear case fitting snug against the coil in the holder. Check the coil connection, power and placement with a initial test before placing it in the car.

Step 3: 3D Printing a Better Phone Holder

For a more professional look, I printed a 3d case that contains the same mounting ball joint and has enough space to fit the entire circuit/coil behind the phone. The structure is more robust and has a wider area to grip the phone then the Garmin bracket. The geometry was designed in a way the power and volume controls can still be accessed.  To download this file or modify it for your project please view the item at http://www.thingiverse.com/thing:173097

Step 4: Final Testing

Once your charger is complete, fix the mounting bracket to the back of platform. Mount it to wherever is suitable like this dedicated cubby space or the windshield, for example. Wire the power cable through the dash to conceal it. Be sure that the amperage of the charger in the car matches the required amperage of the circuit. Plug it in and attach your phone to the new charging mount!