Build a Hidden Qi Wireless Phone Charger!

Phone docks are expensive and platform-specific. Charging cables are annoying and unsightly. Wireless chargers alleviate some of these inconveniences, but still leave a lot of polish to be desired. I set out to eliminate all of these complaints, and in building a wireless charger into a nightstand or desk, I am now able to plop my phone down on my nightstand and watch as the battery fills up - like magic.

For this Instructable, I will be demonstrating the process of building a wireless Qi charger into a desk or nightstand. The results are polished, convenient, and impressive. Done right, you'll make your phone-charging experience seamless and attractive.

Step 1: Supplies

In terms of supplies for the project, you'll need the following parts and tools ready to use. You may have to hunt around to find a MakerSpace with a ShopBot CNC Router, but you could (in theory) chisel out your wood surface instead.

• PowerBot Qi standard induction charger (any color!)
  • I chose the red model knowing that I wanted to use one of the rubber rings to indicate where my charging pad is hidden.
  • This model comes with a USB cable long enough to use for this project!
• Any 5v AC - USB power adapter, 1.5A output or greater works best
  
  • You can use any 5v USB adapter, including the one that came with your phone. A higher output adapter will charge your phone faster.
• Small phillips screwdriver
• Small flathead screwdriver
• Hot glue gun
• Router (CNC or manual)
  • I used a ShopBot, see if your MakerSpace has one!

You'll also need the obvious:

• A desk or nightstand that you're comfortable taking apart and manipulating
  • I used a board of walnut to illustrate my project since my desk is made of glass and my nightstand is ugly.
• A phone that supports induction charging via the Qi standard
  • iPhones are not supported
  • Most Samsung Galaxy phones are supported with a special back cover
    • Example: Samsung Galaxy S4 Qi Battery Cover
  • Many recent Windows Phones and Android Phones support Qi
    • Phones with MicroUSB charging ports that do NOT natively support Qi can use the following adapter to add Qi charging capability using the MicroUSB port
      • MicroUSB Qi Charging Film

Step 2: Disassemble the PowerBot

Dig in! Peel away what you can of the plastic housing with your flathead screwdriver, then pry the rest off. The PowerBot casing is in two halves, you'll need to separate the two. With the PCB exposed (it's screwed into the top half of the casing), use your phillips screwdriver to remove the guts of the PowerBot. What you see in my final picture here is where the magic happens - that's an induction coil you're looking at! Your Qi compatible phone has a similar coil inside it, to receive the electromagnetic field produced by the PowerBot.

The induction charging system can only work within a limited distance. The coil in your phone can't be too far away from the coil from the PowerBot, so removing the PowerBot's casing reduces unnecessary obstruction between the two coils. This will come into play in the next step...

Step 3: Find the Maximum Charging Distance

As you can see in these pictures, I've confirmed that the naked PowerBot is working with my phone, and I've confirmed that the PowerBot continues to charge my phone when the phone is raised above the induction coil. I estimate from this test that it will continue to charge up until around 0.3 inches. If you have a case on your phone, this may be a little tight - you'll definitely need to use a CNC router for better precision. If you keep your phone case-free, you may be able to get away with a hand router (or even a chisel!).

Remember - GREEN means it's charging. RED means there's no connection.

Step 4: Get Your CNC File Ready (for ShopBot Only)

I measured the size of the naked PowerBot, and accounted for the room that the included MicroUSB cable needs. After creating a quick 2D vector in Adobe Illustrator, I imported the vector lines into my school's ShopBot software, figured out how deep I wanted the router to cut (With my 1 inch wood slab, I cut in 0.8 inches. This leaves me with a little over 0.1 inches of wiggle room for charging.), and started the task.

Attached are all the files I used in the process of using the CNC router.

Step 5: Fit and Attach Naked PowerBot

With my included CNC files, your naked PowerBot will fit in just about perfectly! You shouldn't have to use any excessive force sliding the naked PowerBot into the hole, and the MicroUSB cable should fit happily, too. Make sure the MicroUSB cable is plugged in BEFORE sliding the naked PowerBot into place.

After confirming that the naked PowerBot fits and still functions (red light means "Ready to Charge!" in the second picture), use your hot glue gun to (CAREFULLY) glue the naked PowerBot into place. This is key - you don't want your hidden charger falling fate to gravity. I glued in/around the existing screw holes, and my naked PowerBot is held snugly in place. Keep your MicroUSB cable ATTACHED throughout this process, but keep your 5v AC/USB adapter UNPLUGGED from the wall.

Step 6: Flip Your Surface Over and Test!

Success! I drop my phone onto my hidden charger, and immediately it begins to charge. I also hot-glued the red rubber ring from the first step to the top of the surface (desk or table) to indicate where the charger is. You can now reassemble your desk or table, and enjoy your hidden charger!