OK, so the first thing to keep in mind is the construction of the SPH-10BT. The thing is more or less hollow — no DVD or CD to worry about, it just takes up space. That means we could do what we did.

First off, when installing the thing, we spliced off of the positive and ground to the stereo itself after the harness interface with one of these:

https://www.amazon.com/WYMECT-Charger-Socket-Waterproof-Outlet/dp/B07TXG4XJ3/ref=sr_1_3?dchild=1&keywords=12v+usb&qid=1594087669&sr=8-3

This we positioned under the HVAC ducts. Then we ran a thin USB cable from the USB adapter through the stereo's body. Inside of the stereo, we added this circuit board and attached it to the USB for power:

https://www.amazon.com/Gikfun-Wireless-Charger-Circuit-Charging/dp/B073W7P5T8/ref=sxts_sxwds-bia-wc-p13n2_0?cv_ct_cx=qi+coil&dchild=1&keywords=qi+coil&pd_rd_i=B073W7P5T8&pd_rd_r=6bbc9f72-0c74-472e-b78e-c8120a4b1585&pd_rd_w=VmFXF&pd_rd_wg=9XKk7&pf_rd_p=1da5beeb-8f71-435c-b5c5-3279a6171294&pf_rd_r=Y4AANKQ3MD409T3KZZB0&psc=1&qid=1594087652&sr=1-2-70f7c15d-07d8-466a-b325-4be35d7258cc

We ran the two wires from the board out the front of the head unit and then to the coil itself, which we superglued to the cradle. Then I covered it with electrical tape until I can think of a better way to make it look pretty.

It works! But there are a couple things we had to adjust, such as the position of the coil. If it's not dead-center on the phone, it doesn't charge. The coil I linked to above is a 5w, which is standard, but if I'm streaming Spotify and have Waze going, even 5w isnt' enough, and it slowly starts using the battery, which defeats the purpose. So to that, we're going to swap it out for one of these 15w fast charge modules which should do the trick nicely. I've also got calipers to measure it out so that we can maybe try to find a 3D printed panel to sort of go around the coil and make it look nicer.

So that's it, it's really not that crazy once you see all the components. Another cool thing is I've got an available USB port in the dash in case I get a dash cam or something later on. I'm also planning on modding the flashlight port in the glovebox with a USB multi-charger and GPS tracking device, among other things. One of the reasons I chose the e46 is because it's so easy to get into the good stuff and that it's also pre-wired for so much that can be adapted for nerd stuff.

Now I'm trying to find a how-to on changing the color of my dash lights. I'm red-green colorblind, so that red light isn't the best for me in certain situations.