5 VDC from the HeavensWhen I got the Nexus 5, one of the features I was most excited about was the Qi wireless charging built in. All I had to do was get a little charging pad, toss the phone on top of it, and I was suddenly in the future. No more wires to plug in, the energy was transfered into the phone via Tesla-esque moonbeams.
Of course, it wasn't long until I started to loath my other devices for still requiring lewd USB penetration to charge themselves. Why couldn't they evolve past such carnal desires? Had they no shame?
Like a missionary, I decided to start converting the wayward devices in my life and put them on the righteous path towards the miracle and glory of wireless charging. The first to go was my Nook Simple Touch.
Qi ReceiverThe first step was to find a Qi receiving module that I could fit into the Nook. As it turns out, this was pretty easy, as there is a rather large market for retrofitting Qi charging into existing smartphones. They come in the form of very thin modules which get shoehorned into the back of the phone where the battery goes. All I needed to do was find one cheap and small enough.
I looked at the ones available on eBay, and on what was essentially a whim, I decided to get a Qi receiver intended for a Samsung S3. I figured the S3 was a (relatively) small phone, and as such, the receiver wouldn't be too large.
As it turns out, the Samsung S3 Qi receiver was a perfect fit for the area behind the Nook's battery. It's almost like the thing was made to nestle in there. A few drops of glue tacked the receiver down, and a couple snips at the plastic around the battery tray gave me a spot to route the receiver's wires out.
WiringThere are Qi receivers out there that have a USB male end on them, and you can plug them directly into whatever it is you want to charge. But I thought that was just too hokey, I wanted to wire the Qi receiver directly into the Nook's USB port on the inside.
Taking out the Nook's mainboard and flipping it over gets you access to the USB port's pins, and from there it's just a matter of some thin wires and steady hands. I used some wire from a 40-pin IDE cable, which is actually a little thicker than I'd like, but I couldn't find an 80-pin IDE cable in any of my parts boxes.
It took me a few tries to solder the positive lead on without bridging the pins, and for the sake of simplicity I soldered the negative side right to the USB port's outer shielding.
End ResultAfter closing the Nook back up, I was happy to see it readily start charging when I dropped it on my Qi charging pad. I left it on there for an hour or so and saw that the battery percentage went up by about 20%, so that's a good enough test for me. I only charge the Nook every month or so anyway, so even if it was a slow charge, it would hardly matter.
For the record, the USB port still does work as expected if you connect a standard charger or plug it into the computer. I was originally worried I'd need to add a diode between the USB port and the Qi receiver, but I'm guessing it must already have some kind of blocking circuitry built in, as the receiver being attached to the USB port full time doesn't seem to have any negative effect on operation.