Notices

I was wondering if anyone tried to install one of these qi wireless charging receivers:

http://www.ebay.com/itm/Universal-QI...item2c83141608

There are versions for both micro usb connection and directly to the battery connection points (but not for N900 - for galaxy types)
.
looking for 2 things:
1. to be certain that it'll work with the N900
2. to make it as invisible as possible (even use soldering if needed to the battery connectors)

I would like to install it since i have qi chargers at home for my android tablet and would like to use them for this.

any insights on this would be appreciated.

I wouldn't mind wireless charging on my N900.

I remember chatting to someone a while ago about it on IRC.
I believe it could be possible to design a battery with the induction charger built around the battery. Obviously to fit charging coils around it the battery would have slightly less capacity. I have yet to find one compatible with the N900
However, if possible or available it would mean no modifications need doing to the device, which would be a must for me.

i won't mind to attach the coil (if it is only the thin part) to the back cover from the outside - something like this (but with only the coil being out):

http://renerento.wordpress.com/2012/...less-charging/

I don't know if it helps but here are some links to my old N900 Powermat mod:
http://ruedigergad.com/2011/08/04/th...-powermat-mod/
http://talk.maemo.org/showthread.php?t=72753

I can say that when installed the Palm Touchstone wireless charging is the bees-knees!
I had it on a N900 with broken USB port and while it is tricky filing down the charge control board to fit inside a Mugen cover with a double Scud battery it is worth is in the ease of use. Clunk and charge overnight, dead easy and no worry about falling onto the USB cable.
If there were a way to trick the N900 charge system to accept charge without shorting the data pins it would be possible to have everything soldered easy internally to USB pads and show charge state just as if you had a USB cable plugged in. I have never gotten an affirmative answer from our charging and USB expert Pali on if this would be possible so I assume not.
http://talk.maemo.org/showthread.php?t=56950

Wonko above is the guy who put a dip switch on his data pads to internalize charging, but I am a big lover of USB host mode and this is inconvenient as having to reboot to use Android apps in Nitdroid. I prefer we come up with a software fix like we did in HEN and later USB host mode manager, still hoping for a OSS Alien Dalvik for the N900 too to avoid unneeded reboots.

Back then I also experimented with an improved version that does not require the switch.
See post #19:
http://talk.maemo.org/showthread.php?t=72753&page=2
Essentially, this was created based on a hint by woody14619 to use an opto-isolator to short the USB data pins.
The idea of the depicted circuit is to only shorten the date pins when power is provided via the wireless charger and to allow the normal operation otherwise.
The soldering is a bit tricky and back then I think I burned the opto-isolator during one of my experiments while soldering but iirc it used to work.

Wow, $3.50 for ten TLP421 opto-isolators on ebay. Great a chance to solder on one of the last new N900s ever sold. Why not take a chance at ruining my precious when the payoff is inductive charging fully integrated into the phone.

a question - should this receiver work - i mean if i'll connect it to the usb and put the charger on a qi charger - should it charge?

I can tell you that generic QI micro-usb charger pads work fine with the N900. I have one similar to this (has mylar cable to uUSB plug) and use it inside an otterbox case (slight back cover mod w/ a dremel). I use this as a charger at work, and Samsung plate at home.

The connector does take the port up though, and getting it out is a pain. So if you're using the USB port more than once a week for data or misc, this is not for you. If you can't recall the last time you used the USB port for anything but charging, it could still save lots of wear and tear on your connector. (I generally sync and file transfer over wifi or bluetooth.)

One thing to keep in mind is that most pads/plates only supply 500mA to 1A. Some go as high as 1500mA, but that's about the limit right now. Those usually need a 2A brick, since even high-end Qi chargers are in the 70% to 80% efficiency range. (Qi requires 60% for their logo, logoed tend to be over 70%, non-logoed usually in the 40% to 60% range.)

The ones the OP linked above are not Qi logoed. I'm betting they want a full 1A plate to deliver their 650mA current, giving them a 65% efficiency, not bad actually. Put that on a 500mA plate though, and you'll only get 325mA, which may not be enough to even charge an N900. Worse, if your charge plate is crap, you can lose efficiency there too, so it could be less.

Summed up: Yes, they work, but don't skimp if you get it. Get a good high-end pad (500mA min) and plate (1500mA min). Anything less and you may wind up draining more than you charge.

This is great news then. I'll be ordering one to test - getting this to work will be huge