If you find an add-on Qi charger which fits the N900 and has shorted data pins please post your source to this thread!!
A description of how to modify an inexpensive Qi universal microUSB type B plug equipped wireless inductive charge receiver's data pins to interface with N900 charging circuitry(and also how to install Pali's new BME to avoid the hardware mod, additionally a pair of script based module driver swap and return to normal as a software work around the need for shorted pins or the need to install KernelPower or CSSU) and installation of the receiver into or onto a Mugen cover/double-Scud battery equipped N900, this should also work with stock N900 battery cover.
This is a comprehensive way to safely charge without worrying that you phone will fall and snap off the fragile N900 USB port.
Read warning at bottom and whole post before proceeding, this could destroy your phone, Qi charger, or burn down your house, may contain peanuts and gluten.
see also:
http://talk.maemo.org/showthread.php?t=72753
http://talk.maemo.org/showthread.php?p=1253353
http://talk.maemo.org/showthread.php?t=93289

I ordered one of the very inexpensive ($6US) universal Qi chargers from ebay, they are also available from most of the Asian import web stores. This is an example with several fits available the correct one seems to be "Middle/Narrow Interface Up" with a micro-B-USB or microUSB type B plug http://www.amazon.com/Universal-Wire.../dp/B00I1D4DWO
When the charger arrived the USB plug was the wrong direction, upside down, this could have been my error in ordering the first time. It was actually not important to me because I ended up rebuilding the plug, it will be very important to you if use the no-solder methods, non-BME charging module, or the BME replacement upgrade.


Best solution: 100% compatible USB data pin-short mod and external install!
The main problem with all of the Qi add on adapters we have reviewed so far, is that they lack the shorted data pins required for the stock N900 to start the charging cycle, in this charger though there are empty spaces which we can use to add the missing data pins. I had to find some compatible pins and short them in the space available. In my opinion finding a source for a Qi charger with shorted pins or doing the add-pins mod is the best solution as it communicates the presence of a high draw charger to the system that is ready to deliver over standard 500mA vs say having a data cable inserted.

I bent the tiny metal tabs on the ribbon side to remove the metal back cap from the USB plug and carefully removed the two power pins from slots number one(+5v) and five(ground) by the microUSB pinout. I desoldered both of the existing pins from the ribbon cable as they were upside down for use with the N900. Next I went into my parts box where I had some DIY microUSB plugs, removing the metal outside I was able to remove the internal pins out the back of the port by grasping the solder tabs with a small forceps. To make the shorted pins I measured the length of the two power pins and the gap between. I bent one of the pins to the right the .5mm distance between the pin spaces and then straight again. I used a locking forceps with smooth jaws to clamp another pin I had removed to the pre-bent one; I then made a sloder joint at the point where the two pins came together at the bends I had made. Once cool I clipped the extra leaving about .5mm of joint and inserted them into slots two and three of the microUSB pinout.

I reattached the power pins to the ribbon cable turned for the correct direction, I tested the ribbon cable connection which soldered to the number one pin to be sure it was not shorted to the data pins. To be sure assembly was correct I inserted the plug into a small bluetooth keyboard, fit was good.

I had seperated the plastic charger cover which is covered on the inside with 'sticky' adhesive and removed the coil and PCB to work on them. I had desoldered the ribbon cable from the charging pad PCB so I put the receiver pad onto the transmitter pad until the blue charging light on the transmitter pad came on, I tested the power output solder pads and soldered down the ribbon cable to the appropriate pads.
The Qi charger has a black pad which blocks the signal and makes the receiver only work from one direction, this is required as assembly without somehow made my receiver pad not work when installed internally against the battery, some reports also have it heating the N900 to rather high temperatures through inductive heating.

As a final test I put the reassembled Mugen battery door onto the charge sender pad, then I connected to the microUSB port on the BT keyboard, red charge light and no smoke. I added a bit of tape on the inside of the metal back side USB plug cap, then replaced the cap and bent down the tabs, tested again on the BT keyboard with good charging, the plug also inserted cleanly and flush into my N900 for the first time offering a charging solution that protected the vulnerable USB port. I had already cut away the unneeded plastic charger cover tabs meant to protect the ribbon cable(the extra plastic tabs block the camera opening) and re-folded the ribbon cable so it makes a 90 degree turn to correctly pass the camera window and then on to the phone's USB port without slack.

I used several parallel strips of good electrical tape terminating under the battery cover, another trimmed strip looping through the Mugen battery cover camera window to secure the ribbon cable, the tape doesn't snag on my pocket or phone pouch. Some people have successfully installed under the battery cover with a stock N900 battery cover and standard single battery. Since I broke one of the tiny metal tabs on my USB plug cap I potted my Qi chargers USB plug with (boiling water softening) Polymorph plastic, including for about 3mm around the ribbon cable as a stress relief to the solder joints. http://www.amazon.com/InstaMorph-Mol...dp/B004MFLU4Y/

Finally we have industry standard integrated N900 Qi wireless inductive charging that works correctly with Maemo and internal charging circuitry, though Pali's BME replacement make all of this hardware work mostly unnecessary. It is too bad they couldn't add shorted data pins at the factory where it would be easy, post if you find a universal Qi that has the shorted pins. Ribbon cable and plug are flush with just enough slack to remove when I need the port for host mode. I much prefer this system with a ribbon cable and flush fit protective USB plug to my previous Touchstone wireless charger which required bypassing the internal charging circuitry and stuffing a Li-ion charge regulator to directly charge the battery which confused the Maemo charge monitoring circuitry and software. Read below for a hacked way to charge without installing data pins.

No solder software hack, BME stays active!
Warning, might result in an unbootable system or worse, though most likely problem is you could be stuck with a non-working BME and charge meter. I recommend using backup manager app to have a restore ready if you mess up. Failure to switch back to normal charge mode might cause permanent damage to a computer or other USB port if you plug in your N900 in Qi no-short charge mode. If you use this method and leave the Qi charger in as a semi-permanent protection for your USB port comment out the sleep and return to normal mode lines, then you only need to click the Qi charge button once after reboot, using USB host mode or the required switching back to 'auto' or normal for using USB mass storage require switching back to Qi or 'dedicated' BME mode to Qi charge again.
The downside is that you must callibrate your battery using a full discharge cycle, this could take a few long and tricky tries.
These scripted buttons can also be used by people wishing to hard wire install an charger to their USB 5V+ pad and ground for either an inductive charger which leaves the USB port free and open or for cases where the USB port has been destroyed and the data pin pads can't be repaired.

1-install(or have) up to date Kernel Power and CSSU testing
2-add Pali's BME replacement repo
web address - http://maemo.merlin1991.at/cssu/bme-replacement/
distribution - fremantle
Components - free
3-apt-get update and upgrade(this will install the new upgraded BME)
4.run this command in command line

Above saves lot of frustration with getting completely BS values posing as correct, when battery gauge is not calibrated (at all 0 like, lost calibration data due to battery out of device for too long and dead bupbat).

5. Reboot
6. charge to green light
7. let run until battery dies(battery is now calibrated, dont rush or you will end up having to redo, last few hundred mA should be spent with backlight , CPU, and things like WiFi off)
8. enter command to BME for unshorted charging9. if you need to plug into your computer rather than Qi charge enter command to BME for normal mode chargingOnce you have done the above then you can enter the below to create two toggle buttons which can be placed in your desktop apps to switch between a timed charging via your unmodded Qi charger and quick return to normal charge button so you can plug into normal computers

Make a file named qi_charge and keep it in /usr/local/bin
make a file in /usr/local/bin called normal_charge to kill the timed charge early
make them executable
.desktop file to get app buttons to start and stop qi_charge
create /usr/share/applications/hildon/qi_charge.desktop
create /usr/share/applications/hildon/normal_charge.desktop
The timed Qi charge scripts will continue to run even after the revert button is clicked returning the system to standard charging, this can be a problem requiring you to kill the instances of scripts found by running ps -e if you toggle charge modes back and forth a few times.

Easy no calibration - no solder software hack.
Not as seamless an integration into Maemo as the shorted data pins but is allows the common unshorted Qi charge adapter and N900 to be used 'out of the box'
This keeps the old BME which requires no long and sometimes repeated battery calibration steps, this is perfect for the average user who charges overnight.
Tested and enters desired mode from these toggle scripts. This is less invasive and more stable than Pali's new BME replacement above but lacks a fully functional battery manager.
make a file in /usr/local/bin called qi_charge
make a file in /usr/local/bin called bme_charge to turn off Qi charging mode early
make them executable
.desktop file to get app buttons to start and stop qi_charge
create /usr/share/applications/hildon/qi_charge.desktop
create /usr/share/applications/hildon/bme_charge.desktop
In order for these buttons to show up among your other apps place qi_charge.desktop and bme.charge.desktop files in /usr/share/applications/hildon/ you can stick the app toggle buttons on your desktop for convenience.

On a non-CSSU system you will need to edit as sudo or root /etc/sudoers.d/qicharger1.sudoers with these files so the scripts will work.
then do this as root or sudo
The timed Qi charge script will continue to run even when the revert button is clicked returning the system to standard charging, this can be a problem requiring you to kill the scripts found by running ps -e if you toggle back and forth a few times.

Always remove data and power pins from the plug for soldering so you do not melt the plastic plug housing. Once you have everything assembled use a cheap USB charged device to give a final test of your work, you do not want to fry your N900's USB port. Test polarity constantly and refer back to the microUSB pinout so you are 100% sure you have installed everything correctly and in the right direction and power polarity, also be sure to check for shorting.

Update
The tape on solution is ugly but seems to work so far.
The plug is weak and prone to damage if you remove the cover to change SD cards or doing host mode. After repairing my Qi plug I potted the whole thing including a bit of the ribbon cable with Polymorph low temp plastic(amazing stuff) which is similar in strength to nylon plastic. I am hoping this will toughen the system, prevent unwanted hyperflexation, and extend it to a long life.

http://www.instructables.com/id/DIY-...c--a-thermal-/

I just finished my wife's N900, I did much nicer job since I knew exactly what to do without experimentation. I decided to add shorting pins even though there is the BME command to bypass this. I didn't need to resolder the power pins as I had ordered the correct adapter this time.
The second try at an improved tape down external method does require trimming off the adapter's cover sheet tabs and moving the ribbon cable about 1cm to the right and refolding it.
I secured the receiver pad with three stripes of electrical tape which terminate under the cover, a fourth strip is cut to fit the camera hole and secures the ribbon cable.
I am less concerned with unplugging, wife doesn't use host mode or other USB now that she has inductive charging, so I don't feel the need to use Polymorph plastic to reinforce the plug and cable.
It still is a tape job but more professional, unless someone documents a system that fits really well under a Mugen cover double-Scud equipped N900 I think this is where I will stay.

Thank you very much for all your effords, Biketool. I'm very interested in your achievements since I also want to adapt my n900 to the Qi charging standard (I have already done so with a Note II mobile and a Lg G Pad 8.3 tablet). I've got one of this Qi universal adapters (the X02 that is shaped to fit nicely in n900 profile), but as it's already known, the n900 does NOT detect it as a proper charging current due to the data +/- pins issue.

Would it be possible to post some pictures of your recent wife's n900 layout (sorry, but my english is quite lacking and I didn't get well from your ample explanations).

Also, you've mentioned something about a "BME command" in order to avoid fiddling with the data pins (shorting them or whatever), could you point out the app (if any), program or script in order to achieve this?

Having my three devices charging in the same single Qi charger would be great.

Has anyone found a Qi receiver with the data pins shorted yet?
While biketool has done a great job explaining his hack, I think we need to find source of a compatible receiver for N900.
It is a standard to have the data pins shorted, so seems silly that no one produces them.

If you have KP and maybe CSSU too this is the software hack said to work without bothering with adding shorting pins, added this to the first post. Others confirm this working.
This would be a great thing to add to settings or just become part of CSSU so that we can all be free of the shorted data pins problem, even now this needs to be done at every startup. I don't remember the right way to change the kernel module load settings in /etc/modprobe.d/blacklist or something?
I did a nicer job taping down my receiver to my Mugen/double-Scud cover, it looks pretty good for parallel tape, still looking for a vacuum form plastic machine.

After a few weeks I just can't imagine going back, unlike the Touchstone mod this works AND it protects my precious USB port both by covering and plugging it and also by moving to a world where I only ever need to plug-unplug if I want to play with USB host mode. See the current and rising pinacle of that insane awesomeness here thanks mostly to Xes http://talk.maemo.org/showthread.php?t=91182

aramburuyy, that sticky pedestal charger might not totally stick to the N900 with stuck down Qi. Instead make one like this http://www.amazon.com/TYLT-Wireless-.../dp/B00DG8NUC8 though obviously not at that price would be good if you want to watch movies or monitor music playback.
You can get a cheaper Qi stand, or DIY charge pad parts on dx.com and aliexpress.com and add it to a 3D printed, wood, or plastic desktop photograph or plaque stand, even Legos would work to build the frame and would look cool.
I used one shaped like the X01, cut the extended bit of cover off and then refolded the wire to bypass the camera, it is pretty easy after you un-stick the protective cover, the X02 would require a similar mod back towards center.

Thank you very much for your advise, Biketool. The Nokia N900 sits perfectly in the tilted (and not very well designed, I admit) charger that I got. Despite it's quite slippery (specially when a dusty layer builds up in the rubber ring that it's supposed to hold devices in place), the N900 manages itself to be in good position held by the protuberance that surrounds the camera part.

I applied the software solution you pointed:
(I´ve got "CSSU testing" an "Kernel Power 52" installed, I think... not sure).

After that, both battery indicators (the 'system one' in the top left area, and another one battery widget I put in the main desktop) go off.

Then I put the N900 in the Qi charging station and its supposed to start charging. There is not sign showing that it's doing so, since the battery indicator doesn't monitor the process any more. Neither the usual yellow bar signal indicating that the process has started (or ended) shows in the screen. The N900's notification LED lights up in orange colour, but does not blink as expected, it just keeps steady on. This the only sign that indicates that 'something' is happening.

The phone looks really neat because the Qi coil charger stays behind the original n900 cover stuck to the Nokia battery. Only a small part (7mm or so) of the ribbon is visible as it reaches the black and very flat micro USB conector, so this mod is barely noticeable. Since the Qi receiver (I've got the X02 variety) has the ribbon protruding from the side of the coil pad, it easily clears the camera area as it reachs the MicroUSB plug. No folding of the ribbon was necessary, only a small cut was made in the plastic protector sheet in order to not been shown through the camera opening hatch, but this was made purely in aesthetics.

Definitively, it charges wirelessly. I've checked twice... and it seems that it does at a good speed. The trade off is I can't tell the actual level of charging due to batt monitors not working unless I reboot the phone. So rebooting is the only way I have figured out to check the level of charge achieved. Annoyingly, It will require to run that script again prior to another wireless charging process. Also, since I didn´t dare to leave the N900 charging wiressly for more than hour, I don´t know if the N900 does stop charging when it gets at the proper level or if it keeps overcharging and eventually damaging the battery or even worse the device itself. Thats a possibility because nothing seems to me to be controlling the charging process. I want to point out than when charging, the N900 gets quite warm, but this is expected since my LG Pad 8.3 tablet behaves in the same way when charging with the same charging solution, and I've been using this method for months with no problems at all. On the other hand, my Galaxy Note 2 does not get so warm when being in the same station. But Note 2 was designed with Qi wireless charge in mind with proper Qi accessories. Note 2 software even detects wireless charging and prompts a message on the screen indicating if the alignment with the wireless charger is correct.

So my questions are: if I follow your method of shortening somehow the data (+/-) pins in a modded microUSB connector, will I be able to monitor the charging process (yellow bar, standard battery monitors and widgets) as if it was charged with the standard way?
Will it stop charging when reached the required level?
Will the notification LED work as usual (blinking orange colour while charging that turns into steady green when the process has ended)?

Although I know the is still room for improvement, I really like the idea of Qi Wireless Charging. My desk is now much more tiddy than the usual mess of chargers and cables it used to be.

You are so right!

The Universal Qi Wireless than I trying to use in my N900 is flat and black, sitting beautifully in place in compact appearance. The short ribbon rapidly disappears beneath the N900s lid. Almost seems a part of the original device as it does not alter much its original appearance.

But what is driving me crazy, is the difficulty I'm finding in order to short the data pins in the connector itself. I´m trying for now to avoid tinkering with the data pads in the N900s main board.

The Qi receiver I've got even does not have data pins at all in the micro USB connector. There are only pins in the sides (5v & Ground) leaving the three central ones completely empty in the small plastic mould. Therefore, I do not see an easy way to bridge Data (+) and Data (-) because there is nothing there to connect. That's why Biketool went through the 'transplant' process he posted which seemed no easy for my skills, I´m afraid.

I've googled for "Universal Qi receivers" with "shorted data pins" with no success. That's quite surprising because I agree it should be a standard, as you say. I'm completely novice but I don´t believe that next century technology is needed for developing such a thing.
All what I´ve got were charging cables with such a big connectors that do not appear to be a neat solution for modding them in the N900.

Now, I´ll try to find a connector with the central pins somehow accessible in order to bridge the data (+/-) and connect the ones in the extremes (5v & GND) to the ribbon of my Qi charging receiver. But I´m afraid that finding a unit that is at the same time workable, small, flat, black and nice... well, that's is asking to much ...Maybe should I quit the black and nice part!

I´ll post back in case something is found.

Just if were possible for CSSU/ Kernel Power people to provide with a reliable software solution equal the Android devices support...

WIth the shorted pins you would never know that you were not using the Nokia high power mains charger, the battery meter works the same, orange light pulses the same, everything is running as stock so responds as expected. In my mind a shorted USB is superior unless we can fix the BME issues. I have no idea how to google search for shorted pins because 99.(% of people have no idea how a charger, a phone, or a microwave works and advertising shorted pins probably makes the average person think they are selling a broken charger. I would post pics of my setup but I cant get TMO to take the upload, it really likes to link to instagram or some other website.
Maybe write a script to kill the BME, load the new charge driver, rmmod it and restart BME after so much time.
try this but dont cry if your phone catches fire or it unleashes zombies on us all, it should give you six hours of charging.
Put this in MyDocs so it is easy to use leafpad edit the wait time for how long you thing charging should last.
save the script name as qi_charge
make it executable
Make this to get a button in your app list to run qi_charge(works)
This is how to get Maemo to find the qi_charge.desktop file in order for it to show up among your other apps, by placing it in /usr/share/applications/hildon/ you can stick the app button on your desktop for convenience if you like.