many thanks for the feedback! see http://neo900.org/resources Hackerbus Specification

/jOERG

I just got several of the magnetic USB charging cables.
While Qi/inductive is neat from a tech perspective, a magnetic connect is just as easy, especially considering how tricky it is to align a Qi receiver pad for optimal charging current.
I can't say how well they will last but they do short the smart charge data pins which is more than the universal Qi pads I found did.
There is no exposed ribbon, just a microusb to magnetic adapter plug which fits pretty flush inside the phone.
The cable has a USB male side and the magnetic attach side, it pulls pretty hard on the phone adapter and anything else magnetic is comes near. Watch your credit cards and any floppy disks you still have laying around.
So far the magnetic microUSB to USB charge cable and adapter is doing almost everything I had hoped from the Qi pad, including (I hope) protecting my microUSB port.
The only downside I see two hours into using the mag adapter is the fear of loosing the little adapter plug if using anything else in my USB port.

(sigh)
So the magnetic charger was unreliable as it would occasionally be pulled down by gravity and I would wake to an uncharged phone, not such a big deal.
Then I had it in the shop where I was do ing some light grinding of some stainless steel, apparently the dust was magnetically attracted to the charger and when I grabbed it form the bench I noticed it was partly melted.
That and having to keep track of the tiny charge adapter when I was using regular microUSB chargers and cables(no data on the mag-cable).
I guess I am back to regular microUSB and being super careful with my N900.
I am probably down to my last of 5-6 N900s between a few crap fake "new' Chinese refurbs and a few real N900s which either broke the microUSB or failed SIM, which again happened last week to my phone. I took my Wife's N900 and she is leaving the Maemoverse.
I think that this thread being about Qi I will make what is probably a final comment on the topic. Qi is a neat idea, but it really needs to be installed in a phone specific fitted tray or drop in stand, these universal pads are universal, but there is no way to know if you are getting optimal or anything above minimal charge.

This is how I solved that problem with my Jolla mod. The charging pad (the "transmitter" part) is fed from a normal USB source. I fed it through an inline meter (like, for example, this one), found the point of the highest current, made a mark on the pad, job done.

pichlo,
great idea, I did something similar, think I ran a script giving me the charge mA. but it is a problem when you want to charge different devices and I had a problem of knocking the phone off of optimal charge both day and night.
The best charging experience I have had was a drop in charger for my old Sharp SL-5500 Zaurus, what a great handheld Linux PDA/net tablet/computer. We could do that for the N900 with a 3D printed cradle, though it would require portrait mode for the N900 in normal gravity, it would also require finely aligning the microUSB tip as a bad alignment would threaten the USB port if dropped in too casually. I guess a cradle or tray and the Qi charge mod from this thread would work too, but my experience is that the mod works but is too fragile for everyday use. OTOH a drop in for a Qi enabled phone seems pretty reasonable, especially if it includes a nice BT audio amp also running on mains or automobile power.

I had actually considered such a two sided video-out/microUSB pwr clamp arrangement with a N900 for video out in the car to have a better screen for GPS-nav but never even tried to build it. I might still get around to doing something similar but installed for openstreetmaps with a Pi zero and a touchscreen.