n900 USB charging solved!

USB charging has become an official USB standard this year:

http://www.usb.org/developers/devcla...arging_1_1.zip

To summariize this: A USB charger is expected to shorten the USB data lines D+ and D-.

Some older devices (especially iPods) implement something different and e.g. keep the data lines on 2.5V via two pairs of 25k resistors.

My car adapter also did not work with the n900. So i opened it to find those four iPod resistors (i don't own an ipod, so i can't tell you if a ipod would actually be charged on this).

I then just bridged the D+ and D- line in my car adapter (the two middle ones on the usb socket) with a 200 ohms resistor (in fact 2*100 ohms in series). And guess what? Now it charges my n900 just fine.