Charging the Garmin Nüvi with USB

I have a Garmin Nüvi 660, with which I have generally been happy. One thing I noticed, however, was its stubbornness in staying in USB mode (as when connected to a computer) when I plug it into a car adapter that has an USB 5V output. (The car adapter that came with it apparently had a short problem, as it burned out a new fuse every time I plugged it in.) To keep external power on when I drive, I ended up having to use the original Garmin AC wall adapter on top of an DC/AC inverter. Ugly solution, but it sort of worked.

Anyway, after digging around on the internet, I saw that many people were annoyed by the same problem (see, e.g., this discussion). I had suspected that that original AC adapter probably played some trick on the signal pins of the USB. It turns out that it's the X pin that was connected through a 18k resistor to ground that signals the device that it's connected to a Garmin adapter and not a third-party one. Apparently other companies, such as some cell phone manufacturers, use the same trick -- by design to increase sales of accessories?

Thus it was a delight that I discovered this trick in the aforementioned discussion thread: (1) power on the Garmin and wait for it to enter USB mode; (2) disconnect the power -- a few seconds later it will reboot into regular mode -- and as soon as the USB/computer graphic disappears from the screen, reconnect the power again. This will cause the device not to enter USB mode again, and it's usable again.