Rider 550 power requirement?
AFAIK, the car mount comes with a USB cable connector. Good news so far. However it seems that the TT docs say the 550 needs its own USB source that must be able to handle the current demanded to keep the battery from discharging. The car mount comes with a car plug in adapter which is supposed to be able to keep the 550. There's no mention about whether the "magical" TT adapter does something special or one of the TT USB ports is a 2.1A port.
Phrased differently, how much current does the Rider 550 need?