Seidio seems to use the 5v port....
I just got the G2500 cradle and it works like this....if you plug it into the car or axim power pack (it works with the axim power pak, yayaya, they dont say this but the plug fits and the light comes on :) ) the unit turns on the power light to orange, but if you go to the battery status screen, it does not say charging or anything (just like when you have it plugged into usb without a power adapter)
So i believe the seidio works like when you have your axim plugged in via usb...it only charges when it is off....kind of a bummer since that means it wont charge while you are using it in the car...
i have yet to totally test this out, but i dont believe the battery is charging when the unit is on considering it doesnt say charging in the battery status screen....but the power light does turn to orange saying it is getting some power
any thoughts, sorry if this is explained confusingly :)