Originally Posted by JoeSchmoe007
By "directly" I mean using regular USB data cable (most likely USB->Micro USB) and NOT special charge only cable that has data pin shortened to draw higher current.
The reason for this post is that I found that my new phone (Moto X) doesn't charge when connected directly via regular data USB cable even though charging indicator is on. When idle it still loses several %/ hour, when running Google maps - much more.
After Googling I found that if the phone is connected as USB media device it draws less power from USB and it may not be sufficient to charge phones with high capacity batteries. Workarounds include using charge-only USB cables that have data pins shorted, cigarette lighter chargers or AC charger if your car is equipped with AC socket (mine is, but what a pain to have to use it for this!).
Here is my situation on '11 WK2 with 430N (2 USB ports, Android phones are recognized as media device on both):
Old phone (Droid Incredible, 1300 mAh battery) charged fine when idle via regular data cable even though it was in media player mode. I haven't really used it when running Google Maps much so can't comment on that.
New phone (Moto X, 2200 mAh battery) doesn't charge via regular data cable (even though indicator shows phone charging). When idle it still loses several %/ hour, when running Google maps - much more. I tried 500 mA cigarette lighter charger and it charges it fine in idle, haven't tried while running Google Maps yet.
The port probably doesn't provide enough power for a power hungry newer Android phone.
I use a dual port (2.1 and 1amp) USB charger that inserts into the 12v power port in the dash compartment.
I took it apart and soldered the 2 middle (data) connections together to 'short' them out. This tells the android device that it can draw as much power as the device can provide.
Most of these 12v USB chargers are designated for Apple products and won't provide full power to Android devices unless the two middle conductors are shorted together.
I've used it to charge/power a Galaxy S4 while using Google Maps/Navigation and it works.