Like many folks I have been scratching my head (and searching the forums) for the reason my D3 did not seem to charge when plugged into the built-in USB charging connection in my car. After installing Battery Spy (great app) I was able to figure out that the USB DEBUGGING setting controlled the charging condition when plugged into the car. It took one D1 and two D3s all running Battery spy for me to finally find the right condition that isolated the problem. On the D1, it didn't matter. USB Debugging on or off - it charges. On the D3, it does matter. USB Debugging on - will not charge on the car. It initially says charging for a second then switches to discharging. With USB Debugging off - it charges. All this is with the D3 USB setting set to charge only. I hope this helps some other folks too. I know I was getting a little frustrated at using the D3 in the car and even though it was plugged in for charging, my battery just kept dropping. Make sure USB debugging is set to OFF while in the car.