Many people have been complaining about the DX not charging when using the GPS. I did find the same thing. What I did discover by accident is the dash mounted DX being in the sun for long periods will cause the battery to stop charging. It does not matter if you are using the GPS or not. I took a 4hr trip and the DX was in the sun for most of it. The AC was on but the DX still got very hot and DID stop charging. On the way home, it was cloudy and the DX stayed at 100% charge the entire trip. In conclusion, I believe the problem is in the HEAT and not the GPS.