One thing that I'm finding massively annoying is that the Nexus 7 doesn't seem to be capable of charging the battery while the GPS is active. I have a 2.1amp adapter in the car which should be providing sufficient power, but the charge level doesn't alter. If I shut down the GPS app it will charge of the adapter.
It's a bit of PITA in the having to remember to shutdown the Nexus every time you turn the ignition off.
cheers
Paul

