Just wondering , if I change my car battery would :

1) the d3 reset and start from scratch again (learn again);

2) the bt module require you to reregister your phone and would you need to input all contacts again ?

thanks

Well the D3 would reset, not sure about the learning process, I have unplugged mine to rewire some stuff and it kept its learning... now the bluetooth would reset too... by that I mean, the d3 would lose any presets, backgrounds, etc and the bt would lose paring...

I don't know about the bluetooth... but I know the D3 will lose saved presets, changed backgrounds, and things like that. But no, it will not lose any of the learning time that has been put into it. I've had my battery out of my car for a few days straight, and when I hooked everything back up, the 3D learning bars were all right where I left them.