I have a HP-2 mounted in my vehicle. The way I have it mounted (on the headliner) I chose not to keep the 4 AA batteries in it due to the increased weight of the batteries causing more pressure on the 2 screws holding it to the headliner. I have a USB cable via a cigarette lighter power cord attached to it so that it turns on when I start the vehicle and turns off when I turn off the engine. Over the last several months the HP-2 upon startup many times needs to have the correct time/date put into it before it can go into receive mode. I was wondering if there was an internal battery in it that may need replacing.