I want to install a mobile transceiver in my pickup (05 GMC 2500). I understand the reasons for connecting the power leads directly to the battery. This truck has dual batteries. Do I just pick the most convenient one? How do I determine which is the primary (look for the one connected to the starter?) vs the secondary battery? My understanding is that the secondary is used for accessories. I am probably overthinking this but I really don't want to fry anything. My search of the interwebs only comes up with info to install a second battery. Any insight is greatly appreciated.