i installed a batteryisolator under the hood replacing the alternator plug with a new one for the sense and put the secondary batt in the trunk using a sealed optoma battery and a battery box. did this for future use and upgrades, i currently only have my infinity baselink II hooked to it.
my main reason for this isolator setup was so that if the secondary battery drains with the car off it will not drain the primary and i can still start the car