With my S80 I would like to retrofit an AHK. The electric kit should also be equipped with a charging line for the caravan so that the caravan battery can be recharged and the fridge can be operated during the journey (with the caravan the refrigerator is not on a continuous plus but on the charging line). The question now is how to connect this best, since the instructions normally provide that the vehicle battery is in the engine compartment. I have to have a cable from the switching relay d irkt to the alternator and each plus and minus directly to the battery. Do I now put the whole relay history and cabling in the engine compartment or in the trunk? Can I directly access a plus connection in the engine compartment or also minus to the battery?