If I were to install a battery kill switch to prevent battery drain over a period of 72hrs. or more would this cause other problems.

 

Any time you disconnect the battery, you will most likely have to "reference" the window
up and down switches individually and sometimes the moonroof and rear window shade. You can do this by turning on the ignition and pushing down on each window switch completely and HOLDING the switch down for 5 seconds or so. That makes them work properly when you go to the one-touch up or down feature. Same deal with the rear window shade (if you have one on your car) and the moonroof. Press and HOLD the switches to make them work properly again. Your car may or may not run well after the new battery. My '05 runs great right after the power has been disconnected for any length of time, but each car may be a bit different. Even my fuel mileage is good after doing this. But let me say this....if you have to disconnect the 12V from your car because you are worried about a drain after 72 hours of letting it sit, you have another problem! Have you checked some of the more notorious things some of our cars are famous for in this category? Like the seat modules? Yes? Of course, it can be lots of things, but your car battery should stay charged for a lot longer than that. Hope this helps.