I do have a red isolator switch on my S4 in the engine bay but I don't want to use that as I then have to reset windows when powered back on, I keep all my cars on a ctek but my battery drains quite quickly if not used and I am planing trips where we won't have access to charging and in the autumn stood in hotel car parks may test the battery.
My thinking is not the overall life of the battery but how long it takes to drain it and so a heavier duty battery seems one possible solution.
Michael
