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
Typically a cars immobiliser and alarm should take about 50ma so a 50AH battery should last 30 days and still have enough juice to start the car. Starting the car will typically take juts half an amp hour. So your battery at 50AH should be more than sufficient.
There could be one of three issues if you are getting problems. First is that car batteries arent designed for deep discharge and if you do that more than a few times you affect the capacity of the battery. That capacity declines with age anyway.
Second issue is that you may have a 60 am alternator but its unlikely ever to put more than maybe 45 amnps into the battery and then only when its deeply discharged. On my boat I have found that it takes almost 6 hours engine running to fully charge a 50% discharged battery with the charging rate dropping from 45 amps initially to less than 5 amps towards the end.. What I am getting at is that its very easy with a lightly used car to get into a vicious spiral of discharge and then not fully recharge .
Third issue is that you have something taking leccy that shouldnt be doing so whilst the car is standing.
None of these issues go away if you just buy a bigger battery.
