The stupid alarm system drains current from the battery in a week or two, ultimately killing the battery, I never bothered to find out at what rate, I just remove a battery terminal if the car is going to be unused for more than a few days.
As the battery is only a piddly little thing, it doesn’t take much of a drain to flatten it.
At one stage I had it connected to a solar charging system, but that was useless as the bastard alarm just drained the battery faster than it could be charged.
"Keep calm, relax, focus on the problem & PULL THE BLOODY TRIGGER"