As for flat, it won't flat by those small activity (opening/closing door); When economy mode active, many lights won't even work anymore until you start the car again.
Just don't let your battery discharge (drain) and not charge it properly.
If worry, using of "external" items like charger could also be a culprit, especially if those items/charger are faulty or?
From what I know, if you frequently drive short trips and frequent start-and-stop, you might face shorter battery life issue. The battery is not fully/properly charged for these short trips. Correct me if I'm wrong.
ya....betul.........battery is not fully charged for short trips.
That's why my toyota last so long....coz i travel jauh everyday...