one mahaguru here told me that MF ( Maintenance Free...not Mother Fxxx ) batteries dun last under our tropical heat, esp if mounted in front near the engine - added heat kills it faster.
I tend to agree......cos my e30 if left alone for 2 weeks with alarm on, wun crank for sure. Battery is abt 1 year old.
It was not cheap also...RM3XX . ( cannot recall exact )