I don't agree Bill, and a little research will tell you that AGM batteries are less tolerant of an old-school constant charge of 14v like many old cars put out with light or no load.
For motorcoaches many of us would buy charge controllers for alternators when we change to AGM to create proper charge profiles, or if charged by the inverter system we select the AGM settings on the control panels. We have larger investment in our house battery banks than most people's older Mercedes are worth and do extensive research on how to properly maintain them.

Keep your batteries charged when not in use regardless of type and they should last a long time. My boat batteries are walmart flooded cell and just finished their 6th summer without any water added, a quality 3-stage charger year-round. My first motorcoach had a bank of Sam's Club golf-cart GC-6 flooded cell, 10-years old when I sold it and only needed to add water less than once/year, regularly deep-cycled but charged by a proper 3-stage inverter/charger. I don't invest heavily in AGM because flooded cell works well if maintained oroperly. All batteries will live a shorter life if not used and maintained properly.
Buy a good digital volt meter, watch your voltage when you drive, if it constantly dips below or floats above the correct charging voltage for your battery it's going to have a less than optimum life.

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Gone to the dark side

- Jeff