As I recall, AGM batteries were initially adopted mostly for Class B van campers because using flooded batteries was such a problem. You couldn’t place flooded inside, and if mounted under the van, it made watering very difficult.
At first, AGM batteries were mounted under the van floor, but some builders started moving inside to make access easier, and also to protect from extreme temperatures.
I do not recall seeing any Class A or C RV with AGM batteries inside the living space.
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