I got 14 years of heavy usage out of two sets of non-AGM batteries. What possible advantage would AGM batteries give you over GelCell or flooded lead acid?

1995 thru 2002 had two 8D GelCells in the house bank. Lived aboard 2000 - 2002 and cruised Mexico 2001 - 2002. One 8D was still in very good condition after seven years - the other 8D had one bad cell.

December 2002 replaced the two 8D GelCells with four Trojan T-105s (flooded lead acid). Lived aboard and cruised in Mexico 2003 - 2004. September 2009 replaced the four T-105s with six T-105s. Two of the four original T-105s were still in good condition. The other two were damaged because I consistently overfilled the cells with water. My fault!

The GRP27 start battery was a GellCell 1996 - 2002 and has been a flooded lead acid since then and is still in perfect condition. That means the start battery is now eight years old and in perfect condition.

I purchased the six T-105s for $88 each in September 2209.

They require no maintenance other than a quick water level check every four months. I had hydrocaps (water savers) on the batteries 2005 - 2009 but they did not seem to reduce the water usage. The current batteries have standard caps on each cell. I've only had to put water in once since installing them in September 2009.

The batteries get a full charge EVERY day from my 500 watts of solar panels - even on cloudy days the batteries are at 14.25V by late afternoon. The batteries get a serious workout since we have heavily used microwave, TV, electric blankets, and big refrigerator.

I can see no reason to ever use anything except high quality lead acid batteries - the economics just don't make sense for GelCell or AGM.