I forgot to mention that we replaced the two six volt golf cart batteries that power the coach today as well. The old ones were four years old and would no longer run the inverter and add-on fridge when we stopped for an hour or so. Recently the inverter would go into low voltage condition and shut down after only a few minutes. We went to a Sam's Club in San Antonio this morning where I bought new batteries. I talked to the Mexican kid on duty for a while about our time in Mexico before asking for the batteries. He must have liked me because he gave me two of his freshest stock, dated April / 12!
He wheeled them out for me and said to call if I needed help. I disconnected the old ones and lifted them out but had trouble putting the new ones in as I had to lift the battery with two hands while holding the cables out of the way with the other. Oops, not enough hands and Norma is not getting down on the floor yet. I went back and got my new amigo to give me a hand. I held the cables aside while he used his twenty some year old back to lift the batteries into place. I hooked up the cables, checked everything for tightness and water and we were done. The Sam's Club Exide batteries were $78 each, more than I paid four years ago but much cheaper than the Trojan brand.
I guess four years is enough. These batteries were used hard in mostly hot weather. I check them for water level often and try not to draw the voltage down below 12.5 so I think I did OK.