Trojan T105s in lead acid. Second set in 15 years. Wouldn't have to replace them except where we stored it they forgot to check the batteries before they closed up apparently for a few months. They were bone dry. They came back up but damage done.
We are having Deca maintenance free batteries installed in a few days and hopefully we won't be dealing with checking the batteries again. 13.5 is a good reading if setting stored an not connected.
We always stored ours connected to 50 amp but now we don't have enough voltage where we store, for now. The transformer won't work on 115. The batteries are turned off.
We never did discharge our batteries much if at all. and should have deep discharged them a few times.