Has anyone switched over to Lithium batteries? I have a 2.5 year old coach with four acid house batteries. I have installed a single point fill system and have keep the terminals clean. I have been told life is 3 to 4 years. These are the batteries that came with the coach, so I suspect they are not "top of the line". I would like to get rid of the fill feature and at least go to a sealed battery. I do not boondock, but live in the coach about 4 months out of the year hooked to power.