a battery combiner and AGM batteries and like the combiner idea a lot. I've never had trouble with it once I forced myself to pop for the larger size. The original one was supposed to large enough but failed twice after a year or so. It was just undersized contacts for the size load. Once I figured that out the problem was solved. I have both alternators connected to the batteries but my port side alternator regulator is unplugged at the regulator. My charging system is so robust that I only use the port alternator as a back up in case I have a failure on my primary starboard unit. I never switch batteries when starting the engine or the generator and just start from the house batteries. When my Lifelines failed 5 years ago I had the start battery to start the generator and main engine. It took almost three weeks to get new AGM's sent down to Las Hadas so we just set in the anchorage for three weeks using the hotel pool. The down side was that the solar panels and wind generator held up everything during the day but the voltage would drop during the night until the low battery alarm would wake us up about 3 in the morning. One of us would have to get up and run the generator for an hour. It was like having a child again. The down side to AGM's is that when their done, their done. No warning, their just done. At least that was my experience. Having said that I sure wouldn't go back to regular batteries again. They cost you an arm and a leg but IMHO, worth every cent. Back to the combiner, I have a push button which will cause the combiner to close manually so as to combine all the batteries in an emergency which I think is a good idea and option.