[C320-list] DC power system upgrade advice

[Magnuson's Ragtime]

Hull 205--- I need to replace the 4D batteries, and am not sure if I should stay with the flooded or go to the Gel cells.  My 30 amp Newmar charger is humming a 60hz tone that pier walkers can hear, which started this project. I think I understand the pros and cons of both types of battery and I think that a new 40A  Xantrex charger will handle either while at the slip. I have the Perkins engine with the original alternator. If I choose the gel technology now, and buy the new charger, do I also need to buy an external regulator? Does anyone know the output specs of the OEM alternator? Any danger of the OEM alternator damaging the gel cells? Option 2 is to stay with the wet cells, and the Xantrex charger and keep the internally regulated OEM alternator. (KISS)   

I did buy the reference book suggested earlier, but it seems to give me a lot of choices, that can become expensive and complicated. 
Normal use is shore power most of the time with two or three day trips sailing the Apostle Islands.  We are planning a two week trip to the Lake Superior North shore, and I am concerned with the charge rate of the batteries if we don't spend a lot of time under power. I have considered paralleling the two new batteries, and taking along a deep cycle battery with jumper cables as an emergency back up just for the duration of the trip. 

  
Gary Magnuson
Time-A-Weigh #205