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When I purchased the boat it had and still has AGM, group 31, house bank. Time to replace them. Would love thoughts on which way to go. Data points:
1. F38 which lives on a mooring.
2. Have wind generator which we put on after we leave boat.
3. Batteries on F38 are under the nav station which means to check and fill flooded cell have to empty nav station and go down through it (at least I think so).
4. We use our fridge when cruising so have to run engine periodically to maintain charge if wind generator doesn't keep up, which it generally doesn't.

With this "fact set" which way would you go? A pair of Rolls AGMs (going 6 volt in either case I believe) wold be $600 while Flooded Cells would be $440, not an insignificant difference.

Appreciate your thoughts.

Hi Ed:
We had Lifeline agms, two 31s for house and a 27 for starting. House was under the nav table like yours starting was in the aft cabin replacing the lower drawer next to the berth.

In my opinion agms are the way to go with this setup. "Out of sight, out of mind" occurs to me if you have flooded batteries in a spot like that. As we all know, fluid must be maintained in flooded batteries or their life will be very short which will offset their lower cost quickly.

My lifelines were going strong after five years when I sold my f36. Boat was on a mooring and had only the engine alternator for recharging source. Alternator was 100 amp.

Agms plates are held between the glass mats. This makes it harder for the plate material to fall off and fall to the bottom shorting the cell. This allows them to accept higher charging current. You need to make sure that your voltage regulation matches the battery's requirements to ensure long life.

I haven't gone AGM route based on past reading that you need to have appropriate charging setup. Maine Sail's site outlines some considerations as I recall, including alternator voltage output, etc. in my case I would have had to replace the alternator as well in order to charge them such that the expected life would be possible.

Golf cart batteries. Sam's club. You get the most AH/$. Less to worry if you kill one and much easier to take on and off.

Im still abit old fashioned. I like the 6v Trojans. I just believe they very forgiving if some how me or my various charging devices screw up, which does and has happened.
Cheers Dale
Freeform.

I also have an F38. The PO installed 4 6v trojans under the port side settee just forward of the sink. Very easy access. I also have two 12v starter batteries under the nav station. The ones under the nav station are a pain to get to they should not need as much servicing. In my previous boat I had a similar setup. Since staring batteries lose very little charge during starting they charge quickly and do not lose as much water in my experience. I check them maybe twice a season and rarely have to add water.

Michael Belanich
Dolcetto, F38 #65

Our F32 came with a house bank of four 6v AGMs (Lifeline GPL-4CT). Because I highly respected the work and judgment of the PO and because the batteries fit quite tightly, when I replaced them I bought the exact same. They are certainly costly but it would be awkward maintaining water level in flooded batteries, especially our 3 wedged under the companionway stairs.
Now I have a related issue. Need to replace the starting battery, a 12v located awkwardly under the settee just to port of the engine. It is charged by placing the battery selector on "both" and running the engine or (rarely) plugging into shore power. I need a maintenance free battery, but does it need to be (or should it be) an AGM? I have read that starting batteries need to have different performance characteristics than deep-cycle house batteries. Also concerned that my charging systems will treat all the batteries equally. Comments?
Dale