New House Bank for Flutterby

[mepsnbarry]

When I returned to the boat after summer storage including hurricane Irene, I saw that the house battery bank looked dead. A bit of time in the boatyard has confirmed that it is, and now is my chance to "start over" as I hadn't even finished properly mounting them in their new location. Let me describe my circumstances here:

1. Starting bank--year old sealed group 24 flooded battery. NO CHANGES.

2. Charging system:
2A. 20A AC charger, new-ish, smart 3/4-phase system. I would like to get the temperature probe for it someday, but don't plan other changes.
2B. 270W Solar w/ 15A (max) charger. NO CHANGES
2C. Alternator--Lightly used, 5-year old factory 60A Yanmar, with the factory regulator. No immediate changes. I might consider trying to add a 3-stage regulator, but don't intend to right away. Flutterby spends most of her life either on AC power, or on the hook (solar panels), so the bulk of my battery charging is not done by the alternator anyhow.

3. System Load: We live aboard, and can spend way too much time doing geeky stuff, so computers are the big one, probably 30~60AH per day, with occasional higher usage. Stereo and lighting are very small in comparison. We may add a small electric cooler/fridge eventually, but I hope to get away with less than doubling the high end of usage for us. Last winter in Florida, the solar panels got the batteries up to 100% just about every day.

4. OLD house bank...2X G27 West Marine AGM's, 92AH each.

So my question is: What to get as a NEW house bank. My assumptions/requirements are as follows:

A. I'll pick the shape/size based on fitting them under the quarterberth. It should be 2 or 3 G27 or G31 batteries, or possibly 2 6V Golf Cart batteries

B. I do not want to check water levels in cells, nor do I wish to deal with acid dribbling out of the batteries. (I have always seen some leakage on unsealed flooded cells.)

.........OK, there is the background, now here's the question: What should I buy? Both technology and brand?

A friend of mine has been replacing Delco deep cycle sealed lead acid batteries every five years since 1980, and is happy with it.

The AGMs that lasted five years don't seem better to me, although they were "dual purpose" instead of deep cycle.

Gels don't seem quite right for me, especially as they would want a significantly different charging voltage than my start battery.

[Florida Mike]

There used to be and probably still are battery caps available that will condense the vapor back to water. With the flood batteries you always get some gassing during charge and discharge. I would put a small vent fan on your battery compartment that will run any time you are charging from shore power or your engine alternator. For a house bank I personally prefer golf cart batteries ( cheap ). Just my two cents, Mike.

[mepsnbarry]

I've spent some time under my quarterberth, and I've found that I can't fit golf cart batteries--they are too tall. It looks like my new battery bank is going to be three Group 31 batteries.

My only problem now is figuring out where to find a proper sealed deep cycle battery...or spend around double for AGM's when I don't really believe I'll get twice the lifespan on them anyhow.

Any recommendations on brands/sources, or different suggestions for me?

[colemj]

Sealed deep cycle batteries are simply flooded lead acid batteries with no access to the cells for adding water. This is a bad idea on a boat because you will lose water with charging and the battery life will be short. And you still can't put them on their sides to fit spaces. Better to either get batteries you can maintain water levels on properly or gell or AGM's that can be mounted in odd configurations and don't need topping up.

Mark