Quote:
Originally Posted by sunchaser
In talking with the pros, they talked me into group 31 AGMs for the internal cabin safety and off the gassing issue alone. My first set made it about 5 years, less life IMHO than a well maintained LA but again, off gas minimized.
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While generally I agree about the "less life"....I think you may be comparing apples to oranges as far as application goes. IOW, LA batteries in the same application would have lasted less time than in a less harsh application....like a house bank. Bow thruster service is pretty severe/harsh service. Apples to apples, I think the AGMs would outperform the LAs in this application.
Also, I do own and operate 5 Sears Platinum Marine GRP31 AGM Batteries. They are indeed the same batteries as the Odyssey 2150. I went looking on line for the Sears version and they come up "Unavailable". Something tells me the agreement between Sears and Odyssey may have expired. I paid $260 per for mine. I think Odyssey sells them for $390???? I do believe they represented a good value at $260. Would I pay $390 a piece for them???? I don't think so. As I type this I googled real quick and found them for $310. Still pretty stiff but I think I might go that far. I have had them for 3 years now and not even a twitch or flicker so I expect them to last a good while....we shall see.
To answer OP's question....AGM all the way. 2 GRP31s in series....and preferably a hearty GRP31 like the Odyssey. When one GRP31 weighs 50lbs and another weighs 80lbs, I don't know what it means(more lead I assume) but I would think it is a better battery. That is what those Odysseys weigh. Crazy heavy for a GRP31....but I imagine it means it's a better battery.
As an aside....My previous boat, Mainship Pilot 30, had 2 GRP 27s for house...starting...windlass...AND bow thruster!!!!!! Basically those 2 GRP27s for EVERYTHING!!!!! Let's just say they don't last that long when they are punished that severely. Nor does a bow thruster burst remain strong after the first 5 seconds...it starts to fade. If you need more than 5 seconds of thruster, generally speaking, you aren't doing it right!