Hey, it's Chatty Cathy back from a long weekend of boat commissioning, repair and modifications, and I'm looking for yet more free advice. This time it concerns sizing batteries.
I have plenty of space in my engine compartment. Let's say for argument's sake I could put one 8D AGM on starboard and two 8D AGMs on port. Let's say I could weld angle iron frames to hold them at about 15 degrees so that I could haul them out instead of directly up, thus facilitating removal.
Now add the advice of a friend with a similar metal boat. He has 2 8D Deka-brand AGMs, side by side under the floorboards in his saloon. While he is happy with the batteries, he thinks he made a horrible mistake getting 170 pound/75 kgs. 8Ds, because they are a horror to install and remove. And he isn't talking about lifting them over an engine, but simply lifting them straight up and then up a companionway. He is strongly urging me to get 4Ds or even Group 31s because they are easier to handle...or relatively so.
That's one advantage. Another is that if I get a bad battery, or one that goes bad, I can more easily and cheaply replace it and/or diagnose it.
A disadvantage to my mind is the greater number of short lengths of expensive copper wire and lugs, plus the greater potential for failure in a larger number of connections. Regardless, I want the amp capacity that two or preferably three 8Ds can store, so I can be on the hook with solar and wind charging for a week or so before I have to run the diesel.
Rolls makes a modular 8D wet cell battery: 12 HHG 8DM Rolls Marine Battery
that has a great design. Is there an AGM modular equivalent that anyone knows of? If I could get an 8D AGM that came apart into six 30 pound "bricks", that would be the ideal.