I've got some free space in the back compartment now that I don't need a oil reservoir and I'm looking into putting in a 5th battery. (currently running a Group 31 AGM as the 4th battery)
I've read a number of guys running two batteries in parallel, but I haven't read too much on running them truly independent of each other.
So here's what I'm thinking.
Battery 1 - Group 27 deep cycle to the carbons only (2x HDS9 and 1x HDS12).
Battery 2 - Group 27 cranking to the motor and everything else other than the TM. (pumps, lights, NMEA network, poles etc)
I'd have battery 1 connected to the 4th bank on my charger so that it would charge when I plug the boat at the end of the day.
Battery 2 would get it's charge from the motor's alternator so in theory, much like a car battery, it wouldn't necessarily need to be charged like the others (other than a long term storage trickle).
Based off how we used the cranking battery before these giant power hungry graphs came into our world, I would imagine a Group 27 would be more than enough to start the motor and run the smaller accessories. My concern is if a group 27 would be enough to run three graphs all day without the supplemental charge that normally comes from the big motor when running.
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