Thank you for the great info.
So, given this math...
The 55 Amp Hour Group 24 compatible optima battery (Advertised C/20 of 55)
... will run 11 amps for 5 hours before dying?
With only room for 5 group 24's in the quarter birth compartment, it looks like the most time I can get at 11 amps on my house side would be 3 of these batteries for 15 hours? Sounds like we need to just bring an ice chest.
We've been just daySailing throughout the summer but with fall around the corner we'd like to do some anchor-out weekend trips. Concerned I don't have the juice to handle the comforts of the cabin, though.
My Link 2000 shows 9-11 amps being consumed when the cabin fans are on, a few cabin lights, the frigoboat fridge, VHF, Radio, Radar and the iPad charging off the DC port on the companionway entrance.
My start bank has two batteries... Any good reason to not go down to 1 battery for start and 4 for the house? (Then just switch over if I get in trouble with the start battery)
All of these AGM deep cycles seem to have enough CCA to start my atomic 4.
Previous owner bought the same batteries for both banks.. My house bank and start bank are the same SRM-24's. Each bank with two of them. The start bank is pretty solid, for the moment -- holds a charge. I'm guessing having been kept charge through the alternator, they are fine.
My house bank, however-- won't hold more than 11.6 volts and never get into the chargers' maintenance mode. Cells are all equal height when I check them..
I'm guessing, like you said and like I've been reading -- the house bank batteries weren't really designed for this and are degraded considering the charge/recharge cycles being put on them.
I wanted to go to AGM's to resolve the future issue on the house bank, get to a lower maintenance battery and maybe be able to use the flexible mounting to squeeze in 1 or two more batteries on the house side for larger capacity to help run the boat's DC powered fridge that averages 5-6 amp draw and we never use on weekend trips for fear of drain..
BTW: My local Sams carries "Energizer" AGM's.. any indication as to who really makes those and if they are solid or not?