340DA Battery Question?

timemachine

timemachine

Member
Jul 11, 2009
403
Watch Hill, RI
Boat Info
2005 48 Sundancer
Engines
Cummins 530HO
I went thru my manuel to confirm what I needed for batteries and it said I needed group 31, etc... So here I come with my new batteries and turns out I have group 27s in the boat. They are the original 2006 batteries? Anyone else notice this issue.

Heres my 2 questions? Should I buy new trys and move up to Group 31s of stay with the 27s?

My second question and information I need confirmed is the battery setup. Seems my port batteries are my house and port engine starting battery and my starboard is pretty much dedicated to the hatch lift and starting the starboard engine. I beleive the Generator runs of the house battery as well. Is this correct?
 
Im thinking of moving to the 31s. My trays are about a 1/4 short length wise. I dont think I can squeese them in so I would have to replace the trays. Its and extra 100 lbs if I replace them all but thats not a big concern.
 
I replaced all 4 of my batteries this year, I called the marina and told them to install the 31 group battery. They told me my boat uses the 27 group and the 31 will not fit. So I replaced them with 4 SeaVolt AGM batteries.
 
Unless you spend loads of time anchored out, I don't see the need for changing to 31s. Fridge is the biggest draw on the batteries. Even then, if you start the gen once each day to charge things up, you won't get stuck. I'm guessing you have a "jump start" switch on your dash. If so and the house/starting battery bank dies after a night on the hook, you can start off the other one, which should be fresh as a daisy since it basically does nothing.
 
rondds said:
Unless you spend loads of time anchored out, I don't see the need for changing to 31s. Fridge is the biggest draw on the batteries. Even then, if you start the gen once each day to charge things up, you won't get stuck. I'm guessing you have a "jump start" switch on your dash. If so and the house/starting battery bank dies after a night on the hook, you can start off the other one, which should be fresh as a daisy since it basically does nothing.
Click to expand...

Bingo!

The biggest issue with batteries is just how you use them. If you don’t spend lots of time (I mean overnight on the hook type of time), you really do not need to move up to the extra capacity of the group 31’s. If on the other hand you do use a lot of your house battery power I would switch the group 31’s and go with AGM’s.

My boat was stock with group 31 “cranking” batteries and my battery setup is exactly as the OP described in the first post. BUT…. I do spend a lot of time on the hook and do use a lot of my battery power, which is why I switched my port side battery bank over to AGM’s. My starboard OEM supplied batteries are still good and I will most likely get another year out of them. When I wear them out I will most likely change them for AGM’s as well, although the load on them is not great so the AGM’s would be overkill, but I will put them in anyway just to remain consistent.
 
I don't spend much time anchored out - maybe 5-6 hours a week, if that. That's not even enough time to run the fridge on battery power. I got 4 seasons out of the house/stbd engine starters (2 paralleled deep cycle lead acid group 31s) and I am going into my 7th season on the other, which is a single group 27 lead acid starting battery, which solely starts the port engine and the genny. I take my batteries out of the boat in the off season and I monitor the water levels very carefully during the season. At the slip the converter is always on and my batteries are very easy to get to, sit in front of and examine.

That's another thing to consider - how easy is it for you to get to your batteries? If they are impossible to access, the care free nature of the AGMs are likely the way to go.
 
I ended up ordering 4 new group 31s through a friend at West Marine. I will get 2 seasons with a 100% replacement and 3 years prorated after that. They were on the best deal on the couple brands that would fit my trays. I really liked the Sears/Oddesy batteries but I did not want to take on the project of changing the trays plus I save about 50.00 per battery. I do spend lots of time on the hook and wanted the extra juice for the frigs since I have 2 of them. I think I made the best decision and with the extra discount they unded up only about 30.00 more each over the group 27s.
 
I also thought about 31s on the house side and 27s on the starboard which is primary starting but was unsure how the charger would perform with different sizes. For the 60.00 extra I can also have the ability to rotate the batteries yearly.
 
My 320 came with group 24's, should have had 27's. When I replaced all four last season I put in 27's for the extra reserve, the tray size was just fine. Actually the tray size in my boat could have handled 31's if I remember correctly but felt the 27's would be more than fine. Either way I agree you will enjoy the extra reserve, I know I do. I think the dealer that splashed my boat originally was just not paying attention when they put in 24's, the old saying "just use what we have in stock" solution....
 
Funny this came up. Back in 03 When I bought my 34 it came with 27's as well . I to noticed in my manual that it stated 31's. 4 of us purchased 34's that year all from same dealer. In the end they replaced everyones batterys with 31's . The boat is not shipped with batteries and is the dealers responsibility .

Rob
 
I figure next year I will swap banks and that way the use will stay pretty even as the starboard do not see as much use as the port house batteries do.
 
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