Battery help

streetdoc432

Member
Sep 16, 2010
114
Memphis, TN. Docked on Kentucky Lake, TN River
Boat Info
1988 Sundancer 270, Onan genset, camper canvas, marine a/c, Lowrance HDS-5
Engines
4.3 twins with Cobra drives
I need to replace the batteries on my 270 weekender.. The boat is 2 hours away from me... It has the twin 4.3 and the generator. I know there are three batteries. Can someone tell me the group size of the batteries, so I can buy them before I head up to the boat? Thanks!
 
I'd bet they are group 27....but you're taking a bit of a risk not knowing for sure! Can you find your owners manual online? It should tell you what group size they are. I think SeaRay has just about every manual available. You just have to register on their website...
 
You have options. First, what's currently on your boat doesn't mean that's what's best. Secondly, a lot of it comes down to how you use your boat. Essentially, you can do whatever you want - don't base it on what you have right now - base it on what you WANT your batteries to do with you. The other thing to take into account is how the boat is wired - and at nearly 30 years old, that's anyone's guess.

Some food for thought... Group 24 starting batteries are perfectly fine for starting the engines. For house use, I would go with AT LEAST Group 27 DC. The larger the better, though.
 
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Thank you, everyone.. Dennis, the previous owner had three different brand batteries, three different sizes.
I have been having issues with my panel circuit breaker tripping whenever the power goes out at the marina. It does not reset itself. Therefore, batteries don't charge & die a slow death...
 
Regardless of what the previous owner had in there, you can still put whatever you want in there. Still depends on how the batteries are currently hooked up and how you want to use the batteries.

Generally, it's best to have starting batteries for the engines and a deep cycle for your house loads (see the sizes I mentioned above). While it's not "best practice", you could cheat a little and just get (3) DC's. Supposedly they won't last as long when used for starting, but it's not like you're starting a power-hungry engine.

Until you get the electrical issue sorted out, you might want to keep all DC breakers turned off when you leave. At least that way your batteries won't die off on you. But I wonder why all three batteries are dying, rather than just the house battery?
 
I just upgraded my batteries from group 27s to group 31s this year and the difference is noticeable. My 12v refrigerator can run for almost 2 full days on 1 battery and I can still start the engine off of that same battery. With the group 27s in there, I couldn't start the engine after a battery ran the fridge for 10 hours. I'd recommend getting the largest size your battery holder will accommodate.

Which breaker is popping?
 
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While it's not "best practice", you could cheat a little and just get (3) DC's. Supposedly they won't last as long when used for starting, but it's not like you're starting a power-hungry engine.

I did exactly this. I went with three deep cycles that have CCA ratings well above what is generally considered "required" for my standard compression big blocks. I feel like today's deep cycles are more dual purpose. Plenty of CCA's with lots of reserve...
 
I went with 4 Group 31 AGM's on my 340DA last year. It's really great being able to run both fridges on the hook and not have to run the generator (except for the blender... those mudslides require the 110V bar blender!) We happened to get Interstate AGM's, http://www.interstatebatteries.com/m/product/agm/marine-agm but there are many good options out there. I know West Marine has a sale this week on batteries, although even on sale, their prices aren't great. 20% off West Marine brand starting batteries, and 15% off Northstar AGM's.
 
Sams club has duralast group 31 agm batteries for $180, was worth paying for the membership
 

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