Battery size for 04 Gulfstream

spike

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Hi Folks,

I think I want to replace my batteries in the spring but the boat is already shrink wrapped so I can't see what batteries I have on the boat. Does anyone know what size batteries I need to fit in an 04 Gulfstream ??

Thanks in advance guys !!
 

DennisG01

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There's no "standard" size battery based on boat model. It could be 24... could be 27... could be 29 or 31... who knows. 24 and 27 are typically the most common, though. Since you're not buying them till the Spring, does it really matter right now? :D If you really want to know, install a zipper in the wrap.
 

Harpoon

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Mine has two group 24's.
 

spike

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Thanks guys. The reason I ask now JJC99 is that a friend has decided to put 4 new batteries on his 30 foot grady so they are all new (they are mismatched now). They are all group 31's but 2 of them are only a couple of years old and I don't know whether I can use them on my gulfstream. I only have 1 F250 and not a lot of electronics on my boat. My guess is the group 31's are overkill but I don't see why I couldn't use them - and free makes it a pretty good price
 

Doc Stressor

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The type of engine and the number of accessories you have determines the battery size requirement, not the boat. Each engine has it's own cold cranking amperate, marine cranking amperage, and reserve capacity specifications.

Some engines, like your F250, draw current from the battery when they are operating at low rpm. The alternator can't keep up with the current draw for the engine alone until you reach higher rpm. The computer, sensors, and electronic fuel pumps draw between 10-20 amps. Big Yamahas can't run with a dead battery. Some other brands and models can run independently from the attached battery. When you throw in the draw from instruments, fish finders, radar, and a sound system you can understand why Yamaha specs batteries with a minimum of 182 minutes of reserve capacity.

No group 24 and very few group 27 starting batteries have that much reserve capacity. Grady used to recommend the Deka Marine Master 27m6, which is a group 27 dual purpose (starting and deep cycle) battery that was specifically designed to meet the Yamaha specs. I don't know what they are using now. I've had great luck with these batteries and replaced the original pair after 6 years just because of age. They still passed a load test. They are valve regulated batteries that recycle the hydrogen and oxygen that is generated during charging. So you don't have to add water very often.

You can get away with lighter group 24 batteries as long as you don't do a lot of trolling below 1500 rpm or use many accessories. I had a pair of group 24s in a previous boat with an F150 that speced the same 182 min reserve capacity. I think mine had only 140 min RC. They did fine, but I didn't do any trolling.

Most Group 31 dual purpose batteries will meet the 182 min RC spec. I would not recommend using true deep cycle batteries for starting. Many do not meet the cranking amperage requirements of big outboards and they don't hold up well when they are continuously charged by the engine.
 

spike

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Thanks for taking the time to explain and type all that up for me Doc and the rest of you guys. Have a great Thanksgiving men !!