2004 280da battery switch wiring

[SAshton]

I only have group 27 interstate deep cycles and a group 24 for the port starting. A larger 24 that's equal to my 27 though. Seems to be good. I've gone out overnight with fridge running and didn't kill it. Only once tho as I didn't get the boat until mid sept

 

[JBFins22]

I only have group 27 interstate deep cycles and a group 24 for the port starting. A larger 24 that's equal to my 27 though. Seems to be good. I've gone out overnight with fridge running and didn't kill it. Only once tho as I didn't get the boat until mid sept

So we have the same boat and you have 27's. I wonder what original equipment was. I can't imagine your previous owner downgraded, so I assume that one of my previous owners upgraded. Only thing is the battery trays look original. Regardless, I have 31's and that's what i'll be going with. Guess i'm still doing my homework.

 

[ttmott]

My thoughts exactly. I did see that the cranking amps are up there. That's around what i'm at now but I have 2 different lead acid, unknown age batteries. Also, my starting is an Optima AGM and I don't think that's good for my charger, having different type batteries. I'm going to mull it over for a month and see what my electrician friend comes up with too. Still might just head to Sam's I can always grab them in Jersey since my father in law has a membership. I'll be there for Easter anyway!

CCA seem to be not the most important factor for what you are trying to accomplish. The Ah (Amp hour) is probably what you should be evaluating. FYI most 12 V dual purpose and deep cycle batteries with an Ah over 80 will crank a gasoline engine simply due to their heavier buss structure.
For the dual purpose and deep cycle batteries the Ah should be the determining factor as that will establish the capability on a charge.
So, even though the prices of the AGM's have gone down the cost / life is still not there for me - yet. I get about 6 years out of the lead acid batteries at about $85 per battery and if you should be lucky enough to get 10 years out of an AGM at $225 per battery it simply doesn't make economical sense. This argument is sans the lower maintenance with AGM of course.
Now in my case I have a high quality modern charging system and that as well as how much the bank is discharged between charging is the determining factor in the batteries life; Hence six years minimum in my case.... And, the batteries are always on an active charger except when out somewhere and the engines or generator is not running.
So about different battery types and sizes on a single charging circuit; this is a recipe to greatly shorten the life of the batteries. It is important to have matching batteries and ultimately the same age batteries so the charging system raises the banks at compatible rates all together.
Group 27 vs 31 batteries - For me the cost / Ah seems better with the 27's; but that's my take.

 

[JBFins22]

CCA seem to be not the most important factor for what you are trying to accomplish. The Ah (Amp hour) is probably what you should be evaluating. FYI most 12 V dual purpose and deep cycle batteries with an Ah over 80 will crank a gasoline engine simply due to their heavier buss structure.
For the dual purpose and deep cycle batteries the Ah should be the determining factor as that will establish the capability on a charge.
So, even though the prices of the AGM's have gone down the cost / life is still not there for me - yet. I get about 6 years out of the lead acid batteries at about $85 per battery and if you should be lucky enough to get 10 years out of an AGM at $225 per battery it simply doesn't make economical sense. This argument is sans the lower maintenance with AGM of course.
Now in my case I have a high quality modern charging system and that as well as how much the bank is discharged between charging is the determining factor in the batteries life; Hence six years minimum in my case.... And, the batteries are always on an active charger except when out somewhere and the engines or generator is not running.
So about different battery types and sizes on a single charging circuit; this is a recipe to greatly shorten the life of the batteries. It is important to have matching batteries and ultimately the same age batteries so the charging system raises the banks at compatible rates all together.
Group 27 vs 31 batteries - For me the cost / Ah seems better with the 27's; but that's my take.

This is some good, interesting information. I'm going to take Ah into consideration instead of just CCA. After all, daily life and longevity is what i'm after. I do like the AGM because of its safer technology. Sealed batteries without the possible leaks and gas output sounds good. Regardless, I must get my batteries of the same type and same age. I can't understand why someone would replace one and make it an Optima DP AGM and leave 2 other unalike wet cell batteries in service alongside.

 

[JBFins22]

that's a pretty weak "brochure" if you ask me

I wouldn't sweat it too much. I just went to the basement and took a look at my batteries. They say "Marine / RV Deep Cycle" on them. They also provide 1000CCA which is more than what my previous batteries had. Someone else I was talking with on this forum also uses the exact same battery to start his Mercruiser 8.1's. They should be more than enough for your motor.

I called the number on the Sam's website. It was the customer service number at Eastern Penn Manufacturing. The batteries you bought at Sam's are, in fact, dual purpose. The rep told me that anything that is AGM is a DP battery. I was able to find the same battery at Batteries Plus in Seekonk for 239.00 (though it looks a little different in their pictures, EPM confirmed it). I'll be heading to Sam's to grab 3 new Duracell Platinum AGM soon. It is the best deal and its identical to Deka and Intimidator, all made by Eastern Penn.

 

[SmilingMonkey]

Good info. Thanks for the follow up