Group 27 to 31 battery???

[Rich (P303)]

I need to replace a couple of batteries and don't want to get into a bunch of wiring or start a new project (I have enough to do). Question... If I have 2/group 27's... and have the room in the battery box for 2/group 31's. Can I change to the larger size without any complications?My alternator is a 30amp on a 2GMF Yanmar.What I would really like to do is connect 2/31's AGM's together for house... and add a deep cycle someplace for starting. Electrically challanged,Rich

 

[ruedi ross]

As long as you have the room

you can replace the 27s with 31s, no problem. 'If you are going to add a dedicated start battery you don't really need a deep cycle for that battery.

 

[Jim Rushing]

Easy Mod

To add Group 31's in place of Group 27's. I did this on my old Hunter 35.5 years ago. Adding a starter battery is more of a challenge. You have the problem of charging the starter battery separately from the house bank. You need a charger with a echo charger output for the starter battery. The charger in your boat may or maynot have this function.

 

[Maine Sail]

Yes easy to do..

Yes that is very easy to do. Why the AGM's? I know they are great batts but certainly not necessary for coastal cruising. You can buy Groups 31's from Battery World (in Portland) for well under $100.00 each..If I were in your situation I'd buy some deep cycles lead acid batteries and spend the savings on an alternator upgrade!Putting AGM's into use with a 30 amp alternator is like putting a class three trailer hitch on Toyota Yaris. Just my .02..

 

[Stu Jackson]

Yes, easy to do, no wiring changes required

Think of the wiring both TO and FROM your batteries: you have the alternator output going TO the batteries (whether directly or through the 1-2-B switch for this discussion doesn't matter), and you have the batteries out going TO the 1-2-B switch. The electrical loads are not changing, i.e., your alternator is still the same one and you are not changing anything that the batteries are providing power to, right?So the ONLY thing you are changing is the capacity of your storage "facility", the batteries.No wiring changes required.Do the start bank thing, you'll wonder why you put it off so long once you do it, because you'll now have a healthier bigger house bank and can stay on the hook a tad longer.

 

[Don S/V ILLusion]

the only caveat

Not sure how old your existing batteries are - be careful when selecting the new batteries in terms of the design of the battery posts. I suspect you are aware that new batteries have different size (diameter) posts such that different cable ends are required.

 

[Rich (P303)]

Thanks all...

I guess I can't get into too much trouble.Like the Yaris analogy... Very funny.Thanks for the posts,Rich