Need 12v Battery Recommendation

The problem with parallel batteries, When one cell is down, the other batteries in the bank, come down with it.
You may consider charging and load testing all one at a time.
I'm having great results with DP Deka 31 on bow thrusters.
One Wesmar boat has 4 in series (yes, 48Vdc) and doing well for years now.
West marine sells the same battery with a better price and fair warranty.
https://www.westmarine.com/west-mar...marine-battery-860-mca-group-31-19751684.html

Their AGM31 matches your model @ 105 but taller price than the DP.

I don't mean to push WM all the time, But they are near everywhere and warranties are easy.

We are using Lifeline when capacity is our first concern, and Odyssey Extreme when cranking amps are more important.

I've read paralleling more than 4x 12V batteries isn't great (dunno exactly why).

I'd have guessed a complement of Lifeline 6V AGMs (GPL-4CT, etc.) would somehow be fittable (?) into a footprint of 6x G27s. Series-parallel wiring.

I have read Full River are decent. I've also read Northstar are decent, but they've recently been subsumed by Odyssey (merger or acquisition or something).

-Chris

The DP31 is 100AH, The AGM31 is 105AH.
Interesting so close.
The AGM can cycle lower than the DP is where the AGM comes thru.
I know your talking G27s and I'm talking G31s.
I think they fit in the same box. Don't they?

WM has a Gell battery @ 88AH. That's for really deep cycling.

How far down are you draining your bank that requires lots of AH thought?

Check out Discover Batteries. My client, who owned a 58' passagmaker for many years, owns this company. They have a marine division so I would hope that personal experience might have had positive ramifications on his battery development.

Used to have Lifeline for the house bank. I'll attest that they are very good based on our experience.

However, I wanted to increase my house bank capacity - within a very limited footprint. After doing some due diligence I switched to Firefly (wasn't prepared then to take the step to lithium). They used to offer a different size - taller with a smaller footprint - that I could squeeze in my limited space, increasing my capacity significantly. The only Fireflys offered now are built to G31 dimensions.

As an aside, our Firefly house bank plus upgraded dual inverter/chargers plus a solar array has worked extremely well for us. More than a straightforward battery change, thought.

Yep, I had to look it up. G31s are an inch longer.
It was the universal boxes that lead me to believe they were close to the same size.
However, it is interesting somebody made a box just for G27s.
Or, your fitting 3 bats in an old 8D box...

I did find a 110AH. G27 on Amazon;

https://www.amazon.com/s?k=VMAX+XTR...ed+Deep+Cycle+High+Performance&ref=nb_sb_noss

Further searches show comparable 100AH batts with free shipping.
https://www.amazon.com/Renogy-Batte...sprefix=g27+agm+battery,automotive,151&sr=1-2

@DOCKMASTER any chance your boxes can hold 6v golf cart AGMs? I have six of these for my house bank. I am getting pretty good longevity as my current bank is 2018 install. I can't recall the brand. I do recall prior to the AGM I had lead acid and not having to watch and fill the cells distilled water is sooooo nice. I will do the same for the house bank again 6x6v AGMs.

Firefly has apparently left the US market.

And there are several reports on-line about failures in their batteries after having moved production offshore.

-Chris

That would be my first recommendation, for a house bank.

In the last boat, we fitted 4x Lifeline GPL-4CTs (6V) into a little bit more space than we had been using previously for 3x G31s. Seems to me their horizontal footprint was similar to G24s, maybe almost the same height as G31s. Something like that. Actual dimensions are easily available on the Lifeline site.

-Chris

Bummer on the battery box, but you really need to stick that for sure.


I am happy to say I save every "boats" email related to invoices, quotes, projects in the email folder called "boats". I just accessed it yesterday to find a work order from 2018. Done with paper files mostly. Yep, it reads Boats, plural. Current fleet is 50' Californian by Navigator, 37' Beneteau sail, 12' Apex RIB, Seadoo Spark and Hobie Cat to tow behind the Class B RV Van Okay, and a few SUP boards filed there too.

Bummer. Although AGMs offer alternative positioning, anything but upside-down I think. Also, Odyssey offers a few very odd 12V sizes/shapes, and some of those might fit sideways in your box.

Maybe worth a check if that whole "max 4 batteries in parallel" has any credibility. (I'm not electrically-educated enough to know...)

-Chris

Interesting. Hadn’t heard they’d left the US market or that there have been some “failures”. Any details available on how exactly they failed?

Mine were manufactured in 2019, so hopefully onshore.

Napa auto parts, on line has a plethora of batteries to look at with all the specs, AMG commercial ,marine , etc. If you are an Auto club member you get another 10% off. That's where I get my batteries from, they generally have the best number. Not sure if Napa is in your area though. They are all over my neck of the woods.

No details; have only seen related comments about the situation on two other boating forums. Don't remember when production moved to India, but Ocean Planet (I think?) may be able to speak to your particular batteries. OTOH, if they ain't broke...

-Chris

Absolute best would be Lifeline, I'd guess Rolls would be 2nd and are about the same price as full river now. Interstates are good too.