bertram31.com

The time has come to replace our batteries; we currently run 3x 4D Rolls batteries; one for each motor (454s) and a house battery. Our yard has recommended replacing the Rolls with AGMs. Does anyone have a strong opinion on Rolls vs. AGM?

We don't have a generator; the house battery needs to run a small fridge, electronics, pumps, etc.

Rolls batteries are definitely considered the Rolls-Royce (no pun intended) among batteries... And there is a premium associated with that... Whether it's justified I wouldn't know... Having said that, I believe Rolls batteries ARE AGM batteries...

Rolls are good - replaced existing batts in our last boat (32' BHM) with a set. But, I would strongly recommend you not go to a yard, but to a commercial independent battery store, someone who sells to trucking companies, heavy equipment users etc. In our 31, we have 4 - 6v golf cart batts, and a single combo deep cycle/starting 12v batt shared by both engines to use as starting. Works very well, also runs frig and electronics w/o use of generator. I believe top of the line with similar amp hour in this setup was about 1/2 of the cost of Rolls, and will last a long time unless unnecessarily boiled by overcharging at dock. Here's the place we use in CT. http://midstatebattery.com/

Moguls

Prior to our repower, we eventually replaced our Surrettes (same as Rolls) with Group 31's to spin our 454 Mercruisers. Never had a problem with them turning over an engine. One for each engine.

Currently for my Cummins, after the repower, I am just trashing Interstate Group 31's that I got 8 years out of. Not too shabby. I have Two per engine and one house, so I am running 5 batteries. The current ones are INterstate truck batteries.

I would say 8 years says to me not worth going AGM's. But I bet I don't get 8 years with the next set. I am replacing them with Group 31's from Deka (East Penn Manufacturing). $115 a piece, so at least half the cost of AGM's. Reason for going over to the 31's is weight. Trying to pull those Surrette's or Rolls for the boat is tough. We remove ours over the winter. Store them in a garage and keep them constantly topped up.

In the spring I desufate them just before putting them back in the boat.

I know a lot of the guys run AGM's but just don't know if they are worth the money.

Thanks Tony!

my odyssey AGM batteries are 2005 still perfect .two house,one port,and one starboard all isolated thru isolation diode blocks.splash boat Wednesday all batteries at 13.4,13.2. type 27

Bob

One grp 27 spins over those Cummins?

2750-S the S stands for threaded stud because i use compression lugs with silver coated 4/0 (2000 volt) aviation wire. the engines harmonic balancers move 1/4" and start in 40 degree weather.you actually need a photo tach to see tape on balancer move.lets say they start instantly. one 2750 AGM battery is roughly equivalent to a 8D flooded type battery @(1100 CCA).

Bob

The grp 31 Deka's I have have 1000 cca and 185 reserve. So about the same as the ones you run. I have one house and 4 start. I was thinking about going down to two start and two house with a parrell switch and battery switch combo to bring all 4 online if needed. Right now I can bring all 5 on line. A little overkill.

all 5 on line for emergency welding i guess but what other reason ?incidentally do you have all 4/0 marine cabling from positive terminal to input of battery switches and from negative terminal (daisy chained) to large style grounding block ?

Bob
2/0 cable. Not sure what the large style grounding block looks like. I have grounding blocks but not sure how large large is.