batteries

[redhead78]

Hi all, I am lookin at getting 2 new house batteries, I have a starting batt, which group should I use, I am lookin at defenders power tech agms, are these a good choice. Rite now I am at a mooring, use boat every weekend, couple of trips week at time, going solar soon but prob not till next year, 100 amp alt.....thanks Red

 

[FourPoints]

I would suggest you get the solar done first, otherwise you'll have a new and expensive set of batteries hanging on a mooring without being properly charged / maintained, which may significantly shorten their life span.

 

[Chef2sail]

I would suggest you get the solar done first, otherwise you'll have a new and expensive set of batteries hanging on a mooring without being properly charged / maintained, which may significantly shorten their life span.

Agreed AGM like to be kept back to 100%. A waste if keeping at 85%. Youd be better off with wet cells if you can maintain them ( water).

I would either get 4- 6 volt Trojans (440 ah) or 2 -6 volts. Depends on how much room and what you were replacing. 6 volt batteries are heavier plates and have more cycles to them, easier to manage weight wise as they weight about 65 lbs each, and their foot print is a lot smaller the the other 12 volt batteries of similar amp hours. Height is generally a small amount taller. You dont have to get Trijans, Sams Club has good 6-volt batteries also.

Dave

 

[KingAirDriver]

Agreed. 6 Volt golf cart batteries are the way to go. That is my plan. I only need a pair to get the job done for my boat.

 

[Chef2sail]

Just a note, the total amount of amp hours you can use is half what's available as you don't draw the batteries down less than 50%. Good to do an electrical diet in ah per day to see what your normal usage is.

Dave

 

[Maine Sail]

Just a note, the total amount of amp hours you can use is half what's available as you don't draw the batteries down less than 50%. Good to do an electrical diet in ah per day to see what your normal usage is.

Dave

And once you are more than 1 day away from the dock, and a 100% state of charge, your new usable capacity is 30-35% of the rated capacity. When cruising you are cycling between 50% and 80-85% and using only 30-35% of the capacity.. So that 450Ah bank that seems large is really quite small at around 130Ah's of real usable capacity..........

I drew this to try and illustrate what a "cruising" capacity looks like..

 

[redhead78]

6 volt?

Am I better with a pair of 6 volt batteries?

 

[FourPoints]

Am I better with a pair of 6 volt batteries?

Probably, but you still want to get your charging system done first, otherwise your expensive new batteries will be sitting on the mooring sulfating without a full charge.

I recall someone, perhaps Maine Sail, saying that batteries on a mooring without solar or wind to keep them charged up average 2-3 years before they need replaced, batteries on a mooring with solar and or wind to keep them properly charged and proper water maintenance average 6-7 years before they need replaced.

 

[mitiempo]

I agree with Fourpoints.

The 6 volt golf carts are a better choice for several reasons. They have thicker plates which means a longer service life, more room at the bottom for sludge to build up before the plates short than 12 volt batteries, and more room at the top for more acid over the plates so they stay covered at an angle. Everything that applies to a good battery for a golf cart also applies to batteries for boats.

And because the golf industry is large they are not very expensive for what you get.

 

[Steve Dion]

Am I better with a pair of 6 volt batteries?

I don't think you are better off with a "pair" of 6vdc batteries. If you lose one of those batteries you no longer have anything in that bank. If you have 4 6vdc battieries you stilll have 1/2 of your bank in reserve (no telling how long).

If you are operating on a 12vdc bank, you can remove the bad battery and still have something. If you have 4 6vdc batteries you can remove the bad set out of your system and still have housekeeping too.

 

[Maine Sail]

I don't think you are better off with a "pair" of 6vdc batteries. If you lose one of those batteries you no longer have anything in that bank. If you have 4 6vdc battieries you stilll have 1/2 of your bank in reserve (no telling how long).

If you are operating on a 12vdc bank, you can remove the bad battery and still have something. If you have 4 6vdc batteries you can remove the bad set out of your system and still have housekeeping too.

Been doing this a long time and never seen it happen with 6V batteries. Sounds good in theory but in practice I think it's one of those 0.001% problems. Also this is why you have a second bank..... 6V batts eat the lunch of typical G24, 27 & 31 batteries in longevity and durability as well as price. For me if 6V batts fit height wise I would always choose them, even if the bank was two not four..

Even Trojan rates their 6V GC2 batteries at 50% longer cycle life than their G 24, 27 & 31's...

 

[redhead78]

What is a good batt brand 6 or 12v , i don,t want cheap , a good value? Red

 

[DJW]

I just put in 4 new Costco 6 volt golf cart batteries on Friday. I replaced the 4 Sam's Club 6 volt golf cart batteries that I had installed 6 years ago.

Dennis

 

[Maine Sail]

What is a good batt brand 6 or 12v , i don,t want cheap , a good value? Red

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