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yellotaxi 09-09-2016 05:27

Right batteries for cruising
Batteries: 6 volt in series or 12 volt in parallel ?

Looking for the better way to go for cruising. A well respected friend mentioned that when he was sailing/cruising 15 years ago, 6 volt golf cart batteries were the way to go. However, he raise the question if with the new technology thsi may no longer be true.

StuM 09-09-2016 06:06

Re: Right batteries for cruising
Hang on, while I get the popcorn...

What battery technology are you considering, Lithium of some type of LA?
If the latter, FLA, AGM, Gel?

How large a bank (how many Ah)?

StuM 09-09-2016 06:16

Re: Right batteries for cruising
This should keep you going for a while until the debate starts yet again:

(Hint, I located these in a few seconds by clicking on Search at the top of the page and entering "batteries 6v or 12v" into the Google Custom Search box)

DDabs 09-09-2016 06:25

Re: Right batteries for cruising
I use golf cart batteries, they have been going strong for almost 3 years now with extremely low maintenance. I have solar panels that keep them topped off at all times but I'm very happy. They were very affordable and if I need to replace, I can pretty much get one anywhere.

pcmm 09-09-2016 07:52

Re: Right batteries for cruising
alot of it comes down to preference. GC2's ( 6v golf cart) are popular due to their energy density and weight. you might have to carry double the number of batteries but a GC2 generally weighs around 70lbs an can be carried by one pwerson. 4D or 8d needs the help of others to move as they weigh alot more. GC2's are also high volue batteries which tends to lead to lower costs per battery. EG I bought my GC2's at sams club (Identical to west marine as they're the same manufacturer) for $85 each. Westmarine in comparison ( for the same identical battery except for the label) chargers $240.... the math is pretty good in favour of the Sam's club GC2's

barnakiel 09-09-2016 07:55

Re: Right batteries for cruising
I never use 6V in a 12 or 24V system.

Asked others the answer seems in a big boat only 6V units are easy to manage without a crane. I agree.

As long as the boat bank is not 'huge', I would always use 12V units in a 12V wired boat.


Adelie 09-09-2016 08:04

Re: Right batteries for cruising
The analyses I've seen indicate that the best bang for the buck by a large margin is golf cart FLAs, with 6v batteries having some cycle life advantage over 12v.

LIon: Unless you want to home brew your own battery system with cells over the internet you would pay $3200 for a 180ah battery of which 140ah is usable, plus upgrades to your charging system so it doesn't get fragged by the battery. Alternators need special regulators to limit output, otherwise the alternators overheat and die.

Gel: You can get significantly more cycles out of Gels than FLAs if they are treated perfectly. The extra cycles probably probably comes close to making the money equation even for upfront purchase, but to get the life you also need to upgrade the alternator system with a smart charger. Unfortunately any damage from incorrect charging is pretty much permanent with at least a little decrease in capacity.

AGM: AGMs can't even match the number of cycles of FLAs and cost more. To get the advantage of faster charging that is regularly touted for AGMs you need to install a high output alternator and regulator for something in the vicinity of $1k plus maybe a new serpentine belt for several hundred dollars more. At the very least you need to install a special regulator on your alternator to limit output since, like LIons, it will accept very high initial charging currents which will kill the alternator.

Battery manufacturers are advertising higher cycle life for AGMs than golfcart FLAs and recent developements in AGM may actually mean that is true, but I am doubtful and am waiting to see what outside sources say in several more years.

For golfcart FLAs, the 6v batteries have a longer life expectency than 12v so in general they are the better deal.

That said, I am going with 12v for my own boat. My boat is a special case, it is very small and fitting in 2 batteries is a push. I am choosing the 12v because with 2-12v batteries if one dies I still have capacity I can use until I make it somewhere to replace the batteries. With 2-6v batteris if one cell in a battery dies I get 10.8v which may or may not do what is needed.

AGM Batteries - Making The Choice | Forums

Evans Starzinger has a very good discussion of batteries on his & his wife's website which is currently not responding for me:

zeehag 09-09-2016 08:10

Re: Right batteries for cruising
i use happily 2 banks each of 4 golf cart 6v batteries wired as 12 v for maxistorage of tricities., had considered converting to 12v, but didnt find the pricing to be worth while for me. as i amnot able to lift a 3 man and a boy hernia causing 160 pound 8d, i remain happy with the lighter but still heavier than ..... t 105 type batteries. they last a long time and they are easily maintained.

DDabs 09-09-2016 08:22

Re: Right batteries for cruising
I honestly don't understand how cruisers, especially retired cruisers, have huge AGM batteries. How the hell do you lift them out of the boat? depend on others i guess

meridian28 09-09-2016 08:34

Re: Right batteries for cruising
AGM 6v #70

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reed1v 09-09-2016 08:39

Re: Right batteries for cruising

Originally Posted by yellotaxi (Post 2209276)
Batteries: 6 volt in series or 12 volt in parallel ?

Looking for the better way to go for cruising. A well respected friend mentioned that when he was sailing/cruising 15 years ago, 6 volt golf cart batteries were the way to go. However, he raise the question if with the new technology thsi may no longer be true.

We preferred big 2 volt battery banks, lead acid. Easy to maintain and easily available throughout the planet. Part of the KISS philosophy.

Captain Puget 09-09-2016 08:54

Re: Right batteries for cruising
For total cost of ownership, I chose the Firefly carbon foam batteries.

See: Firefly International Energy

molo0928 09-09-2016 09:11

Re: Right batteries for cruising
+1 for the Firefly Carbon Foam. Going today to pick 3 up. First time building a house bank so we'll see how they do. A few reputable people in the industry have recommended them.

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roverhi 09-09-2016 10:13

Re: Right batteries for cruising
Firefly sounds interesting but what do they cost??? With all the new battery technology it comes back to bang for the buck which Golf Cart Batteries seem to continue to win.

S/V Alchemy 09-09-2016 10:18

Re: Right batteries for cruising
There is no one answer, as there is no one boat or variety (or paucity) of charging sources.

AGMs are expensive and (to my mind) a little oversold in terms of lifetime. On the other hand, if you are trickle-charging them (at the voltage they prefer) on a boat on a mooring, or if the flatness of your bilges means they can lie on their sides happily, they are a great choice.

The newer carbon foam batteries need to go through a cycle of ownership before we can judge.
The Li-Ons are great (particularly for a race boat) but are they rugged enough to go to sea? Are they worth the higher cost per Ah over time? Dunno. I do know I had a Li-On battery in a laptop burn on me once. A full-sized marine battery would be a nightmare shading into "abandon ship". Both carbon foam and Li-On are going to be hard to replace in distant lands. I mean, there's cruising the ICW and the Caribbean, and cruising New Guinea or Micronesia. Very different scenarios.

I have six L-16s, a fairly heavy (120 pounds, but I can manage it) 6 VDC FLA battery. They are series-parallel wired to make one considerable 1,575 Ah house bank. I've got a full keel steel cutter, so keeping 800 pounds of batteries right beneath the mast actually stiffens the boat a bit. I have multiple charging sources but I wanted to extend their life by sticking to the 75%-100% range, which in theory gives me 3,000 discharge cycles if I'm clean and do my care and feeding. So my energy budget is actually only 25% of 1,575 Ah...I'll have to run a tight ship if it's cloudy, I'm not motoring, it's calm and the two Honda 2000s are busted. You can see where I'm going with this. Asking about battery types for cruising is so utterly contigent on so many factors (style of cruising, type of boat, access, where you are going, how do you charge them, how many loads you run, etc.) that there's no one answer. Just best answers for you.

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