Considering going to golf cart batteries

oomfh · #1 07-28-2010

I must be missing something . . . I typed "battery" "batteries" "golf cart batteries" "golf cart battery" into the forum search window and received the "No matches found" message.

I read a previous thread here on this topic and have a couple-three questions:

(1) Are golf cart batteries overkill for a 25', outboard with alternator, mostly inland lake sailboat? We will be trailering to the North Channel next summer - expecting to live aboard for about 2 weeks.

(2) Are there any diagrams on this site for wiring golf cart batteries into a 12 volt system? Yes, most things are simpler than they first appear - but I need to grasp the basic concept.

(3) When I did read the above referenced thread - I thought it said Exide was as good or better than the high-priced spread? I wasn't able to locate a source for the Exide brand - any suggestions?

Any thoughts, help will be apprecited!

jcalvinmarks · #2 07-28-2010

The only thing I can speak to is the wiring of batteries. This link [CLICKY] should explain it pretty well. I wired two deep cycle batteries together to give one extra-long life battery. I just used lawn mower battery leads from Wal-Mart to connect them. No problem.

I'm intrigued by the idea of getting extra long life out of a bank of batteries, though. I am so sick of dealing with the gasoline outboards I have trying to get them to work reliably that I'm considering going to a 60 lb. trolling motor for my 19 footer. Otherwise, one day I'm going to pitch one of these outboards overboard in a fit of rage. And then I'll get a ticket from DNR. And I'll be stranded in the middle of the lake. And it'll be an all-around bad day.

night0wl · #3 07-28-2010

Going to golf cart batteries is a good idea...if you take a holistic view of your electrical system and your cruising needs. How long do you plan on being away from shore power and how much motoring do you do where the alternator can charge up the batteries? Are you willing/able to simply run the engine to top up the batteries?

*edit*Flooded batteries, which most 6v golf cart batteries are, can be *end edit* a bit of pain as it relates to accepting charge. They do take a good initial charge to get them up from deep discharge, but their internal resistance as charge level goes up gets higher. That means getting them to full charge takes a loooong time...which is tough to do if you're using the engine to power them up. Especially if you have an outboard with an alternator. So you'll probably need a couple of charging mechanisms for these...your alternator and perhaps solar charging.

Speaking of which, even though you have an outboard with an alternator, will your alternator be the right size to keep the charge up on those deep cycles after usage? Two golf cart (6 v set up in series) will give you ~220 Amp Hours (Ah). You really should have four batteries set up in series/parallel because if you have the two 6v battery configuration, if you lose a single battery you've lost your whole bank! So that means with four batteries in series/parallel...thats ~440 Ah of capacity. To keep your batteries charged up, a good rule of thumb is to have an alternator which has output of 25-40% of the size of your battery bank. For you in a series/parallel configuration, thats a minimum of a 100 Amp alternator...somehow, I doubt that your alternator is that large on an outboard that pushes a sailboat...different story on an inboard diesel. BTW - a good 100 Amp alternator is usually in the $600-$700 range from what I've seen.

But wait, there's more! Now that you have such a big battery bank, you'll need to make sure you dont fry those batteries when they're charging from the solar secondary charging mechanism to keep them fully topped up. Now you're talking a regulator too....another set of boat bucks :-)

To be honest, my opinion on golf cart batteries is that its great for cruisers that are away from marinas for days, weeks, if not months on end. If thats the kind of sailing you intend to do, then go for the golf cart batteries....their capacity cant be beat for the price and they're pretty universally available. But if you go that route, dont half ass the installation....otherwise, you'll find yourself needing to buy another set of batteries in a couple of years because the first set never were kept in the right state of charge and prematurely wore out.

4arch · #4 07-28-2010

I'm assuming you'd have just two golf cart batteries with no reserve battery? The problem with only 2 golf cart batteries is that if one completely fails you're only left with 6 volts. That might be ok with an outboard that can be pull started but you'd still have no lights, electronics, etc. I think in this case you'd be better off with two Group 29/31's wired in parallel. The downside is they're slightly bigger and heavier for about the same or just slightly more amp hours. But if one fails you still have the other giving you 12 volts. They can be had at Wal Mart for well under $100 each.

I've gone through a similar dilemma for my own boat and concluded the golf cart batts seem to be best for large banks over 400 AH (4, 6, 8 GC batts in a bank) but don't have a clear advantage for smaller banks.

Vasco · #5 07-28-2010

Quote:

Originally Posted by 4arch

I'm assuming you'd have just two golf cart batteries with no reserve battery? The problem with only 2 golf cart batteries is that if one completely fails you're only left with 6 volts.
.

Not quite correct. Trojan makes a 12v golf cart battery. T1275 150 amps. I use these as they are not as tall as the 6v batteries and fit better on my boat.

4arch · #6 07-28-2010

Quote:

Originally Posted by Vasco

Not quite correct. Trojan makes a 12v golf cart battery. T1275 150 amps. I use these as they are not as tall as the 6v batteries and fit better on my boat.

Looking back at previous threads, I'd say that when someone here mentions golf cart batteries I think it's safe to assume we're talking 6 volt GC2 batteries unless told otherwise. From the context of the original post, I'd say that's what he has in mind too.

As for the T1275, it is indeed marketed as a golf cart battery but according to the Trojan spec sheets it's 2 1/2" longer and 20lbs heavier than the 6 volt GC2 batteries with the width and height being the same as their 6 volt T105 GC2 battery. The T1275 is actually very close in dimension to a Group 29/31 but slightly larger and about 15 lbs heavier.

mitiempo · #7 07-28-2010

Golf cart batteries are an economical way of getting a lot of AH for a small footprint and a fairly low price. 4 are better than 2 but in a 25' boat with outboard I'd install 2. The outboard is able to be hand started if necessary. But a single larger 12 volt might be a better idea.

As far as charging goes, whatever battery bank you have you only have to replace the AH you use. The outboard will not supply much charging but if you are charging while at the dock with shorepower that should work ok. A solar panel would be a good idea if away from the dock for longer periods.

I do not think deep cycle batteries have any great issues in accepting a charge. AGM batteries have a much greater acceptance rate due to lower internal resistance but all batteries have increasing resistance when above 80% SOC. And AGM would be overkill in this situation.

Here's a wiring diagram for 6 volt batteries wired for 12 volts in a 2 and 4 battery bank.

RainDog · #8 07-28-2010

This link will bring you to other threads on this subject. Sometimes the Google search is easier then the built in.

Let me google that for you

DwayneSpeer · #9 07-28-2010

By the way. A friend of mine bought new golf cart batteries for his HC38 Spring of 2009. Went away for the winter and came back to find out that his batteries were completely useless. It turns out that he unknowingly bought 8 volt golf cart batteries and his 12 volt charger ruined both of his then 16 volt battery banks.

MAKE SURE YOU KNOW WHAT YOU ARE GETTING!

night0wl · #10 07-28-2010

Quote:

Originally Posted by DwayneSpeer

By the way. A friend of mine bought new golf cart batteries for his HC38 Spring of 2009. Went away for the winter and came back to find out that his batteries were completely useless. It turns out that he unknowingly bought 8 volt golf cart batteries and his 12 volt charger ruined both of his then 16 volt battery banks.

MAKE SURE YOU KNOW WHAT YOU ARE GETTING!

Another thing to worry about...if you live in a warm weather climate and have *ANY* flooded battery, then just leaving them on the charger and going away for several months is a recipe for ruined batteries.

Flooded deep cycle batteries (including golf cart batteries) are not EVER maintenance free...they need monthly topping up of fluid...sometimes more in really hot weather environs. Again, caveat that with flooded deep cycle batteries.