Golf cart batteries?

[seahouse]

Based on what you have told us, Sirlandsalot, your easiest logical course of action is to replace your house battery with another deep cycle 12V battery. This will conveniently occupy the two battery spaces and use the connectors already provided on your boat. A straight, easy swapout, and 12V's are more readily available than 6V if you ever find yourself in a bind somewhere.

Using two 6V to replace your house battery, and still keeping your starter battery will require three spaces and additional wiring and connectors, doable, but it's not convenient to install, or maintain. Not to mention quite unnecessary for your stated needs. And not a great advantage (but there are some) over simply installing two equivalent 12V house batteries plus your starter battery.

If you are considering replacing both of your 12V batteries with just two 6V batteries, don't do that either- you will then be giving up a 12V backup in case of failure of one of them, and depending on your charger setup, it will be more complicated to deal with as well.

Does your charging system charge each battery individually (two leads from charger to each battery, a total of 4 charging output leads?) or are they charged together as one?

If they are charged together as one, then replacing both batteries with two matching deep cycle batteries is another option to consider as well. You could wait until the starter battery fails (partly depends its condition and on how old it is) and replace it with a deep cycle (same brand and size as the other one) at that time; although that does carry with it the risk of placing the longevity of your new deep cycle in jeopardy due to charge mismatch. A deep cycle battery in the size we are discussing will have ample capacity to start a modern outboard the size of ours, and will suffer no harm doing it.

And if you are considering going to just one 12V deep cycle battery consider this... Even if you do not utilize them fully with power-drawing accessories, having two batteries does not double your cost over time of having just one, because, if managed properly, you will be discharging them each less than you would a single battery, which extends their life, meaning they will need to be replaced less frequently.

-Brian.

[Boblee]

Yup Seahouse.

[bwygirl]

I will have Todd answer your questions tonight. As he and Brian have rigged all our boats, his answer will be much better then mine!

[DaveB]

Actually the 6 volt batteries weigh about 7 lbs more than the deep cycle wet batteries.(due to heavy thicker lead plates that don't sulfate).
Marine deep cycle 12 volt wet cells can only go down to 50% without harm. Golf Cart Trojans can go down to 30 % discharge without harm and recycle many more times than the 12volt.
I know how much you can abuse the 6volt batteries as I maintain them in golfcarts at our water park were they don't get proper maintance but run.
I also used twin Trojans on my Compac 19 with refig.
Cost for energy , 6volt Trojan wins hands down over 12 volt marine deepcycle wet cell batteries.
For those who have high energy demands, twin 6 volt Trojans for house batteries is recommended.
They cost the same as marine 12 volt.
Dave

OK try this: Go down to the store and see and feel and LIFT that 6V Gulf Cart Battery and imagine if you will man handling that up into the boat and then down into the cabin and then into position in a storage area .. If That works for you? Go for it

[seahouse]

Dave has nicely summarized the advantages of golf cart batteries over marine deep cycle batteries. Quality golf cart batteries with heavier plates of different alloys are more robust and are able to take the rough handling and bumping that a golf cart gives it. Golf cart batteries, like all batteries, also vary in their quality.

Any battery with thicker plates, for the same case size (and the term “golf cart” simply referrs to case size) has compromised on some performance because it also holds a reduced volume of electrolyte. As a side note - AGM batteries suffer this same loss (a small percentage) because the glass mat takes up some volume that would otherwise have been occupied by electrolyte – reducing performance.

But for an apples to apples comparison you need to compare golf cart batteries that are deep cycle to 12V batteries that are also deep cycle; that is, that are not “marine” deep cycle batteries. The “marine” designation means that they are somewhere (and who knows where???) on a continuum between starting batteries (likely closer to) and true deep cycle batteries (likely not very close to).

The marine-designated battery, while it will deliver more current for starting purposes than a true deep cycle battery (which, as already discussed and demonstrated, you don't need in this engine class) is not as capable of withstanding continued deep cycling to the level that a true deep cycle battery can. Meaning it won't last as long under deeper discharge cycling, exactly as you've found, Dave.

So, if you were to compare the lifespan and performance of 6V deep cycle golf cart batteries to the lifespan and performance of 12V deep cycle batteries of equal quality and rating, giving them equal depth of discharge cycling, then the difference between the two would be greatly reduced, or negligible.

I have a series -parallel wired bank of 6V (full case size) batteries for a stationary solar panel array with an inverter in my house, as a hobby. One of the advantages of having 6V over 12V is that you can more closely meet the charge and discharge requirements of the individual cells (because there are only 3 instead of 6) which extends their life, if you have a 6V charger. No 2 cells are exactly alike in any battery, it is, in fact, a reason for their failure; the cell which is most different from the others, chronically either gets overcharged, or undercharged (which are both equally bad, BTW), and fails first.

If you wire two 12V batteries together to the same charger you have multiplied this same risk by twice again, for the same reason, the charger is unable to resolve the needs of the batteries individually, so it averages or misreads what is required of it, which reduces their lifespan. Which is why I advise against it when battery longevity is a consideration.

- B.

[Boblee]

Never had anything to do with golf cart batteries but thought they would be sealed like a pair we have in an invalid ? scooter but saw this ad today, are they good quality? they look too high to fit in the battery space
http://www.golfcartbattery.com.au/?utm_ ... 7ae3c702b9 pretty dear too.

[DaveB]

Thanks Seahouse on your added comments .
I will add that I have twin 105 deep cycle batteries group 30 and one deep cycle 24 group as starter battery and has a Yandina Diode that seperates house from starter battery . The Engine and Solar Panels charge Starter and House Batteries Separate and give the highest charge to the weeker battery.
I have had this for past 4 years and batteries are still in excellent shape due there on a constant built in auto10 amp charger pluged into AC next to home.
My next set will be twin Trojan 6 volt golf batteries for house and a 24 group 12v deep cycle for starter and both system will be separate, can start engine on either bank by selector switch.
I have had twin Trojens 6 volt golf batteries on my Compac 19 and you can get them down to 70-80 % discharge and they always come back full power.
So those who run frig. and can only go down to 50% ON 12V DEEP CLYCLE. This gives a much larger range before you need to recharge.
I also may add, the 6 plates on the 6 volt batteries are much thicker than 12v deep cycle batteries and much less for failure and sulfate.
Those who do not have AC hookup can use a 40 watt solar panel with controller to keep your batteries up.
Dave

Dave has nicely summarized the advantages of golf cart batteries over marine deep cycle batteries. Quality golf cart batteries with heavier plates of different alloys are more robust and are able to take the rough handling and bumping that a golf cart gives it. Golf cart batteries, like all batteries, also vary in their quality.

Any battery with thicker plates, for the same case size (and the term “golf cart” simply referrs to case size) has compromised on some performance because it also holds a reduced volume of electrolyte. As a side note - AGM batteries suffer this same loss (a small percentage) because the glass mat takes up some volume that would otherwise have been occupied by electrolyte – reducing performance.

But for an apples to apples comparison you need to compare golf cart batteries that are deep cycle to 12V batteries that are also deep cycle; that is, that are not “marine” deep cycle batteries. The “marine” designation means that they are somewhere (and who knows where???) on a continuum between starting batteries (likely closer to) and true deep cycle batteries (likely not very close to).

The marine-designated battery, while it will deliver more current for starting purposes than a true deep cycle battery (which, as already discussed and demonstrated, you don't need in this engine class) is not as capable of withstanding continued deep cycling to the level that a true deep cycle battery can. Meaning it won't last as long under deeper discharge cycling, exactly as you've found, Dave.

So, if you were to compare the lifespan and performance of 6V deep cycle golf cart batteries to the lifespan and performance of 12V deep cycle batteries of equal quality and rating, giving them equal depth of discharge cycling, then the difference between the two would be greatly reduced, or negligible.

I have a series -parallel wired bank of 6V (full case size) batteries for a stationary solar panel array with an inverter in my house, as a hobby. One of the advantages of having 6V over 12V is that you can more closely meet the charge and discharge requirements of the individual cells (because there are only 3 instead of 6) which extends their life, if you have a 6V charger. No 2 cells are exactly alike in any battery, it is, in fact, a reason for their failure; the cell which is most different from the others, chronically either gets overcharged, or undercharged (which are both equally bad, BTW), and fails first.

If you wire two 12V batteries together to the same charger you have multiplied this same risk by twice again, for the same reason, the charger is unable to resolve the needs of the batteries individually, so it averages or misreads what is required of it, which reduces their lifespan. Which is why I advise against it when battery longevity is a consideration.

- B.

[mastreb]

I'll just add that the majority of our engines are small enough and easy enough to start that they don't require anything like a starter battery or even a marine deep cycle. Full deep cycle will start them just fine.

[raycarlson]

Totally true, I have to chuckle to myself everytime I see that someone wastes valuable space by having a dedicated starting battery installed. I guess they just don't understand and are doing what they read about in the sailing magazines, not realizing a big four or six cylinder turbo-charged diesel is an entirely different animal then our little low compression motors. I try to always coach new persons to go ahead and actually start their motor at home in the driveway with the rope pull just so they can see how easy it is and so if they ever have to they already have done it and know what is involved. Now if they are handicapped or just plain old and feeble I can understand why they would not consider rope pull as a back-up...

[dlandersson]

You mean everybody doesn't have a li'l hamster running around on a li'l wheel like I do?

Totally true, I have to chuckle to myself everytime I see that someone wastes valuable space by having a dedicated starting battery installed. I guess they just don't understand and are doing what they read about in the sailing magazines, not realizing a big four or six cylinder turbo-charged diesel is an entirely different animal then our little low compression motors. I try to always coach new persons to go ahead and actually start their motor at home in the driveway with the rope pull just so they can see how easy it is and so if they ever have to they already have done it and know what is involved. Now if they are handicapped or just plain old and feeble I can understand why they would not consider rope pull as a back-up...

[Boblee]

Agree totally. we have in effect a start battery but it is or can be used in conjunction with the house.
As we now need two new batteries I will almost certainly buy two deep cycle 120 ah batteries, which gives me over 100ah more than the existing with the opportunity to use our spare 100ah dual purpose battery as a spare.
More than enough power for what we use and certainly for starting the motor, the only problem with dedicated deep cycle batteries is some unlike our dual purpose battery don't accept charge very quick and putting back in +25% what we take out can be a trap if not careful resulting in batteries not getting time for full charge.
Then all I have to work out is how to fix the two larger batteries in the space along with all the other jobs in the next two weeks before we head off for some sunshine.

[Three Gypsies]

As others have mentioned , golf cart batteries are big and heavy . unless you have need of this much power why bother ? Do you just use the boat on weekends or do you plan to live aboard ?

Remember that you have to charge these giant batteries and a 50 or 90 hp outboard just doesn't have that big of an alternator on them . So you will need to plug them into a charger when at dock .

That said we have two deep cycle batteries and two start/deep cycle batteries aboard our Gypsy . In addition to the motor alternator we have 200 watts of solar cells on the hardtop.

We operate a Engel freezer in addition to the usual gadgets , TV , stereo , computer , etc .
And we live aboard for most of the year

[yukonbob]

Totally true, I have to chuckle to myself everytime I see that someone wastes valuable space by having a dedicated starting battery installed. I guess they just don't understand and are doing what they read about in the sailing magazines, not realizing a big four or six cylinder turbo-charged diesel is an entirely different animal then our little low compression motors. I try to always coach new persons to go ahead and actually start their motor at home in the driveway with the rope pull just so they can see how easy it is and so if they ever have to they already have done it and know what is involved. Now if they are handicapped or just plain old and feeble I can understand why they would not consider rope pull as a back-up...

Maybe you can come show me how to pull start my 70hp Driveway’s a lot different from 6-8 ft seas in the rain a hundred miles from the nearest community in a place that can go a month without seeing the sun.
I keep a dual purpose marine as a dedicated starter cause it’s the smart thing to do. I’d rather lose a little space, rather than look like an idiot to some fishing boat captain out on the coast when I’m dead in the water. I’d feel and look a whole lot dumber then.

[mastreb]

Definitely test pull starting your outboard from your boat in the water.

Just getting the cowls off and the rope wrapped is not trivial--On ETECs the starter solenoid blocks the ability to easily wrap the cord and you have to kind of thread the rope through it.

What I've also found is that there's no room for me (6'5") to get leverage between the engine-well and the helm. I have to use a longer rope so that I can pull from forward of the helm, and this lets me put a turning block on the bottom of the helm So I can "clean jerk" the rope at a very convenient angle while seated in front of the companionway with my feet braced on the helm pedestal.

Anyway, DEFINITELY TEST your ability to pull start your motor aboard your boat before you rely on it, as it is much easier to pull start in the driveway or at the ramp from outside the boat.

[bartmac]

I'm another who installed 2 not just one starting battery (and nearly 400 Ah of gel batteries)......and now will NOT perpetuate that mistake