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Marine Battery question


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Harryh
User

Jul 9, 2014, 7:33 AM

Post #1 of 11 (1124 views)
Marine Battery question Sign In

Not exactly an auto question, but I thought someone might know.

As I understand it a marine battery can be safely discharged to a lower voltage than a car battery without damaging it. Does anyone know how low a marine battery can be safely discharged?

Thanks
Harry


Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 9, 2014, 8:23 AM

Post #2 of 11 (1116 views)
Re: Marine Battery question Sign In

Was big into boating up to yachting. Marine should have deeper cycle capability as you mentioned and dual ways to hook it up. They SHOULD also tolerate more trauma than plain automotive batteries and hold more flakes at the bottom before they would short out by themselves. Do all of them? Who knows.


Other is "Deep Cycle" designed to run and maintain a good line of power till it drops off near dead and intention is to tolerate that repeatedly better. Marine use would be for example an electric trolling motor.


Still need to know the power and amp specs for your needs on any. You didn't ask but if for a larger boat with more than one battery you should isolate one from the other so one can't take both or all down at once. Last yacht I worked on had six monster batts with a dial thing just bank 1 or bank 2 set up is common for those.


More - They are still lead/acid batteries and should be left charged when not in use or right after draining one some or a lot. Batteries freeze (even these) if totally dead and you don't want that by surprise. Best friend for these and many is a constant battery maintainer all the time. Auto on/off types not expensive and always ready for you plus they plain make batteries last longer and better.


The best of them still don't want to be totally dead - still harmful TMK to them,



T



(This post was edited by Tom Greenleaf on Jul 9, 2014, 8:25 AM)


Harryh
User

Jul 9, 2014, 9:14 AM

Post #3 of 11 (1107 views)
Re: Marine Battery question Sign In

Thanks Tom.

The battery I have is an Exide Stowaway deep cycle. It also says Marine/RV. It's 105 Amphour and 182 minutes reserve capacity. I use it on a trolling motor that draws about 36 amps at max thrust.

I've been checking into this more since I posted the question, and apparently a deep cycle battery can generally be discharged to 20% capacity, although 50% for longer life of the battery. The two pages that I found differ on the voltage at 20%. One says 11.98 volts, and the other says 11.58, so I'll check into that a little more or test it myself with a specific gravity meter. Apparently specific gravity should be 1.148 at 20%.

I was surprised to see that deep cycle batteries can be discharged so low. I'll get myself an accurate 12V panel meter to keep an eye on the battery voltage. Also surprised to see that deep cycle and marine batteries are different. Deep cycle is as you said, a little heavier duty, and a marine is somewhat of a hybrid between deep cycle and a regular car battery.


Tom Greenleaf
Ultimate Carjunky / Moderator
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Jul 9, 2014, 9:29 AM

Post #4 of 11 (1105 views)
Re: Marine Battery question Sign In

Right - Mix of "Deep Cycle", Marine and for cars and such. If you wail the heck out of these all the time check (I'd have to) on the gel cell jobs that I think can really take a beating and last very well but huge bucks!


It gets involved. Rumor has it virgin lead is better too vs recycled. What seems to be the demise in time is plain flaking off the plates that accumulates at the bottom. They do leave room for that - some more some less and if older it's a pile that if touches bottom of the plates is self destructive and dangerous with hydrogen gassing. Good reason not to tip over liquid filled batteries no matter how well made.


You seem to know your stuff on this and what you need for your purposes. Think about those "maintainers" as mentioned. I have at least a 12 year old car battery on an emergency generator still strong and that's more than double realistic life.


Hey - Who makes batteries is in question to me anyway. Name brands of companies get sold off for the name and you don't know it quickly or at all. Dog eat dog out there to make a buck and buy a good brand name. Not sure how to guard about that or know for sure?


Tom



Harryh
User

Jul 9, 2014, 10:47 AM

Post #5 of 11 (1095 views)
Re: Marine Battery question Sign In

These appear to be a couple of decent articles on batteries.

Links deleted .................. not allowed


(This post was edited by Hammer Time on Jul 9, 2014, 11:49 AM)


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Jul 9, 2014, 12:59 PM

Post #6 of 11 (1081 views)
Re: Marine Battery question Sign In

Ya - Please don't post links to other sites. If you wish use the Private message system. My point is we don't know who is making what of anything so easily. Hard to be brand loyal, that's all, Tom


Harryh
User

Jul 9, 2014, 1:14 PM

Post #7 of 11 (1077 views)
Re: Marine Battery question Sign In

That's understandable.


GypsyGene
Novice

Jul 9, 2014, 4:31 PM

Post #8 of 11 (1071 views)
Re: Marine Battery question Sign In

All good advice, I'd just like to add that some outboard motors (I have a Honda 8hp on my sailboat) have an internal alternator. I bought an adapter that plugs into the motor, and it keeps my cabin lights battery charged.


GypsyGene
Novice

Jul 9, 2014, 4:36 PM

Post #9 of 11 (1069 views)
Re: Marine Battery question Sign In

Good point about "who makes batteries." FYI the EPA just closed the last US lead smelter, so it's unlikely there will be any American made batteries anymore, if there are any now. Also, guess where your ammo will be coming from...


Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Jul 10, 2014, 2:36 AM

Post #10 of 11 (1055 views)
Re: Marine Battery question Sign In

What about Johnson Controls who already makes most of the supply?



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GypsyGene
Novice

Jul 10, 2014, 5:57 AM

Post #11 of 11 (1048 views)
Re: Marine Battery question Sign In

Sorry, I didn't mean to hijack the thread, but just to put the final touch on the lead smelting issue, here's a quote from Forbes Magazine: "St. Louis-based Doe Run Co., the world’s third-largest producer of lead from mines, said it will stop smelting operations as part of a $65 million agreement with the U.S Environmental Protection Agency and the state of Missouri. The company has operated the facility since 1986." Doe Run was the only remaining U.S. lead smelter.
The Forbes article spins it by saying that we don't need new lead, since the recycling effort has been so successful. IMHO, you can recycle only what is in current existence. What happens when the demand goes up, which is what will happen when most people finally give in and start driving electric cars.
Regarding Johnson's battery production, they closed the plant after a group of employees and the UAW won a landmark Supreme Court case against Johnson involving lead exposure and women's reproductive rights, although one of the plaintiffs was a male (499 U.S. 187, 111 S.Ct. 1196).
Please, someone, stop me before I go on any longer!






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