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12V Marine Deep Cycle Battery Post is Moving -- Is the Battery Damaged?

  1. Oct 13, 2016 #1
    The battery post is moving up and down. It doesn't seem to want to come all the way out. Will the battery still perform properly or is it damaged? Can it be repaired?
    Pictures attached.

    Thanks in advance.

    Attached Files:

  2. jcsd
  3. Oct 13, 2016 #2


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    It looks pretty new, so it will probably perform properly.
    But it is damaged, and I would return it, and get your money back.
    Or at least, get the deposit back, if the damage was your fault.

    Using such a battery, will probably result, either in your death, our your face being burned off with sulphuric acid.

    Your choice. :smile:
  4. Oct 13, 2016 #3


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    You need to learn what makes a lead acid battery dangerous and what conditions will create an explosion or bad situation.
    I have a quart jar filled with battery acid and a positive and negative electrode hanging over the top of the jar, just a cheap learning lab to test little electric motors and crazy thoughts that might come to mind, well secured and inside a 5 gallon plastic bucket ( for safety ) almost twenty years and it still takes a charge and works for a few seconds when needed.
    Leakage or gas vapor explosion are the only two things you need to worry about, corrosion or damage from acid vapors and water and dirt penetration.
    If you have any warranty use it, if not, be careful and use the battery til it quiets working. :wink: old school thinking :smile:
  5. Oct 13, 2016 #4

    jim hardy

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    Looks like the stainless steel bolt is loose in the lead(pb) internal connector ?

    Looseness is an invitation for ingress of battery acid and corrosion.

    The danger there is that after a prolonged charge when the battery has substantial hydrogen inside you'll get a spark there and the battery will explode. As OmCheeto suggested.

    I had one do that once. It was an internal connector between the cells that was loose. Caused the battery to behave as if it were weak, would barely start daughter's car. So i left it on trickle charge all night, next morning i opened the hood , hooked a voltmeter and said "Contact". When she turned the key and the starter engaged, the battery went off like shotgun and neighbors came running out to see what'd happened.

    Top blew completely off the battery. Ii was looking right down into the six cells. My clothes were spattered with battery acid it ruined a good shirt and pair of Dockers. My glasses saved my eyes...
    One of the heavy connectors inside between cells was loose, cracked at a fastener. Clearly the heavy starter current had caused a spark that set off the explosion.

    So my advice is get rid of that battery. Loose connections and heavy current don't mix especially around hydrogen.
    Murphy will get you, probably in the middle of the Gulfstream.

    old jim
  6. Oct 13, 2016 #5


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    I have witnessed several lead acid battery explosions. It is quite a violent event. As Jim said, the top of the battery literally blows off. I found several pieces of battery plastic at least a hundred feet away. Funny thing is a battery with the top blown off will still start and run an engine. Little risk of explosion at that point, but plenty of chances of sulfuric acid getting where it shouldn't be.
    A while back I tried to start my '65 Ford and all I got was about 1 second of cranking and then nothing. When I investigated closer I noticed that when slightly loaded the battery would gurgle and the voltage on the posts would drop to nothing. I assumed something broke loose inside and promptly got rid of it.
    Another time I recall trying to start an engine and ended up with a carburetor fire (yes, I am old) due to a backfire. No fire extinguisher, nowhere close to water. The engine had caught a couple of times so I just kept on cranking it hoping to get it to run. Yes, this will extinguish carb fires. Long story short is that it worked. But that battery was never the same. Something must have gotten hot enough inside to come apart from extended heavy loading because when I returned it they said it got hot when charging. It had good electrolyte levels and the unloaded voltage was way up there. But it could not run any significant load. In my opinion, no decent car battery should be able to destroy itself from cranking, but that's just my opinion.
    At any rate, be careful with batteries. I would ditch the battery in question if I were you foolios.
  7. Oct 14, 2016 #6


    Staff: Mentor

    The others gave good advice. Get rid of it.

    In addition, on your boat always store your batteries in a plastic battery box with a strapped on lid, designed for the purpose. The box will contain the acid after a disaster.
  8. Oct 14, 2016 #7
    Thanks all for the advice. I will hopefully be able to return it. It's close to the one year mark on the warranty.
    Seriously considering going with an AGM battery this time though. Those posts on that marine battery do suck.
  9. Oct 14, 2016 #8


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    I'm curious how it happened.
    A couple of the people in the electric vehicle association I subscribe to have mentioned that if the connections aren't properly tightened, the posts will get so hot, that the lead will melt. Looking over the images when googling melted battery post, it's universally at bolt on connections. Of course, EVs can draw hundreds of amps continuously. So without knowing what you're using your battery for, it's hard to say whether or not it will happen to your next battery.
  10. Oct 14, 2016 #9


    Staff: Mentor

    Inferior quality is likely a function of the brand, not the battery type. If you get a brand x AGM, and it is bad you'll be out even more money.
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