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Old 18-07-2012, 15:41   #1
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12V battery question

Dumbest question any of you have probably been asked, but I wonder if a person can be electrocuted in a boat that might take on water with a 12V Marine battery on board?
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Old 18-07-2012, 15:57   #2
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Re: 12V battery question

Welcome to forum
There are no dumb questions.

Not with 12v
The lowest lethal voltage is generally thought to be around 40v.

If you have a device with a higher voltage, like an inverter, powered by 12v it is possible.

Flooded lead acid batteries also can give off toxic gas if flooded with seawater, this is a more serious risk. Gel and AGM do not have this problem.

It is worth rembering there are lots of hazards also in a home or car, so keep any boat hazards in perspective.
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Old 18-07-2012, 16:05   #3
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Re: 12V battery question

Noelex i was always on the understanding that chlorine was given off when a charged battery is submersed in seawater because of the electrical reaction?

Am i wrong? Maybe a dumb question??
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Old 18-07-2012, 16:18   #4
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Re: 12V battery question

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Originally Posted by Lagoon4us View Post
Noelex i was always on the understanding that chlorine was given off when a charged battery is submersed in seawater because of the electrical reaction?

Am i wrong? Maybe a dumb question??
It's the battery acid (sulphuric) mixed with seawater that gives off the deadly chlorine gas.
It can be a problem given that batteries are mounted low, so the batteries may be covered long before the vessel sinks. People I emergancy situations have described how they were unable to enter the boat because of gas levels.
It does not happen with a gel or AGM battery because the water does not reach the acid.
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Old 18-07-2012, 16:22   #5
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Re: 12V battery question

Now that was a marine myth be-bunked!!! lol

Second one :-
When an AC power lead drops into water it doesn't often trip the earth leakage, is this because a gas forms around the metal (prob brass) forming a semi insulating gas?

Cheers
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Old 18-07-2012, 17:07   #6
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Re: 12V battery question

Greetings and welcome aboard the SJMB.
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Old 18-07-2012, 17:43   #7
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Re: 12V battery question

i do think it is possible to be 'electrocuted' by a 12v marine battery, but, BUT, it would have to be an extreme circumstance...........

remember, it is not the voltage that kills but the current...

I would think that two electrodes placed in proper proximity to the heart or brain could do the trick, along with appropriate electrolites to conduct/promote current flow...
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Old 18-07-2012, 19:52   #8
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Re: 12V battery question

Ya could fall on an anchor and kill your self to LOL but mostly ya get burnt fingers and such from shorted dc at 12 volts or 24 volts I sapose in some extream way it might be possible, but very little chance of that happening!! clorine gas tho is a killer ! I like my batterys a little higher then the bilge!! I guess ya will have to worry something else cus the 12 volts wont kill ya !! LOL have fun sailing
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Old 18-07-2012, 20:15   #9
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Re: 12V battery question

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Originally Posted by Lagoon4us View Post
Now that was a marine myth be-bunked!!! lol


Cheers
Was that a sealed battery used in the de-bunking test? I remember reading the dangers submariners faced with the old diesel/electric propulsion systmes. What I read indicated chlorine cause at least one German sub to be abandoned.

Getting back to 12vdc dangers. The safe limit for exposed voltages is in the neighborhood of 50vdc. But there are other dangers than being electrocuted. I believe the voltage used with older mine detectors (ships) was only a couple of volts DC. But they had the capacity to supply thousands of amperes.

If one got a bracelet, a ring or any conductive metal across the different polarities, it would almost instantaneously melt that short circuit. If that was watch bracelet on your arm it to would suffer great harm. And yes, absolutely a charged 12vdc or for that matter a charged 6vdc battery will do the same. Maybe not melt the shorting metal but it will darn well glow with instant instant heat.

Foggy
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Old 18-07-2012, 20:21   #10
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Re: 12V battery question

In certain freak cases, the battery can make an almost direct connection to the nervous system where the nerves are close to the surface and the skin is wet, thus ionising the nerves so that they will not work correctly. Result is death.

That being said, you should never stick your tongue or anus across the + / - terminals.

Hope this is clear
Your boat may need labeling to ensure this does not happen.

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Old 18-07-2012, 20:26   #11
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"Electrocute" is to kill with electric current thru the body. As such it is very unlikely with 12 volts. One can get a slight "shock" from only 12 volts - actually more of a "tingle". Usually when one's skin is very sweaty.
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Old 18-07-2012, 20:50   #12
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Re: 12V battery question

As soon as my batterys got flooded, I thought I was going to have a fire, sparks and flames shooting up, But the sea water just covered them and put the fire out and the batterys were instantly dead,

I was standing in the water and didnt get a shock,
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Old 19-07-2012, 07:45   #13
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Re: 12V battery question

to get shocked or electrocuted you would need to be between the conductors...

and yes, the likely hood is extremely low/small and the situation would have to be uncommon...

I would think electrodes in an open would across the chest/heart, or brain.... or otherwise paralyzed/frozen in place until you die of something else.....

it only takes miliamps to stop a heart so the issue would be to remove/reduce the resistance of the flesh/muscle/tissue, to get the electrodes closer to the heart...
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