Author Topic: What would happen if you dropped a battery in a bucket of salt water?  (Read 1015 times)

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Offline CatalinaWOW

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #25 on: December 21, 2018, 06:48:19 am »
While I am sure that all of the above answers are technically correct, I would trust only the ones that report actual experience. 

My experience is that it is usually hard to tell that anything is happening with short (seconds to minutes) exposure to fresh water, brackish water or sweat.  I am sure that some current is being drawn which will reduce battery life, but no bubbles of gas, no heat, no swelling of battery.

Can't really report any personal experience with exposure in the minutes to hours duration range.

Longer exposures (days to weeks) do result in corrosion of exposed metal parts, but no noticeable heating or swelling of the battery.  Battery life is definitely impacted, and often ended.

Very long exposures (months to years) turns the battery into a nasty corroded pile of gunk.

All of these observations are subject to change under conditions other than what I have observed.  For example the nasty corroded pile of gunk stage can probably be achieved in only a few days or weeks under some conditions, say a hot ocean beach for example.

 

Offline cdev

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #26 on: December 21, 2018, 08:26:48 am »
One thing I find interesting is that pure distilled water is an excellent insulator and also has a fairly high dielectric constant. Enough that one could make useful capacitors perhaps using it.

the only problem is even if you start out with distilled water salts are present in so many places and things they degrade that perfect nonconductance in almost all real life situations.
« Last Edit: December 21, 2018, 08:29:11 am by cdev »
"What the large print giveth, the small print taketh away."
 

Offline amyk

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #27 on: December 21, 2018, 12:21:11 pm »
Many years ago, I was talking to one of the guys in the Power group of the Telco where I worked.  He was quite sure that if water flooded one of our offices, it would blow the breaker if the water got into an outlet.  I took a power cord, cut the end off it and stripped back the insulation so there was exposed copper.  Then I dropped it into about a one liter bowl of tap water.  The current was something like a hundred milliamps at 110 Vac.  There is no significant electrolysis when you're using AC because the polarity reverses too fast for the reaction to get going.

When I was a kid (back when dinosaurs roamed the earth), we had a vaporizer at home to put steam into the air when you were sick and having trouble breathing.  It stopped working so I took it apart and found that it was nothing but two large metal plates directly connected to the mains.  I cleaned the hard water deposits off the plates and it worked fine.  The large plates were needed to get enough current flow to heat the water so it would turn into steam.  The instructions said to add a pinch of salt if the unit didn't produce lots of steam.  The nice thing about that design is that when you ran out of water, the steam and the current flow stopped.  There was no danger of overheating.

Ed
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Offline engineheat

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #28 on: December 21, 2018, 02:45:47 pm »
Saltwater WILL conduct electricity.

The battery itself will be discharging at a pretty significant rate.  Usually the entire case is the anode and thus only a fraction of an inch from the cathode (+).  In salt water, this would be a pretty high current, low resistance discharge.  The battery could burst but that would depend on its construction and how much the surrounding water was cooling it.

I understand salt water will conduct, but according to Google the conductance of sea water is only 5 Siemen/m, this is orders of magnitudes lower than most metals. I'm primarily concerned with "short circuit" current and heat, not so much about corrosion or battery damage.

I think by putting the battery in salt water, the current out of the battery is way lower than if one short circuited with a wire. For an AA battery, a "rough" calculation shows it's akin to connecting the ends of the battery with a 30 ohm or 50 ohm resistor. Yes it'll drain the battery but it won't explode or burn someone, I think...
 

Offline james_s

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #29 on: December 21, 2018, 04:55:59 pm »
I dunked a device in the ocean once by accident, it corroded the hell out of contacts, component leads and PCB traces in the few minutes it took me to retrieve it and get the battery out but it wasn't very exciting at all. If you were to drop a AA in seawater it would drain the battery flat over a period of a few hours while simultaneously rusting the ends, but it's not going to be exciting. Salt water is a conductor, but not an exceptionally good one. It used to be common to use barrels of salt water as rheostats for low budget theatrical lighting.
 


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