Author Topic: What would happen if you dropped a battery in a bucket of salt water?  (Read 1815 times)

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Offline engineheat

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Say, a NiMh AA battery. What it short circuit and explode? If you place an ammeter in the water, would you measure a large current everywhere?
 

Online Brumby

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #1 on: December 20, 2018, 03:13:48 pm »
Salt water might conduct electricity, but it's not a great conductor.  A single AA NiMH battery is not going to be able to push out a lot of current at all.

If it's terminal voltage is above 1.23V you might get some electrolysis, but since the nominal voltage is 1.2V, you are only going to get that happening at the start of discharge of a fully charged cell.

It would be difficult to directly measure any current unless you took special measures, because you are in a 3D conductive environment - but you could waggle meter probes all around for voltage measurements.

Bottom line - it's going to be pretty tame to look at.
 

Online coppercone2

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #2 on: December 20, 2018, 03:40:33 pm »
you can easily measure it by connecting a battery to wires and putting them in water or by gluing the battery into a extension with a inline ammeter with a plate exposed to the water.
 

Offline engineheat

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #3 on: December 20, 2018, 03:55:56 pm »
I'll do an experiment...

but honestly, the reason I asked is kinda lame and paranoid. I'm trying to design a battery operated device to be attached to the body. The body can sweat and I'm a bit worried that the sweat will get into the battery compartment and cause a short circuit even if the rest of the circuit is well designed. Obviously, this will require a LOT of sweat and the compartment will have to be poorly designed. But just in case, even in the worst scenario if the battery is submerged or covered in an ionized fluid like sweat, how dangerous is it? I'm talking a AA Nimh battery.

I googled sea water conductance and it's about 5 S/m, much worse conductor than most metals, so perhaps just like someone mentioned, having the battery covered in sweat is NOT equivalent to shorting it with a wire. It might lead to a relatively large current and heat up a bit but that's about it?

Thanks
 

Offline capt bullshot

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #4 on: December 20, 2018, 06:08:43 pm »
I'll do an experiment...

but honestly, the reason I asked is kinda lame and paranoid. I'm trying to design a battery operated device to be attached to the body. The body can sweat and I'm a bit worried that the sweat will get into the battery compartment and cause a short circuit even if the rest of the circuit is well designed. Obviously, this will require a LOT of sweat and the compartment will have to be poorly designed. But just in case, even in the worst scenario if the battery is submerged or covered in an ionized fluid like sweat, how dangerous is it? I'm talking a AA Nimh battery.

I googled sea water conductance and it's about 5 S/m, much worse conductor than most metals, so perhaps just like someone mentioned, having the battery covered in sweat is NOT equivalent to shorting it with a wire. It might lead to a relatively large current and heat up a bit but that's about it?


The battery contacts will corrode, rendering the thing unusable and leave some (disgusting to some people) remains - that's all what will happen. No heat, explosions, whatever.
Safety devices hinder evolution
 

Offline hendorog

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #5 on: December 20, 2018, 06:30:37 pm »
Have you checked out fitness watches, garmin's etc.
 

Online Brumby

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #6 on: December 20, 2018, 06:55:32 pm »
you can easily measure it by connecting a battery to wires and putting them in water or by gluing the battery into a extension with a inline ammeter with a plate exposed to the water.

That's an example of what I meant by:

.. unless you took special measures
 

Online beanflying

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #7 on: December 20, 2018, 07:06:17 pm »
As someone who submerged a Motorola bag phone way back in the day in sea water (It is a very very long story  :palm: ). They ran an external 6V SLA battery no smoke came out I wasn't electrocuted in the boat that was full of seawater (part of the story ;) )  and there was no heat in the pack when it got lifted out but the battery was toast due to internal corrosion.

My heart rate monitor for riding btw runs an o'ring seal where the battery goes in with a screw down hatch. No signs of any corrosion or sweat related issues internally apart from the elastic band which reeks after a long ride  :phew:

So don't worry about the safety of the wearer but the life expectancy of the battery if you don't seal it in.
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Online vk6zgo

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #8 on: December 20, 2018, 07:48:00 pm »
Say, a NiMh AA battery. What it short circuit and explode? If you place an ammeter in the water, would you measure a large current everywhere?
To answer your heading, but not your question, the battery would get wet!
Apart from that, very little would happen.
An AA battery would be battling to supply a "large" current to a short circuit, let alone the several thousand \$\Omega\$ of salty water, due to its own fairly high internal resistance.
 

Online coppercone2

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #9 on: December 20, 2018, 08:35:11 pm »
keep in mind in water the battery will also be well cooled
 

Online beanflying

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #10 on: December 20, 2018, 08:43:32 pm »
keep in mind in water the battery will also be well cooled

As it was not specified by the initial poster that conclusion is purely speculative on your part as no temperature was mentioned unlike the reply of vk6zgo stating a definate fact that the battery would be wet.
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Online coppercone2

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #11 on: December 20, 2018, 08:45:00 pm »
so something defined as a bucket of salt water is slightly damp only?
i figure its not that bad of a description.
 

Online beanflying

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #12 on: December 20, 2018, 10:54:10 pm »
keep in mind in water the battery will also be well cooled

Your statement is what is undefined and as such is speculative and based on information never stated by the original poster in any post.

First Law of Thermodynamics applies to your statement but can not be defined due to that lack of information.

'Water is wet' is defined no matter the salt concentration or not so vk6zgo is correct to point this out.
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Offline amyk

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #13 on: December 20, 2018, 11:53:47 pm »
The answer is "nothing much." Keep in mind that water also has a very high specific heat.
 

Online vk6zgo

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #14 on: December 21, 2018, 12:59:40 am »
I once dropped a Fluke 77 in a bucket of salt water.

A friend had suggested that you could calculate the % of salinity of the water by measuring the resistance between two identically sized pieces of Copper clad board (PCB), then using a suitable correction factor.
I was interested in this because I had a saltwater chlorinator in my pool.

Anyway, I fumbled it, & dropped the meter in the bucket of water.
I removed it immediately, cleaned the outside, then opened it up----strangely, very little water had got in.
A quick wash with distilled water, followed by methylated spirits, then left it in the Sun for several hours.
The only thing that failed was the continuity beeper.

It was a work meter, gave no other problems.
After some time, it was due to go to Philips for a routine fixed price checkup & calibration check.
It came back fitted with a new beeper.
 

Offline cdev

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #15 on: December 21, 2018, 01:03:44 am »
Electrolysis, of course.
"What the large print giveth, the small print taketh away."
 

Offline Wan Huang Luo

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #16 on: December 21, 2018, 01:53:54 am »
Say, a NiMh AA battery. What it short circuit and explode? If you place an ammeter in the water, would you measure a large current everywhere?
:palm:


 :palm:



 :palm:




 :palm:





 :palm:
 

Offline GeoffreyF

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #17 on: December 21, 2018, 02:22:39 am »
Saltwater WILL conduct electricity.

There will be electrolysis with Hydrogen appearing at the - Electrode and Oxygen appearing at the + electrode.  If these gasses are contained in some way, they can recombine explosively.  With a single battery, there would not be enough to do more than offer a "Pop" sound.  With a larger battery it can be significant as an explosion.

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.

US Amateur Extra W1GCF.
 

Offline Wan Huang Luo

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #18 on: December 21, 2018, 02:30:26 am »
You won't get jack diddly squat out of a 1.5v AA battery.
 

Offline cdev

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #19 on: December 21, 2018, 02:33:42 am »
Try it, it will even work with a nearly dead battery. You'll see bubbles and such. You could also electroplate things (or remove rust).

Don't inhale the fumes, as there is also chlorine in there. (very bad for your lungs)
« Last Edit: December 21, 2018, 02:35:33 am by cdev »
"What the large print giveth, the small print taketh away."
 

Online maginnovision

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #20 on: December 21, 2018, 04:38:30 am »
I've put 12v lipo batteries into buckets of salt water and not much happened. Few bubbles and over a couple of days they fully discharged with no heat, smoke, or puffing.
 

Offline Red Squirrel

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #21 on: December 21, 2018, 04:55:55 am »
Electrolysis will happen.  It will generate hydrogen and oxygen (and maybe other gases such as chlorine if salt?) and also produce heat due to the resistance.  Basically the water will act as a load.  The battery will eventually deplete.

You can put 120v ac into water and do the same thing, you'll see more bubbles the closer the probes are.  (use a GFCI for your safety if you're going to do that)
 

Online Kleinstein

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #22 on: December 21, 2018, 05:18:12 am »
Electrolysis will happen, but with the more normal metals use there will be no or very little oxygen. Instead the would be extra corrosion dissolution of the positive side metal. This way there is also a possible current and gas formation at low voltage: the oxidation of something like iron of copper gives the extra energy to produce some hydrogen even below 1.2 V.
 

Offline schmitt trigger

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #23 on: December 21, 2018, 05:46:13 am »


The only thing that failed was the continuity beeper.



Many moons ago, we produced a product that used water-washable flux AND a beeper. It was one of those self oscillating ones.

We would get a very low occurrence, but daily beeper failures. And yes, the seal was not removed until after the board had passed thru the dryer.

It turns out that the drier, in an attempt to increase throughput, would still leave a not-quite-dry board, and minuscule droplets could still ingress into the beeper after the seal was removed.

Increasing the drying time solved the problem. I was surprised how little humidity is required to damage one of those beepers.
 

Offline edpalmer42

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Re: What would happen if you dropped a battery in a bucket of salt water?
« Reply #24 on: December 21, 2018, 06:26:07 am »
Electrolysis will happen.  It will generate hydrogen and oxygen (and maybe other gases such as chlorine if salt?) and also produce heat due to the resistance.  Basically the water will act as a load.  The battery will eventually deplete.

You can put 120v ac into water and do the same thing, you'll see more bubbles the closer the probes are.  (use a GFCI for your safety if you're going to do that)

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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