Author Topic: How dangerous is a wet 18650?  (Read 967 times)

Offline PeteHall

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How dangerous is a wet 18650?
« on: July 31, 2019, 09:38:14 pm »
Spotted a rather wet and slightly corroded 18650 in The Narrows down Charterhouse today.

I nearly brought it out, but I recall people saying that they can explode when wet, so I left it under a rock instead.

Any thoughts? Is it safe to bring out or might it explode if it gets knocked?
Is it a hazard where it is?

And before anyone asks, I didn't think to look at the brand, but it was green if that helps  :-[
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Offline royfellows

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Re: How dangerous is a wet 18650?
« Reply #1 on: July 31, 2019, 09:52:38 pm »
I doubt that its dangerous, but very likely useless if corroded.
What you would probably get is an electrolytic effect between anode and cathode, very close at the top. This would hasten corrosion and drain the battery.
Over discharge can render them dangerous, but the fun would start on an attempt to recharge.

Its an interesting question actually, and one I don't have real answers too. If anyone knows more I would be interested to hear it.
Glad NAMHO 2019 over.

Offline PeteHall

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Re: How dangerous is a wet 18650?
« Reply #2 on: August 01, 2019, 07:22:53 am »
Thanks Roy.

Assuming nobody has any different advice, I'll bring it out next time I'm down there and make sure not to try charging it  :o
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Offline alastairgott

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Re: How dangerous is a wet 18650?
« Reply #3 on: August 01, 2019, 05:53:56 pm »
Bring it out, i'm sure it will be fine.

I carried around an 18650 with a slight scratch in the side in my laptop bag, I think the positive and negative shorted on my laptop. So now I have an ever so slightly melted laptop.

But I did carry the bugger around with me for a couple of weeks!

Offline ogofmole

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Re: How dangerous is a wet 18650?
« Reply #4 on: August 04, 2019, 09:53:44 pm »
I found two of these 18650 batterys in Pant Mawr Pot today, and Yes I did bring them out ready to be recycled at the Recycling bank.

Offline royfellows

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Re: How dangerous is a wet 18650?
« Reply #5 on: August 05, 2019, 08:55:34 am »
Just a heads up warning about these batteries in use.

The cheaper OEM cells have only a thin outer wrapping, retailers will fit a protection board to the base and then their own outer label. The outer label will act as an extra layer of insulation.
Risk is torches that load the cells in series, nose to tail. If the body of a cell shorts to the aluminium torch case what you will have is a pipe bomb. If you think about it the negative body of the upper cell is the positive of the lower.

Short circuits are normally often not catastrophic as a single wire or copper strip on a pcb will melt, in effect acting as a fuse. A cell body to aluminium torch case is a different beast.

Over discharging a Li Ion cell can cause internal short circuits, but obviously by then capacity is low and hence so is the amount of energy available for release as heat. Attempting to recharge is potentially dangerous. Cells with voltages of less than 2.5V should be scrapped, they be NG anyway.

All batteries are dangerous if short circuited, this can cause fire and injury. However Lithium Ion can suffer from an effect known as "thermal runaway".

18650 cells are Lithium Ion Phosphate which is generally the safest form of Lithium Ion battery. Lithium Ion Polymer is an entirely different chemistry and some batteries of this type have been known to explode if subjected to violent shock.
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Offline Ian Ball

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Re: How dangerous is a wet 18650?
« Reply #6 on: August 05, 2019, 12:49:25 pm »
Hello Roy, please could I ask where would you say is a good place to read about the Lithium Ion chemistry?

Offline royfellows

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Re: How dangerous is a wet 18650?
« Reply #7 on: August 05, 2019, 01:30:27 pm »
Hello Roy, please could I ask where would you say is a good place to read about the Lithium Ion chemistry?

Good old Wiki is a start

https://en.wikipedia.org/wiki/Lithium-ion_battery

https://en.wikipedia.org/wiki/Lithium_polymer_battery

Torchy the battery boy
http://www.torchythebatteryboy.com/

and manufacturers data sheets, typically Samsung, Panasonic and Sanyo

Plus of course, anything else turned up by web browsing, as long as its factual not some of contrived rubbish on YouTube


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Offline NewStuff

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Re: How dangerous is a wet 18650?
« Reply #8 on: August 05, 2019, 07:14:49 pm »
There's also battery university, which will tell you, in detail if you want, about pretty much any battery/ell technology I can think of. Even the really weird ones.

https://batteryuniversity.com/
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