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Old Sep 12, 2004, 10:08 AM
RCAPA #14
Myron's Avatar
United States, TX, Wimberley
Joined Mar 2004
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Be careful pokin holse in Lipos before soaking them

Hey guys,

I mentioned in an earlier thread that I had my first set of lipos puff out on me.. Well, when I went to poke a hole so I could soak them, They went off like a magnisum fuse!... I didnt see a fire, but the smoke was so thick it would be hard to see anyway... It was one of the cells, si I still gotta figure how to safely dispose of the other two in the pack... I have pics, but they are high res so I cant post them....

Myron
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Old Sep 12, 2004, 10:08 AM
now that's a wattmeter...
simingx's Avatar
Singapore
Joined May 2002
1,136 Posts
You probably short circuited the battery when you pierced it...
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Old Sep 12, 2004, 10:27 AM
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Walled Lake, MI, USA
Joined Feb 2000
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Hoppy has done a lot of hard work to accumulate all of the causes for various Li-poly accidents reported on this forum. From the sticky at the top of the forum ( http://www.rcgroups.com/forums/showthread.php?t=209187 ), here is the total involving puncturing ballooned Li-polys prior to this most recent incident:

Ballooned pack ignites when punctured. (20)

If you did not follow the exact procedure for disposing of ballooned Li-polys outlined by Jim McPherson in the sticky linked to above, that's another good reason why all Li-poly users should read the sticky very carefully!

If you did follow the procedure and still had this failure, then perhaps that part of the sticky needs to be rewritten.
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Old Sep 12, 2004, 10:52 AM
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United Kingdom, Hull
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why would anyone want to punch a hole in a li-po in the first place??????
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Old Sep 12, 2004, 11:01 AM
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I have disposed if two puffed lipo cells, the first about 18 months ago (tab broke off, then cell puffed when I tried to charge it after repairing with siver-bearing epoxy), the second about three months ago when it gradually puffed, probably because of a defective seal.

In each case, the cell discharged to inertia when soaked in salt water. I don't know how long it took, actually. I left them alone for a month (outside, of course) and they measured 0 volts when I took them out of their bath.

What's the hurry?

- RD
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Old Sep 12, 2004, 03:42 PM
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Chicago
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The purpose of salt bath is not to saturate cell internally but slowly discharge it to 0V.
So there is no need to puncture the cell, and it also is somewhat dangerous.
I dont remember whats the disposal procedure in the stickies, I'll have to look it up I guess.
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Old Sep 12, 2004, 04:07 PM
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San Jose, CA
Joined Jun 2002
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I found that if you imerse it in water and then puncture the covering all it will do is bubble a lot. I used a sharpe ice pick and puctured several holes all around the cell(s) I didn't use salt water but can see that it would not be a problem to do so. They quit bubbleing in about 2 hours. They tested to zero volts and all I did was toss them in the garbage can. Caution is the rule no matter how you dispose of them. Gud Flying.....Dick
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Old Sep 12, 2004, 07:22 PM
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Dick, one of the unwritten rules is to puncture only after the cell is fully discharged. But an added safety measure is to puncture with a non-metallic item to avoid shorting just in case there is any charge left.

This goes way back. The salt water bath is to discharge an unpunctured Li-poly cell. After it's discharged, puncturing the cell and soaking again in salt water neutralizes the cell's electrolyte. But I believe it was finally decided that the electrolyte didn't need to be neutralized as long as the cell is fully discharged.

This might be worth revisiting. It would be nice to get a consensus from the experts. It may be that the sticky needs editing in this area. There's no need to mention puncturing in the sticky if puncturing is not really needed to safely dispose of a fully discharged cell.
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Old Sep 12, 2004, 07:42 PM
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San Jose, CA
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I agree Dave, but in my case the tab broke off and there really was no way I could discharge it. I should have soaked it in a salt brime to allow it to discharge that way first. Thanks for correcting me. Gud Flying....Dick
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Old Sep 13, 2004, 04:56 AM
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East Anglia, UK
Joined Sep 2002
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Ive got a pair of kokams that have puffed due to omplete low discharge. I am gonna toss them on a bonfire to see what happens.

Not recommended, just curious to see what happens.
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Old Sep 13, 2004, 09:03 AM
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Olathe, KS
Joined Aug 2003
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Quote:
Originally Posted by Myron
Hey guys,

Well, when I went to poke a hole so I could soak them, They went off like a magnisum fuse!

Myron
Lemme guess you used a metallic object to pierce the pack People do what Dave has already stated. Just drop em in a bucket of saltwater...its a lot safer. Plus no more threads like this. I never punctured a pack and they all drained to nil for disposal.
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Old Sep 13, 2004, 09:37 AM
RCAPA #14
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United States, TX, Wimberley
Joined Mar 2004
1,915 Posts
Hey Guys,

I was under the impression that they had to be punctured so the salt water could saturate/drain the electrolytes in the cell and only then were they safe to be tossed... I understand the salt water method now... Electricity will flow through water, salt speeds the process up a little, plus if the pack does decide to go off, it is in water and chances of a fire are minimal..... As for the metalic object comment..... Had I poked it with a plastic one and still peirced the layers of electrolyte material, the pack may still go off. Cause of the pack failure.. 2 fold... an impact caused a dent in one corner. It tested fine on the volt meter, so I stuck it on the charger.. I forgot to change my charger from a 4 cell to a 3 cell so I was charging the pack at too high of a voltage. The whole incident is "Newbie to Lipo" related.... Totally my fault and absolutely no fault of the pack...

Myron
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