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Old May 10, 2005, 08:34 PM
fortune favours the bold
gjestico's Avatar
Vancouver Boundary, Canada
Joined Dec 2001
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Another LIPO fire .

http://www.runryder.com/helicopter/t177482p1/

He caught it just in time.

Greg
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Old May 10, 2005, 08:51 PM
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Walled Lake, MI, USA
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Lots of fundamental LiPo safety precautions ignored there. Yet again, it fits the recent pattern of someone who knew all of the safety precautions and got lazy about following them.
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Old May 10, 2005, 09:15 PM
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yup. Very surprising to see as well. Another reminder about lipos: Lithium is not your average metal. If you pour water on it, it could potentially spark an even bigger flame as water reacts with lithium and releases energy. Lithium oxide forms, hydrogen gas is released, and if the heat is high enough and hydrogen concentration high enough, a secondary explosion could happen where the hydrogen and oxygen (from the air) fuse into water again, releasing even more energy. Use the sand, special fire extinguisher, fire box, etc. Thankfully this is just lithium, and it wont be as severe of an explosion as say sodium, or potassium. So you know, a piece of potassium reacting with water, only the size of say half a pea, set off the fire alarm at my last high school. Lithium is far less, but with so much lithium in these packs, I wouldn't be surprised if you get close to that kind of a fire. Now, I don't know what kind of metal he was using in that flybar, let's say it's iron. Iron melts at 2800 degrees farenheit, so you need to get relatively close to that temperature to make it fuse to iron. Aluminum is about 1200 degrees farenheit. Either way, that's really freaking hot!



CLASS D FIRE EXTINGUISHER! GET ONE!
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Old May 10, 2005, 11:00 PM
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Li Polymer batteries contain NO lithium metal, only lithium salts which have completely different chemical properties.

http://www.ulbi.com/msdsheets/MSDS014.pdf
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Old May 11, 2005, 12:38 AM
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hmm... didn't know that. Lithium Cobalt Oxide, sheesh! I'd like to know how it's battery chemistry works... well, sorta.
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Old May 11, 2005, 12:44 AM
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Quote:
Originally Posted by hoppy
Li Polymer batteries contain NO lithium metal, only lithium salts which have completely different chemical properties.

http://www.ulbi.com/msdsheets/MSDS014.pdf
Actually metalic lithium can be present in the cells if abused.

Steve
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Old May 11, 2005, 07:25 AM
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Walled Lake, MI, USA
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http://www.paguk.com/lithium_ion.htm

"Consistent overcharging can cause the plating of metallic Lithium within the cell. Bringing metallic Lithium back into the equation will cause instability, especially if the cell is of lower manufactured quality, and especially if any moisture has been introduced inadvertently during the production stage. "
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Old May 11, 2005, 10:35 AM
Does anyone hear a cat?
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Tallahassee, FL
Joined Sep 2003
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I feel bad, but the description of the re-kindled repeatedly flames made me chuckle and think about birthday cakes with trick candles.

I think i'm going to stick to 4000mAh packs of 4s or lower. These big packs sure do burn.
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Old May 11, 2005, 11:23 AM
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For a hint of what it's like to have a couple of dozen Li cells going off one after the other, check out the military Li-ion pack in the video at the following link, and imagine yourself trying to put out the flames with a typical home fire extinguisher:

http://www.valence.com/SafetyVideo.asp
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Old May 11, 2005, 11:32 AM
Space Coast USA
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Quote:
Originally Posted by e-sailpilot86
hmm... didn't know that. Lithium Cobalt Oxide, sheesh! I'd like to know how it's battery chemistry works... well, sorta.
http://www.tf.uni-kiel.de/matwis/mat..._poly_elec.pdf
http://en.wikipedia.org/wiki/Lithium_polymer_cell
http://pubs.acs.org/cen/coverstory/8...ectronic3.html
http://www.quallion.com/pdf/ECS%20Abs%20425.pdf
http://www.formulasun.org/asc/tech/lithiumcontrol.pdf

Try the last one first.
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Old May 11, 2005, 11:33 AM
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Quote:
Originally Posted by sneu
Actually metalic lithium can be present in the cells if abused.

Steve
http://www.formulasun.org/asc/tech/lithiumcontrol.pdf

Read 3.2 of the reference to find out what happens to the Li plated out during overcharging (abusing). Soft shorts and degradation of the electrolyte.
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