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Old May 15, 2003, 12:09 PM
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BigDave's Avatar
Conway, Arkansas
Joined Dec 2002
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Li cells can cause a fire

It's my fault... But beware!

This is a word to the wise. If you charge a two cell Li battery with the charger set on three cells, a disaster can result. I am not blaming the battery or the charger this was a pure lack of attention. Nevertheless, the fire that resulted could have been avoided if the battery had been charging in a fire-resistant container.

The battery launched itself off of my charging bench, disconnected itself from the charger, and landed on the carpeted floor where it spewed hot contents onto the carpet and started a fire. I was able to extinguish the fire but some damage was done to my hobby room and a couple of planes went up in smoke.

It would be very wise to put Li packs in a fire proof container when charging and not just on a fire resistant surface. I would HIGHLY suggest placing them inside something similar to a Pyrex bowl with a Pyrex lid.

I like the packs, like the performance, and I won't be without them. But, be CAREFUL when charging.

I wonder if my wife will miss her big casserole dish?
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Old May 15, 2003, 01:01 PM
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Walled Lake, MI, USA
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There were discussions here a few months ago about similar incidents. Sorry that you didn't have a chance to see them and learn about this potential problem before your accident. Thankfully, no one was injured and it sounds as if you were able to keep damage to your home to a minimum.
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Old May 15, 2003, 01:09 PM
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Li-Ion or Li-Poly?

Hi!

Which cells were involved?


If you do mention a brand, that in no way would imply an unsafe product, it's just good to know the failure mode of specific cells.




Thanks.
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Old May 15, 2003, 02:11 PM
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Re: Li cells can cause a fire

Quote:
Originally posted by BigDave


I wonder if my wife will miss her big casserole dish?
You better worry about her rolling pin

hoppy
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Old May 15, 2003, 10:26 PM
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as the world turns.....

used to be that automatic lithium cell chargers experienced fires and cell bloating due to wrong charger settings and user inattention.

with better software, these chargers are now reasonably reliable.

now, there are reports of manual (jumper settings) lithium cell charger experiencing fires and cell bloating due to wrong charger settings and user inattention.


JT
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Old May 19, 2003, 08:14 AM
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BigDave's Avatar
Conway, Arkansas
Joined Dec 2002
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Re: Li-Ion or Li-Poly?

Quote:
Originally posted by meteor
Hi!

Which cells were involved?


If you do mention a brand, that in no way would imply an unsafe product, it's just good to know the failure mode of specific cells.




Thanks.
This particular pack was a Lithium Polymer.

As you stated, this does not imply an unsafe battery, just a precaution as to what CAN happen.
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Old May 19, 2003, 09:12 AM
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It can happen to any type of battery: http://www.rcgroups.com/forums/showt...220#post943220

mw
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Old May 19, 2003, 10:45 AM
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Forney, TX
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HOLY COW!!! I had heard that the packs would "just balloon up", but clearly that is not the case. Thank you for bringing this to our attention. I've been doing all my charging in the garage, but after seeing this I may take additional precautions.
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Old May 19, 2003, 10:56 AM
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Exactly my point...

This is exactly what I wanted folks to realize. Hopefully, by admitting my error, others will be aware of what CAN and DID happen.

House still smells like smoke but it could have been MUCH worse.

Be safe, charge them in a container of some kind....
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Old May 19, 2003, 05:30 PM
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Bigdave
Thanks for posting your experience. The picture is a real eye opener. I have been using a pyrex dish in the middle of my garage (concrete) floor and had wondered if that was overkill. Now I Know that it isn't
Don.
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Old May 19, 2003, 06:00 PM
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Wrapped too tight?

I've observed the application of traditional cell "wrapping" techniques on Li-Poly packs for quite a while...


I've noticed quite a few modellers use the traditional paradigm of wrapping their Li-Poly "packs" with multiple layers of heat-shrink plastic wrap, or tape, or whatever... (Heat-shrink has a pretty high tensile strength, and will resist expansion even more under heat)


Does this not seem like a very bad thing to do to a cell whose designed failure mode is physical expansion?

I'm not sure if there's test data to support it, but if you constrict the ability of a Li-Poly cell to expand, you will probably create the opportunity for a violent rupture.



Thoughts?
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Old May 19, 2003, 06:35 PM
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Columbia, South Carolina, United States
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Does it matter how Lipolys ARE STORED? Reason I ask is that I have 2 - 2 cell packs from Wilds R/C that I havent used in a few months cause I went to 3 cell. Now I have a Tiger Moth and when I hooked up the 2 cell, the radio just glitched. Then I noticed the pack was bloated! The second pack did the same thing but felt fine. I dont remember charging them in some time. I do have a 2 and 3 cell charger so maybe I just had it on 3 and ruined them. Just wierd cause I dont remember even touching them since I bought the new 3 cell charger cause I didnt need them. What else can cause them to bloat or quit working. Just sitting around???
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Old May 19, 2003, 07:16 PM
DNA
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JJ Hong (ceo of kokam) quote from Jan 4...

"FMA instruction of no full charge storage for more than a month
means if you ate food always full,your stomach will be demaged.This is same reason.normally we charge 50% for the shipping.I think around 4.0 volt will be o.k "
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Old May 19, 2003, 08:56 PM
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You know, the more you start putting all of these little "gotchas" together, the less user friendly LiPo cells appear to be. Imagine charging your LiPo cells for the last flight of the season, and then having a snowstorm hit. You store your fully charged cells away for the winter, and next spring you pull them out and they are screwed.

You really have to be willing to put up with lots of little things like this. The rewards are pretty good, and many people will be willing to put up with them. But a lot of people are programmed to think of modern products as "plug and play." LiPos aren't there yet. I have a feeling that we are going to be reading lots of messages from casual users who are having various problems with LiPos.
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Old May 20, 2003, 12:29 PM
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Conway, Arkansas
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Contained somehow

Quote:
Originally posted by defranci
Bigdave
Thanks for posting your experience. The picture is a real eye opener. I have been using a pyrex dish in the middle of my garage (concrete) floor and had wondered if that was overkill. Now I Know that it isn't
Don.
Only thing I would add to this is that the pack needs to be "contained" somehow. I would suggest a lid on the dish or something similar.

The pack actually accellerated itself (I can only visualize a rocket-like reaction) and launched off of the charging bench. I did not see the disaster in motion so this is just a guess.

Again, I have no intention of changing battery types. I have several Li packs and really like their performance when it is controlled (well, as 'controlled' as RC planes get anyway).
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