From: RussellMc <apptechnz@gmail.com>
To: Microcontroller discussion list - Public. <piclist@mit.edu>
CC: ApptechNZ <apptechnz@gmail.com>
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Date: Fri, 13 Nov 2020 03:06:01 -0800
Subject: Re: [EE]:: Lithium batteries - fire risks
Thread-Topic: [EE]:: Lithium batteries - fire risks
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I found an old small laptop/notebook in a dumpster.
After cleaning up it powered up OK when the power supply was connected but
had no or minimal battery life.
It did not seem to take charge.

I (very stupidly) left it plugged into the power supply, battery in, and
sitting on some papers on a couch in our lounge.
It remained that way for some days - maybe 1 to 2 weeks.

One evening I was attracted by loud yells, stage lounge off.
I entered to find a classic example of 'vent with flame' in progress.
Laptop and I exited stage left rapidly and I removed the battery in the
yard and left it to burn.

Somewhat surprisingly the laptop survived the conflagration, somewhat
warped but still operational, as the battery was clipped on at the rear and
relatively unshrouded by the case proper.
The papers on the couch were nicely charred. A paper exercise book
immediately below the flame point acted as a complete downward firebreak
for the brief period concerned.
The cloth surface couch was blackened by the copious black smoke but
cleaned up with only some residual scuffing to show for its ordeal.
Had this happened when we were not in the room the loss of the house would
have been a ppssibility.
Some lessons were learned.

   Russell



On Fri, 13 Nov 2020 at 23:36, James Cameron <quozl@laptop.org> wrote:

> Yes, interesting.  Page 11 on thermal runaway of a 2.9 Ah pouch-type
> battery depending on state of charge at failure;
>
> 21 kW peak heat release rate over a period of 20 seconds when the
> state of charge is 100%.
>
> Versus 13 kW over 50 to 100 seconds when the state of charge is 50%.
>
> Versus 2.6 kW over 300 seconds at zero state of charge.
>
> And that's only based on oxygen consumption of the reaction.
>
> Time to update my evacuation plans, and store more of my prototype
> children's laptops somewhere else.
>
>
--=20
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