Re: lithium explosion

On 13/04/2024 12:21 am, John Larkin wrote:

On Fri, 12 Apr 2024 13:16:40 +0200, "Carlos E.R."
<robin_listas@es.invalid> wrote:
 

On 2024-04-12 07:19, Bill Sloman wrote:

On 9/04/2024 3:03 am, Jeroen Belleman wrote:

On 4/8/24 18:35, John Larkin wrote:

https://www.bbc.com/news/uk-england-london-68744317
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It doesn't look like that one was charging.
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Lithium battery fires are a big deal in New York too.
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San Fancisco is swarming with illegal, unlicensed electric scooters,
surfboards, wheelie things, bikes, and motorcycles.

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As the energy density of batteries goes up, failures will
become more spectacular. It's not a good idea to store
both oxidizer and fuel in close proximity in the same
container. It's a recipe for an explosive.

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Lithium batteries don't explode spontaneously.
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The "explosion" is actually the last stage in a process that starts when
the batteries start self-discharging more rapidly than they should,
which warms them up a little.
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Any properly designed battery management system monitors this
self-heating, with temperature sensors at the core of the battery, and
on it's surface.
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If the battery gets hot enough, the higher temperature can lead to a
higher discharge rate, and at a battery temperature between 130C and
160C which depends on the battery chemistry, the process can run away
leading to something that looks like an explosion.
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Any properly designed designed battery management system would warn the
user when this were incipient and would start discharging the battery if
it had a safe place to dissipate the stored energy.
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It follows that any lithium battery pack that explodes either didn't
have a properly designed battery management system, or was being looked
after by somebody who ignored the early warnings.
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All this is too complicated for John Larkin to keep in mind - we've
discussed it here often enough that he should know it by now.

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Or the battery wasn't attended.
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Battery fires have happened when nobody was near the battery; maybe
charging.

 Or just parked somewhere, not charging. I wonder how long it takes a
tiny separator defect to spread into an explosive meltdown. Some
references suggest seconds.

And who thinks that separator defects lead to thermal run-away and battery ignition?
John Larkin does pick up on other people's silly ideas, and has a few of his own - not all that many or he'd have got himself a patent or two.
--
Bill Sloman, Sydney