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NNTP-Posting-Date: Sat, 13 Apr 2024 16:36:49 +0000
From: John Larkin <jjSNIPlarkin@highNONOlandtechnology.com>
Newsgroups: sci.electronics.design
Subject: Re: lithium explosion
Date: Sat, 13 Apr 2024 09:35:10 -0700
Organization: Highland Tech
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On Sat, 13 Apr 2024 16:14:07 +0100, liz@poppyrecords.invalid.invalid
(Liz Tuddenham) wrote:

>Bill Sloman <bill.sloman@ieee.org> wrote:
>
>> On 13/04/2024 3:39 am, Liz Tuddenham wrote:
>> > Bill Sloman <bill.sloman@ieee.org> wrote:
>> > 
>> >> On 12/04/2024 6:55 pm, Liz Tuddenham wrote:
>> >>> Bill Sloman <bill.sloman@ieee.org> wrote:
>> >>>
>> >>>> ... if
>> >>>> it had a safe place to dissipate the stored energy.
>> >>>
>> >>> What if it didn't?
>> >>
>> >> Then it probably needs to include a louder hooter and brilliant flashing
>> >> lights to serve the same purpose, if more slowly than a purpose designed
>> >> dissipator.
>> >>
>> >>>> ..was being looked
>> >>>> after by somebody who ignored the early warnings.
>> >>>
>> >>> That includes 99% of battery users who wouldn't know what to do it they
>> >>> noticed the warnings or wouldn't be able to do it anyway.
>> >>
>> >> A voice message could be pretty explicit. All the message needs to say
>> >> is to move the battery outside to where it can't do much damage if it
>> >> bursts into flames. EV car batteries are big enough that that's quite a
>> >> way, but cars are designed to move appreciable distances.
>> > 
>> > It's not really a very good selling point.  "Oh, by the way, this model
>> > has the latest upgrade and tells you when it is going to explode, so you
>> > can get out of the way".
>> 
>> You don't seem to have been paying attention. If you deal with the 
>> warning by discharging the battery, and making it safe, it won't explode.
>
>
>Who it the 'you' in that sentence?  Do you mean the average user,  in
>which case this is a hopeless scenario as most users of batteries
>wouldn't have a clue.  
>
>Until recently batteries have been inherently safe: unless you did
>something stupid they were unlikely to give any trouble.  You are now
>supporting a type of battery that is inherently unsafe and will catch
>fire or explode unless the user takes some positive action.  Even if the
>user delegates this action to an automated system there is no guarantee
>that the action will be taken every time it is needed.
>
>'Safety' that depends on taking a positive action to prevent a disaster
>is not safe at all.

References say that a tiny separator defect spreads radially at
centimeters per second. Any somehow-sensed defect will explode in
flames in well under a minute, from the bad cell into the whole pack.
See Youtube examples... smoke to explosion in seconds.

If I heard an alarm from a lithium battery pack, I wouldn't try to fix
it, I'd run in the opposite direction. What automated system could
discharge an 80 KWH battery pack in a few seconds? Or even 1 KWH?

And a defect sensor would have to constantly snoop every cell of a
pack. A typical Tesla might have 7000 cells.