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From: Bill Sloman <bill.sloman@ieee.org>
Newsgroups: sci.electronics.design
Subject: Re: lithium explosion
Date: Sat, 13 Apr 2024 16:06:40 +1000
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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
>>>>>
>>>>> It doesn't look like that one was charging.
>>>>>
>>>>> Lithium battery fires are a big deal in New York too.
>>>>>
>>>>> San Fancisco is swarming with illegal, unlicensed electric scooters,
>>>>> surfboards, wheelie things, bikes, and motorcycles.
>>>>
>>>> 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.
>>>
>>> Lithium batteries don't explode spontaneously.
>>>
>>> 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.
>>>
>>> Any properly designed battery management system monitors this
>>> self-heating, with temperature sensors at the core of the battery, and
>>> on it's surface.
>>>
>>> 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.
>>>
>>> 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.
>>>
>>> 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.
>>>
>>> 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.
>>
>> Or the battery wasn't attended.
>>
>> 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