Re: lithium explosion

On 12/04/2024 9:16 pm, Carlos E.R. 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.

 Or the battery wasn't attended.

Warning systems can be designed to be quite attention getting.

Battery fires have happened when nobody was near the battery; maybe charging.

A proper battery management system wouldn't let you charge a battery that had got close to going into thermal runaway

Here, several cities have prohibited personal electric things with wheels from entering the urban public transport system after a few fires.

A slightly better informed city administration could adopt a more sensible rule. Personal electric things with wheels can be designed to be quite unlikely to catch on fire. One's that aren't shouldn't be on sale in the first place, and would be prohibited imports in any sensible region.
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Bill Sloman, Sydney