Re: lithium explosion

On 13/04/2024 2:52 am, john larkin wrote:

On Fri, 12 Apr 2024 12:22:00 -0400, bitrex <user@example.net> wrote:
 

On 4/12/2024 10:04 AM, Bill Sloman wrote:

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
>
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.

>
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.

>
The US is the kind of place that will instate outright bans on e bikes,
vape sticks, and books with gay people in them, but in most states it's
perfectly legal to buy crates of fireworks at at time with way more
explosive power than that, on the honor system. Kaboom!
>
And fretting about the hazards of exploding batteries with 300 million
guns floating around is pretty schizophrenic. Compared to being injured
by an exploding bike (or shot by a stranger for that matter) your
chances of being shot by a police officer are at least the same, or higher.

 About 1300 people were killed by police in the US last year, out of a
population of 333 million, about 4 PPM. Cops rarely shoot polite
law-abiding citizens; don't threaten people, especially cops, with
guns or knives.
 There were 617 homicides in Chicago last year. I suspect few were
attacks by strangers.
 NYC alone had 18 lithium battery fire deaths last year, something like
2 PPM, and that number seems to be trending up.

If US legislators could understand statistics they'd have introduced sensible gun control years ago. Finding a form of words that the US Supreme Court wouldn't object to might have been difficult.
--
Bill Sloman, Sydney