Path: ...!eternal-september.org!feeder3.eternal-september.org!news.eternal-september.org!.POSTED!not-for-mail From: Bill Sloman Newsgroups: sci.electronics.design Subject: Re: lithium explosion Date: Sat, 13 Apr 2024 16:01:13 +1000 Organization: A noiseless patient Spider Lines: 95 Message-ID: References: <66195fa8$0$897417$882e4bbb@reader.netnews.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Injection-Date: Sat, 13 Apr 2024 08:01:28 +0200 (CEST) Injection-Info: dont-email.me; posting-host="18cfad8459c755af471d45d3e7233960"; logging-data="3012175"; mail-complaints-to="abuse@eternal-september.org"; posting-account="U2FsdGVkX1+6YtRBuSoVHefHOPA9p9Jy9HROiWpEs3E=" User-Agent: Mozilla Thunderbird Cancel-Lock: sha1:gzyz6JVOb6XVfo2iB0Ao0zUMI+4= In-Reply-To: Content-Language: en-US Bytes: 5621 On 13/04/2024 2:52 am, john larkin wrote: > On Fri, 12 Apr 2024 12:22:00 -0400, bitrex 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