Posted on 01/11/2024 4:06:45 PM PST by george76
The buses were built with the battery packs in the ceiling of the buses.
Just like some of the electric school buses purchased as part of the borrowed money plan congress passed.
Kids will sit underneath and on top of battery packs that can fail like this one - from the point the failure begins on the video how many seconds would children have to evacuate keeping in mind that the “smoke” prior to flames is incredibly toxic and can incapacitate you within seconds.
In this video a passerby thankfully saw smoke coming from the bus and notified the driver who evacuated the bus so there was a delay between a citizen notification and the fireworks show.
https://www.youtube.com/watch?v=uA7SoM2DWuM
In fairness to Hertz, OJ had not yet turned into Captain Stabsalot when they hired him and he was quite popular and well liked.
With the jets these things give off when they ignite its a wonder they don’t try to achieve orbit.
If you need a daily dose of EV bashing, MGUY does a good job.
https://www.youtube.com/@MGUYTV
He discusses the London bus fire here.
https://www.youtube.com/watch?v=vgipzSObrYo
And always will be.
“Tetraethyllead”
Hah...I remember that stuff. Kept the knock out of my Austin Healey 3000 back in the ‘70’s.
The bus didn’t explode.
Thanks for the link. After viewing it, I clicked the next link of an e-bike fire. Very interesting video just after the 9:15 timestamp where it caught on fire.
https://www.youtube.com/watch?v=wxr1iXEf9lY
My guess is cold temps below 30, followed by running the bike at fastest speed, and then stopping with regen brakes pumping excess energy back into hot batteries. Defective BMS (battery management system)? Anyway, technology could be improved on these new systems but let the buyer beware of vendors that have safety issues.
The internal failure had already begun long before the batteries began venting in that video. They can go go up to 1800F in a second and once a single cell within a pack does this the cells next to it begin to heat and enter thermal runaway also.
The “smoke” you see is actually vapors being expelled from the pressure relief vents within the batteries to stop them from overpressuring and exploding. The vapors consist of hydrogen gas, carbon monoxide, carbon dioxide, hydrogen flourine (a particularly toxic and noxious gas), and other nasty stuff depending on the specific chemistry. It also will contain droplets of the ignitable liquid solvent chemistries such as ethanes and others.
The battery chemistry is unstable in a thermodynamic sense.
It is a testament to engineering that we do not have more problems than we do and many appliances have perfected the use of the battery such as small consumer electronics like our phones or laptops (extraordinarily small rate of failures).
General rules of thumb for these are to keep them between 40-110F or somewhere close (generally they like the same temperature ranges we do), prevent mechanical damage or hard bumps that can do internal damage or impact the electrical connections, use them smoothly and avoid rapid charging or discharging, charge and keep them between 20-80%, never leave them on a charger, and pay attention to them.
If they get too hot while charging or discharging that is a very bad sign and you can do internal damage to them that you won’t see and this damage can accumulate leading to failure.
Many e-bikes or scooters do not have a BMS of any note nor do they have a thermal management system like EV’s (vehicles) which have a lot of internal engineering to avoid problems. Many of them also have sketchy chargers or people use the wrong charger because the cord fits leading to problems.
The fact that people in the Pentagon are pushing for electric combat vehicles in our military is disheartening. It is NOT the right technology and one penetration may easily kill the crew from immediate fire or toxic gas. It’s just a bad idea all the way around from both a performance and safety standpoint. I feel the same way about buses.
The technology (electric motors) is not the problem - the batteries present challenges.
It did not explode thankfully. The newer designs are being designed and built to fail like this one where the battery packs are separated so that they do not cause a rapid conflagration. Manufacturers are trying to engineer safeguards against risks associated with current battery chemistries and this incident was a good illustration of this where the failure was contained at the rear of the bus without spreading.
These were likely LFP or lithium iron phosphate batteries and those have a higher ignition temperature. However, the downside is that without flames they can put off huge volumes of flammable vapors and toxins so we trade one hazard for another and while rare in open air in confined spaces (such as inside the bus) you can easily create a vapor cloud explosion. NMC and LCO batteries tend to burn violently when they fail - LFP can burn but its far slower if they ignite, but they can vent large and toxic vapor clouds until the chain reaction is broken (by cooling or containment).
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