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After bus fire, CT pulls electric fleet from service

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Re: After bus fire, CT pulls electric fleet from service

#121

Post by woodruffw »

nomel wrote: post #119
woodruffw wrote: post #110

Earlier quoted context omitted.

I don't understand this point. Buses don't have inherently fixed routes, so that isn't why they go down the road empty. It's because, in many places, their routes haven't been replanned to compensate for suburban sprawl, and their service is bad . The fixed-route nature of trolleys is not an inherently bad thing. In fact, it was the dominant (and eminently sustainable) form of urban expansion for over 75 years[1]. It…

> Buses don't have inherently fixed routes In my city, they haven't changed the bus routes in several decades.

Right, that was the point about bad service: trolleys and buses can have stable routes but, paradoxically, that stability is generally good for trolleys and not good for buses.

Re: After bus fire, CT pulls electric fleet from service

#122

Post by crinkletoes »

ceeplusplus wrote: post #73
velcrohacker wrote: post #64

Earlier quoted context omitted.

Umm, it did. In CT. Last month. https://archive.ph/FZ2wv

I think the difference here is that an EV battery fire quickly spreads to the entire length of the bus, because the battery spans the entire length of the bus internally. Whereas the diesel fire is contained to the fuel tank and engine block, which could allow passengers to more easily escape to whatever end of the bus isn't on fire. New battery chemistries like LFP should solve the thermal runaway issue.

No, the bus batteries involved here do not propagate quickly. When it can't be contained, it takes more than 20 minutes to spread, which is plenty of time to evacuate the bus.

Re: After bus fire, CT pulls electric fleet from service

#123

Post by crinkletoes »

starkd wrote: post #60
ShakataGaNai wrote: post #19

While this is unfortunate to have happened, this says more about CT being smart and having an over abundance of caution, than lack of faith in a technology. BART, which has been running for 50 years recently [1] had an issue with the heat that caused a train to derail. For several days that section of track was totally shut down. For weeks afterwards they ran the trains at an extremely low speed through the miles of…

Yes. Good thing to ground them, but it also shows these vehicles are not ready. Even if its an act of sabotoge, like someone shooting at the battery. It would not happen with a regular diesel bus.

Shooting the battery pack won't cause the pack to do anything quickly. People would still have plenty of time to get out.

Re: After bus fire, CT pulls electric fleet from service

#124

Post by kwhitefoot »

quartesixte wrote: post #55
nathanaldensr wrote: post #3

Earlier quoted context omitted.

The entire point is that you can't "deal" with it. Since car batteries contain the fuel and the oxidizer, there isn't a way to separate them short of blowing the whole thing up. Fires can stop and start spontaneously, and often do (see pictures and videos of Teslas on fire in junkyards).

Add to the fact that the fuel is Lithium and you’re in for a badddddd time

There really isn't as much lithium in a battery pack as people seem to think. The 450 kg pack in a Model S has about 60 kg of lithium. Dutch fire fighters dump the whole car in a skip full of water to cool it down once they have contained the fire so that it burns out but doesn't set light to anything else.

60 kg is roughly 9 kmol and 1 mol has a heat of combustion of 300 kJ/mol so if burnt in air it would release 3e5 * 9e3 = 27e8 J which is about 75 kWh (coincidentally about the same as the battery capacity). Enough energy to raise a ton of water by 67.5 K. So if you can submerge it in water it will pose no further risk.

I presume that the lithium water reaction releases a similar amount of energy if the hydrogen burns, someone with a better knowledge of the chemistry could correct me.

Re: After bus fire, CT pulls electric fleet from service

#125

Post by londons_explore »

KennyBlanken wrote: post #87
londons_explore wrote: post #8

Earlier quoted context omitted.

Electric cars could totally be designed to be re-ignite-proof. For example, you'd have the battery pack detect a breach - for example through a lack of pressurised coolant. That would then trigger each battery cell to have a PTC resistor discharge it - that could be entirely mechanical. The PTC resistors would discharge the battery in a few hours, maintaining the battery temperature at say 120C. As water is doused on…

> The PTC resistors would discharge the battery in a few hours, maintaining the battery temperature at say 120C Thermal runaway in lithium ion batteries starts at 100C and is a significant danger at 60C. Maybe learn more about subjects before you come up with all these opinions on how things should be done.

Only in unpressurized cans. Pressurized sealed cells can have much higher thermal range, which is why nearly all EV manufacturers use them.

For example, even DEC can be made safe to 175C at 3 bar[1]. 3 bar isn't a lot for a liquid filled metal can.

[1]: https://upload.wikimedia.org/wikipedia/commons/a/ae/Vapour_p...

Obviously they can still suffer thermal runaway, but it happens at much higher temperatures.

Re: After bus fire, CT pulls electric fleet from service

#126

Post by kazinator »

ShakataGaNai wrote: post #19

While this is unfortunate to have happened, this says more about CT being smart and having an over abundance of caution, than lack of faith in a technology. BART, which has been running for 50 years recently [1] had an issue with the heat that caused a train to derail. For several days that section of track was totally shut down. For weeks afterwards they ran the trains at an extremely low speed through the miles of…

Why don't we pull diesel bus fleets off the road whenever there is a diesel bus fire?

Re: After bus fire, CT pulls electric fleet from service

#127

Post by DemocracyFTW2 »

woodruffw wrote: post #82

I think it's fantastic that smaller-to-midsized towns are bringing EV buses into service, but I'll mention my perennial bugbear again: all of these towns had dedicated trolley service under a century ago. The lines were torn up and replaced with less frequent, traffic encumbered bus routes. Hamden, for example, had three lines between it and New Haven[1]. [1]: http://www.hamdenhistoricalsociety.org/trolleys.html

Very true. For the disbelievers, have a gander at this fine map: https://www.flickr.com/photos/115892967@N03/49373818816

Be sure to zoom in all the way—the interurbans of Michigan, Ohio and Indiana are not restricted to the red lines, the black lines (marked up with an indication of the company running it and circles for stops) are covering the entire map in a fine mesh. Legend has it that for some time you could ride from New York to Chicago by hopping from one interurban to the next, with a gap of a few miles in-between that you would have to cover with some other mode of transportation. All those who claim that public transport is infeasible neglect that it used to be very feasible. This map does not show local streetcar lines, e.g. here's a 1940s map of Detroit streetcars: https://detroitography.com/2013/10/12/detroit-streetcar-rail...

Re: After bus fire, CT pulls electric fleet from service

#128

Post by secabeen »

woodruffw wrote: post #121
nomel wrote: post #119

Earlier quoted context omitted.

> Buses don't have inherently fixed routes In my city, they haven't changed the bus routes in several decades.

Right, that was the point about bad service: trolleys and buses can have stable routes but, paradoxically, that stability is generally good for trolleys and not good for buses.

Stability is good, but only to a point. A bus can divert around double-parked car, or a closed road, but a trolley is stuck until the blockage is cleared.

Re: After bus fire, CT pulls electric fleet from service

#129

Post by pathartl »

kazinator wrote: post #126
ShakataGaNai wrote: post #19

While this is unfortunate to have happened, this says more about CT being smart and having an over abundance of caution, than lack of faith in a technology. BART, which has been running for 50 years recently [1] had an issue with the heat that caused a train to derail. For several days that section of track was totally shut down. For weeks afterwards they ran the trains at an extremely low speed through the miles of…

Why don't we pull diesel bus fleets off the road whenever there is a diesel bus fire?

Complacency.

Re: After bus fire, CT pulls electric fleet from service

#130

Post by pathartl »

woodruffw wrote: post #82

I think it's fantastic that smaller-to-midsized towns are bringing EV buses into service, but I'll mention my perennial bugbear again: all of these towns had dedicated trolley service under a century ago. The lines were torn up and replaced with less frequent, traffic encumbered bus routes. Hamden, for example, had three lines between it and New Haven[1]. [1]: http://www.hamdenhistoricalsociety.org/trolleys.html

Always love myself a good ol' trolley. Those things are beautiful.
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