3 ms·

What was the chemistry of the battery? I'm guessing it wasn't LFP, but then again I've heard that LFP isn't quite as fire bulletproof as it was advertised.

hgomersall 3y ago
Where have you heard that? I've seen videos of people actually sinking axes into LFP cells which just vent a bit compared to say NMC which burst into flames.
rightbyte 3y ago
I have never heard that LFP would be fire safe. Just safer compared to other lithium cell types.
- TheLoafOfBread 3y ago
  Correct. That energy stored in the battery needs to go somewhere. Failing fully charged LFP is no less dangerous than any other chemistry.
  - ianburrell 3y ago
    The electrolyte in lithium ion batteries is very flammable. It combusts on contact to air which is why batteries if punctured. LiFePO4 batteries don't have super flammable electrolyte; they can burn but not easily and violently.
  - avianlyric 3y ago
    It’s is less dangerous, because LFP has lower energy density that other lithium chemistries so which means either less energy to dissipate per kg of battery, or more surface area to dissipate the energy per joule. Also LFPs don’t contain components with negative temperature coefficients of resistance (I.e. stuff that gets more conducive as it heats up), which reduces the risk of thermal runaway because LFPs increase their resistance as they get hot, reducing their max output power. Rather other chemistries that reduce resistance as they get hot, increasing their output power.
janice1999 3y ago
Edit: See comment below. The first fire was a fully electric bus, not a hybrid. > "The vehicle utilises a 32kWh capacity energy storage system, comprising third generation lithium nickel manganese cobalt battery technology" I think it might be this hybrid but I could not find a confirmation [0]. [0] https://www.alexander-dennis.com/alexander-dennis-enviro400er-gives-electric-range-with-new-hybrid-option/ https://www.alexander-dennis.com/alexander-dennis-enviro400e...
- rsynnott 3y ago
  Almost certainly one of these: https://en.wikipedia.org/wiki/Switch_Metrodecker https://en.wikipedia.org/wiki/Switch_Metrodecker , based on the details in the story. Full battery bus, not a hybrid. Been around for 10 years, so probably unlikely to be LFP.
  - janice1999 3y ago
    Thanks. I haven't heard of Switch Mobility before.
  - vidarh 3y ago
    You're likely right. Here's a site that lists the vehicles used on the specific route mentioned a few days ago [1] and now [2]. All the ones starting Me appears to be Metrodecker's (click through the vehicle number). Notice how they've been replaced by "SE" (which appears to be ADL Environ200's) and others. https://bustimes.org/services/200-raynes-park-wimbledon-mitcham/vehicles?date=2024-01-10 https://bustimes.org/services/200-raynes-park-wimbledon-mitc... https://bustimes.org/services/200-raynes-park-wimbledon-mitcham/vehicles?date=2024-01-14 https://bustimes.org/services/200-raynes-park-wimbledon-mitc...
  - deleted 3y ago
    [deleted]
- michaelt 3y ago
  The article is actually about two bus fires - one in west london, south of the thames: > a double-decker caught fire on Thursday [...] The fire started during the morning rush hour in Wimbledon [...] the operator, London General - a subsidiary of Go-Ahead London - and the bus manufacturer, Switch And also one a day later, in east london, just north of the thames: > On Friday, a hybrid double-decker bus was destroyed in a fire [...] in North Woolwich. [...] the operator, Go-Ahead, and the manufacturer, Alexander Dennis [...] we have no reason to suspect that this fire on a hybrid bus was linked to an earlier incident on an electric bus

hgomersall 3y ago

Where have you heard that? I've seen videos of people actually sinking axes into LFP cells which just vent a bit compared to say NMC which burst into flames.

rightbyte 3y ago

I have never heard that LFP would be fire safe. Just safer compared to other lithium cell types.

TheLoafOfBread 3y ago
Correct. That energy stored in the battery needs to go somewhere. Failing fully charged LFP is no less dangerous than any other chemistry.
- ianburrell 3y ago
  The electrolyte in lithium ion batteries is very flammable. It combusts on contact to air which is why batteries if punctured. LiFePO4 batteries don't have super flammable electrolyte; they can burn but not easily and violently.
- avianlyric 3y ago
  It’s is less dangerous, because LFP has lower energy density that other lithium chemistries so which means either less energy to dissipate per kg of battery, or more surface area to dissipate the energy per joule. Also LFPs don’t contain components with negative temperature coefficients of resistance (I.e. stuff that gets more conducive as it heats up), which reduces the risk of thermal runaway because LFPs increase their resistance as they get hot, reducing their max output power. Rather other chemistries that reduce resistance as they get hot, increasing their output power.

janice1999 3y ago

Edit: See comment below. The first fire was a fully electric bus, not a hybrid. > "The vehicle utilises a 32kWh capacity energy storage system, comprising third generation lithium nickel manganese cobalt battery technology" I think it might be this hybrid but I could not find a confirmation [0]. [0] https://www.alexander-dennis.com/alexander-dennis-enviro400er-gives-electric-range-with-new-hybrid-option/ https://www.alexander-dennis.com/alexander-dennis-enviro400e...

rsynnott 3y ago
Almost certainly one of these: https://en.wikipedia.org/wiki/Switch_Metrodecker https://en.wikipedia.org/wiki/Switch_Metrodecker , based on the details in the story. Full battery bus, not a hybrid. Been around for 10 years, so probably unlikely to be LFP.
- janice1999 3y ago
  Thanks. I haven't heard of Switch Mobility before.
- vidarh 3y ago
  You're likely right. Here's a site that lists the vehicles used on the specific route mentioned a few days ago [1] and now [2]. All the ones starting Me appears to be Metrodecker's (click through the vehicle number). Notice how they've been replaced by "SE" (which appears to be ADL Environ200's) and others. https://bustimes.org/services/200-raynes-park-wimbledon-mitcham/vehicles?date=2024-01-10 https://bustimes.org/services/200-raynes-park-wimbledon-mitc... https://bustimes.org/services/200-raynes-park-wimbledon-mitcham/vehicles?date=2024-01-14 https://bustimes.org/services/200-raynes-park-wimbledon-mitc...
- deleted 3y ago
  [deleted]
michaelt 3y ago
The article is actually about two bus fires - one in west london, south of the thames: > a double-decker caught fire on Thursday [...] The fire started during the morning rush hour in Wimbledon [...] the operator, London General - a subsidiary of Go-Ahead London - and the bus manufacturer, Switch And also one a day later, in east london, just north of the thames: > On Friday, a hybrid double-decker bus was destroyed in a fire [...] in North Woolwich. [...] the operator, Go-Ahead, and the manufacturer, Alexander Dennis [...] we have no reason to suspect that this fire on a hybrid bus was linked to an earlier incident on an electric bus