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> it could release highly toxic hydrogen sulfide gas. How bad is it in real world conditions? Because from what I'm reading it's not the "it makes you sick" ki

> it could release highly toxic hydrogen sulfide gas. How bad is it in real world conditions? Because from what I'm reading it's not the "it makes you sick" kind of toxic, but rather the "it kills you in seconds" kind of toxic.

runnerup 3y ago
Current lead acid batteries can do this as well. Smells awful and pretty unsafe situation. H2S is quite dangerous but it’s rare that they’d create an IDLH situation as long as there’s a bit of breeze.
- kragen 3y ago
  i'd be surprised if lead-acid batteries produce detectable quantities of hydrogen sulfide; isn't their sulfur bound up in an extremely stable oxoanion? still, https://web.archive.org/web/20161005164308/http://www.wesh.com/news/medical-examiner-confirms-suspected-cause-of-deaths-in-turnpike-mystery/41939954 https://web.archive.org/web/20161005164308/http://www.wesh.c... certainly doesn't sound like sulfuric acid
  - akira2501 3y ago
    I've discovered damaged lead acid batteries in equipment by following the rotten egg smell back to it's source. Twice, both small current 12V DC batteries.
  - extraduder_ire 3y ago
    Humans are _very_ sensitive to the smell of H2S. Unless you meant that it might produce enough to kill your sense of smell, which is possible.
    - kragen 3y ago
      no, i meant i don't understand how you get from sulfate to prussiate at room temperature
- ttymck 3y ago
  Yes this was my initial reaction: what if a tesla battery comes in contact with water? What degree of "more dangerous" are we talking about?
lstodd 3y ago
Rotten eggs smell is just about everything you can get from this kind of experiment. Now if they scale it up. but at any scale that makes sense economically you can get suffocated by just about any gas you can think of. Like helium or hydrogen.
- rzzzt 3y ago
  H2S is also a byproduct of crude oil processing. The nose is easily overwhelmed by the smell even at low concentrations, and it becomes hard to notice before it strikes.
jncfhnb 3y ago
Depending on concentrations required for consequences a smelly gas is much safer than something like CO
- arcticbull 3y ago
  I believe you go noseblind to hydrogen sulfide very quickly. [1] [1] https://dodtec.com/news/the-potential-dangers-of-hydrogen-sulfide-exposure.html https://dodtec.com/news/the-potential-dangers-of-hydrogen-su...
- peterdsharpe 3y ago
  Perhaps "safer than CO" is fair, but "much safer than CO" may be a bit of a stretch. H2S is the #2 cause of fatal chemical inhalations in the workplace, behind CO: https://www.bls.gov/opub/ted/2019/fatal-chemical-inhalations-in-the-workplace-up-in-2017.htm https://www.bls.gov/opub/ted/2019/fatal-chemical-inhalations...
bell-cot 3y ago
MSDS for H2S - https://www.airgas.com/msds/001029.pdf https://www.airgas.com/msds/001029.pdf The Occupational Exposure limits are fairly low 'ppm' numbers, and LC50 is 712ppm for 1 hour. (That is the concentration at which 50% of the exposed rats died.)
hadlock 3y ago
Someone else pointed out LD50 is ~700ppm It's unlikely you'd be exposed to this level for any period of time unless the battery ruptured into the car, underwater, with the windows up, in which case you have bigger problems. You're unlikely to to see 700ppm in an outdoor situation like a car wreck or battery malfunction on the highway during a rainstorm. Atmospheric CO2 is about 450ppm for comparison. Ammonia is a superior refrigerant (widely used in industrial circles, and causes no ozone depletion, is biodegradable, etc) but not used in residential applications because it's highly toxic if there's a catastrophic seal failure and not vented outside, despite the fact that humans are very efficient at smelling even the slightest ammonia leak.
- peterdsharpe 3y ago
  I think H2S is somewhat bigger of a safety risk than presented here. For example, check out this case where what you describe (battery rupture) happened, killing both occupants from H2S inhalation: https://web.archive.org/web/20161005164308/http://www.wesh.com/news/medical-examiner-confirms-suspected-cause-of-deaths-in-turnpike-mystery/41939954 https://web.archive.org/web/20161005164308/http://www.wesh.c... And this was only from a starter battery, not a battery sized for vehicle locomotion.
  - solardev 3y ago
    It's interesting that Porsche put the battery under the driver's seat (in the cabin? unclear). Wonder if that made it more dangerous. Are modern EV batteries also in the passenger area or in their own little armored section...?
    - npunt 3y ago
      It was probably put there for weight distribution as Porsche would be more likely to optimize for that despite the user inconvenience it may cause
      - mdekkers 3y ago
        Possibly for a Carrera, but for a Cayenne? Despite the Porsche brand, that isn’t anywhere close to a sports car. The platform is shared with the Audi Q7 and the VW Touareg. It’s a tractor with nicer seats. The weight of a battery fitting under a driver seat would be similar to a big shopping run, so weight distribution wouldn’t have been a consideration. Manufacturing logistics probably played a bigger role.
_a_a_a_ 3y ago
HS is funny stuff. Does nothing then zap, ur dead. UK figures for safe working concentration in air, from memory, hydrogen cyanide 11ppm, hydrogen sulphide 10ppm
npsomaratna 3y ago
I remember synthesizing H2S in high school (for chemistry practicals, I think). I made the mistake of attempting to smell it. This was for a fraction of a second—but during that time, I could feel the individual bubbles of gas entering my nose; and I almost passed out.
snowwrestler 3y ago
There’s no way to concentrate energy without creating some danger. Gasoline is quite dangerous but we drive around with tanks full of it now. Natural gas and high-amp electricity are dangerous but we have them coming into many houses. So I would propose the question shouldn’t necessarily be, “how bad is the worst-case scenario”—it’s pretty bad for all energy sources. I think a better question is “how reliably and efficiently can we prevent or mitigate the dangers.” That will go a long way toward determining its commercial viability.

runnerup 3y ago

Current lead acid batteries can do this as well. Smells awful and pretty unsafe situation. H2S is quite dangerous but it’s rare that they’d create an IDLH situation as long as there’s a bit of breeze.

kragen 3y ago
i'd be surprised if lead-acid batteries produce detectable quantities of hydrogen sulfide; isn't their sulfur bound up in an extremely stable oxoanion? still, https://web.archive.org/web/20161005164308/http://www.wesh.com/news/medical-examiner-confirms-suspected-cause-of-deaths-in-turnpike-mystery/41939954 https://web.archive.org/web/20161005164308/http://www.wesh.c... certainly doesn't sound like sulfuric acid
- akira2501 3y ago
  I've discovered damaged lead acid batteries in equipment by following the rotten egg smell back to it's source. Twice, both small current 12V DC batteries.
- extraduder_ire 3y ago
  Humans are _very_ sensitive to the smell of H2S. Unless you meant that it might produce enough to kill your sense of smell, which is possible.
  - kragen 3y ago
    no, i meant i don't understand how you get from sulfate to prussiate at room temperature
ttymck 3y ago
Yes this was my initial reaction: what if a tesla battery comes in contact with water? What degree of "more dangerous" are we talking about?

lstodd 3y ago

Rotten eggs smell is just about everything you can get from this kind of experiment. Now if they scale it up. but at any scale that makes sense economically you can get suffocated by just about any gas you can think of. Like helium or hydrogen.

rzzzt 3y ago
H2S is also a byproduct of crude oil processing. The nose is easily overwhelmed by the smell even at low concentrations, and it becomes hard to notice before it strikes.

jncfhnb 3y ago

Depending on concentrations required for consequences a smelly gas is much safer than something like CO

arcticbull 3y ago
I believe you go noseblind to hydrogen sulfide very quickly. [1] [1] https://dodtec.com/news/the-potential-dangers-of-hydrogen-sulfide-exposure.html https://dodtec.com/news/the-potential-dangers-of-hydrogen-su...
peterdsharpe 3y ago
Perhaps "safer than CO" is fair, but "much safer than CO" may be a bit of a stretch. H2S is the #2 cause of fatal chemical inhalations in the workplace, behind CO: https://www.bls.gov/opub/ted/2019/fatal-chemical-inhalations-in-the-workplace-up-in-2017.htm https://www.bls.gov/opub/ted/2019/fatal-chemical-inhalations...

bell-cot 3y ago

MSDS for H2S - https://www.airgas.com/msds/001029.pdf https://www.airgas.com/msds/001029.pdf The Occupational Exposure limits are fairly low 'ppm' numbers, and LC50 is 712ppm for 1 hour. (That is the concentration at which 50% of the exposed rats died.)

hadlock 3y ago

Someone else pointed out LD50 is ~700ppm It's unlikely you'd be exposed to this level for any period of time unless the battery ruptured into the car, underwater, with the windows up, in which case you have bigger problems. You're unlikely to to see 700ppm in an outdoor situation like a car wreck or battery malfunction on the highway during a rainstorm. Atmospheric CO2 is about 450ppm for comparison. Ammonia is a superior refrigerant (widely used in industrial circles, and causes no ozone depletion, is biodegradable, etc) but not used in residential applications because it's highly toxic if there's a catastrophic seal failure and not vented outside, despite the fact that humans are very efficient at smelling even the slightest ammonia leak.

peterdsharpe 3y ago
I think H2S is somewhat bigger of a safety risk than presented here. For example, check out this case where what you describe (battery rupture) happened, killing both occupants from H2S inhalation: https://web.archive.org/web/20161005164308/http://www.wesh.com/news/medical-examiner-confirms-suspected-cause-of-deaths-in-turnpike-mystery/41939954 https://web.archive.org/web/20161005164308/http://www.wesh.c... And this was only from a starter battery, not a battery sized for vehicle locomotion.
- solardev 3y ago
  It's interesting that Porsche put the battery under the driver's seat (in the cabin? unclear). Wonder if that made it more dangerous. Are modern EV batteries also in the passenger area or in their own little armored section...?
  - npunt 3y ago
    It was probably put there for weight distribution as Porsche would be more likely to optimize for that despite the user inconvenience it may cause
    - mdekkers 3y ago
      Possibly for a Carrera, but for a Cayenne? Despite the Porsche brand, that isn’t anywhere close to a sports car. The platform is shared with the Audi Q7 and the VW Touareg. It’s a tractor with nicer seats. The weight of a battery fitting under a driver seat would be similar to a big shopping run, so weight distribution wouldn’t have been a consideration. Manufacturing logistics probably played a bigger role.

_a_a_a_ 3y ago

HS is funny stuff. Does nothing then zap, ur dead. UK figures for safe working concentration in air, from memory, hydrogen cyanide 11ppm, hydrogen sulphide 10ppm

npsomaratna 3y ago

I remember synthesizing H2S in high school (for chemistry practicals, I think). I made the mistake of attempting to smell it. This was for a fraction of a second—but during that time, I could feel the individual bubbles of gas entering my nose; and I almost passed out.

snowwrestler 3y ago

There’s no way to concentrate energy without creating some danger. Gasoline is quite dangerous but we drive around with tanks full of it now. Natural gas and high-amp electricity are dangerous but we have them coming into many houses. So I would propose the question shouldn’t necessarily be, “how bad is the worst-case scenario”—it’s pretty bad for all energy sources. I think a better question is “how reliably and efficiently can we prevent or mitigate the dangers.” That will go a long way toward determining its commercial viability.