So you own an electric glider with a sizeable lithium-based battery, how do you fight a battery fire? Experience with fighting electric car fires is not encouraging because you can't cut off the supply of oxygen to the fire like you can with a carbon fuel such as gasoline - the chemistry of the battery supplies its own oxygen.

There was a very large (mega) battery fire in OZ that took three days to extinguish. The fire really wasn't extinguished, just all of the lithium was consumed. Firefighters were given advice on how to fight the fire by Tesla, the batterie's designer, and UGL, the installer (https://www.theguardian.com/australia-news/2021/aug/02/tesla-big-battery-fire-in-victoria-burns-into-day-three):

“They are difficult to fight because you can’t put water on the mega packs … all that does is extend the length of time that the fire burns for.”

Firefighters have taken advice from experts including Tesla, the battery’s creators, and UGL, who are installing the battery packs.

“The recommended process is you cool everything around it so the fire can’t spread and you let it burn out,” Beswicke said.

It is somewhat like fighting large forest fires: you wait for Nature to put it out naturally with rain and/or snow, except worse. A fire in aircraft lithium battery pack will likely result in the complete destruction of the plane, even if it is on the ground when the fire started. If the fire starts while airborne your only option is to bail out (if you are not incapacitated by smoke first like the Taurus Electro fatal accident in NZ). The original GP-15 design did not provide for this option, but it is now included as an option. Obviously, the GP-15 designers had not thought thru the consequences of a battery fire.

Tom

On 8/8/2021 4:00 PM, 2G wrote:
>
> It is somewhat like fighting large forest fires: you wait for Nature to put it out naturally with rain and/or snow, except worse. A fire in aircraft lithium battery pack will likely result in the complete destruction of the plane, even if it is on the ground when the fire started. If the fire starts while airborne your only option is to bail out (if you are not incapacitated by smoke first like the Taurus Electro fatal accident in NZ). The original GP-15 design did not provide for this option, but it is now included as an option. Obviously, the GP-15 designers had not thought thru the consequences of a battery fire.
>
> Tom

Please note that the cells, the battery packs, and their placement in the Taurus are
significantly different than in the GP15.

Anyone interested in the GP 15 should not rely on 2G's remarks, as he does not have any
particular knowledge of what the designers have thought about; instead, contact the dealer
for information, or the factory.

--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

On Sunday, August 8, 2021 at 8:25:22 PM UTC-7, Eric Greenwell wrote:
> On 8/8/2021 4:00 PM, 2G wrote:
> >
> > It is somewhat like fighting large forest fires: you wait for Nature to put it out naturally with rain and/or snow, except worse. A fire in aircraft lithium battery pack will likely result in the complete destruction of the plane, even if it is on the ground when the fire started. If the fire starts while airborne your only option is to bail out (if you are not incapacitated by smoke first like the Taurus Electro fatal accident in NZ). The original GP-15 design did not provide for this option, but it is now included as an option. Obviously, the GP-15 designers had not thought thru the consequences of a battery fire.
> >
> > Tom
> Please note that the cells, the battery packs, and their placement in the Taurus are
> significantly different than in the GP15.
>
> Anyone interested in the GP 15 should not rely on 2G's remarks, as he does not have any
> particular knowledge of what the designers have thought about; instead, contact the dealer
> for information, or the factory.
>
> --
> Eric Greenwell - USA
> - "A Guide to Self-launching Sailplane Operation"
> https://sites.google.com/site/motorgliders/publications/download-the-guide-1

Yeah, I probably don't know what the GP-15 battery pack design is because GP is redesigning the WHOLE GLIDER. So, neither does Eric. And if you go to GP's website you will learn nothing about it except that the batteries are lithium ion (ALL lithium batteries are "lithium ion"). Nonetheless, all lithium batteries share the common characteristic that they have oxygen atoms as an integral part of their chemistry, which makes fighting lithium battery fires so difficult (actually impossible).

One interesting thing on GP's website is:

GP 15 E/SE JETA
is the most sophisticated, multitask 15 m, electric self-launching GP GLIDER to date, designed and developed fully in-house.

This is precisely contrary to Schleicher's approach which, as Eric pointed out, uses experts in different disciplines from universities and industry. Let's face it: GP Glider's expert is ONE GUY! I honestly don't see how GP can do this "fully in-house."

Tom

On 8/8/21 11:48 PM, 2G wrote:
> I honestly don't see how GP can do this "fully in-house."

Well they can't, that was just Marketing puffery.

They actually have MGM-Compro doing the electrical system, a company
with considerable experience in the area.

On Monday, 9 August 2021 at 02:00:46 UTC+3, 2G wrote:
> So you own an electric glider with a sizeable lithium-based battery, how do you fight a battery fire?
>
> A fire in aircraft lithium battery pack will likely result in the complete destruction of the plane, even if it is on the ground when the fire started. If the fire starts while airborne your only option is to bail out (if you are not incapacitated by smoke first like the Taurus Electro fatal accident in NZ).
> Tom

Wait didn't you just answer your question? Yes it burns like hell, and no you can't extinguish it before the fire burns trough the structure. Two solutions: 1) insure it and hope for the best, 2) don't buy it and fly pure gliders.

Fire has never mixed well with airframes and probably never will. The goal is necessarily isolating the fire and its gas products. I don't see any solution other than holding the battery in an appropriate flameproof container that vents outside the glider. Perhaps a double walled box with insulation in between. A new glider design may make it possible to also eject the battery in flight or on the ground. There must be provision for an emergency landing and protecting most of the glider for future use would be nice. Bailing out is not an option in many circumstances. What are the solutions that allow certification of VTOL air taxis?

The FAA released a pretty good report in March 2017 entitled "Fire Hazard Analysis for Various Lithium Batteries." https://www.fire.tc.faa.gov/pdf/TC-16-17.pdf

It is fairly technical, but the conclusions are easily understood. I don't have a dog in this fight, as I probably won't ever be able to afford a motorglider, electric or not. I am basically happy to just rent an airplane for a six or seven minute tow and then fly around for five hours or so on the energy in the atmosphere. I get to look down on all the wind farms and solar arrays springing up in New Mexico. All of which pop up from magic beans and happy thoughts, with absolutely NO environmental impact at all. (Yes, that was sarcasm.)

On 8/9/21 7:32 AM, Mark Mocho wrote:
> The FAA released a pretty good report in March 2017 entitled "Fire Hazard Analysis for Various Lithium Batteries." https://www.fire.tc.faa.gov/pdf/TC-16-17.pdf
>
> It is fairly technical, but the conclusions are easily understood. I don't have a dog in this fight, as I probably won't ever be able to afford a motorglider, electric or not. I am basically happy to just rent an airplane for a six or seven minute tow and then fly around for five hours or so on the energy in the atmosphere. I get to look down on all the wind farms and solar arrays springing up in New Mexico. All of which pop up from magic beans and happy thoughts, with absolutely NO environmental impact at all. (Yes, that was sarcasm.)
>

The article that Tom cited had a quote from the incident commander,
saying that the Australia fire was the first at an energy storage
facility like that.

Actually, there was one in Arizona, with cells made from our friends at
LG Chem, which are implicated in the GM and Hyundai car fires:

https://www.greentechmedia.com/articles/read/lg-chem-battery-cell-mcmicken-arizona-fire

They've also had five 'thermal events' in home storage systems.

A link in that article points out S. Korea has had 23 fires in energy
storage facilities, leading to a shutdown in 522 of the country's 1490
energy storage projects!

https://www.spglobal.com/marketintelligence/en/news-insights/trending/bVy2KGU3Opsle5Vv8QG0-Q2

Apparently this is what happens when governments start throwing around
big bucks to promote virtue signalling, instead of common sense and good
engineering practices.

-Dave

Many decades ago, I worked at a research lab where colleagues were developing a sodium/sulfur battery (molten sodium and molten sulfur separated by a porous ceramic membrane). It was abandoned after many years of development.. I witnessed some of the fires, if you could call them that! (The firefighting technique was to run away as fast and as far as possible!)

I note that lithium is the metal next to sodium on the periodic table, but inside a battery is probably orders of magnitudes safer than molten sodium! However, as a seasoned Luddite, all my glider batteries are still lead acid.

Mike

On Monday, August 9, 2021 at 7:26:49 AM UTC-4, wtwisn...@gmail.com wrote:
> Fire has never mixed well with airframes and probably never will. The goal is necessarily isolating the fire and its gas products.

I think this is about the best comment here. I am unaware of any plan to extinguish fuel tank fires in aircraft, and the tragic tale of TWA 800 shows the consequences. We have learned through many years to manage the risk of gasoline and other flammables.

The energy required for self-launching a 500kg plane is on the order of 200mL of gasoline so it's easy to think this is a much more manageable problem than it seems at first glance.

(If three days for a massive battery farm sounds like a long time, consider that it took *two years* to extinguish a tire fire in California: https://www.sfgate.com/bayarea/article/After-2-Years-Smoking-Tires-Close-to-3236405..php. And we're still dealing with the fire consequences of Chernobyl and Fukushima. In general, anytime you concentrate energy, the fires last for a long time.)

When it comes to managing lithium fires, it must be understood that the lithium fire is not the problem but the problem's source. Think of it like a fire starter cube you'd throw under the charcoal to get the charcoal fire going. You can't really extinguish the firestarter (battery) once it's going, but if you can keep it from igniting the charcoal (airframe), then once it source burns itself out you've dodged a bullet. And it will burn itself out somewhat quickly, as the amount of oxygen generated inside the decomposing battery is not that much.

If the battery is fuselage-mounted[*], there are two possible routes which come to mind for doing this. One is to eject the battery, and the other is place it in an airtight and fireproof box with a vent to the outside. Ejecting the battery can be dicey because of its impact on the CG, but venting the battery to the outside sounds plausible.

The design we're considering is a large metal tube with a pressure release valve. If a battery starts outgassing, then the pressure rises and the valve pops, allowing the hot gasses to escape to the underside of the aircraft. A variety of strategies for fireproofing the box are things such as intumescent paint or simply wrapping it in ceramic insulation.

[*] If the battery is wing-mounted you have as many options as the towplane with its 50gal of gasoline does: none.

On Monday, August 9, 2021 at 7:06:38 AM UTC-7, kinsell wrote:
> On 8/9/21 7:32 AM, Mark Mocho wrote:
> > The FAA released a pretty good report in March 2017 entitled "Fire Hazard Analysis for Various Lithium Batteries." https://www.fire.tc.faa.gov/pdf/TC-16-17.pdf
> >
> > It is fairly technical, but the conclusions are easily understood. I don't have a dog in this fight, as I probably won't ever be able to afford a motorglider, electric or not. I am basically happy to just rent an airplane for a six or seven minute tow and then fly around for five hours or so on the energy in the atmosphere. I get to look down on all the wind farms and solar arrays springing up in New Mexico. All of which pop up from magic beans and happy thoughts, with absolutely NO environmental impact at all. (Yes, that was sarcasm.)
> >
> The article that Tom cited had a quote from the incident commander,
> saying that the Australia fire was the first at an energy storage
> facility like that.
>
> Actually, there was one in Arizona, with cells made from our friends at
> LG Chem, which are implicated in the GM and Hyundai car fires:
>
> https://www.greentechmedia.com/articles/read/lg-chem-battery-cell-mcmicken-arizona-fire
>
> They've also had five 'thermal events' in home storage systems.
>
> A link in that article points out S. Korea has had 23 fires in energy
> storage facilities, leading to a shutdown in 522 of the country's 1490
> energy storage projects!
>
> https://www.spglobal.com/marketintelligence/en/news-insights/trending/bVy2KGU3Opsle5Vv8QG0-Q2
>
> Apparently this is what happens when governments start throwing around
> big bucks to promote virtue signalling, instead of common sense and good
> engineering practices.
>
> -Dave

These incidents should be sobering for anyone considering an electric MG. These battery farms are controlled environment installations not subjected to the shock, vibration and altitude of aircraft use. And even given the onsite monitoring inherent to these facilities, they can't definitively identify the root cause of the fire.

Also troubling is the lithium dendritic growth failure mechanism, which creates an internal short in the cell, which leads to thermal runaway. Well, there's good news! The root cause of dendritic growth has been found by my former employer, the Pacific Northwest National Laboratory. But, wait, there is also bad news: the culprit is ethylene carbonate, an indispensable solvent added to the electrolyte to achieve the necessary energy densities (https://www.sciencedaily.com/releases/2019/10/191014111723.htm). PNNL is working on alternatives to ethylene carbonate with promising alternatives, but current generation batteries still use it and probably will for some time.

Tom

On 8/9/21 4:17 PM, 2G wrote:
> On Monday, August 9, 2021 at 7:06:38 AM UTC-7, kinsell wrote:
>> On 8/9/21 7:32 AM, Mark Mocho wrote:
>>> The FAA released a pretty good report in March 2017 entitled "Fire Hazard Analysis for Various Lithium Batteries." https://www.fire.tc.faa.gov/pdf/TC-16-17.pdf
>>>
>>> It is fairly technical, but the conclusions are easily understood. I don't have a dog in this fight, as I probably won't ever be able to afford a motorglider, electric or not. I am basically happy to just rent an airplane for a six or seven minute tow and then fly around for five hours or so on the energy in the atmosphere. I get to look down on all the wind farms and solar arrays springing up in New Mexico. All of which pop up from magic beans and happy thoughts, with absolutely NO environmental impact at all. (Yes, that was sarcasm.)
>>>
>> The article that Tom cited had a quote from the incident commander,
>> saying that the Australia fire was the first at an energy storage
>> facility like that.
>>
>> Actually, there was one in Arizona, with cells made from our friends at
>> LG Chem, which are implicated in the GM and Hyundai car fires:
>>
>> https://www.greentechmedia.com/articles/read/lg-chem-battery-cell-mcmicken-arizona-fire
>>
>> They've also had five 'thermal events' in home storage systems.
>>
>> A link in that article points out S. Korea has had 23 fires in energy
>> storage facilities, leading to a shutdown in 522 of the country's 1490
>> energy storage projects!
>>
>> https://www.spglobal.com/marketintelligence/en/news-insights/trending/bVy2KGU3Opsle5Vv8QG0-Q2
>>
>> Apparently this is what happens when governments start throwing around
>> big bucks to promote virtue signalling, instead of common sense and good
>> engineering practices.
>>
>> -Dave
>
> These incidents should be sobering for anyone considering an electric MG. These battery farms are controlled environment installations not subjected to the shock, vibration and altitude of aircraft use. And even given the onsite monitoring inherent to these facilities, they can't definitively identify the root cause of the fire.
>
> Also troubling is the lithium dendritic growth failure mechanism, which creates an internal short in the cell, which leads to thermal runaway. Well, there's good news! The root cause of dendritic growth has been found by my former employer, the Pacific Northwest National Laboratory. But, wait, there is also bad news: the culprit is ethylene carbonate, an indispensable solvent added to the electrolyte to achieve the necessary energy densities (https://www.sciencedaily.com/releases/2019/10/191014111723.htm). PNNL is working on alternatives to ethylene carbonate with promising alternatives, but current generation batteries still use it and probably will for some time.
>
> Tom
>

Interestingly, the same folks involved in the 2019 Arizona fire had a
pilot project go up in flames in 2012. Apparently there were more
lessons to be learned. Maybe third time's a charm?

https://www.spglobal.com/marketintelligence/en/news-insights/latest-news-headlines/burning-concern-energy-storage-industry-battles-battery-fires-51900636

But there's hope on the way, IEEE says the dreaded sodium isn't so
dangerous after all, it offers promise for large scale storage projects
even cheaper and safer than lithium.

https://spectrum.ieee.org/sodium-ion-battery

Probably about two years away.

-Dave

On Sunday, August 8, 2021 at 6:00:46 PM UTC-5, 2G wrote:
> So you own an electric glider with a sizeable lithium-based battery, how do you fight a battery fire? Experience with fighting electric car fires is not encouraging because you can't cut off the supply of oxygen to the fire like you can with a carbon fuel such as gasoline - the chemistry of the battery supplies its own oxygen.
>
> There was a very large (mega) battery fire in OZ that took three days to extinguish. The fire really wasn't extinguished, just all of the lithium was consumed. Firefighters were given advice on how to fight the fire by Tesla, the batterie's designer, and UGL, the installer (https://www.theguardian..com/australia-news/2021/aug/02/tesla-big-battery-fire-in-victoria-burns-into-day-three):
>
> “They are difficult to fight because you can’t put water on the mega packs … all that does is extend the length of time that the fire burns for.”
>
> Firefighters have taken advice from experts including Tesla, the battery’s creators, and UGL, who are installing the battery packs.
>
> “The recommended process is you cool everything around it so the fire can’t spread and you let it burn out,” Beswicke said.
>
> It is somewhat like fighting large forest fires: you wait for Nature to put it out naturally with rain and/or snow, except worse. A fire in aircraft lithium battery pack will likely result in the complete destruction of the plane, even if it is on the ground when the fire started. If the fire starts while airborne your only option is to bail out (if you are not incapacitated by smoke first like the Taurus Electro fatal accident in NZ). The original GP-15 design did not provide for this option, but it is now included as an option. Obviously, the GP-15 designers had not thought thru the consequences of a battery fire.
>
> Tom
Tom, this may have been the by far largest Lithium battery fire in history, it just happened at the end of June in Morris IL, about 10 miles from the Chicago Glider Club. Start at the bottom, notice that the fire was never extinguished but burned out, all 184,000 lbs of batteries. It took about 4 days, a retardant called Purple K was used by the fire department but without visible success. The warehouse this happened at was an illegal storage and Internet sales operation and had all sizes of batteries in it.
https://response.epa.gov/site/site_profile.aspx?site_id=15259
Herb

On 8/9/2021 3:17 PM, 2G wrote:
> On Monday, August 9, 2021 at 7:06:38 AM UTC-7, kinsell wrote:
....
>> The article that Tom cited had a quote from the incident commander,
>> saying that the Australia fire was the first at an energy storage
>> facility like that.
>>
>> Actually, there was one in Arizona, with cells made from our friends at
>> LG Chem, which are implicated in the GM and Hyundai car fires:
>>
>> https://www.greentechmedia.com/articles/read/lg-chem-battery-cell-mcmicken-arizona-fire
>>
>> They've also had five 'thermal events' in home storage systems.
>>
>> A link in that article points out S. Korea has had 23 fires in energy
>> storage facilities, leading to a shutdown in 522 of the country's 1490
>> energy storage projects!
>>
>> https://www.spglobal.com/marketintelligence/en/news-insights/trending/bVy2KGU3Opsle5Vv8QG0-Q2
>>
>> Apparently this is what happens when governments start throwing around
>> big bucks to promote virtue signalling, instead of common sense and good
>> engineering practices.
>>
>> -Dave
>
> These incidents should be sobering for anyone considering an electric MG. These battery farms are controlled environment installations not subjected to the shock, vibration and altitude of aircraft use. And even given the onsite monitoring inherent to these facilities, they can't definitively identify the root cause of the fire.
>
> Also troubling is the lithium dendritic growth failure mechanism, which creates an internal short in the cell, which leads to thermal runaway. Well, there's good news! The root cause of dendritic growth has been found by my former employer, the Pacific Northwest National Laboratory. But, wait, there is also bad news: the culprit is ethylene carbonate, an indispensable solvent added to the electrolyte to achieve the necessary energy densities (https://www.sciencedaily.com/releases/2019/10/191014111723.htm). PNNL is working on alternatives to ethylene carbonate with promising alternatives, but current generation batteries still use it and probably will for some time.
>
> Tom

At the end of March, Schleicher had over 60 orders for the AS33 and AS34; JS also has
"many" orders for their JS3 with electric self-launch. This indicates a very strong
interest in electric propulsion. Are these pilots fools to take what Tom thinks are huge
risks? Or are they correct to believe that AS and JS are demonstrably competent sailplane
designers and manufacturers that have a good safety record, and would not put their
customers at undue risk? That they have carefully evaluated the technology and implemented
it with their resources, and those of multiple experienced individuals and companies?
That's an easy question for me: go with AS or JS.

And for anyone that feels fires in huge power stations is relevant to glider design, I
suggest you stay away from gasoline engine self-launchers, because huge refineries making
gasoline have exploded and burned with incredibly intense heat all around the world.

--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

On 8/9/2021 2:40 PM, Kenn Sebesta wrote:
> On Monday, August 9, 2021 at 7:26:49 AM UTC-4, wtwisn...@gmail.com wrote:
>> Fire has never mixed well with airframes and probably never will. The goal is necessarily isolating the fire and its gas products.
>
> I think this is about the best comment here. I am unaware of any plan to extinguish fuel tank fires in aircraft, and the tragic tale of TWA 800 shows the consequences. We have learned through many years to manage the risk of gasoline and other flammables.
>
> The energy required for self-launching a 500kg plane is on the order of 200mL of gasoline so it's easy to think this is a much more manageable problem than it seems at first glance.
>
> (If three days for a massive battery farm sounds like a long time, consider that it took *two years* to extinguish a tire fire in California: https://www.sfgate.com/bayarea/article/After-2-Years-Smoking-Tires-Close-to-3236405.php. And we're still dealing with the fire consequences of Chernobyl and Fukushima. In general, anytime you concentrate energy, the fires last for a long time.)
>
> When it comes to managing lithium fires, it must be understood that the lithium fire is not the problem but the problem's source. Think of it like a fire starter cube you'd throw under the charcoal to get the charcoal fire going. You can't really extinguish the firestarter (battery) once it's going, but if you can keep it from igniting the charcoal (airframe), then once it source burns itself out you've dodged a bullet. And it will burn itself out somewhat quickly, as the amount of oxygen generated inside the decomposing battery is not that much.
>
> If the battery is fuselage-mounted[*], there are two possible routes which come to mind for doing this. One is to eject the battery, and the other is place it in an airtight and fireproof box with a vent to the outside. Ejecting the battery can be dicey because of its impact on the CG, but venting the battery to the outside sounds plausible.
>
> The design we're considering is a large metal tube with a pressure release valve. If a battery starts outgassing, then the pressure rises and the valve pops, allowing the hot gasses to escape to the underside of the aircraft. A variety of strategies for fireproofing the box are things such as intumescent paint or simply wrapping it in ceramic insulation.
>
> [*] If the battery is wing-mounted you have as many options as the towplane with its 50gal of gasoline does: none.

How about a 6 foot long metal tube/tray (doesn't have to be round) that slides into the D
tube in the wing? Having the tube in the wing, with external venting, would keep battery
gases out of the cockpit.

There is plenty volume in that area, and it could hold 200+ 18650 cells easily, over 2.2
kWh. Or use a high temperature composite if the tray needs to be a complex shape. The
interior of the D tube (or the exterior of the tray) could be painted with intumescent
paint to protect the wing. A fire suppression system that released gas into the tray
during a cell fire might keep the composite tube from burning until the cell's energy was
exhausted.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

I'm one of these fools who ordered an electric self-launcher :-). I am also a bit sceptic about electric cars being the solution to all future mobility problems. But in case of self-launching gliders, I am convinced that electric propulsion is a significant improvement of current technology available in gliding, both in terms of reliability and operational safety. I did not place the order for environmental reasons.

Our Ventus2cM has a fire warning light in its panel, for a reason. A lot of fire potential is stored behind my back (or in troublesome plastic bags inside of the wings) and there were quite a few instances where the combustion process took place outside of the engine of self-launching motorgliders. But what worries me more is the operational and technical complexity of the engine system itself. We do the annualy checks quite thoroughly and there is always something to be adjusted, replaced or repaired. Sure, Li-Ion batteries will have to be treated with care. But the same goes for the fuel system in any other motorglider.

The glider manufacturers have different safety concepts about storing the batteries on board. To me, storing the batteries in the wings with wider separation between the cells seemed the best mitigation towards the risk of a battery fire.

On Tuesday, August 10, 2021 at 10:12:03 AM UTC-7, Eric Greenwell wrote:
> On 8/9/2021 3:17 PM, 2G wrote:
> > On Monday, August 9, 2021 at 7:06:38 AM UTC-7, kinsell wrote:
> ...
> >> The article that Tom cited had a quote from the incident commander,
> >> saying that the Australia fire was the first at an energy storage
> >> facility like that.
> >>
> >> Actually, there was one in Arizona, with cells made from our friends at
> >> LG Chem, which are implicated in the GM and Hyundai car fires:
> >>
> >> https://www.greentechmedia.com/articles/read/lg-chem-battery-cell-mcmicken-arizona-fire
> >>
> >> They've also had five 'thermal events' in home storage systems.
> >>
> >> A link in that article points out S. Korea has had 23 fires in energy
> >> storage facilities, leading to a shutdown in 522 of the country's 1490
> >> energy storage projects!
> >>
> >> https://www.spglobal.com/marketintelligence/en/news-insights/trending/bVy2KGU3Opsle5Vv8QG0-Q2
> >>
> >> Apparently this is what happens when governments start throwing around
> >> big bucks to promote virtue signalling, instead of common sense and good
> >> engineering practices.
> >>
> >> -Dave
> >
> > These incidents should be sobering for anyone considering an electric MG. These battery farms are controlled environment installations not subjected to the shock, vibration and altitude of aircraft use. And even given the onsite monitoring inherent to these facilities, they can't definitively identify the root cause of the fire.
> >
> > Also troubling is the lithium dendritic growth failure mechanism, which creates an internal short in the cell, which leads to thermal runaway. Well, there's good news! The root cause of dendritic growth has been found by my former employer, the Pacific Northwest National Laboratory. But, wait, there is also bad news: the culprit is ethylene carbonate, an indispensable solvent added to the electrolyte to achieve the necessary energy densities (https://www.sciencedaily.com/releases/2019/10/191014111723.htm). PNNL is working on alternatives to ethylene carbonate with promising alternatives, but current generation batteries still use it and probably will for some time.
> >
> > Tom
> At the end of March, Schleicher had over 60 orders for the AS33 and AS34; JS also has
> "many" orders for their JS3 with electric self-launch. This indicates a very strong
> interest in electric propulsion. Are these pilots fools to take what Tom thinks are huge
> risks? Or are they correct to believe that AS and JS are demonstrably competent sailplane
> designers and manufacturers that have a good safety record, and would not put their
> customers at undue risk? That they have carefully evaluated the technology and implemented
> it with their resources, and those of multiple experienced individuals and companies?
> That's an easy question for me: go with AS or JS.
>
> And for anyone that feels fires in huge power stations is relevant to glider design, I
> suggest you stay away from gasoline engine self-launchers, because huge refineries making
> gasoline have exploded and burned with incredibly intense heat all around the world.
> --
> Eric Greenwell - USA
> - "A Guide to Self-launching Sailplane Operation"
> https://sites.google.com/site/motorgliders/publications/download-the-guide-1

Obviously I haven't called anyone a "fool" as Eric suggests. This subject is very complex, even for a degreed electronic engineer, such as myself, because it is multidisciplinary. Indeed, I am in the learning mode on this subject, and the more I learn the more concerned I get. The Pipistrel Taurus Electro fatal accident was a real eye-opener for me, both in how a hard landing can trigger a battery failure and an on-board fire that incapacitates the pilot in seconds.

The difference between batteries and fuel is that fuel does not spontaneous combust in the fuel tank. If you have a fire you can shut off the fuel valve which cuts off the fuel supply to the fire. And gasoline fires can be fought with standard fire extinguishers, while lithium battery fires cannot (which was the original subject of this thread).

I have no knowledge as to what battery chemistry either Schleicher or Jonkers is using, but it is very likely that it includes the problematic ethylene carbonate. German interest in electric motorgliders is being driven, in part, by their airport noise abatement regulations. Perhaps a German MG owner can expound more on this.

Finally, as I have said before, we are all adults here (mostly) and must make our own decisions about equipment and safety. I am merely presenting the scientific and accident evidence on the subject - whether you even read it, let alone follow it, is entirely up to you.

Tom

On 8/10/21 2:16 PM, Eric Greenwell wrote:
> On 8/9/2021 2:40 PM, Kenn Sebesta wrote:
>> On Monday, August 9, 2021 at 7:26:49 AM UTC-4, wtwisn...@gmail.com wrote:
>>> Fire has never mixed well with airframes and probably never will. The
>>> goal is necessarily isolating the fire and its gas products.
>>
>> I think this is about the best comment here. I am unaware of any plan
>> to extinguish fuel tank fires in aircraft, and the tragic tale of TWA
>> 800 shows the consequences. We have learned through many years to
>> manage the risk of gasoline and other flammables.
>>
>> The energy required for self-launching a 500kg plane is on the order
>> of 200mL of gasoline so it's easy to think this is a much more
>> manageable problem than it seems at first glance.
>>
>> (If three days for a massive battery farm sounds like a long time,
>> consider that it took *two years* to extinguish a tire fire in
>> California:
>> https://www.sfgate.com/bayarea/article/After-2-Years-Smoking-Tires-Close-to-3236405.php.
>> And we're still dealing with the fire consequences of Chernobyl and
>> Fukushima. In general, anytime you concentrate energy, the fires last
>> for a long time.)
>>
>> When it comes to managing lithium fires, it must be understood that
>> the lithium fire is not the problem but the problem's source. Think of
>> it like a fire starter cube you'd throw under the charcoal to get the
>> charcoal fire going. You can't really extinguish the firestarter
>> (battery) once it's going, but if you can keep it from igniting the
>> charcoal (airframe), then once it source burns itself out you've
>> dodged a bullet. And it will burn itself out somewhat quickly, as the
>> amount of oxygen generated inside the decomposing battery is not that
>> much.
>>
>> If the battery is fuselage-mounted[*], there are two possible routes
>> which come to mind for doing this. One is to eject the battery, and
>> the other is place it in an airtight and fireproof box with a vent to
>> the outside. Ejecting the battery can be dicey because of its impact
>> on the CG, but venting the battery to the outside sounds plausible.
>>
>> The design we're considering is a large metal tube with a pressure
>> release valve. If a battery starts outgassing, then the pressure rises
>> and the valve pops, allowing the hot gasses to escape to the underside
>> of the aircraft. A variety of strategies for fireproofing the box are
>> things such as intumescent paint or simply wrapping it in ceramic
>> insulation.
>>
>> [*] If the battery is wing-mounted you have as many options as the
>> towplane with its 50gal of gasoline does: none.
>
> How about a 6 foot long metal tube/tray (doesn't have to be round) that
> slides into the D tube in the wing? Having the tube in the wing, with
> external venting, would keep battery gases out of the cockpit.
>
> There is plenty volume in that area, and it could hold 200+ 18650 cells
> easily, over 2.2 kWh. Or use a high temperature composite if the tray
> needs to be a complex shape. The interior of the D tube (or the exterior
> of the tray) could be painted with intumescent paint to protect the
> wing. A fire suppression system that released gas into the tray during a
> cell fire might keep the composite tube from burning until the cell's
> energy was exhausted.

Not sure what gas you would propose to suppress a fire, but it wouldn't
be effective. In the warehouse fire Herb noted, they tried dumping 28
tons of dry concrete powder on the batteries, they kept right on burning.

Interesting video from Germany, with typical Teutonic efficiency, they
rollout the big RedBox to deal with a car fire. They must have done this
before.

https://www.youtube.com/watch?v=2W4NzUQffcE

On Tue, 10 Aug 2021 15:34:10 -0600, kinsell wrote:

> On 8/10/21 2:16 PM, Eric Greenwell wrote:
>> On 8/9/2021 2:40 PM, Kenn Sebesta wrote:
>>> On Monday, August 9, 2021 at 7:26:49 AM UTC-4, wtwisn...@gmail.com
>>> wrote:
>>>> Fire has never mixed well with airframes and probably never will. The
>>>> goal is necessarily isolating the fire and its gas products.
>>>
>>> I think this is about the best comment here. I am unaware of any plan
>>> to extinguish fuel tank fires in aircraft, and the tragic tale of TWA
>>> 800 shows the consequences. We have learned through many years to
>>> manage the risk of gasoline and other flammables.
>>>
>>> The energy required for self-launching a 500kg plane is on the order
>>> of 200mL of gasoline so it's easy to think this is a much more
>>> manageable problem than it seems at first glance.
>>>
>>> (If three days for a massive battery farm sounds like a long time,
>>> consider that it took *two years* to extinguish a tire fire in
>>> California:
>>> https://www.sfgate.com/bayarea/article/After-2-Years-Smoking-Tires-
Close-to-3236405.php.
>>> And we're still dealing with the fire consequences of Chernobyl and
>>> Fukushima. In general, anytime you concentrate energy, the fires last
>>> for a long time.)
>>>
>>> When it comes to managing lithium fires, it must be understood that
>>> the lithium fire is not the problem but the problem's source. Think of
>>> it like a fire starter cube you'd throw under the charcoal to get the
>>> charcoal fire going. You can't really extinguish the firestarter
>>> (battery) once it's going, but if you can keep it from igniting the
>>> charcoal (airframe), then once it source burns itself out you've
>>> dodged a bullet. And it will burn itself out somewhat quickly, as the
>>> amount of oxygen generated inside the decomposing battery is not that
>>> much.
>>>
>>> If the battery is fuselage-mounted[*], there are two possible routes
>>> which come to mind for doing this. One is to eject the battery, and
>>> the other is place it in an airtight and fireproof box with a vent to
>>> the outside. Ejecting the battery can be dicey because of its impact
>>> on the CG, but venting the battery to the outside sounds plausible.
>>>
>>> The design we're considering is a large metal tube with a pressure
>>> release valve. If a battery starts outgassing, then the pressure rises
>>> and the valve pops, allowing the hot gasses to escape to the underside
>>> of the aircraft. A variety of strategies for fireproofing the box are
>>> things such as intumescent paint or simply wrapping it in ceramic
>>> insulation.
>>>
>>> [*] If the battery is wing-mounted you have as many options as the
>>> towplane with its 50gal of gasoline does: none.
>>
>> How about a 6 foot long metal tube/tray (doesn't have to be round) that
>> slides into the D tube in the wing? Having the tube in the wing, with
>> external venting, would keep battery gases out of the cockpit.
>>
>> There is plenty volume in that area, and it could hold 200+ 18650 cells
>> easily, over 2.2 kWh. Or use a high temperature composite if the tray
>> needs to be a complex shape. The interior of the D tube (or the
>> exterior of the tray) could be painted with intumescent paint to
>> protect the wing. A fire suppression system that released gas into the
>> tray during a cell fire might keep the composite tube from burning
>> until the cell's energy was exhausted.
>
>
> Not sure what gas you would propose to suppress a fire, but it wouldn't
> be effective. In the warehouse fire Herb noted, they tried dumping 28
> tons of dry concrete powder on the batteries, they kept right on
> burning.
>
> Interesting video from Germany, with typical Teutonic efficiency, they
> rollout the big RedBox to deal with a car fire. They must have done this
> before.
>
> https://www.youtube.com/watch?v=2W4NzUQffcE

Looks like a BMW i3, so an 18-38 kWh battery and 80 - 150 mile range
without the range extender which was, originally a 650cc petrol generator
pack and, later models, just a bigger battery extending the range to 200
miles. In case you're wondering, my neighbour has one of the older ones
with the 650cc range extender generator pack.

--
--
Martin | martin at
Gregorie | gregorie dot org

On 8/10/2021 2:34 PM, kinsell wrote:
>> There is plenty volume in that area, and it could hold 200+ 18650 cells easily, over 2.2
>> kWh. Or use a high temperature composite if the tray needs to be a complex shape. The
>> interior of the D tube (or the exterior of the tray) could be painted with intumescent
>> paint to protect the wing. A fire suppression system that released gas into the tray
>> during a cell fire might keep the composite tube from burning until the cell's energy
>> was exhausted.
>
>
> Not sure what gas you would propose to suppress a fire, but it wouldn't be effective.  In
> the warehouse fire Herb noted, they tried dumping 28 tons of dry concrete powder on the
> batteries, they kept right on burning.

CO2 maybe, just something to keep the composite tube from burning, to help move the hot
gases to the external vent, and is compatible with cell gases, It's not something intended
to extinguish the cell fire, but to mitigate the effects of the fire. The situation I
described was one cell, not 100 TONS of batteries!

I wonder what that mountain of batteries cost, and owner of the batteries (and the
building) said he didn't have insurance.

--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications/download-the-guide-1

On Tuesday, August 10, 2021 at 6:39:35 PM UTC-4, Eric Greenwell wrote:
> On 8/10/2021 2:34 PM, kinsell wrote:
> >> There is plenty volume in that area, and it could hold 200+ 18650 cells easily, over 2.2
> >> kWh. Or use a high temperature composite if the tray needs to be a complex shape. The
> >> interior of the D tube (or the exterior of the tray) could be painted with intumescent
> >> paint to protect the wing. A fire suppression system that released gas into the tray
> >> during a cell fire might keep the composite tube from burning until the cell's energy
> >> was exhausted.
> >
> >
> > Not sure what gas you would propose to suppress a fire, but it wouldn't be effective. In
> > the warehouse fire Herb noted, they tried dumping 28 tons of dry concrete powder on the
> > batteries, they kept right on burning.
> CO2 maybe, just something to keep the composite tube from burning, to help move the hot
> gases to the external vent, and is compatible with cell gases, It's not something intended
> to extinguish the cell fire, but to mitigate the effects of the fire. The situation I
> described was one cell, not 100 TONS of batteries!
>
> I wonder what that mountain of batteries cost, and owner of the batteries (and the
> building) said he didn't have insurance.
> --
> Eric Greenwell - USA
> - "A Guide to Self-launching Sailplane Operation"
> https://sites.google.com/site/motorgliders/publications/download-the-guide-1
Eric - the D-tube area is primary structure...if you can only paint it white I think you can forget about using it for heat containment. Just bail out!

On Tue, 10 Aug 2021 15:39:24 -0700, Eric Greenwell wrote:

> On 8/10/2021 2:34 PM, kinsell wrote:
>> Not sure what gas you would propose to suppress a fire, but it wouldn't
>> be effective.  In the warehouse fire Herb noted, they tried dumping 28
>> tons of dry concrete powder on the batteries, they kept right on
>> burning.
>
> CO2 maybe, just something to keep the composite tube from burning, to
> help move the hot gases to the external vent, and is compatible with
> cell gases, It's not something intended to extinguish the cell fire, but
> to mitigate the effects of the fire. The situation I described was one
> cell, not 100 TONS of batteries!
>
I don't think what gas you use matters much provided it doesn't contain
oxygen and isn't flammable: nitrogen is probably as good as any and
cheaper than a lot of other possibilities. Colder would be better too.

--
--
Martin | martin at
Gregorie | gregorie dot org

On Tuesday, August 10, 2021 at 4:07:34 PM UTC-7, sgs...@gmail.com wrote:
> On Tuesday, August 10, 2021 at 6:39:35 PM UTC-4, Eric Greenwell wrote:
> > On 8/10/2021 2:34 PM, kinsell wrote:
> > >> There is plenty volume in that area, and it could hold 200+ 18650 cells easily, over 2.2
> > >> kWh. Or use a high temperature composite if the tray needs to be a complex shape. The
> > >> interior of the D tube (or the exterior of the tray) could be painted with intumescent
> > >> paint to protect the wing. A fire suppression system that released gas into the tray
> > >> during a cell fire might keep the composite tube from burning until the cell's energy
> > >> was exhausted.
> > >
> > >
> > > Not sure what gas you would propose to suppress a fire, but it wouldn't be effective. In
> > > the warehouse fire Herb noted, they tried dumping 28 tons of dry concrete powder on the
> > > batteries, they kept right on burning.
> > CO2 maybe, just something to keep the composite tube from burning, to help move the hot
> > gases to the external vent, and is compatible with cell gases, It's not something intended
> > to extinguish the cell fire, but to mitigate the effects of the fire. The situation I
> > described was one cell, not 100 TONS of batteries!
> >
> > I wonder what that mountain of batteries cost, and owner of the batteries (and the
> > building) said he didn't have insurance.
> > --
> > Eric Greenwell - USA
> > - "A Guide to Self-launching Sailplane Operation"
> > https://sites.google.com/site/motorgliders/publications/download-the-guide-1
> Eric - the D-tube area is primary structure...if you can only paint it white I think you can forget about using it for heat containment. Just bail out!

Any fire in that tube is going to generate very high temperatures very quickly that will heat up the rest of the cells in the tube. Obviously, adjacent cells will get the brunt of the heat, but the only way to vent the gases is out the ends of the tube structure. A necessary test during development is setting one cell on fire and measuring the temperatures of the other cells in the tube. The tube would have to be metal because of the temperatures.. These battery fires go very quickly as the video shows, so an emergency landing is likely not possible unless you are on short final - bailing out is a better option if you are high enough. A BRS would only make things worse.

To repeat myself, lithium battery fires CANNOT be "put out," only slowed down until all of the fuel is consumed, because they inherently provide their own oxygen. Pouring A LOT of water on a battery fire MAY keep adjacent cells below the critical combustion temperature while the burning cells complete their combustion. This seems unlikely if they are sealed up in a tube inside a wing.

Tom

>
> Interesting video from Germany, with typical Teutonic efficiency, they
> rollout the big RedBox to deal with a car fire. They must have done this
> before.
>
> https://www.youtube.com/watch?v=2W4NzUQffcE

No, they haven't! As the gentleman from 'OelWehr', who spoke last explained, this was the first 'hot' application of this Red Box. They had practiced with another car before, which was not on fire but this was the first real one for them. He mentioned that the container was specifically built for this application and that is has been tested to make sure it is leak-proof, since the e-vehicle will remain flooded for 24 hours. The company is also equipped to dispose of the water after the cool-down period in an environmentally safe and approved way.

Uli
'AS'

> > https://www.youtube.com/watch?v=2W4NzUQffcE
> Looks like a BMW i3, so an 18-38 kWh battery and 80 - 150 mile range
> without the range extender which was, originally a 650cc petrol generator
> pack and, later models, just a bigger battery extending the range to 200
> miles. In case you're wondering, my neighbour has one of the older ones
> with the 650cc range extender generator pack.
>
>
>
> --
> --
> Martin | martin at
> Gregorie | gregorie dot org

No, Martin - it is an Opel (GM) model, not a BMW. ;-)
Take a look at the video at time stamp 12:50.

Uli
'AS'