Our club is kicking around the idea of buying a Pipistrel Electro 2.5 to supplement our current training ships (L23, K21 and Grob Twin), one of which would probably be sold. Preliminary impressions are pretty favorable. I'm looking for any first-handexperience anyone may have with this particular glider. Thanks in advance.
MikeA recent discovery I found is that it can actually be trailered in a Cobra trailer and assembled without much trouble. Big plus I think.
Our club is kicking around the idea of buying a Pipistrel Electro 2.5 to supplement our current training ships (L23, K21 and Grob Twin), one of which would probably be sold. Preliminary impressions are pretty favorable. I'm looking for any first-handexperience anyone may have with this particular glider. Thanks in advance.
MikeContact the dealer for names of customers that have used it for training or in a club. Or
On 11/3/2022 8:02 AM, Michael Fadden wrote:experience anyone may have with this particular glider. Thanks in advance.
Our club is kicking around the idea of buying a Pipistrel Electro 2.5 to supplement our current training ships (L23, K21 and Grob Twin), one of which would probably be sold. Preliminary impressions are pretty favorable. I'm looking for any first-hand
MikeContact the dealer for names of customers that have used it for training or in a club. Or
just start calling Taurus owners in the FAA register - not that many to go through.
Our club is kicking around the idea of buying a Pipistrel Electro 2.5 to supplement our current training ships (L23, K21 and Grob Twin), one of which would probably be sold. Preliminary impressions are pretty favorable. I'm looking for any first-handexperience anyone may have with this particular glider. Thanks in advance.
Mike
Thanks, Curt. I don't how much consideration has been given to trailer options but that's good to know. While its not listed as definite cause of the fire/crash, its clear the owner of the NZ Taurus didn't maintain the battery in accordance with themanufacturer's instructions. The whole battery safety issue is part of the discussion we are having. I was hoping that some owners (worldwide, not just U.S.) of the Electro 2.5 were users of this group and might relay their real world experiences.
Mike
... the electrical arcing was immediately followed by rapid inflation of the pouch, followed by light grey smoke, followed by flames. <<
Battery technology will advance and improve with the advent of EVs, so I will wait a little more before placing my order for an electric motor glider.
On 11/5/2022 12:35 PM, AS wrote:
Battery technology will advance and improve with the advent of EVs, so I will wait a little more before placing my order for an electric motor glider.How long did you want to wait? Place an order now, and you'll likely wait 2, 3, or more
years due to order backlogs. But, if you are waiting for batteries that can survive
sledgehammer attacks and multiple 10 foot drops onto a steel floor (as Battlebots endure),
you'll have to wait much longer.
Eric
drop.How long did you want to wait? Place an order now, and you'll likely wait 2, 3, or moreThese batteries can't even survive the bouncing and jarring that typical trailering causes. The Taurus Electro had a gear-up landing that may have contributed, and probably did, to its battery failure. Gear-up landings are not the same as a 10-foot
years due to order backlogs. But, if you are waiting for batteries that can survive
sledgehammer attacks and multiple 10 foot drops onto a steel floor (as Battlebots endure),
you'll have to wait much longer.
Eric
On 11/5/2022 9:19 PM, 2G wrote:drop.
These batteries can't even survive the bouncing and jarring that typical trailering causes. The Taurus Electro had a gear-up landing that may have contributed, and probably did, to its battery failure. Gear-up landings are not the same as a 10-foot
Is there more evidence for these concerns than this Taurus, particularly for the later
generation batteries from FES?
On Sunday, 6 November 2022 at 13:53:01 UTC+1, Eric Greenwell wrote:drop.
On 11/5/2022 9:19 PM, 2G wrote:
These batteries can't even survive the bouncing and jarring that typical trailering causes. The Taurus Electro had a gear-up landing that may have contributed, and probably did, to its battery failure. Gear-up landings are not the same as a 10-foot
follow the certification requirements as current sailplane certified batteries do. That said, I don't know the exact battery type it does use.Is there more evidence for these concerns than this Taurus, particularly for the later
generation batteries from FES?
The Taurus Electro is not a FES system. In fact it's one of the first electrical gliders (after Antares), and predates the first FES equipped glider by a couple of years. And being built to ultra light rules, it both predates and is not required to
On 11/5/2022 9:19 PM, 2G wrote:drop.
How long did you want to wait? Place an order now, and you'll likely wait 2, 3, or moreThese batteries can't even survive the bouncing and jarring that typical trailering causes. The Taurus Electro had a gear-up landing that may have contributed, and probably did, to its battery failure. Gear-up landings are not the same as a 10-foot
years due to order backlogs. But, if you are waiting for batteries that can survive
sledgehammer attacks and multiple 10 foot drops onto a steel floor (as Battlebots endure),
you'll have to wait much longer.
Eric
Is there more evidence for these concerns than this Taurus, particularly for the later
generation batteries from FES?
Of course, Uli can choose to wait for an electric glider using cylindrical lithium
batteries, which are inherently more rugged than the pouch style.
On Sunday, November 6, 2022 at 4:53:01 AM UTC-8, Eric Greenwell wrote:drop.
On 11/5/2022 9:19 PM, 2G wrote:
How long did you want to wait? Place an order now, and you'll likely wait 2, 3, or moreThese batteries can't even survive the bouncing and jarring that typical trailering causes. The Taurus Electro had a gear-up landing that may have contributed, and probably did, to its battery failure. Gear-up landings are not the same as a 10-foot
years due to order backlogs. But, if you are waiting for batteries that can survive
sledgehammer attacks and multiple 10 foot drops onto a steel floor (as Battlebots endure),
you'll have to wait much longer.
Eric
found that the cylindrical cells stressed in the z-direction also experienced degradation and failures."Is there more evidence for these concerns than this Taurus, particularly for the later
generation batteries from FES?
Of course, Uli can choose to wait for an electric glider using cylindrical lithium
batteries, which are inherently more rugged than the pouch style.
Yes, this is an of intense interest. Here is one surprising scientific review that surveyed all studies in this area (https://journals.sagepub.com/doi/full/10.1177/14613484211008112):
"The authors concluded that the pouch cells showed no degradation or failure in any of the tests; however, the cylindrical cells shaken in the y-direction experienced mandrel loosening during the shock and long-term vibration tests. In addition, it was
andvibration environment."
"The reliability analysis and optimization of internal and external complex structures are urgently needed in the development of battery pack to eliminate all kinds of potential safety hazards in the design stage especially under the shock and
These results are in direct contradiction to your claim that pouch cells are more dangerous than cylindrical cells. The construction of cylindrical cells involves the rolling of four layers simultaneously; apparently this rolling action introducesstresses into the material, especially the separation layers.
Tom
On Sunday, November 6, 2022 at 4:53:01 AM UTC-8, Eric Greenwell wrote:drop.
On 11/5/2022 9:19 PM, 2G wrote:
How long did you want to wait? Place an order now, and you'll likely wait 2, 3, or moreThese batteries can't even survive the bouncing and jarring that typical trailering causes. The Taurus Electro had a gear-up landing that may have contributed, and probably did, to its battery failure. Gear-up landings are not the same as a 10-foot
years due to order backlogs. But, if you are waiting for batteries that can survive
sledgehammer attacks and multiple 10 foot drops onto a steel floor (as Battlebots endure),
you'll have to wait much longer.
Eric
found that the cylindrical cells stressed in the z-direction also experienced degradation and failures."Is there more evidence for these concerns than this Taurus, particularly for the later
generation batteries from FES?
Of course, Uli can choose to wait for an electric glider using cylindrical lithiumYes, this is an of intense interest. Here is one surprising scientific review that surveyed all studies in this area (https://journals.sagepub.com/doi/full/10.1177/14613484211008112):
batteries, which are inherently more rugged than the pouch style.
"The authors concluded that the pouch cells showed no degradation or failure in any of the tests; however, the cylindrical cells shaken in the y-direction experienced mandrel loosening during the shock and long-term vibration tests. In addition, it was
andvibration environment."
"The reliability analysis and optimization of internal and external complex structures are urgently needed in the development of battery pack to eliminate all kinds of potential safety hazards in the design stage especially under the shock and
These results are in direct contradiction to your claim that pouch cells are more dangerous than cylindrical cells. The construction of cylindrical cells involves the rolling of four layers simultaneously; apparently this rolling action introducesstresses into the material, especially the separation layers.
TomPouch cells are much more prone to damage that could lead to a fire as has happened a few times with FES ships and the referenced Taurus.
On Sunday, November 6, 2022 at 2:54:07 PM UTC-5, 2G wrote:drop.
On Sunday, November 6, 2022 at 4:53:01 AM UTC-8, Eric Greenwell wrote:
On 11/5/2022 9:19 PM, 2G wrote:
How long did you want to wait? Place an order now, and you'll likely wait 2, 3, or moreThese batteries can't even survive the bouncing and jarring that typical trailering causes. The Taurus Electro had a gear-up landing that may have contributed, and probably did, to its battery failure. Gear-up landings are not the same as a 10-foot
years due to order backlogs. But, if you are waiting for batteries that can survive
sledgehammer attacks and multiple 10 foot drops onto a steel floor (as Battlebots endure),
you'll have to wait much longer.
Eric
was found that the cylindrical cells stressed in the z-direction also experienced degradation and failures."Is there more evidence for these concerns than this Taurus, particularly for the laterYes, this is an of intense interest. Here is one surprising scientific review that surveyed all studies in this area (https://journals.sagepub.com/doi/full/10.1177/14613484211008112):
generation batteries from FES?
Of course, Uli can choose to wait for an electric glider using cylindrical lithium
batteries, which are inherently more rugged than the pouch style.
"The authors concluded that the pouch cells showed no degradation or failure in any of the tests; however, the cylindrical cells shaken in the y-direction experienced mandrel loosening during the shock and long-term vibration tests. In addition, it
vibration environment."
and
"The reliability analysis and optimization of internal and external complex structures are urgently needed in the development of battery pack to eliminate all kinds of potential safety hazards in the design stage especially under the shock and
stresses into the material, especially the separation layers.
These results are in direct contradiction to your claim that pouch cells are more dangerous than cylindrical cells. The construction of cylindrical cells involves the rolling of four layers simultaneously; apparently this rolling action introduces
Pouch cells are much more prone to damage that could lead to a fire as has happened a few times with FES ships and the referenced Taurus.
Tom
Lion cylinder type cells may fail from vibration but the just die due to open circuits.
That said my battery comes out of the glider for trailering.
UH
On 11/6/22 4:22 PM, Hank Nixon wrote:foot drop.
On Sunday, November 6, 2022 at 2:54:07 PM UTC-5, 2G wrote:
On Sunday, November 6, 2022 at 4:53:01 AM UTC-8, Eric Greenwell wrote: >>> On 11/5/2022 9:19 PM, 2G wrote:
How long did you want to wait? Place an order now, and you'll likely wait 2, 3, or moreThese batteries can't even survive the bouncing and jarring that typical trailering causes. The Taurus Electro had a gear-up landing that may have contributed, and probably did, to its battery failure. Gear-up landings are not the same as a 10-
years due to order backlogs. But, if you are waiting for batteries that can survive
sledgehammer attacks and multiple 10 foot drops onto a steel floor (as Battlebots endure),
you'll have to wait much longer.
Eric
was found that the cylindrical cells stressed in the z-direction also experienced degradation and failures."Is there more evidence for these concerns than this Taurus, particularly for the laterYes, this is an of intense interest. Here is one surprising scientific review that surveyed all studies in this area (https://journals.sagepub.com/doi/full/10.1177/14613484211008112):
generation batteries from FES?
Of course, Uli can choose to wait for an electric glider using cylindrical lithium
batteries, which are inherently more rugged than the pouch style.
"The authors concluded that the pouch cells showed no degradation or failure in any of the tests; however, the cylindrical cells shaken in the y-direction experienced mandrel loosening during the shock and long-term vibration tests. In addition, it
vibration environment."
and
"The reliability analysis and optimization of internal and external complex structures are urgently needed in the development of battery pack to eliminate all kinds of potential safety hazards in the design stage especially under the shock and
stresses into the material, especially the separation layers.
These results are in direct contradiction to your claim that pouch cells are more dangerous than cylindrical cells. The construction of cylindrical cells involves the rolling of four layers simultaneously; apparently this rolling action introduces
Perhaps in your experience they only fail with open circuits, but therePouch cells are much more prone to damage that could lead to a fire as has happened a few times with FES ships and the referenced Taurus.
Tom
Lion cylinder type cells may fail from vibration but the just die due to open circuits.
That said my battery comes out of the glider for trailering.
UH
have been quite a few cases where cylindrical cells have combusted.
Sure glad these things are getting so much safer:
https://gothamist.com/news/e-bike-fire-injures-38-in-midtown-east-apartment-building
On 11/6/22 4:22 PM, Hank Nixon wrote:...
Pouch cells are much more prone to damage that could lead to a fire as has happened a
Tom
few times with FES ships and the referenced Taurus.
Lion cylinder type cells may fail from vibration but the just die due to open circuits.
That said my battery comes out of the glider for trailering.
UH
Perhaps in your experience they only fail with open circuits, but there have been quite a
few cases where cylindrical cells have combusted.
Sure glad these things are getting so much safer:
https://gothamist.com/news/e-bike-fire-injures-38-in-midtown-east-apartment-building
Conclusion: fly at your OWN RISK!
On 11/6/2022 8:40 PM, 2G wrote:
Conclusion: fly at your OWN RISK!It's always been that way, Tom, even before the Wright brothers. Corollary: since it's OUR
risk, we don't have to prove anything to you.
You are welcome to offer opinions, but understand you do so at your own risk. Corollary:
If you don't want people to question your claims, don't offer them.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation" https://sites.google.com/site/motorgliders/publications
On Sunday, November 6, 2022 at 8:59:48 PM UTC-8, Eric Greenwell wrote:dependent applications. Remember, it was YOU that asked for this information!
On 11/6/2022 8:40 PM, 2G wrote:
Conclusion: fly at your OWN RISK!It's always been that way, Tom, even before the Wright brothers. Corollary: since it's OUR
risk, we don't have to prove anything to you.
You are welcome to offer opinions, but understand you do so at your own risk. Corollary:
If you don't want people to question your claims, don't offer them.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
Well, that is refreshing - you don't claim that egliders are risk free. I am only trying to offer OBJECTIVE scientific data (not opinion as you say) on the risks of lithium batteries. In my judgment the technology is not ready for CRITICAL life-
Tom
The clear attitude of eglider enthusiasts here is that
we skeptics must prove that lithium batteries are unsafe
(which I think I have done, BTW).
My attitude is that the proponents, especially the manufacturers,
MUST prove that they are safe.
This HAS NOT happened to date. Conclusion: fly at your OWN RISK!
On 11/6/2022 9:24 PM, 2G wrote:dependent applications. Remember, it was YOU that asked for this information!
On Sunday, November 6, 2022 at 8:59:48 PM UTC-8, Eric Greenwell wrote:
On 11/6/2022 8:40 PM, 2G wrote:
Conclusion: fly at your OWN RISK!It's always been that way, Tom, even before the Wright brothers. Corollary: since it's OUR
risk, we don't have to prove anything to you.
You are welcome to offer opinions, but understand you do so at your own risk. Corollary:
If you don't want people to question your claims, don't offer them.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
Well, that is refreshing - you don't claim that egliders are risk free. I am only trying to offer OBJECTIVE scientific data (not opinion as you say) on the risks of lithium batteries. In my judgment the technology is not ready for CRITICAL life-
TomI don't think anyone here has claimed egliders are risk free, or that any motor/engine
installation is risk free, but many of us believe the risk can be managed to an acceptable
level. We've learned to manage the risks of unconnected controls, of leaving spoilers
unlocked, of kiting during tow, and all the other risks involved in flying gliders, and we
can learn to manage our propulsion systems, too.
Note that it's an inclusive "we": pilots, soaring organizations, manufacturers, and
regulators.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation" https://sites.google.com/site/motorgliders/publications
On Monday, November 7, 2022 at 5:21:11 AM UTC-8, Eric Greenwell wrote:https://sites.google.com/site/motorgliders/publications
There is a level of risk above which the technology SHOULD NOT be used regardless of what its proponents say is acceptable. Given the stringent risk levels imposed by the FAA on aircraft systems I say it is UNQUESTIONED that lithium battery problemsnot easily, but vastly, exceed those levels. The technology simply is not ready for aircraft use.
Tom
On 11/7/2022 6:01 PM, 2G wrote:not easily, but vastly, exceed those levels. The technology simply is not ready for aircraft use.
On Monday, November 7, 2022 at 5:21:11 AM UTC-8, Eric Greenwell wrote:https://sites.google.com/site/motorgliders/publications
...
There is a level of risk above which the technology SHOULD NOT be used regardless of what its proponents say is acceptable. Given the stringent risk levels imposed by the FAA on aircraft systems I say it is UNQUESTIONED that lithium battery problems
Tom90 miles north of you, the US LAK dealer has sold electric gliders for years; meanwhile,
EASA certifies egliders, manufacturers build them, pilots buy and fly them. UNQUESTIONED
left the building a long time ago.
"I am only trying to offer OBJECTIVE scientific data (not opinion as you say) on the risks
of lithium batteries", but you are not meeting your own standards: "There is a level of
risk above which the technology SHOULD NOT be used..." is not a scientific fact, but your
judgement. Stick to the data, and your remarks will be better received.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation" https://sites.google.com/site/motorgliders/publications
On Tuesday, November 8, 2022 at 11:33:02 AM UTC-8, Eric Greenwell wrote:not easily, but vastly, exceed those levels. The technology simply is not ready for aircraft use.
On 11/7/2022 6:01 PM, 2G wrote:
On Monday, November 7, 2022 at 5:21:11 AM UTC-8, Eric Greenwell wrote:https://sites.google.com/site/motorgliders/publications
...
There is a level of risk above which the technology SHOULD NOT be used regardless of what its proponents say is acceptable. Given the stringent risk levels imposed by the FAA on aircraft systems I say it is UNQUESTIONED that lithium battery problems
under the rug.90 miles north of you, the US LAK dealer has sold electric gliders for years; meanwhile,
Tom
EASA certifies egliders, manufacturers build them, pilots buy and fly them. UNQUESTIONED
left the building a long time ago.
"I am only trying to offer OBJECTIVE scientific data (not opinion as you say) on the risks
of lithium batteries", but you are not meeting your own standards: "There is a level of
risk above which the technology SHOULD NOT be used..." is not a scientific fact, but your
judgement. Stick to the data, and your remarks will be better received.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
Eric, then come up with ONE peer-reviewed scientific paper that says the dendrite growth problem in lithium batteries has BEEN SOLVED. Just ONE. Until then, you have just got a bunch of scientist wannabees that are only known for sweeping problems
Tom
On 11/8/2022 9:06 PM, 2G wrote:problems not easily, but vastly, exceed those levels. The technology simply is not ready for aircraft use.
On Tuesday, November 8, 2022 at 11:33:02 AM UTC-8, Eric Greenwell wrote:
On 11/7/2022 6:01 PM, 2G wrote:
On Monday, November 7, 2022 at 5:21:11 AM UTC-8, Eric Greenwell wrote: >> https://sites.google.com/site/motorgliders/publications...
There is a level of risk above which the technology SHOULD NOT be used regardless of what its proponents say is acceptable. Given the stringent risk levels imposed by the FAA on aircraft systems I say it is UNQUESTIONED that lithium battery
under the rug.90 miles north of you, the US LAK dealer has sold electric gliders for years; meanwhile,
Tom
EASA certifies egliders, manufacturers build them, pilots buy and fly them. UNQUESTIONED
left the building a long time ago.
"I am only trying to offer OBJECTIVE scientific data (not opinion as you say) on the risks
of lithium batteries", but you are not meeting your own standards: "There is a level of
risk above which the technology SHOULD NOT be used..." is not a scientific fact, but your
judgement. Stick to the data, and your remarks will be better received. >> --
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
Eric, then come up with ONE peer-reviewed scientific paper that says the dendrite growth problem in lithium batteries has BEEN SOLVED. Just ONE. Until then, you have just got a bunch of scientist wannabees that are only known for sweeping problems
TomWould you consider an electric glider powered by LiFe cells safe enough?
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation" https://sites.google.com/site/motorgliders/publications
On Wednesday, November 9, 2022 at 8:12:40 AM UTC-8, Eric Greenwell wrote:problems not easily, but vastly, exceed those levels. The technology simply is not ready for aircraft use.
On 11/8/2022 9:06 PM, 2G wrote:
On Tuesday, November 8, 2022 at 11:33:02 AM UTC-8, Eric Greenwell wrote:
On 11/7/2022 6:01 PM, 2G wrote:
On Monday, November 7, 2022 at 5:21:11 AM UTC-8, Eric Greenwell wrote: >> https://sites.google.com/site/motorgliders/publications...
There is a level of risk above which the technology SHOULD NOT be used regardless of what its proponents say is acceptable. Given the stringent risk levels imposed by the FAA on aircraft systems I say it is UNQUESTIONED that lithium battery
under the rug.90 miles north of you, the US LAK dealer has sold electric gliders for years; meanwhile,
Tom
EASA certifies egliders, manufacturers build them, pilots buy and fly them. UNQUESTIONED
left the building a long time ago.
"I am only trying to offer OBJECTIVE scientific data (not opinion as you say) on the risks
of lithium batteries", but you are not meeting your own standards: "There is a level of
risk above which the technology SHOULD NOT be used..." is not a scientific fact, but your
judgement. Stick to the data, and your remarks will be better received. >> --
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
Eric, then come up with ONE peer-reviewed scientific paper that says the dendrite growth problem in lithium batteries has BEEN SOLVED. Just ONE. Until then, you have just got a bunch of scientist wannabees that are only known for sweeping problems
dense, making them marginal for use as an eglider.I will take that as you can't even find ONE scientific paper that says the dendrite problem has been solved. LFP cells are just less likely to catch fire than other lithium chemistries - not a ringing endorsement. They are also considerably less energyTomWould you consider an electric glider powered by LiFe cells safe enough? --
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation" https://sites.google.com/site/motorgliders/publications
TomSolved in mass sale batteries?, no. But a much better understanding on the lab scale (as published spring 2021 from multiple sources) of dendrite formation and prevention.
under the rug.Eric, then come up with ONE peer-reviewed scientific paper that says the dendrite growth problem in lithium batteries has BEEN SOLVED. Just ONE. Until then, you have just got a bunch of scientist wannabees that are only known for sweeping problems
dense, making them marginal for use as an eglider.Would you consider an electric glider powered by LiFe cells safe enough?
Tom
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
I will take that as you can't even find ONE scientific paper that says the dendrite problem has been solved. LFP cells are just less likely to catch fire than other lithium chemistries - not a ringing endorsement. They are also considerably less energy
TomI haven't looked for a paper that asserts anything about dendrites, because I don't think
On 11/9/2022 4:51 PM, 2G wrote:under the rug.
Eric, then come up with ONE peer-reviewed scientific paper that says the dendrite growth problem in lithium batteries has BEEN SOLVED. Just ONE. Until then, you have just got a bunch of scientist wannabees that are only known for sweeping problems
energy dense, making them marginal for use as an eglider.Would you consider an electric glider powered by LiFe cells safe enough? >> --
Tom
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
I will take that as you can't even find ONE scientific paper that says the dendrite problem has been solved. LFP cells are just less likely to catch fire than other lithium chemistries - not a ringing endorsement. They are also considerably less
TomI haven't looked for a paper that asserts anything about dendrites, because I don't think
it's information I need.
I am still curious about this: Would you consider an electric glider powered by LiFe cells
safe enough? You already use at least one Life battery in your glider, so it occurred to
me they might be acceptable for propelling a glider.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation" https://sites.google.com/site/motorgliders/publications
On Wednesday, November 9, 2022 at 8:26:03 PM UTC-8, Eric Greenwell wrote:under the rug.
On 11/9/2022 4:51 PM, 2G wrote:
Eric, then come up with ONE peer-reviewed scientific paper that says the dendrite growth problem in lithium batteries has BEEN SOLVED. Just ONE. Until then, you have just got a bunch of scientist wannabees that are only known for sweeping problems
energy dense, making them marginal for use as an eglider.Would you consider an electric glider powered by LiFe cells safe enough? >>>> --
Tom
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
I will take that as you can't even find ONE scientific paper that says the dendrite problem has been solved. LFP cells are just less likely to catch fire than other lithium chemistries - not a ringing endorsement. They are also considerably less
Your answers were plain, but you didn't answer the question either time: Would youI haven't looked for a paper that asserts anything about dendrites, because I don't think
Tom
it's information I need.
I am still curious about this: Would you consider an electric glider powered by LiFe cells
safe enough? You already use at least one Life battery in your glider, so it occurred to
me they might be acceptable for propelling a glider.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
I am curious why YOU asked for more scientific information on a subject that you didn't need.
I thought my answer was plain enough, but let me state it this way: at this time I don't consider ANY electric glider to be safe, at least by aviation standards.
Tom
The packs are better but still not all glider-pilot proof.
We also discussed means of tracking abuse and the pack
disabling itself (drop it on the pavement and it shuts off
permanently). Not currently in certification requirements!
Some of us enthusiasts are also healthy skeptics and engineers
and live in the real world. And try to improve it.
On 11/9/2022 9:27 PM, 2G wrote:problems under the rug.
On Wednesday, November 9, 2022 at 8:26:03 PM UTC-8, Eric Greenwell wrote:
On 11/9/2022 4:51 PM, 2G wrote:
Eric, then come up with ONE peer-reviewed scientific paper that says the dendrite growth problem in lithium batteries has BEEN SOLVED. Just ONE. Until then, you have just got a bunch of scientist wannabees that are only known for sweeping
energy dense, making them marginal for use as an eglider.Would you consider an electric glider powered by LiFe cells safe enough?
Tom
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
I will take that as you can't even find ONE scientific paper that says the dendrite problem has been solved. LFP cells are just less likely to catch fire than other lithium chemistries - not a ringing endorsement. They are also considerably less
I haven't looked for a paper that asserts anything about dendrites, because I don't think
Tom
it's information I need.
I am still curious about this: Would you consider an electric glider powered by LiFe cells
safe enough? You already use at least one Life battery in your glider, so it occurred to
me they might be acceptable for propelling a glider.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
I am curious why YOU asked for more scientific information on a subject that you didn't need.
I thought my answer was plain enough, but let me state it this way: at this time I don't consider ANY electric glider to be safe, at least by aviation standards.
TomYour answers were plain, but you didn't answer the question either time: Would you
consider an electric glider powered by LiFe cells to be safe enough?
I asked for more evidence about vibration induced problems the Taurus might have suffered,
not specifically scientific evidence. That knowledge might actually be of value to me and
others, as handling the batteries is up to the pilot. I did not ask for evidence on
dendrites, as there is nothing I can do about them.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation" https://sites.google.com/site/motorgliders/publications
On 11/7/22 6:42 AM, Dave Nadler wrote:
The packs are better but still not all glider-pilot proof.
We also discussed means of tracking abuse and the pack
disabling itself (drop it on the pavement and it shuts off
permanently). Not currently in certification requirements!
Some of us enthusiasts are also healthy skeptics and engineers
and live in the real world. And try to improve it.
Some things just can't be solved with technology. I keep remembering how a large
percentage of the FES battery packs were shipped back to the factory fully charged, even
after explicit instructions not to do that (and after three fires!). Seems like some
people just haven't gotten the word yet that storing lithium batteries fully charged
stresses them and encourages the dendrite formation. The Electro Taurus pilot was known
to store his batteries fully charged, but that appears to be uncommon practice.
My cell phone is smart enough to not charge the battery fully until just before I
typically get up in the morning. Doing something similar for electric gliders is a much
tougher problem.
On 11/9/2022 9:27 PM, 2G wrote:problems under the rug.
On Wednesday, November 9, 2022 at 8:26:03 PM UTC-8, Eric Greenwell wrote:
On 11/9/2022 4:51 PM, 2G wrote:
Eric, then come up with ONE peer-reviewed scientific paper that says the dendrite growth problem in lithium batteries has BEEN SOLVED. Just ONE. Until then, you have just got a bunch of scientist wannabees that are only known for sweeping
energy dense, making them marginal for use as an eglider.Would you consider an electric glider powered by LiFe cells safe enough?
Tom
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
I will take that as you can't even find ONE scientific paper that says the dendrite problem has been solved. LFP cells are just less likely to catch fire than other lithium chemistries - not a ringing endorsement. They are also considerably less
I haven't looked for a paper that asserts anything about dendrites, because I don't think
Tom
it's information I need.
I am still curious about this: Would you consider an electric glider powered by LiFe cells
safe enough? You already use at least one Life battery in your glider, so it occurred to
me they might be acceptable for propelling a glider.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
I am curious why YOU asked for more scientific information on a subject that you didn't need.
I thought my answer was plain enough, but let me state it this way: at this time I don't consider ANY electric glider to be safe, at least by aviation standards.
TomYour answers were plain, but you didn't answer the question either time: Would you
consider an electric glider powered by LiFe cells to be safe enough?
I asked for more evidence about vibration induced problems the Taurus might have suffered,
not specifically scientific evidence. That knowledge might actually be of value to me and
others, as handling the batteries is up to the pilot. I did not ask for evidence on
dendrites, as there is nothing I can do about them.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation" https://sites.google.com/site/motorgliders/publications
On Thursday, November 10, 2022 at 10:43:10 AM UTC-5, Eric Greenwell wrote:problems under the rug.
On 11/9/2022 9:27 PM, 2G wrote:
On Wednesday, November 9, 2022 at 8:26:03 PM UTC-8, Eric Greenwell wrote:
On 11/9/2022 4:51 PM, 2G wrote:
Eric, then come up with ONE peer-reviewed scientific paper that says the dendrite growth problem in lithium batteries has BEEN SOLVED. Just ONE. Until then, you have just got a bunch of scientist wannabees that are only known for sweeping
energy dense, making them marginal for use as an eglider.Would you consider an electric glider powered by LiFe cells safe enough?
Tom
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
I will take that as you can't even find ONE scientific paper that says the dendrite problem has been solved. LFP cells are just less likely to catch fire than other lithium chemistries - not a ringing endorsement. They are also considerably less
chargers that charge at a high rate, and then cut off at a point normally determined by voltage run the risk of over charging some cells before cut off to low rate which leads to early failure. Increases heat can lead to more damage. The auto people areI haven't looked for a paper that asserts anything about dendrites, because I don't think
Tom
it's information I need.
I am still curious about this: Would you consider an electric glider powered by LiFe cells
safe enough? You already use at least one Life battery in your glider, so it occurred to
me they might be acceptable for propelling a glider.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation"
https://sites.google.com/site/motorgliders/publications
I am curious why YOU asked for more scientific information on a subject that you didn't need.
I thought my answer was plain enough, but let me state it this way: at this time I don't consider ANY electric glider to be safe, at least by aviation standards.
TomYour answers were plain, but you didn't answer the question either time: Would you
consider an electric glider powered by LiFe cells to be safe enough?
I asked for more evidence about vibration induced problems the Taurus might have suffered,Interesting to challenge 2G m knowledge base which seems to be fairly extensive but selective in interpretation.
not specifically scientific evidence. That knowledge might actually be of value to me and
others, as handling the batteries is up to the pilot. I did not ask for evidence on
dendrites, as there is nothing I can do about them.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation" https://sites.google.com/site/motorgliders/publications
From my investigation I concluded that LiFe cells are not suitable due to low available max discharge rates. The number of cells needed in parallel would be impractical.
Studying available info shows that cell life varies a lot but it is most strongly affected by 3 parameters.
1- How fast is the charge. Fast charge is associated with heating but also significantly increases the rate of dendrite growth which leads to degraded capacity as well as increased internal resistance that reduces current supplying capability. "Fast"
2- Over charge- forcing maximum charge stresses weaker cells more and adds heat. It also accelerates dendrite growth.dropping would probably be to connections. I highly doubt it would hurt individual cells. I wonder how many phones that have have Lipo batteries and caught fire had been dropped.
3- High high a discharge rate. Higher rates lead to more heating and also promote faster dendrite growth affecting life expectancy. It also stresses the weaker cells more.
Generally it can be reasonably said that dendrite growth is more about life of cells than safety.
Safety can be enhanced a lot by:
1- Charge at low rate . I charge my glider battery at 3 amps maximum. My BMS will dissipate all of that as end of charge is reached.
2- Don't charge to max possible voltage. This stresses cells less by not over charging. In my case this sacrifices about 15% of theoretical possible capacity.
3- Discharge well below manufacturer's data sheet rate. My cells are rated at 25 amps and my max rate is 14 amps for 2 minutes, then about 9 amps after that. I never see a meaningful rise in battery pack temperature.
4- Don't over discharge. I limit to about 20% remaining.
5 Don't drop the damn things. At least one of the FES battery failures was associated with mechanical damage due to dropping. FES ships all now get special carrying boxes to protect batteries when not in the ship. In my battery the likely damage from
6- Choice in battery construction. My opinion here- Lion cylindrical(18650 "laptop" style) can be expected to be much more durable than the Lipo pouch type cells. They are simply more robust. That said they are more energy dense per pound and have alot fewer connections to fail. With about 250 sailplanes currently using the Lipo batteries, they far outnumber the ones in use that have Lion cells.
7- Isolate the battery from the flight crew and vent it. My 24EL has a full fire wall, barrier surfaces in the motor bay, and operates with the motor bay doors open. Our ASH25 does not have a fire wall because it is physically not possible to do so.
FWIW- ready for incoming.
UH
Our club is kicking around the idea of buying a Pipistrel Electro 2.5 to supplement our current training ships (L23, K21 and Grob Twin), one of which would probably be sold. Preliminary impressions are pretty favorable. I'm looking for any first-handexperience anyone may have with this particular glider. Thanks in advance.
MikeReturning to the original question.
The fact that the rate and level of charging of lithium batteries affects their longevity and, more importantly, their safety puts them into a separate class altogether from any other propulsion source. I can fill my gas tank at any rate and to anylevel and not have to worry about it catching fire. I can also drain it completely, also without any concern. I can also run the engine at idle or at full power without concern that it will catch fire. Lithium propulsion batteries are JUST NOT ready for
Tom
On 11/10/2022 8:56 PM, 2G wrote:level and not have to worry about it catching fire. I can also drain it completely, also without any concern. I can also run the engine at idle or at full power without concern that it will catch fire. Lithium propulsion batteries are JUST NOT ready for
...
The fact that the rate and level of charging of lithium batteries affects their longevity and, more importantly, their safety puts them into a separate class altogether from any other propulsion source. I can fill my gas tank at any rate and to any
TomGasoline fueled aircraft can leak fuel, which can be ignited and cause a fire. Fuel stored
in hangars has also caused fires. An ASH26E, the predecessor to your ASH31Mi, caught fire
in flight while under power, due to a faulty muffler (miraculously, no injury). Airplane
pilots have died from carbon monoxide poisoning, something electric power avoids. The
vibration from gasoline engines can cause failures as parts crack or break.
Every propulsion system has potential problems. We work to learn to the correct use of
each one, the manufacturers work to make their system easier and safer, and at some point,
each pilot decides the gliders (gas, jet, electric, towed, winched) offered are safe
enough for them, buys one, and flies it.
--
Eric Greenwell - USA
- "A Guide to Self-launching Sailplane Operation" https://sites.google.com/site/motorgliders/publications
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