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Battery safety (againish)



 
 
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  #11  
Old March 18th 19, 04:54 AM posted to rec.aviation.soaring
Eric Greenwell[_4_]
external usenet poster
 
Posts: 1,939
Default Battery safety (againish)

kinsell wrote on 3/16/2019 9:46 PM:


Many of us are flying with multi-cell LiFePO4 batteries that have internal
wiring and are not filled with resin.* Is that a problem?* Or is the location of
the batteries in this specific glider such that the resin is advisable?* A
battery fire anywhere in a glider (even without a fuel tank) is catastrophic.
OTOH I havn't heard of any fires with this type of battery.* It's the
lithium-polymer battery pack (also much larger, with many more cells) in the FES
systems that has had fires.


Well, the service bulletin talks about an LFP that burned.* There was a fire in an
EB-28 in Finland last year with a 10 A-H LFP.* Here's a video of an LFP burning:

https://www.pilotsofamerica.com/comm...-fires.102016/


There have been claims that LFP's don't burn, but that's simply not true.


The Aerovoltz battery that burned did not have a BMS; in fact, none of the
Aerovoltz batteries have a BMS (battery management system). I would not want to
use one, even though the short engine runs typical of self-launchers means
problems would be less likely than in airplanes. The Earth-X batteries all have a
BMS, seem better characterized, and I would trust them a lot more.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1
- "Transponders in Sailplanes - Dec 2014a" also ADS-B, PCAS, Flarm

http://soaringsafety.org/prevention/...anes-2014A.pdf

  #12  
Old March 18th 19, 04:22 PM posted to rec.aviation.soaring
Dan Marotta
external usenet poster
 
Posts: 4,601
Default Battery safety (againish)

I used LiFePO4 batteries in my former LAK-17a for about 3 years before
selling the glider.Â* I charged them out of the glider for the first year
and, thereafter, left them on the provided smart chargers in the glider
between flights.Â* They had battery management systems built-in.Â* Of
course, there's practically no vibration in a pure glider...

On 3/17/2019 9:54 PM, Eric Greenwell wrote:
kinsell wrote on 3/16/2019 9:46 PM:


Many of us are flying with multi-cell LiFePO4 batteries that have
internal wiring and are not filled with resin.Â* Is that a problem?Â*
Or is the location of the batteries in this specific glider such
that the resin is advisable?Â* A battery fire anywhere in a glider
(even without a fuel tank) is catastrophic.Â* OTOH I havn't heard of
any fires with this type of battery.Â* It's the lithium-polymer
battery pack (also much larger, with many more cells) in the FES
systems that has had fires.


Well, the service bulletin talks about an LFP that burned. There was
a fire in an EB-28 in Finland last year with a 10 A-H LFP.Â* Here's a
video of an LFP burning:

https://www.pilotsofamerica.com/comm...-fires.102016/


There have been claims that LFP's don't burn, but that's simply not
true.


The Aerovoltz battery that burned did not have a BMS; in fact, none of
the Aerovoltz batteries have a BMS (battery management system). I
would not want to use one, even though the short engine runs typical
of self-launchers means problems would be less likely than in
airplanes. The Earth-X batteries all have a BMS, seem better
characterized, and I would trust them a lot more.


--
Dan, 5J
  #13  
Old March 19th 19, 08:16 PM posted to rec.aviation.soaring
2G
external usenet poster
 
Posts: 1,439
Default Battery safety (againish)

On Monday, March 18, 2019 at 8:22:43 AM UTC-7, Dan Marotta wrote:
I used LiFePO4 batteries in my former LAK-17a for about 3 years before
selling the glider.Â* I charged them out of the glider for the first year
and, thereafter, left them on the provided smart chargers in the glider
between flights.Â* They had battery management systems built-in.Â* Of
course, there's practically no vibration in a pure glider...

On 3/17/2019 9:54 PM, Eric Greenwell wrote:
kinsell wrote on 3/16/2019 9:46 PM:


Many of us are flying with multi-cell LiFePO4 batteries that have
internal wiring and are not filled with resin.Â* Is that a problem?Â*
Or is the location of the batteries in this specific glider such
that the resin is advisable?Â* A battery fire anywhere in a glider
(even without a fuel tank) is catastrophic.Â* OTOH I havn't heard of
any fires with this type of battery.Â* It's the lithium-polymer
battery pack (also much larger, with many more cells) in the FES
systems that has had fires.


Well, the service bulletin talks about an LFP that burned. There was
a fire in an EB-28 in Finland last year with a 10 A-H LFP.Â* Here's a
video of an LFP burning:

https://www.pilotsofamerica.com/comm...-fires.102016/


There have been claims that LFP's don't burn, but that's simply not
true.


The Aerovoltz battery that burned did not have a BMS; in fact, none of
the Aerovoltz batteries have a BMS (battery management system). I
would not want to use one, even though the short engine runs typical
of self-launchers means problems would be less likely than in
airplanes. The Earth-X batteries all have a BMS, seem better
characterized, and I would trust them a lot more.


--
Dan, 5J


Of all of the articles and papers I have read on rechargeable batteries, this is the first one that talked about modifying the internal construction of the battery. The mere idea of drilling into a battery scares the hell out of me, and I bet it would do the same to the manufacturer.

Tom
  #14  
Old March 19th 19, 10:27 PM posted to rec.aviation.soaring
SF
external usenet poster
 
Posts: 214
Default Battery safety (againish)

I cut one of my K2 batteries open, after one of the cells in it failed. There's not a lot of space available in there for foam, or drill bits.

-nick one of the cells with a drill and it's going to be bad.
-Equal foam filling is unlikely
-Good possibility of the foam compressing the cells or expanding the case.
-The foam is going to interfere with heat dissipation in a big way, its a pretty good insulator.
-When chasing vibration issues, sometimes tightening up the system makes things worse not better.
-LiFePO batteries don't supply their own oxidizer in a fire, No one ever said they wouldn't catch on fire. Just if they do, they can be put out by depriving them of oxygen. Unlike Lithium ion chemistry batteries which supply their own oxidizer if they catch on fire. So the LiFePO batteries are considered to be a safer battery chemistry, but not a completely safe battery.. A plastic box full of lead plates submerged in sulfuric acid isn't completely safe either.

A LiFePO battery(s) with an internal BMS board, with a fuse right at the battery is the way to go, but treat it with the respect that that much energy stored in a small package deserves.

SF
  #15  
Old March 19th 19, 11:53 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 114
Default Battery safety (againish)

On Saturday, March 16, 2019 at 7:23:21 PM UTC-7, Jonathan St. Cloud wrote:
On Saturday, March 16, 2019 at 4:35:22 PM UTC-7, kinsell wrote:
On 3/16/19 1:10 PM, Andrzej Kobus wrote:
On Saturday, March 16, 2019 at 1:04:19 PM UTC-4, kinsell wrote:
On 3/16/19 10:05 AM, Jonathan St. Cloud wrote:
Was wondering if others had read and were doing this:
https://www.dg-flugzeugbau.de/wp-con...2019-103-e.pdf

The ASG-29E has a gas tank directly above two batteries used to power flight instruments.


Interesting that they say to add epoxy to the casing. Putting a fuse at
one of the battery terminals would be a more conventional way of
handling it, and would allow for easier battery replacement.

You are missing the point. The fuse will not protect against internal short.


No, not missing the point. The way I read it, they're talking about an
battery holder added around the battery. You wouldn't normally call
internal wiring "battery cables". Maybe something got lost in translation.

If anybody is using a battery so poorly constructed that it shorts out
internally and catches fire, that battery should be discarded immediately.


The way I read it is a small hole is drilled in the case and resin injected...?


No. Bulletin is suggesting all work is done by the battery manufacturer(Accu-24).
  #16  
Old March 20th 19, 06:03 AM posted to rec.aviation.soaring
kinsell
external usenet poster
 
Posts: 546
Default Battery safety (againish)

On 3/17/19 9:54 PM, Eric Greenwell wrote:
kinsell wrote on 3/16/2019 9:46 PM:


Many of us are flying with multi-cell LiFePO4 batteries that have
internal wiring and are not filled with resin.Â* Is that a problem?
Or is the location of the batteries in this specific glider such that
the resin is advisable?Â* A battery fire anywhere in a glider (even
without a fuel tank) is catastrophic. OTOH I havn't heard of any
fires with this type of battery.Â* It's the lithium-polymer battery
pack (also much larger, with many more cells) in the FES systems that
has had fires.


Well, the service bulletin talks about an LFP that burned.Â* There was
a fire in an EB-28 in Finland last year with a 10 A-H LFP.Â* Here's a
video of an LFP burning:

https://www.pilotsofamerica.com/comm...-fires.102016/


There have been claims that LFP's don't burn, but that's simply not true.


The Aerovoltz battery that burned did not have a BMS; in fact, none of
the Aerovoltz batteries have a BMS (battery management system). I would
not want to use one, even though the short engine runs typical of
self-launchers means problems would be less likely than in airplanes.
The Earth-X batteries all have a BMS, seem better characterized, and I
would trust them a lot more.


Yes, EarthX is well regarded in the homebuilt powerplane world. Dual
redundant BMS boards to make you feel good. Here's a greatpicture of one:

http://www.avidfoxflyers.com/index.p...ttery-warning/

If you poke around, there's a nice video from the Director of
Engineering at EarthX, he talks about the requirement to have a
gas-tight battery box vented to the outside, to use only a three-phase
alternator to charge it, and to add a crowbar circuit to prevent
over-voltage. Wonder how many glider pilots go to all this trouble?

I think I'll stick to SLA, just press the button and the engine starts
in about a second.


-Dave

P.S. That StewartB in the original thread was a real hoot. Said he
worried more about getting mad cow disease than having trouble with his
EarthX battery. Until his battery went bad. Don't know if he still
eats hamburgers or not.


  #17  
Old March 23rd 19, 03:23 AM posted to rec.aviation.soaring
2G
external usenet poster
 
Posts: 1,439
Default Battery safety (againish)

On Tuesday, March 19, 2019 at 10:04:00 PM UTC-7, kinsell wrote:
On 3/17/19 9:54 PM, Eric Greenwell wrote:
kinsell wrote on 3/16/2019 9:46 PM:


Many of us are flying with multi-cell LiFePO4 batteries that have
internal wiring and are not filled with resin.Â* Is that a problem?
Or is the location of the batteries in this specific glider such that
the resin is advisable?Â* A battery fire anywhere in a glider (even
without a fuel tank) is catastrophic. OTOH I havn't heard of any
fires with this type of battery.Â* It's the lithium-polymer battery
pack (also much larger, with many more cells) in the FES systems that
has had fires.


Well, the service bulletin talks about an LFP that burned.Â* There was
a fire in an EB-28 in Finland last year with a 10 A-H LFP.Â* Here's a
video of an LFP burning:

https://www.pilotsofamerica.com/comm...-fires.102016/


There have been claims that LFP's don't burn, but that's simply not true.


The Aerovoltz battery that burned did not have a BMS; in fact, none of
the Aerovoltz batteries have a BMS (battery management system). I would
not want to use one, even though the short engine runs typical of
self-launchers means problems would be less likely than in airplanes.
The Earth-X batteries all have a BMS, seem better characterized, and I
would trust them a lot more.


Yes, EarthX is well regarded in the homebuilt powerplane world. Dual
redundant BMS boards to make you feel good. Here's a greatpicture of one:

http://www.avidfoxflyers.com/index.p...ttery-warning/

If you poke around, there's a nice video from the Director of
Engineering at EarthX, he talks about the requirement to have a
gas-tight battery box vented to the outside, to use only a three-phase
alternator to charge it, and to add a crowbar circuit to prevent
over-voltage. Wonder how many glider pilots go to all this trouble?

I think I'll stick to SLA, just press the button and the engine starts
in about a second.


-Dave

P.S. That StewartB in the original thread was a real hoot. Said he
worried more about getting mad cow disease than having trouble with his
EarthX battery. Until his battery went bad. Don't know if he still
eats hamburgers or not.


Dave,

Perhaps you could post a link to this video - I could not find it. To the contrary, the video I could find extolled the safety of their batteries in aircraft:
https://earthxbatteries.com/product-...ental-aircraft
  #18  
Old March 23rd 19, 05:23 AM posted to rec.aviation.soaring
kinsell
external usenet poster
 
Posts: 546
Default Battery safety (againish)

On 3/22/19 8:23 PM, 2G wrote:
On Tuesday, March 19, 2019 at 10:04:00 PM UTC-7, kinsell wrote:
On 3/17/19 9:54 PM, Eric Greenwell wrote:
kinsell wrote on 3/16/2019 9:46 PM:


Many of us are flying with multi-cell LiFePO4 batteries that have
internal wiring and are not filled with resin.Â* Is that a problem?
Or is the location of the batteries in this specific glider such that
the resin is advisable?Â* A battery fire anywhere in a glider (even
without a fuel tank) is catastrophic. OTOH I havn't heard of any
fires with this type of battery.Â* It's the lithium-polymer battery
pack (also much larger, with many more cells) in the FES systems that
has had fires.


Well, the service bulletin talks about an LFP that burned.Â* There was
a fire in an EB-28 in Finland last year with a 10 A-H LFP.Â* Here's a
video of an LFP burning:

https://www.pilotsofamerica.com/comm...-fires.102016/


There have been claims that LFP's don't burn, but that's simply not true.

The Aerovoltz battery that burned did not have a BMS; in fact, none of
the Aerovoltz batteries have a BMS (battery management system). I would
not want to use one, even though the short engine runs typical of
self-launchers means problems would be less likely than in airplanes.
The Earth-X batteries all have a BMS, seem better characterized, and I
would trust them a lot more.


Yes, EarthX is well regarded in the homebuilt powerplane world. Dual
redundant BMS boards to make you feel good. Here's a greatpicture of one:

http://www.avidfoxflyers.com/index.p...ttery-warning/

If you poke around, there's a nice video from the Director of
Engineering at EarthX, he talks about the requirement to have a
gas-tight battery box vented to the outside, to use only a three-phase
alternator to charge it, and to add a crowbar circuit to prevent
over-voltage. Wonder how many glider pilots go to all this trouble?

I think I'll stick to SLA, just press the button and the engine starts
in about a second.


-Dave

P.S. That StewartB in the original thread was a real hoot. Said he
worried more about getting mad cow disease than having trouble with his
EarthX battery. Until his battery went bad. Don't know if he still
eats hamburgers or not.


Dave,

Perhaps you could post a link to this video - I could not find it. To the contrary, the video I could find extolled the safety of their batteries in aircraft:
https://earthxbatteries.com/product-...ental-aircraft


That video was in an EAA seminar:

http://go.eaa.org/UVqR00U0BE0SOs03oK000hV


Some good info on charging systems he

https://earthxbatteries.com/engine-c...hium-batteries



  #19  
Old March 23rd 19, 06:23 AM posted to rec.aviation.soaring
2G
external usenet poster
 
Posts: 1,439
Default Battery safety (againish)

On Friday, March 22, 2019 at 9:23:17 PM UTC-7, kinsell wrote:
On 3/22/19 8:23 PM, 2G wrote:
On Tuesday, March 19, 2019 at 10:04:00 PM UTC-7, kinsell wrote:
On 3/17/19 9:54 PM, Eric Greenwell wrote:
kinsell wrote on 3/16/2019 9:46 PM:


Many of us are flying with multi-cell LiFePO4 batteries that have
internal wiring and are not filled with resin.Â* Is that a problem?
Or is the location of the batteries in this specific glider such that
the resin is advisable?Â* A battery fire anywhere in a glider (even
without a fuel tank) is catastrophic. OTOH I havn't heard of any
fires with this type of battery.Â* It's the lithium-polymer battery
pack (also much larger, with many more cells) in the FES systems that
has had fires.


Well, the service bulletin talks about an LFP that burned.Â* There was
a fire in an EB-28 in Finland last year with a 10 A-H LFP.Â* Here's a
video of an LFP burning:

https://www.pilotsofamerica.com/comm...-fires.102016/


There have been claims that LFP's don't burn, but that's simply not true.

The Aerovoltz battery that burned did not have a BMS; in fact, none of
the Aerovoltz batteries have a BMS (battery management system). I would
not want to use one, even though the short engine runs typical of
self-launchers means problems would be less likely than in airplanes.
The Earth-X batteries all have a BMS, seem better characterized, and I
would trust them a lot more.


Yes, EarthX is well regarded in the homebuilt powerplane world. Dual
redundant BMS boards to make you feel good. Here's a greatpicture of one:

http://www.avidfoxflyers.com/index.p...ttery-warning/

If you poke around, there's a nice video from the Director of
Engineering at EarthX, he talks about the requirement to have a
gas-tight battery box vented to the outside, to use only a three-phase
alternator to charge it, and to add a crowbar circuit to prevent
over-voltage. Wonder how many glider pilots go to all this trouble?

I think I'll stick to SLA, just press the button and the engine starts
in about a second.


-Dave

P.S. That StewartB in the original thread was a real hoot. Said he
worried more about getting mad cow disease than having trouble with his
EarthX battery. Until his battery went bad. Don't know if he still
eats hamburgers or not.


Dave,

Perhaps you could post a link to this video - I could not find it. To the contrary, the video I could find extolled the safety of their batteries in aircraft:
https://earthxbatteries.com/product-...ental-aircraft


That video was in an EAA seminar:

http://go.eaa.org/UVqR00U0BE0SOs03oK000hV


Some good info on charging systems he

https://earthxbatteries.com/engine-c...hium-batteries


I am confused, is EarthX saying you have to enclose your lithium battery in a sealed box or not? If so, then why don't they say so on their website?
  #20  
Old March 23rd 19, 03:29 PM posted to rec.aviation.soaring
[email protected]
external usenet poster
 
Posts: 465
Default Battery safety (againish)

On Saturday, March 23, 2019 at 12:23:17 AM UTC-4, kinsell wrote:
On 3/22/19 8:23 PM, 2G wrote:
On Tuesday, March 19, 2019 at 10:04:00 PM UTC-7, kinsell wrote:
On 3/17/19 9:54 PM, Eric Greenwell wrote:
kinsell wrote on 3/16/2019 9:46 PM:


Many of us are flying with multi-cell LiFePO4 batteries that have
internal wiring and are not filled with resin.Â* Is that a problem?
Or is the location of the batteries in this specific glider such that
the resin is advisable?Â* A battery fire anywhere in a glider (even
without a fuel tank) is catastrophic. OTOH I havn't heard of any
fires with this type of battery.Â* It's the lithium-polymer battery
pack (also much larger, with many more cells) in the FES systems that
has had fires.


Well, the service bulletin talks about an LFP that burned.Â* There was
a fire in an EB-28 in Finland last year with a 10 A-H LFP.Â* Here's a
video of an LFP burning:

https://www.pilotsofamerica.com/comm...-fires.102016/


There have been claims that LFP's don't burn, but that's simply not true.

The Aerovoltz battery that burned did not have a BMS; in fact, none of
the Aerovoltz batteries have a BMS (battery management system). I would
not want to use one, even though the short engine runs typical of
self-launchers means problems would be less likely than in airplanes.
The Earth-X batteries all have a BMS, seem better characterized, and I
would trust them a lot more.


Yes, EarthX is well regarded in the homebuilt powerplane world. Dual
redundant BMS boards to make you feel good. Here's a greatpicture of one:

http://www.avidfoxflyers.com/index.p...ttery-warning/

If you poke around, there's a nice video from the Director of
Engineering at EarthX, he talks about the requirement to have a
gas-tight battery box vented to the outside, to use only a three-phase
alternator to charge it, and to add a crowbar circuit to prevent
over-voltage. Wonder how many glider pilots go to all this trouble?

I think I'll stick to SLA, just press the button and the engine starts
in about a second.


-Dave

P.S. That StewartB in the original thread was a real hoot. Said he
worried more about getting mad cow disease than having trouble with his
EarthX battery. Until his battery went bad. Don't know if he still
eats hamburgers or not.


Dave,

Perhaps you could post a link to this video - I could not find it. To the contrary, the video I could find extolled the safety of their batteries in aircraft:
https://earthxbatteries.com/product-...ental-aircraft


That video was in an EAA seminar:

http://go.eaa.org/UVqR00U0BE0SOs03oK000hV


Some good info on charging systems he

https://earthxbatteries.com/engine-c...hium-batteries


I'm not convinced that earthx page offers "good info". There are many obviously false statements. E.g., oxidation actually uses up oxygen, rather than create free oxygen. And generator coils do not always put out the same amount of power at a given RPM - disconnect the output and the power will be zero. Most importantly for our discussion here, their claims about what causes overheating of the battery during charging are not convincing, and I'd look for evidence elsewhere.
 




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