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Is the 787 a failure ?



 
 
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  #211  
Old March 22nd 13, 10:02 PM posted to rec.aviation.piloting,rec.crafts.metalworking,rec.aviation.military,talk.politics.misc,alt.society.labor-unions
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Posts: 155
Default Is the 787 a failure ?

On Fri, 22 Mar 2013 16:57:55 -0000, "Keith W"
wrote:

GunnerAsch wrote:
On Fri, 22 Mar 2013 12:40:50 -0000, "Keith W"
wrote:

GunnerAsch wrote:
On Fri, 22 Mar 2013 09:23:17 -0000, "Keith W"
wrote:


The conventional Batteries are sometimes called Sealed Lead Acid
Batteries but they are actually AGM batteries.

Modern passenger aircraft normally use Nickel Cadmium batteries

Why havent they converted over to NmH?

They have a relatively high self discharge rate and can lose
up to 20% of the energy stored in the first 24 hours. This is
acceptable for hybrid vehicles where the battery is primarily a
temporary buffer to capture the energy from regenerative
braking but not good for a system intended to initiate an
aircraft startup sequence after a week in the hangar.

Keith

Thats not true anymore. Since Sanyo developed the Enerloop NiMH
battery..they are being shipped charged from the factories. All the
makers are using the new tech and have been doing so for at least 3
yrs. Ive got NiMH batteries that I only need to put on the charger
ever 6 months, just to top them off.

Gunner


Trouble is they are not available in the size or capacity to be used
in an electric vehicle, last time I checked the largest was a D size.

Keith

Oh, they are available a lot bigger than that. Just not readily
available to the public.

From the mpoweruk site:

Unlike the consumer applications where NiMH has been almost completely
replaced by Lithium ion, NiMH chemistry is still finding use in
automotive applications where it is the technology of choice for
powering HEVs and where it has accumulated over 10 years of trouble
free service and can thus last for the lifetime of the car. The
operating temperature range for NiMH cells has been extended to over
100 °C (-30 °C to + 75 °C) which far exceeds the temperature range
currently achievable by Lithium cells making NiMH technology ideal for
automotive use. NiMH can handle the high power levels typical in EV
applications, the active chemicals are inherently safer than Lithium
based cells and NiMH batteries don't need the complex battery
management systems (BMS) essential with Lithium batteries.

Early cells were susceptible to memory effect and also suffered from
high self discharge, nearly ten times worse than Lead acid or Lithium
batteries, but both of these weaknesses have been overcome and it is
claimed that the most recent cells can hold their charge for a year.


Advantages
High energy density (W/kg), about 50% better than Nicads, but only
about 60% of Lithium ion.

Low internal impedance though not as low as NiCads

Typical cycle life is 3000 cycles.

Can be deep cycled. (80% to 100% DOD)

Using NiMH batteries, more than 3000 cycles at 100 % Depth of
Discharge (DOD) have been demonstrated. At lower depths of discharge,
for example at 4 % DOD, more than 350.000 cycles can be expected.

Robust - NiMH batteries also tolerate over charge and over discharge
conditions and this simplifies the battery management requirements.

Flat discharge characteristic (but falls off rapidly at the end of the
cycle)
Wide operating temperature range

Rapid charge possible in 1 hour

Trickle charging can not normally be used with NiMH batteries since
overcharging can cause deterioration of the battery. Chargers should
therefore incorporate a timer to prevent overcharging.

Because of potential pressure build up due to gassing they usually
incorporate a re-sealable vent valve

Reconditioning is possible.

Environmentally friendly (No Cadmium, Mercury or Lead)

Much safer than Lithium based cells in case of an accident or abuse
due to the use of more benign active chemicals, a particularly
important property in high power and automotive applications.



Shortcomings
High self discharge rate.

Can be stored indefinitely either fully charged or fully discharged.

Suffers from memory effect though not as pronounced as with NiCad
batteries

Battery deteriorates during long time storage. This problem can be
solved by charging and discharging the battery several times before
reuse. This reconditioning also serves to overcome the problems of the
"memory" effect.

High rate discharge not as good as NiCads

Less tolerant of overcharging than NiCads

As with NiCads the cells must incorporate safety vents to protect the
cell in case of gas generation.

The coulombic efficiency of nickel metal hydride batteries could be up
to 85% but is typically only around 65% and diminishes the faster the
charge although this is projected to improve.

While the battery may have a high capacity it is not necessarily all
available since it may only deliver full power down to 50% DOD
depending on the application.

Cell voltage is only 1.2 Volts which means that many cells are
required to make up high voltage batteries. The competing Lithium
cells typically have 3 times the cell voltage (3.2 Volts to 3.7 Volts)
and a much higher energy density.

Lower capacity and cell voltage than alkaline primary cells.

Limited supplies of rare earth element Lanthanum. Mostly in China.





  #212  
Old March 22nd 13, 10:14 PM posted to rec.aviation.piloting,rec.crafts.metalworking,rec.aviation.military,talk.politics.misc,alt.society.labor-unions
Daryl[_2_]
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Posts: 11
Default Is the 787 a failure ?

On 3/22/2013 2:43 PM, wrote:
On Fri, 22 Mar 2013 02:55:46 -0400, Mr. B1ack
wrote:

On Fri, 22 Mar 2013 03:00:07 +0000 (UTC),
(Bradley K.
Sherman) wrote:

Who are you gonna believe, Boeing or your own lying eyes?
|
| Boeing Co. (BA)'s assertion that U.S. investigators ruled
| out a fire within the battery case of a Japan Airlines Co.
| (9201) 787 is premature, a National Transportation Safety
| Board spokesman said.
|
| Investigators examining the Jan. 7 fire aboard the
| Dreamliner in Boston haven't ruled out that flames erupted
| within the lithium-ion battery container, Peter Knudson
| said today in response to questions about the issue.
| ...
| Michael Sinnett, Boeing's chief project engineer, said in
| the briefing that investigators hadn't found evidence of
| flames within the Boston battery's container box, an
| indication it worked as designed to limit damage from a
| battery failure.
|
| A witness who tried to fight the Jan. 7 fire said he saw 3-
| inch (7.6-centimeter) flames outside the lithium-ion
| battery, and the NTSB has found evidence of high
| temperatures within battery cells that failed, according to
| preliminary safety-board documents released March 7.
| ...
http://www.businessweek.com/news/2013-03-15/ntsb-contradicts-boeing-claim-of-no-fire-in-787-battery

--bks


Gawd ... is THIS thread still going on ???????????/

Yes, the 787 is a failure.

Put it this way ... after hearing about its problems *I* will
NEVER fly on one - ever.

And I'm hardly the only one who feels this way.

Not interested in burning to death over the Pacific ....

How about driving in a ford?


Hey, watch it. I owned a 65 Mustang and my exwife owned a pinto.
Never could get her to back into anything during the divorce.

Daryl


  #213  
Old March 22nd 13, 10:16 PM posted to rec.aviation.piloting,rec.crafts.metalworking,rec.aviation.military,talk.politics.misc,alt.society.labor-unions
Daryl[_2_]
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Posts: 11
Default Is the 787 a failure ?

On 3/22/2013 2:59 PM, Jim Wilkins wrote:
wrote in message
...

VERY common problem on "A Piece of Crap" UPS systems (as well as
some
cheaper ones) but when they split they don't leak.

The acid in an AGM battery is Absorbed in the Glass Mat.
jsw



No, the Glass Matt just keeps it from sloshing around. You break open
that case and the solution will leak out post haste.

And you have NEVER seen an accidental leaking of an AGM battery. Now
just admit it.

Those that can: Do. Those that can't: Teach

Daryl


  #214  
Old March 22nd 13, 10:18 PM posted to rec.aviation.piloting,rec.crafts.metalworking,rec.aviation.military,talk.politics.misc,alt.society.labor-unions
Daryl[_2_]
external usenet poster
 
Posts: 11
Default Is the 787 a failure ?

On 3/22/2013 2:54 PM, wrote:
On Fri, 22 Mar 2013 08:07:19 -0600, Daryl
wrote:

On 3/22/2013 7:22 AM, Jim Wilkins wrote:
"Daryl" wrote in message
...
...I have never had a case break open on an AGM. Daryl

Then you haven't looked very hard.

http://nissandiesel.dyndns.org/viewt...60ab1 12d039d
"Problem: APC UPSs sometimes have a float charge voltage that is too
high and tends to cook batteries. Here's a pair of gel/AGM batteries
from a SUA1000 (not an XL) that have swollen so badly that I had to
disassemble the case and pry the batteries out of the metal cage: "


And you haven't seen a burst case either. Bulging, deformed, etc. case
but the juice is contained in the case.

DAryl


I've had them split from top to bottom on both ends - but they are a
"dry" battery. All of the liquid is absorbed in the mat - and by the
time they split they are generally baked dry anyway.


I was talking about accidentally damaging the case on a good battery.
They will leak if you puncture the case. You are right, many are
already cooked and have that ozone smell about them.

Daryl


  #215  
Old March 22nd 13, 10:23 PM posted to rec.aviation.piloting,rec.crafts.metalworking,rec.aviation.military,talk.politics.misc,alt.society.labor-unions
Daryl[_2_]
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Posts: 11
Default Is the 787 a failure ?

On 3/22/2013 3:00 PM, Jim Wilkins wrote:
"GunnerAsch" wrote in message
...

D batteries are what they use in some of the electric vehicles as I
recall. Some 300 of them

Or was it 3000?

Gunner



http://www.insightcentral.net/encycl...enbattery.html




You believe everything you read? Here is a quote from your very own Cite:

"Its operating temperature range is -30C degrees ~ +60C degrees."

I can tell you (but you won't listen) that if you operate that battery
at anywhere near 10 degree or less in F, well above the -30C rating, you
will be damaging your battery on a daily basis. This is why Tesla
includes a battery heating blanket and an Air Conditioner for it's
battery compartment. Otherwise, you have cells that are going to be
damaged until, one day, you won't be able to get to the local quick stop
and back.

Daryl


  #216  
Old March 22nd 13, 10:55 PM posted to rec.aviation.piloting,rec.crafts.metalworking,rec.aviation.military,talk.politics.misc,alt.society.labor-unions
Jim Wilkins[_2_]
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Posts: 52
Default Is the 787 a failure ?

wrote in message
...

Because they believed the air speed indicator that was lying through
it's teeth.


Or maybe they continued to doubt it after the ice cleared?

The report didn't try too hard to reconstruct what they might have
believed, beyond recounting similar incidents. The pilots do appear to
have interpreted what they saw differently and acted without
coordination. The Flight Data Recorder didn't capture all their
displays. The report mentions that pilots fly their mental perception
of the situation.

AFAICT they assumed they still had adequate speed and lift and didn't
understand why the instruments showed them rapidly descending although
they had applied full power and pulled the nose slightly up.
Apparently that aircraft just mushes down flat when it stalls. They
had trouble controlling roll but not pitch.

My guess is that they assumed from the abnormally high air temperature
in the top of the storm that there might be strong vertical air
currents and may have believed they were caught in a turbulent
downdraft. The voice recording reveals mainly confusion.
jsw


  #217  
Old March 22nd 13, 11:07 PM posted to rec.aviation.piloting,rec.crafts.metalworking,rec.aviation.military,talk.politics.misc,alt.society.labor-unions
Jim Wilkins[_2_]
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Posts: 52
Default Is the 787 a failure ?

"Daryl" wrote in message
...
And you have NEVER seen an accidental leaking of an AGM battery.
Now just admit it.
Those that can: Do. Those that can't: Teach
Daryl


Stop trying to change your own conditions. I've seen one that HAD
ruptured, but I wasn't watching when it happened.
jsw


  #218  
Old March 22nd 13, 11:16 PM posted to rec.aviation.piloting,rec.crafts.metalworking,rec.aviation.military,talk.politics.misc,alt.society.labor-unions
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Default Is the 787 a failure ?

On Fri, 22 Mar 2013 15:16:58 -0600, Daryl
wrote:

On 3/22/2013 2:59 PM, Jim Wilkins wrote:
wrote in message
...

VERY common problem on "A Piece of Crap" UPS systems (as well as
some
cheaper ones) but when they split they don't leak.

The acid in an AGM battery is Absorbed in the Glass Mat.
jsw



No, the Glass Matt just keeps it from sloshing around. You break open
that case and the solution will leak out post haste.

And you have NEVER seen an accidental leaking of an AGM battery. Now
just admit it.

Those that can: Do. Those that can't: Teach

Daryl

They are also called "starved electrolyte" batteries - and even when
fractured they do not "leak". They are very similar in that respect to
the older "gell cell"
  #219  
Old March 22nd 13, 11:16 PM posted to rec.aviation.piloting,rec.crafts.metalworking,rec.aviation.military,talk.politics.misc,alt.society.labor-unions
Jim Wilkins[_2_]
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Posts: 52
Default Is the 787 a failure ?


"Daryl" wrote in message
...
On 3/22/2013 3:00 PM, Jim Wilkins wrote:
http://www.insightcentral.net/encycl...enbattery.html


You believe everything you read? Here is a quote from your very
own Cite:


"Its operating temperature range is -30C degrees ~ +60C degrees."

I can tell you (but you won't listen) that if you operate that
battery at anywhere near 10 degree or less in F, well above the -30C
rating, you will be damaging your battery on a daily basis. This is
why Tesla includes a battery heating blanket and an Air Conditioner
for it's battery compartment. Otherwise, you have cells that are
going to be damaged until, one day, you won't be able to get to the
local quick stop and back.

Daryl


Have you been snorting leaded hi-test again? Try to tame those demons;
it's only an example of a D sized battery in a car.
jsw


  #220  
Old March 23rd 13, 12:50 AM posted to rec.aviation.piloting,rec.crafts.metalworking,rec.aviation.military,talk.politics.misc,alt.society.labor-unions
Daryl[_2_]
external usenet poster
 
Posts: 11
Default Is the 787 a failure ?

On 3/22/2013 4:16 PM, wrote:
On Fri, 22 Mar 2013 15:16:58 -0600, Daryl
wrote:

On 3/22/2013 2:59 PM, Jim Wilkins wrote:
wrote in message
...

VERY common problem on "A Piece of Crap" UPS systems (as well as
some
cheaper ones) but when they split they don't leak.

The acid in an AGM battery is Absorbed in the Glass Mat.
jsw



No, the Glass Matt just keeps it from sloshing around. You break open
that case and the solution will leak out post haste.

And you have NEVER seen an accidental leaking of an AGM battery. Now
just admit it.

Those that can: Do. Those that can't: Teach

Daryl

They are also called "starved electrolyte" batteries - and even when
fractured they do not "leak". They are very similar in that respect to
the older "gell cell"


Totally different internal makeup between the two. Like many, you are
confusing the two and thinking the internal makeup is similar. They aren't.

The AGM must be kept upright since it does have free liquid in it. What
you see when it's case is bulged is from the Hydrogen and Oxygen being
unable to be vented due to excessive overcharging or the vent hole is
plugged up. Like the old style Lead Acid, when it vents, it burns off
the H2O breaking it up to Hydrogen and Oxygen Gasses. When you open one
up that has done this, what is left is the other parts of the liquid in
the form of solids or actually, powder. The Plates are still lead.
This one, like the unsealed lead acids can form Sulphates on the plates
which shorten the life of the battery because of running them below 50%.
The good news is the desulphators work offered with low amperage may
recover them to almost new condition when that happens.

When you need a battery that cannot be kept in an upright position, you
choose the Gel Cel. In this battery, the Sulfuric Acid is mixed with
Silica Fume and it makes it into a gel. The Plates are of a Calcium
makeup and are not lead. People confuse the AGM with the Gel Cel all
the time. If you want the best, longest lasting UPS battery, get rid of
the AGM and go with the Gel Cel. They cost more but last much longer.



 




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