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Revelation
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 12:46 pm

WIederling wrote:
That is the regular penalty for not doing your home work early on. See "The Mythical Man Month" must read foundational work.

ROFL :: "poor beasty Boeing can do no wrong gets all the blame". This attitude still around ?

Afaik Boeing had to sign off on some risks because they wanted things done that way ( or could not make up their mind which way ..
and some suppliers must have told them :: not workable :: too ). next step was bamboozling the FAA to nod it off too.

The batteries definitely were a case in point.

Definitely? Then you should be able to show some definite proof how the FAA (and in turn all the other worldwide aviation agencies) were "bamboozled".

Hopefully such proof will not involve freemasonry, the trilateral commission, or the illuminati.
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dtw2hyd
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 1:02 pm

WIederling wrote:
dtw2hyd wrote:
May I remind you 787 program didn't follow traditional outsourcing model. Courtesy of the epic failure "risk-sharing partners" model combined with sloppy contracts Boeing signed, Boeing underwrote all the risk, so-called "risk-sharing partners" did all the mistakes and walked away with impunity.

Wrap six off-the-shelf cells, plastic spacers, and a charger, voila 787 battery system was born.

100s of Boeing engineers worked on the workaround, because they don't know what is going on with the cell.


That is the regular penalty for not doing your home work early on. See "The Mythical Man Month" must read foundational work.

ROFL :: "poor beasty Boeing can do no wrong gets all the blame". This attitude still around ?

Afaik Boeing had to sign off on some risks because they wanted things done that way ( or could not make up their mind which way ..
and some suppliers must have told them :: not workable :: too ). next step was bamboozling the FAA to nod it off too.

The batteries definitely were a case in point.


Aviation is a supplier controlled industry. Boeing, Airbus, and other integrators can only piggyback on advancements made by suppliers.

Boeing's mistake was to assume aviation components generally are very reliable and suppliers historically did their due diligence in design and production of quality products.

That perception changed with 787. Boeing probably asked every supplier to reduce the weight by a certain percentage. So components with very high MTBF started failing rapidly.

Yes, Boeing was a victim of signing sloppy supply chain contracts. How many more years 787 would have delayed if Boeing tried to enforce contract terms written in favor of suppliers.
 
WIederling
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 1:18 pm

dtw2hyd wrote:
Aviation is a supplier controlled industry. Boeing, Airbus, and other integrators can only piggyback on advancements made by suppliers.

Boeing's mistake was to assume aviation components generally are very reliable and suppliers historically did their due diligence in design and production of quality products.

That perception changed with 787. Boeing probably asked every supplier to reduce the weight by a certain percentage. So components with very high MTBF started failing rapidly.

Yes, Boeing was a victim of signing sloppy supply chain contracts. How many more years 787 would have delayed if Boeing tried to enforce contract terms written in favor of suppliers.


Ouch. this sound so Trumpish.

Boeing wanted to be system integrator and LEGOs snapper while getting stinking rich.

As a system integrator you _define_ the interfaces in depth and then supervise
that your well thought out interfaces are adhered to.

Boeing already massively failed at the "define interfaces" station.
Previously Boeing never realized that they had a lack of sharpness in interface defines
as things were fixed "via the short route" on the shop floor. (everybody proud to no end)

contrast with Airbus where from the get go manufacturing subdivision were distinct comercial
units separated by some gulf in processes and culture.
Never a way around to being careful with interfaces.

Changing over to CAD documents on the 747 ( for 748 design work ) exposed
that 747 documentation was incomplete. The union dominated shopfloor had fixed issues without backtrack.
Murphy is an optimist
 
dtw2hyd
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 2:05 pm

WIederling wrote:
Boeing wanted to be system integrator and LEGOs snapper while getting stinking rich.

As a system integrator you _define_ the interfaces in depth and then supervise
that your well thought out interfaces are adhered to.

Boeing already massively failed at the "define interfaces" station.
Previously Boeing never realized that they had a lack of sharpness in interface defines
as things were fixed "via the short route" on the shop floor. (everybody proud to no end)

contrast with Airbus where from the get go manufacturing subdivision were distinct comercial
units separated by some gulf in processes and culture.
Never a way around to being careful with interfaces..


Again Boeing is a victim of its own making, ie., setting voyage on "risk-sharing partner" model by departing from "traditional outsourcing" model and losing control of the supply chain.

In few years Boeing and Airbus may be just brand names, not even integrators.

Thales is Boeing's partner for 787 Electric Power Conversion System. Thales chose GS Yuasa. GS Yuasa supplied off-the-shelf LVP65. I don't see the great effort from GS Yuasa since 2005.

Boeing 787 had issues with batteries, Airbus A320NEO had issues with engines. Both had issues with interiors. There is no evidence that Airbus's deeply involved culture yielded different results from Boeing's hands-off LEGO snapping approach.

It is a supplier controlled industry.
 
blrsea
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 2:17 pm

Not just airlines, many industries are supplier dependent. Even automobiles. Takata had to go into bankruptcy due to airbags issue. Many parts of the car including parts for engines & transmissions, interiors, etc come for multiple suppliers. And for a good reason, as it enables the supplier to build up expertise, and by supplying to multiple manufacturers, enjoys economy of scale.

The days of any major product doing everything 100% in house is long gone.
 
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Revelation
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 2:43 pm

WIederling wrote:
As a system integrator you _define_ the interfaces in depth and then supervise
that your well thought out interfaces are adhered to.

Boeing already massively failed at the "define interfaces" station.

Boeing 787 Dreamliner battery problems gives us:

The National Transportation Safety Board released a report on December 1, 2014, and assigned blame to several groups:[3]
• GS Yuasa of Japan, for battery manufacturing methods that could introduce defects not caught by inspection
• Boeing’s engineers, who failed to consider and test for worst-case battery failures
• The Federal Aviation Administration, that failed to recognize the potential hazard and did not require proper tests as part of its certification process

No mention of problems with interface definition.

So, are you off on a witch hunt?

Seems we should be talking about the current 787 battery status instead of going on tangents about how Boeing had interface problems a decade ago, or how Airbus can't get Pratt to design a bearing seal correctly or can't get Rolls to use mature materials and schedule out testing correctly, or how the Council for Foreign Relations shadow government is controlling the world.
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SomebodyInTLS
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 3:38 pm

Revelation wrote:
WIederling wrote:
As a system integrator you _define_ the interfaces in depth and then supervise
that your well thought out interfaces are adhered to.

Boeing already massively failed at the "define interfaces" station.

Boeing 787 Dreamliner battery problems gives us:

The National Transportation Safety Board released a report on December 1, 2014, and assigned blame to several groups:[3]
• GS Yuasa of Japan, for battery manufacturing methods that could introduce defects not caught by inspection
• Boeing’s engineers, who failed to consider and test for worst-case battery failures
• The Federal Aviation Administration, that failed to recognize the potential hazard and did not require proper tests as part of its certification process

No mention of problems with interface definition.

So, are you off on a witch hunt?


it's clear to me that WIederling was referring to the interface definition with respect to all other aspects of the aircraft as a system, not just physical interfaces. I.e. this object has to fulfill these functions under these conditions with these tolerances and costs. Boeing failed on the conditions and tolerances definition and then failed to test to the conditions and tolerances that they should have defined.
Last edited by SomebodyInTLS on Tue Dec 05, 2017 3:43 pm, edited 3 times in total.
"As with most things related to aircraft design, it's all about the trade-offs and much more nuanced than A.net likes to make out."
 
WIederling
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 3:39 pm

dtw2hyd wrote:
Thales is Boeing's partner for 787 Electric Power Conversion System.
Thales chose GS Yuasa. GS Yuasa supplied off-the-shelf LVP65.
I don't see the great effort from GS Yuasa since 2005.


I don't think so. they had to live with a preselection afaics.
In the whole brohaha around the batteries Thales never got more than a honorary mention.

neither did the hobbyist outfit that did the charger get much attention. < sad, sad >
same for the US subdivision of Yuasa that did the flimsy enclosure and management electronics
while Yuasa Japan did get quite the nice trashing. Bit racist isn't it :-?
Murphy is an optimist
 
WIederling
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 3:46 pm

SomebodyInTLS wrote:
it's clear to me that WIederling was referring to the definition with respect to all other aspects of the aircraft, not just physical interfaces. I.e. this object has to fulfill these functions under these conditions with these tolerances and costs. Boeing failed on the conditions and tolerances definition and then failed to test their own definition.


Yes. obviously.

That is what "interface" refers to in context of systems design.
( you have a Lastenheft ( demands, environment ) and a Pflichtenheft ( what is it supposed to do) :-)
And good design practice is to provide positive margins.
Murphy is an optimist
 
BravoOne
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 3:54 pm

The fact is you are much more likely to have a catastrophic event from a lap top than a 787 battery overheat. The 787 system was redesigned to account for what we know will happen, which is a lot more than you can say for the lap tops hidden in pax luggage..
 
dtw2hyd
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 4:02 pm

WIederling wrote:

I don't think so. they had to live with a preselection afaics.
In the whole brohaha around the batteries Thales never got more than a honorary mention.

neither did the hobbyist outfit that did the charger get much attention. < sad, sad >
same for the US subdivision of Yuasa that did the flimsy enclosure and management electronics
while Yuasa Japan did get quite the nice trashing. Bit racist isn't it :-?


NTSB investigative report claims FDR data showed the draw never exceeded design limit of 32 volts.

When Samsung or Apple have battery issues, battery vendor reproduces the failure condition and Samsung or Apple update their charging/monitoring configuration. The problem goes away without replacing millions of batteries.

Here GS Yuasa continues to claim there is no failure scenario. So neither Thales nor Boeing can offer a fix to charging/monitoring system, other than putting it is a box.

It is a JCAB certified system. Not sure how you can pin blame on somebody else.

Remember the JCAB tantrum with Air India 787 about GS Yuasa faulty battery refit process, refit done by Boeing team, for not filling a non-existing document during a test flight after the refit. It is their own problem, turned it around on AI.

GS Yuasa got a lot of slack while blaming others including 787 operators.

I think the old days of cultural sensitivity is gone with Toyota unintended acceleration, Takata airbags, and GS Yuasa batteries. Time to own up and fix the issue.
 
WIederling
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 4:14 pm

dtw2hyd wrote:
So neither Thales nor Boeing can offer a fix to charging/monitoring system, other than putting it is a box.


parametric use of the battery was "adjusted" in conjunction with the boom box.

i.e. don't try to cram 100% charge into the battery when you have limited knowledge of the actual charge state.
i.e. 75% +-3% known charge state and then blindly send 25% equivalent of juice in you have 50% chance of overcharging.
( the basics of the charger algorithm were published during the NTSB proceedings.)
Murphy is an optimist
 
dtw2hyd
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 4:23 pm

WIederling wrote:
dtw2hyd wrote:
So neither Thales nor Boeing can offer a fix to charging/monitoring system, other than putting it is a box.


parametric use of the battery was "adjusted" in conjunction with the boom box.

i.e. don't try to cram 100% charge into the battery when you have limited knowledge of the actual charge state.
i.e. 75% +-3% known charge state and then blindly send 25% equivalent of juice in you have 50% chance of overcharging.
( the basics of the charger algorithm were published during the NTSB proceedings.)



You seem to know everything except what makes the cell ooze.
 
WIederling
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 5:16 pm

dtw2hyd wrote:
You seem to know everything except what makes the cell ooze.


The break up process is well known. perfectly described in the NTSB report.
range of documents available: https://www.googlecome/search?q=787+battery+ntsb+report

https://en.wikipedia.org/wiki/Lithium_cobalt_oxide
describes why fire from decomposing cell material is difficult to extinguish.
The electrolytes used are lithium salts solved in organic solvents.
(oxygen released in proximity to a flamable liquid.)

Cells are hermetically sealed with burst plate pressure control.
decomposition burst the plate and extrudes remaining electrolyte.

The hermetic cell type in contrast to "aspirating" NiCad cells is one
reason why the initial enclosure was unsuitable. no room for expansion.

The diaphragm like sides of a prismatic cell make it less suitable
for use in an environment that shows repeated pressure cycles.
with each cycle you palpate the internal active bale wound from
electrode and separator materials.
Murphy is an optimist
 
dtw2hyd
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 5:40 pm

WIederling wrote:
The break up process is well known.


So a corporation in battery business since 1915 forgot to include "the box" in its original design.
 
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 6:01 pm

dtw2hyd wrote:
So a corporation in battery business since 1915 forgot to include "the box" in its original design.

Wrong!
Yuasa provide perfectly adequate containers for their cells, which then becomes what we know as a "battery" i.e. a battery of cells.
They will also provide a list of basic requirements, such as temperature limitations, ventilation requirements, risk of exposure to naked flames, etc

It is the responsibility of the vehicle manufacturer (car, motorbike, aircraft) to provide a safe & secure battery box, to hold the Yuasa batteries.

After all, I could buy a Yuasa battery and mount it as a back-up supply for a burglar alarm system in my house (that is actually one of their regular uses). If I mount the battery upside down, or inadequately vented, that is my responsibility.

If the contract between Yuasa and Boeing included providing an additional housing for entire group of batteries, then that is a different matter. But it is not normally Yuasa's business.
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Stitch
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 6:16 pm

dtw2hyd wrote:
So a corporation in battery business since 1915 forgot to include "the box" in its original design.


As SheikhDjibouti notes, the upstream integrator (I believe Thales) and Boeing would have been responsible for the containment definition and implementation (with advice from GS Yuasa). Based on the failure modes the three of them (Boeing, Thales and GS Yuasa) and the FAA determined most-likely to happen (thermal runaway in a single cell), the original basic box was deemed sufficient. Those failure modes didn't include some of the things that happened with the ANA and JAL batteries (for example, they were stored in an unheated shed at sub-freezing temperatures prior to installation) which led to the thermal runaway across multiple cells. So in addition to just putting them in a "better box", the cells are now better-insulated against cold temperatures and the charging/discharging system is less-aggressive to reduce thermal heating within the battery (the extra insulation also helping to better restrict heat transfer between cells) so if one cell does enter thermal runaway, adjacent cells are far less likely to join in.
 
iamlucky13
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 6:26 pm

Revelation wrote:
People should not be shocked by another exploding battery. If that could be ruled out, there would be no need for the containment system. Since there is a containment system (both on 787 and A350) we know the chances that another battery might explode were sufficiently high to require the containment systems.


Related to that, looking back at a few documents from the NTSB investigation in 2013, apparently the original safety criteria for the battery was less than 1 thermal runaway per 10 million flight hours, which I think is a pretty typical criteria for aircraft components.

As a very rough estimate, the 787 fleet is probably somewhere north of 5 million flight hours at the moment, so these failures still seem to be happening slightly more often than they should. As you said, that's why there is a containment system.
 
WIederling
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 6:28 pm

dtw2hyd wrote:
WIederling wrote:
The break up process is well known.


So a corporation in battery business since 1915 forgot to include "the box" in its original design.

So a corporation in airplane business since 1916 forgot to think about the consequences.
shrug.
IMU you have misconceptions about the design process.

Yuasa Japan is the cell manufacturer. (The same basic design is said to sit on the ISS as solar cell buffer.
http://spaceflight101.com/htv-6/htv-6-cargo-overview/ )

Yuasa USA is the contractor for the enclosure and supervisory circuits inside the battery case.
( would I place the data collection inside the enclosure? g forbid no! )
Securaplane is the contractor for the battery charger/manager. ( who blew their lab up in the process. )

Afaics Yuasa USA procured cells from Yuasa Japan.
It is not obvious who decided if these cells were adequate or not.
Apparently nobody asked the right questions and a judicious amount of cargo cult was applied too.
Murphy is an optimist
 
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 6:40 pm

SomebodyInTLS wrote:
The way I see it:

- The hysteria about the contained event is over the top.

- The hysteria about the original uncontained events was entirely warranted

- Fire onboard, to my mind, is something that should always be reported and investigated - I find it very odd that this is not a requirement... especially since these events are still unpredictable!


Agree.
 
dtw2hyd
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 6:51 pm

SheikhDjibouti wrote:
dtw2hyd wrote:
So a corporation in battery business since 1915 forgot to include "the box" in its original design.

Wrong!
Yuasa provide perfectly adequate containers for their cells, which then becomes what we know as a "battery" i.e. a battery of cells.
They will also provide a list of basic requirements, such as temperature limitations, ventilation requirements, risk of exposure to naked flames, etc

It is the responsibility of the vehicle manufacturer (car, motorbike, aircraft) to provide a safe & secure battery box, to hold the Yuasa batteries.

After all, I could buy a Yuasa battery and mount it as a back-up supply for a burglar alarm system in my house (that is actually one of their regular uses). If I mount the battery upside down, or inadequately vented, that is my responsibility.

If the contract between Yuasa and Boeing included providing an additional housing for entire group of batteries, then that is a different matter. But it is not normally Yuasa's business.


Like quite a few others on this thread, you are not seeing the difference between risk-sharing-partner and an outsourced-contractor.

Examples.
NASA awarded Space Shuttle contract to ULA, ULA does everything still NASA invests and holds the IP rights, end products, and responsibility
Boeing 787 chose Mitshibishi as a risk-sharing partner, Mitshibishi invests and owns the IP, end product and takes full responsibility.

These two models may appear the same but significantly different in terms of investment and responsibility. I can write 100 posts, but it wouldn't make any sense without differentiating risk-sharing and outsourcing.
 
BREECH
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 8:19 pm

KarelXWB wrote:
The biggest concern is the risk of a thermal runaway, because it cannot be contained. Hence Boeing did not just built a containment box, they also introduced a venting system to keep the temperature under control.

May I suggest a modest analogy? Instead of buying a dog to guard the house, Boeing bought a bear because it is much stronger and scares away the trespassers. The problem now is who's going to protect them from the bear.
No friendship, love or respect unite people as much as shared hatred towards something.
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iamlucky13
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 8:42 pm

dtw2hyd wrote:
When Samsung or Apple have battery issues, battery vendor reproduces the failure condition and Samsung or Apple update their charging/monitoring configuration. The problem goes away without replacing millions of batteries.

Here GS Yuasa continues to claim there is no failure scenario. So neither Thales nor Boeing can offer a fix to charging/monitoring system, other than putting it is a box.


I'm not sure where you or Wlederling are going with discussions about the charger, since as far as I know the charging system was found to be working properly in both of the incident aircraft as well as in additional production chargers by Boeing, the NTSB, and Underwriters Laboratories. While the incident batteries were too damaged to conclusively identify the cause, internal short circuit appeared to be most likely, and they did observe manufacturing problems at GS Yuasa that could lead to internal shorts that are known to be capable of causing thermal runaway.

I don't know about Apple, but in the case of the Samsung Note 7, it was not a charging issue. They had a battery manufacturing defect. Actually, if I remember right, they had two different manufacturing defects, either of which could cause the runaways, and they were able to identify those in part by dismantling a large number of intact cells.

WIederling wrote:
i.e. don't try to cram 100% charge into the battery when you have limited knowledge of the actual charge state.
i.e. 75% +-3% known charge state and then blindly send 25% equivalent of juice in you have 50% chance of overcharging.
( the basics of the charger algorithm were published during the NTSB proceedings.)


As far as I can find, the flight data recorder monitored an indirect voltage on the lines somewhere downstream of the battery, but the battery management unit monitored it directly. The BMU data was used only locally by the BMU, not transmitted to the FDR, except for a fault indicator if problems were detected. The BMU actually monitored each cell individually, could balance the charge of each cell, and would stop all charging via a relay built into the battery box if any cell exceeded a set limit.

The charge limit was 4.025 V per cell (Docket SA-536, Airworthiness Factual Report Exhibit 17-J, page 29). Normal full charge for lithium cobalt oxide cells is 4.2V, but GS Yuasa appears to have specified the pack to have a nominal full charge of 4.025V per cell. From what I know of lithium ion batteries, I presume this was to keep the battery in a conservative operating range, not due to some novel chemistry they might have been using. In other applications, 4.025V would be around 80-90% SoC. Overcharge testing also was done to 36V (4.5V/cell). This will degrade the battery but should not result in a fire at that point.

I'm still looking through the Boston incident docket and not seeing the claims you're making about the charging algorithm.

That would be an even worse charging algorithm than you're suggesting, because you can't determine state of charge for a partially charged lithium ion battery accurately enough to handle charging that way. Coulomb counting starting at a known state of charge comes close, and is often used for meters, but not for charging. Full charge voltage and full discharge voltage are the known points. The UL report describes the standard lithium-ion charge algorithm - maintain a constant current of 46A until the voltage reaches 32.2V for the pack (4.025V/cell), then switch to constant voltage, at which point the charge current will naturally taper off as the battery approaches full charge.

* Edit - I wonder if some other party might have made some commentary on charging that was misunderstood. The constant current to constant voltage transition usually occurs somewhere around 75% SoC, depending on the charge rate. However, from that point, a fixed amount of energy is not passed to the battery. Voltage is held constant and termination occurs once the charge current has declined to a certain level.
Last edited by iamlucky13 on Tue Dec 05, 2017 8:52 pm, edited 1 time in total.
 
mjoelnir
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 8:43 pm

Stitch wrote:
dtw2hyd wrote:
So a corporation in battery business since 1915 forgot to include "the box" in its original design.


As SheikhDjibouti notes, the upstream integrator (I believe Thales) and Boeing would have been responsible for the containment definition and implementation (with advice from GS Yuasa). Based on the failure modes the three of them (Boeing, Thales and GS Yuasa) and the FAA determined most-likely to happen (thermal runaway in a single cell), the original basic box was deemed sufficient. Those failure modes didn't include some of the things that happened with the ANA and JAL batteries (for example, they were stored in an unheated shed at sub-freezing temperatures prior to installation) which led to the thermal runaway across multiple cells. So in addition to just putting them in a "better box", the cells are now better-insulated against cold temperatures and the charging/discharging system is less-aggressive to reduce thermal heating within the battery (the extra insulation also helping to better restrict heat transfer between cells) so if one cell does enter thermal runaway, adjacent cells are far less likely to join in.


It sounds all so reasonable.

To be clear, the contained version of the battery is OK.

But this apologising of the first concept, the battery without a containment. Both Boeing and the FAA f....d up. The solution in the battery is not water, the danger is not an acid. The solvent is a hydrocarbon liquid. Like a thick oil. If heated if becomes a thin liquid and if heated more it vaporises, producing a fuel air mixture than can explode. You have a box with oil inside. You have a heating element to vaporise the oil, the thermal runaway when something goes wrong in the battery. This you place in an electrical cabinet, were you have plenty of possibilities to produce the spark for the ignition of the air fuel bomb. That nothing happened in the instance the battery went off in the air, is only due to the intervention of lady luck. And people were wondering at that time why the 787 was grounded.

Again, I do not disagree with the current solution
 
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Stitch
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 8:55 pm

mjoelnir wrote:
Again, I do not disagree with the current solution


Nor do I, which is why I am not apologizing for Boeing and the FAA, but instead disagreeing that only GS Yuasa should be considered "at fault" for the issues as the battery manufacturer.
 
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Polot
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 8:59 pm

BREECH wrote:
KarelXWB wrote:
The biggest concern is the risk of a thermal runaway, because it cannot be contained. Hence Boeing did not just built a containment box, they also introduced a venting system to keep the temperature under control.

May I suggest a modest analogy? Instead of buying a dog to guard the house, Boeing bought a bear because it is much stronger and scares away the trespassers. The problem now is who's going to protect them from the bear.

Yes, that stainless steel box (also found on the A350 btw) sure is a ticking timebomb. Who will protect us from the inert metal boxes?
 
iamlucky13
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 9:15 pm

mjoelnir wrote:
The solvent is a hydrocarbon liquid. Like a thick oil. If heated if becomes a thin liquid and if heated more it vaporises, producing a fuel air mixture than can explode. You have a box with oil inside. You have a heating element to vaporise the oil, the thermal runaway when something goes wrong in the battery. This you place in an electrical cabinet, were you have plenty of possibilities to produce the spark for the ignition of the air fuel bomb. That nothing happened in the instance the battery went off in the air, is only due to the intervention of lady luck. And people were wondering at that time why the 787 was grounded.


I assume by solution, you're referring to the electrolyte?

Looking at both the NTSB documents and the airworthiness directive, I'm finding no conclusions parallel to what you are claiming. As far as I know, the grounding was based in large part on the uncertainty about whether the fire could propagate and damage other systems or the aircraft structure or produce hazardous fumes or smoke on the flight deck.

You portray it instead as if there was certainty that the progression would be catastrophic unless unlikely circumstances prevented it.

The original certification including a deliberate runaway of a single cell and measurement of the volume and composition of the gases produced, from which they determined there was not enough present to reach the minimum explosive limit in a volume the size of the electronics bay, although I've not yet found follow up about whether 8 cells venting could. Based on the firefighter's reports, it sounds like in reality the electrolyte burned as it vented.
 
WIederling
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 10:08 pm

iamlucky13 wrote:
You portray it instead as if there was certainty that the progression would be catastrophic unless unlikely circumstances prevented it.


destruction of the electrode material produces heat and nascent oxygen in vicinity of a flammable liquid ( the electrolyte).
i.e. there is no way to quench a fire. neither water nor sand will work. taking out the produced energy via cooling works.
Murphy is an optimist
 
mjoelnir
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 10:13 pm

iamlucky13 wrote:
mjoelnir wrote:
The solvent is a hydrocarbon liquid. Like a thick oil. If heated if becomes a thin liquid and if heated more it vaporises, producing a fuel air mixture than can explode. You have a box with oil inside. You have a heating element to vaporise the oil, the thermal runaway when something goes wrong in the battery. This you place in an electrical cabinet, were you have plenty of possibilities to produce the spark for the ignition of the air fuel bomb. That nothing happened in the instance the battery went off in the air, is only due to the intervention of lady luck. And people were wondering at that time why the 787 was grounded.


I assume by solution, you're referring to the electrolyte?

Looking at both the NTSB documents and the airworthiness directive, I'm finding no conclusions parallel to what you are claiming. As far as I know, the grounding was based in large part on the uncertainty about whether the fire could propagate and damage other systems or the aircraft structure or produce hazardous fumes or smoke on the flight deck.

You portray it instead as if there was certainty that the progression would be catastrophic unless unlikely circumstances prevented it.

The original certification including a deliberate runaway of a single cell and measurement of the volume and composition of the gases produced, from which they determined there was not enough present to reach the minimum explosive limit in a volume the size of the electronics bay, although I've not yet found follow up about whether 8 cells venting could. Based on the firefighter's reports, it sounds like in reality the electrolyte burned as it vented.


Read up what the electrolyte of a lithium ion battery is. I do not talk about an electrolyte because most people start thinking about water and acid. If you do not understand what I am talking about, put a can of oil, another name for the hydrocarbon fluid that is the electrolyte, on an oven and when the liquid is boiling put something that produces sparks above it and see what happens. The original deliberation calculated with the runaway of a single cell, what happened was the runaway of all cells, sparked by the runaway of one cell.
In earnest, why do people still apologise for Boeing and the FAA for the crazy idea to allow this battery without containment into the electrical bay of an airplane?
 
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 10:25 pm

mjoelnir wrote:
iamlucky13 wrote:
mjoelnir wrote:
The solvent is a hydrocarbon liquid. Like a thick oil. If heated if becomes a thin liquid and if heated more it vaporises, producing a fuel air mixture than can explode. You have a box with oil inside. You have a heating element to vaporise the oil, the thermal runaway when something goes wrong in the battery. This you place in an electrical cabinet, were you have plenty of possibilities to produce the spark for the ignition of the air fuel bomb. That nothing happened in the instance the battery went off in the air, is only due to the intervention of lady luck. And people were wondering at that time why the 787 was grounded.


I assume by solution, you're referring to the electrolyte?

Looking at both the NTSB documents and the airworthiness directive, I'm finding no conclusions parallel to what you are claiming. As far as I know, the grounding was based in large part on the uncertainty about whether the fire could propagate and damage other systems or the aircraft structure or produce hazardous fumes or smoke on the flight deck.

You portray it instead as if there was certainty that the progression would be catastrophic unless unlikely circumstances prevented it.

The original certification including a deliberate runaway of a single cell and measurement of the volume and composition of the gases produced, from which they determined there was not enough present to reach the minimum explosive limit in a volume the size of the electronics bay, although I've not yet found follow up about whether 8 cells venting could. Based on the firefighter's reports, it sounds like in reality the electrolyte burned as it vented.


Read up what the electrolyte of a lithium ion battery is. I do not talk about an electrolyte because most people start thinking about water and acid. If you do not understand what I am talking about, put a can of oil, another name for the hydrocarbon fluid that is the electrolyte, on an oven and when the liquid is boiling put something that produces sparks above it and see what happens. The original deliberation calculated with the runaway of a single cell, what happened was the runaway of all cells, sparked by the runaway of one cell.
In earnest, why do people still apologise for Boeing and the FAA for the crazy idea to allow this battery without containment into the electrical bay of an airplane?


I'm aware of what the electrolyte is and why it is flammable, and that under certain conditions could even be made explosive.

You made a specific claim I'm requesting verification of, however, so please provide the source for the following:

The 787 forward electronics bay, following venting of eight LVP65 LiCoO2 cells, contains an explosive concentration of gases that definitely will cause catastrophe unless unlikely conditions (aka "intervention of lady luck") are present to prevent it.

I don't know why people apologize for the failures of GS Yuasa, Boeing, and the FAA between all of them to develop and fulfill a satisfactory certification regimen. You'll have to ask one of the apologists.
 
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 10:51 pm

iamlucky13 wrote:
I'm not sure where you or Wlederling are going with discussions about the charger, since as far as I know the charging system was found to be working properly in both of the incident aircraft as well as in additional production chargers by Boeing, the NTSB, and Underwriters Laboratories. While the incident batteries were too damaged to conclusively identify the cause, internal short circuit appeared to be most likely, and they did observe manufacturing problems at GS Yuasa that could lead to internal shorts that are known to be capable of causing thermal runaway.


I think Wlederling is trying to portray an outsourcing contract scenario where Boeing bought eight cells from GS Yuasa (Japan), electronics and case from GS Yuasa(USA) charger from Securaplane and put them together, hence Boeing, or GS Yuasa(USA) or Securaplane is responsible for the failure. Basically, blame anybody except GS Yuasa(Japan).

I am rebutting that argument with Boeing partnered with Thales for Electrical Power Conversion System for 787. Hence, Boeing has no responsibility. in a risk-sharing-partnership model, other than dealing with customer complaints.

As more members are familiar with traditional outsourcing model than a risk-sharing partner model, gives legs to Wlederling 's argument, even though it is a total fallacy.
 
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 11:11 pm

dtw2hyd wrote:
As more members are familiar with traditional outsourcing model than a risk-sharing partner model, gives legs to Wlederling 's argument, even though it is a total fallacy.


We have your word.

If you can show that Thales bore the financial brunt of the fall out from the battery issue I'd see some credence to your theory.
At the moment I think it is plain wrong.

Going by the patterns visible there were hobbyist at work with all relevant parties involved on the Dreamliner.
I don't think Thales had the option to decide. They had to make it work.

Working for Airbus Thales has gone with SAFT cylindrical cells of a more mature design
from before the Dreamliner ( emergency door actuation and lighting for the A380 main batteries for the A350 ).
same cell type that Lange Aviation used in their electric sailplane. Same time frame as A380 development ( FF 2003 ).
Previously that type had established a position in military hardware. so a reasonable pedigree.

IMHO Boeing had no need to go with the volatile Yuasa cell design if that detail was decided around/after 787 project start.
( My theory: Boeing had selected this tech for the Sonic Cruiser. Thus a hold over from the mid /late 90ties.)
Murphy is an optimist
 
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 11:13 pm

iamlucky13 wrote:
mjoelnir wrote:
iamlucky13 wrote:

I assume by solution, you're referring to the electrolyte?

Looking at both the NTSB documents and the airworthiness directive, I'm finding no conclusions parallel to what you are claiming. As far as I know, the grounding was based in large part on the uncertainty about whether the fire could propagate and damage other systems or the aircraft structure or produce hazardous fumes or smoke on the flight deck.

You portray it instead as if there was certainty that the progression would be catastrophic unless unlikely circumstances prevented it.

The original certification including a deliberate runaway of a single cell and measurement of the volume and composition of the gases produced, from which they determined there was not enough present to reach the minimum explosive limit in a volume the size of the electronics bay, although I've not yet found follow up about whether 8 cells venting could. Based on the firefighter's reports, it sounds like in reality the electrolyte burned as it vented.


Read up what the electrolyte of a lithium ion battery is. I do not talk about an electrolyte because most people start thinking about water and acid. If you do not understand what I am talking about, put a can of oil, another name for the hydrocarbon fluid that is the electrolyte, on an oven and when the liquid is boiling put something that produces sparks above it and see what happens. The original deliberation calculated with the runaway of a single cell, what happened was the runaway of all cells, sparked by the runaway of one cell.
In earnest, why do people still apologise for Boeing and the FAA for the crazy idea to allow this battery without containment into the electrical bay of an airplane?


I'm aware of what the electrolyte is and why it is flammable, and that under certain conditions could even be made explosive.

You made a specific claim I'm requesting verification of, however, so please provide the source for the following:

The 787 forward electronics bay, following venting of eight LVP65 LiCoO2 cells, contains an explosive concentration of gases that definitely will cause catastrophe unless unlikely conditions (aka "intervention of lady luck") are present to prevent it.

I don't know why people apologize for the failures of GS Yuasa, Boeing, and the FAA between all of them to develop and fulfill a satisfactory certification regimen. You'll have to ask one of the apologists.


The danger was deemed serious enough to ground the 787.

As you are the one apologising for for those decisions, you should tell me why you do it.

I do not have to proof for that a hydrocarbon vapour air mixture can be explosive, that is tested to the excess. Even if you would need more hydrocarbon fluid to fill the whole bay to the right air fuel mixture for explosion, that never excludes that you can have the right mixture locally in a part of the bay. It tells me all about your attitude, that the presence of hydrocarbon vapour, air and electrical cabinet does not spell danger to you.
 
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 11:21 pm

BravoOne wrote:
Sounds like the venting system worked as designed?

Yes, but this is A.net (and 2017 for that matter), and one can’t give up his originally stated opinion no matter the facts and evidence against it.
 
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 11:25 pm

BREECH wrote:
KarelXWB wrote:
The biggest concern is the risk of a thermal runaway, because it cannot be contained. Hence Boeing did not just built a containment box, they also introduced a venting system to keep the temperature under control.

May I suggest a modest analogy? Instead of buying a dog to guard the house, Boeing bought a bear because it is much stronger and scares away the trespassers. The problem now is who's going to protect them from the bear.

If that’s the case, what happens when the APU of an erj catches on fire and the whole fire wall is made of stainless steel? Who will protect us from that?

The arguments on this tread are getting silly. How about we just don’t fly, stop improving technology, and stay in our padded rooms with no windows where we know it’s 100% safe.
 
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 11:37 pm

WIederling wrote:
...
If you can show that Thales bore the financial brunt of the fall out from the battery issue I'd see some credence to your theory.
...


Is that the foundation for your argument? Sure Boeing bore the financial brunt because of the stupid decision of risk-sharing-partnership. It also spent a couple of $Billions when Mitsubishi (or) Kawasaki was not up to the task. Had Alan Mulally came from an Automotive or any other outsourcing background, he wouldn't have chosen that path.

It is irrelevant whether LVP65 is successful with different applications like ISS or Airbus. It continues to fail prematurely on 787. That's all matters.
 
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SheikhDjibouti
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 11:40 pm

WIederling wrote:
Working for Airbus Thales has gone with SAFT cylindrical cells of a more mature design...
....same cell type that Lange Aviation used in their electric sailplane. Same time frame as A380 development ( FF 2003 ).
Previously that type had established a position in military hardware. so a reasonable pedigree.

IMHO Boeing had no need to go with the volatile Yuasa cell design....


Yes, yes, yes. :checkmark:

These are the same points I have been trying to make, except your knowledge (and eloquence) is far better than my own.
And the more posts I read from you, the more embarrassed I am with my own feeble contributions from earlier in this thread.
:roll:
(plus I kept getting sidetracked with people falsely thinking I was suggesting Ni-Cds were the only solution..... :shakehead: )

So let's say it again.... Boeing had no need to go with the volatile Yuasa cell design
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 11:50 pm

KarelXWB wrote:
The biggest concern is the risk of a thermal runaway, because it cannot be contained. Hence Boeing did not just built a containment box, they also introduced a venting system to keep the temperature under control.

BREECH wrote:
May I suggest a modest analogy? Instead of buying a dog to guard the house, Boeing bought a bear because it is much stronger and scares away the trespassers. The problem now is who's going to protect them from the bear.

I like it! :lol:

B737BEAR wrote:
The arguments on this tread are getting silly. How about we just don’t fly, stop improving technology, and stay in our padded rooms with no windows where we know it’s 100% safe.

You are absolutely right there Boo-boo; the arguments on this thread are getting very silly.....
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Re: Lithium-ion battery fails on UA 787 flight

Tue Dec 05, 2017 11:59 pm

SheikhDjibouti wrote:
So let's say it again.... Boeing had no need to go with the volatile Yuasa cell design


Going with the Saft design would have required three times as many batteries to provide the same amount of Amp-hours (the 787 has eight 3.7V cells storing 72Ah where as the A350 has 14 3.6V cells storing 45Ah). The A350 battery weighs 30kg, so the entire package would be 180kg on the 787 (for two batteries) whereas the 787's battery came in at 57kg for the pair. While the subsequent changes to the 787 are said to have added 68kg to the system, it's still lighter than using the Saft system plus it takes up one third the space in the electronics bay.

Anyone know when Saft started work on their battery? I am guessing post-2006 when Airbus launched the A350XWB, which would have been years after Boeing had to select the battery design for the 787.

And on the topic of safety, Airbus argued to the FAA that their Li-Ion batteries did not require any additional containment beyond the same basic box the 787 started out with.
Last edited by Stitch on Wed Dec 06, 2017 12:12 am, edited 2 times in total.
 
mjoelnir
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 12:00 am

Boeing went for a high energy density and low battery weight. It really does not matter how often the battery has a runaway. Having a proper containment around the battery should really end the argument in regards to safety. The only thing left is cost, it can not be cheap to exchange it.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 12:12 am

mjoelnir wrote:
The danger was deemed serious enough to ground the 787.


Yes. More specifically, my understanding is that the inability to be certain the level of danger was within any sort of justifiable threshold was the reason for the grounding. I've not seen any quantification at all of what the risk would have been to continue flying before the battery failures were addressed, and most certainly nothing resembling "only due to the intervention of lady luck." The mere fact that the required level of safety could not be demonstrated is sufficient basis for grounding.

The actual airworthiness directive that enacted the grounding is not explicitly clear about level of risk; only that continued incidents were considered likely and that more serious damage than what was observed was possible:

http://rgl.faa.gov/Regulatory_and_Guida ... rgency.pdf
These conditions, if not corrected, could result in damage to critical systems and structures, and the potential for fire in the electrical compartment.

We are issuing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design.



mjoelnir wrote:
As you are the one apologising for for those decisions, you should tell me why you do it.


I am not. Feel free to review my posts for the alleged apologies. I'm trying to arrive at an understanding of the original situation that appropriately acknowledges the risk without falling prey to hyperbolic tendencies.

mjoelnir wrote:
I do not have to proof for that a hydrocarbon vapour air mixture can be explosive, that is tested to the excess. Even if you would need more hydrocarbon fluid to fill the whole bay to the right air fuel mixture for explosion, that never excludes that you can have the right mixture locally in a part of the bay.


I'm not asking for proof of explosiveness. I'm asking for a source for your argument that explosive conditions actually did exist in the forward electronics bays of the incident aircraft. Actually, that's a bit of a digression on my part, because what I'm actually interested in is a source for the implication that the situation was one where catastrophe was going to happen unless unlikely circumstances prevented it.

mjoelnir wrote:
It tells me all about your attitude, that the presence of hydrocarbon vapour, air and electrical cabinet does not spell danger to you.


You're mistaken. I'm not the least bit interested in arguing there was no danger there.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 12:40 am

mjoelnir wrote:
Boeing went for a high energy density and low battery weight. It really does not matter how often the battery has a runaway. Having a proper containment around the battery should really end the argument in regards to safety. The only thing left is cost, it can not be cheap to exchange it.

It should, but this is a.net, so we're going to revisit 2013 and earlier time and time again.
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 1:08 am

SheikhDjibouti wrote:
So let's say it again.... Boeing had no need to go with the volatile Yuasa cell design

Stitch wrote:
Going with the Saft design would have required three times as many batteries to provide the same amount of Amp-hours (the 787 has eight 3.7V cells storing 72Ah where as the A350 has 14 3.6V cells storing 45Ah). The A350 battery weighs 30kg, so the entire package would be 180kg on the 787 (for two batteries) whereas the 787's battery came in at 57kg for the pair. While the subsequent changes to the 787 are said to have added 68kg to the system, it's still lighter than using the Saft system plus it takes up one third the space in the electronics bay.

Whilst it is fantastic to see real numbers used ( :checkmark: ), can you take a step back - I cannot follow your maths here. Not saying it's wrong - just cannot follow it.
B787 = eight 3.7v cells (29.6v) = 75Ah per battery unit, weighing 57kg total for two complete units (fore & aft)
A350= fourteen 3.6v cells (50.4v - or split in some way?), weighs 30kg (in total/for what ??). How many units on board an A350? Did you mean 300kg?? I really cannot guess.
And from this you come up with 180kg for some equivalent unit for the 787. Perhaps you can see that from this data alone, anybody would be lost.

With my "best guessing" brain plugged in, the A350 cells store 45Ah across 14 cells, hence 3.214 Ah per cell, so the 787 would require 23½ cells instead of eight ("three times as many" as you said). I presume it is possible to arrange some cells in series, and some in parallel, to yield 28.8volts or would Boeing be able to utilise 86.4v from each battery pack featuring all 24 cells in series? Obviously they would need some new electronics to handle any changes.
That just leaves us with weight. How did you get to 180kg?
It appears as if you started with 30kg per A350 battery, multiplied this by "three times as many", and then doubled it for the two units on board the B787.
If so, what you should have done was 30kg/14 cells multiplied by 24 cells (to give 75Ah), then doubled. That is 51.4kg per 75Ah battery unit, fore & aft = 102.8kg

If we ignore that for now; for the B787 we have 57kg for two very efficient (if unreliable) batteries, plus 68kg subsequent changes. Total 125kg
Compared to "180kg" (if that is correct), yes indeed the Boeing solution is lighter even with the containment box. But that difference isn't exactly frightening me. Unlike the batteries themselves ...

But if the calculation now comes out as "102.8kg" ......... :scratchchin:

Let's just say I am going to be REALLY INTERESTED to see your alternative math!
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Stitch
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 1:15 am

SheikhDjibouti wrote:
Let's just say I am going to be REALLY INTERESTED to see your alternative math!


Eh when I try and do this stuff too quickly I tend to get derailed onto erroneous paths for my math. :embarrassed2: Each 787 cell is 9Ah of capacity whereas each A350 cell is 3Ah of capacity so I just multiplied the A350 battery by 3, forgetting to take into account that the 787 battery is 8 cells versus 14 cells for the A350 battery. Hence my remarks that you would need three A350 batteries to match a 787 battery - which you would if the Saft battery was 8 cells instead of 14. :banghead:

Anyway, ignoring my original post, the Saft system would take twice as many batteries and space to provide the same Ah capacity. I'm not sure what the charge/discharge rate of the Saft system is compared to the GS Yuasa system and whether or not just doubling the overall Ah capacity to match would meet the energy charge and discharge requirements of the 787 in certain situations (such as an RTO shortly after using the batteries for engine start). We would also need to determine whether you could just put 28 cells together or would that impact the projected safety margins of the 14-cell battery. Same with charging and monitoring - can the existing 14-cell system scale to 28 or would you need to have two units per installation (and two installations per airframe). Then there is the physical installation of the system within the bay and how it connects to the rest of the power distribution system.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 1:32 am

Stitch wrote:
SheikhDjibouti wrote:
So let's say it again.... Boeing had no need to go with the volatile Yuasa cell design


Going with the Saft design would have required three times as many batteries to provide the same amount of Amp-hours (the 787 has eight 3.7V cells storing 72Ah where as the A350 has 14 3.6V cells storing 45Ah). The A350 battery weighs 30kg, so the entire package would be 180kg on the 787 (for two batteries) whereas the 787's battery came in at 57kg for the pair. While the subsequent changes to the 787 are said to have added 68kg to the system, it's still lighter than using the Saft system plus it takes up one third the space in the electronics bay.

Anyone know when Saft started work on their battery? I am guessing post-2006 when Airbus launched the A350XWB, which would have been years after Boeing had to select the battery design for the 787.

And on the topic of safety, Airbus argued to the FAA that their Li-Ion batteries did not require any additional containment beyond the same basic box the 787 started out with.


The A350 doesn't appear to have the 787's massive containment box, but it sounds like it is fully enclosed and vented like the 787's.

I see those specs repeated in various media outlets, but I'm not clear how you're calculating your weight comparison.
* Edit - I see the cross-posted responses. I'm keeping the below in place as how I interpret the specs.

The 787 battery specs are clearly known from the NTSB documents: 8 LVP65 cells at 72 Ah typical (rated 65 Ah minimum) with 3.7V average, for 2131 Whr per battery. There are two of these large batteries - one for the APU startup and one for emergency power for flight controls. There is also a smaller 7 cell LVP10 at 11.5 Ah typical (rated 10 Ah), located in the after electrical bay, for emergency power for electronic systems.

So the total battery capacity on the 787 is 4560 Watt-hours.

A350 battery details are harder to come by. This document claims the A350 battery is rated at 45 Ah at end-of-life, which if based on the usual criteria of 80% of rated capacity, means 56 Ah rated. It doesn't state the cell count, but if it really is 14 cells, then the voltage indicates it is in a 7 series, 2 parallel configuration, meaning each cell is 28 Ah.
https://www.dc-airparts.com/a350-lithiu ... H1_eng.pdf

14 x 28 Ah cells at 3.6 V, multiplied by 4 batteries is 5645 Watt-hours.

Those capacity figures are easily achievable in the weights mentioned, as they're only about 50 Wh/kg. The nice Panasonic NCR (I think lithium cobalt aluminum oxide cathode) batteries I use for flashlights are over 250 Wh/kg for the cell only - not including any extra casing, wiring, battery management, etc.

It appears to me there is more behind the A350 and 787 battery choices and Boeing's decision to stick with GS Yuasa despite their problems than is apparent from what has been disclosed so far.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 1:54 am

iamlucky13 wrote:
It appears to me there is more behind the A350 and 787 battery choices and Boeing's decision to stick with GS Yuasa despite their problems than is apparent from what has been disclosed so far.


I think most of it has been disclosed:

1) The 787 has higher electrical needs than the A350 and therefore needs higher capacity batteries.

2) The 787 uses electricity to power systems that the A350 uses hydraulics or pneumatics for. Some of these systems, like the brakes, are critical and require always-available power to ensure functionality when needed.

3) To that end, the 787 batteries need to be able to be quickly recharged to a level necessary to support those critical systems if discharged to support other functions. Example would be using battery power to perform an engine start then having to perform an RTO soon after.

4) To abandon the existing system would have required Boeing to re-develop and re-cerify at least the battery system and perhaps other parts of the electrical system. This could take significant time on a program that was already years behind schedule. And there was no guarantee those changes would have not caused their own issues.

5) Even with a system deemed less-likely to suffer thermal runaway, the FAA still wanted the A350's batteries to have more robust containment than the standard box EASA accepted. I'm not sure whether or not the FAA got their way, but at the time Boeing would have had to have a stronger enclosure because the FAA would have demanded it of them so they were going to need it whether they kept the existing GS Yuasa unit, switched to the Saft unit, or developed an entirely new unit.
 
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 2:11 am

Stitch wrote:
SheikhDjibouti wrote:
Let's just say I am going to be REALLY INTERESTED to see your alternative math!

Anyway, ignoring my original post, the Saft system would take twice as many batteries and space to provide the same Ah capacity.

Twice as many batteries (cells) does not equal twice as much space. But even if it did, how much space are we actually discussing here?
Image
Really? Is that it? Is that what we are arguing about? :lol:

So..... let's get back to the other bit of nonsense; what about the WEIGHT?
All through this thread, the main thrust was that Boeing made vital WEIGHT savings using this battery design.
I'm not asking just to embarrass you further; I genuinely want to know if my math was correct. Is the difference really just 45kg?

Stitch wrote:
I'm not sure what the charge/discharge rate of the Saft system is compared to the GS Yuasa system and whether or not just doubling the overall Ah capacity to match would meet the energy charge and discharge requirements of the 787 in certain situations.
These are fair questions.
(such as an RTO shortly after using the batteries for engine start)
There is an answer for that too, unless your B787 is flying to an unprepared third-world airport...... avoid using the batteries for start-up.
BTW, I thought the procedure was to start the APU from batteries, and then start the engines from the APU? . Surely the engine start from battery was only if the APU failed. Even then, the specs I have seen sound quite similar to the CCA requirement from my 12v lead-acid car battery. That would be a tall order for ordinary Li-Ion batteries, but these are not ordinary Li-Ion batteries. Please correct me if any of this is wrong.

We would also need to determine whether you could just put 28 cells together or would that impact the projected safety margins of the 14-cell battery. Same with charging and monitoring - can the existing 14-cell system scale to 28 or would you need to have two units per installation (and two installations per airframe). Then there is the physical installation of the system within the bay and how it connects to the rest of the power distribution system.
Yep, all good questions, all with relatively straightforward answers involving a (at worst) small loss of useful payload. A very small loss.

We've come a long way from those who answered me with comments that the 787 couldn't possibly manage with any alternative battery design. It's beginning to look more like a safer battery solution would have cost around one passenger having to give up one suitcase. :roll:
There are two things that happen when you get old.
1. You start to lose your memory.
2. What was I saying again?
 
DL757NYC
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 2:21 am

mjoelnir wrote:
neomax wrote:
This is an incredibly naive question, but if these new Lithium batteries are such a problem, why did Boeing switch to them and what did they use before?

They provide a higher power density at a lower weight. Other types of batteries have other problems.




And to operate more systems electrically rather than bleed. Like cars made today have electric steering as opposed to a power steering pump. Takes more of a load off the motor improving fuel economy and with bleee there was lots of plumbing so a weight savings also.
 
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Stitch
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Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 2:26 am

SheikhDjibouti wrote:
So..... let's get back to the other bit of nonsense; what about the WEIGHT? All through this thread, the main thrust was that Boeing made vital WEIGHT savings using this battery design.


The reason Boeing (and Airbus) went to Li-Ion in the first place was to save weight and maintenance costs compared to the Ni-Cd systems currently in use at the time. The 777's battery, for example, uses 20 24V cells with a weight of 48.5kg that provides 16A of power for airplane power-up compared to the 150A the Li-Ion system does. The Ni-Cd system used on the earliest A350s was said to add 60-80 kg compared to the Li-Ion system (the batteries themselves were only about 10kg heavier, so I am guessing the rest was associated equipment) and needed to be checked every 4-6 months compared to 24 months for the Li-Ion system.


SheikhDjibouti wrote:
I genuinely want to know if my math was correct. Is the difference really just 45kg?


I guess if all you need is twice the cells then I guess it is. But unless someone is able to perform a detailed analysis to determine exactly how much a Saft-based system would weigh compared to the GS Yuasa-based system for the same design conditions, we're in the realm of conjecture.
 
iamlucky13
Posts: 843
Joined: Wed Aug 08, 2007 12:35 pm

Re: Lithium-ion battery fails on UA 787 flight

Wed Dec 06, 2017 2:40 am

Stitch wrote:
iamlucky13 wrote:
It appears to me there is more behind the A350 and 787 battery choices and Boeing's decision to stick with GS Yuasa despite their problems than is apparent from what has been disclosed so far.


I think most of it has been disclosed:

1) The 787 has higher electrical needs than the A350 and therefore needs higher capacity batteries.

2) The 787 uses electricity to power systems that the A350 uses hydraulics or pneumatics for. Some of these systems, like the brakes, are critical and require always-available power to ensure functionality when needed.

3) To that end, the 787 batteries need to be able to be quickly recharged to a level necessary to support those critical systems if discharged to support other functions. Example would be using battery power to perform an engine start then having to perform an RTO soon after.

4) To abandon the existing system would have required Boeing to re-develop and re-cerify at least the battery system and perhaps other parts of the electrical system. This could take significant time on a program that was already years behind schedule. And there was no guarantee those changes would have not caused their own issues.

5) Even with a system deemed less-likely to suffer thermal runaway, the FAA still wanted the A350's batteries to have more robust containment than the standard box EASA accepted. I'm not sure whether or not the FAA got their way, but at the time Boeing would have had to have a stronger enclosure because the FAA would have demanded it of them so they were going to need it whether they kept the existing GS Yuasa unit, switched to the Saft unit, or developed an entirely new unit.


With regards to the first point, the calculations I'm suggesting indicate the A350 seems to actually have more battery capacity (or the capacity is being reported in an unconventional manner, and they're using batteries with terrible energy density).

Something to emphasize here is I'm pretty much certain the 787 batteries are not composed of 8 cells, each 9 Ah in capacity, at 3.7V, for a total capacity of 72Ah at 3.7V. Rather, they should be each 72Ah in capacity, for a total capacity of 72Ah at 29.6V. Likewise for the A350, they're not 3Ah cells totaling 45Ah at 3.6V (or 56Ah as I suggest in my post), but 45Ah cells (or again, 28Ah cells arranged 7s2p) totaling 45Ah at 25.2V.

Your remaining points are taken as is.

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