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787 Batteries and Chargers - Part 2

Thread Part 1 starts here.

Just to get the continuation rolling, so people realize it is open....

Welcome to Part II.

Machaca:

Quote:

It is my understanding both transcripts and videos of all the sessions will be available next week on the NTSB website.

But that will be without the totally hilarious captioning/transcription errors you got from the "live" feed.

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Line 375:
YOU WILL NOTICE IN MY PRESENTATION, WHEN YOU SEE IT ON THE DOCKET, THAT I HAVE INFORMATION FOR BOTH LIVE IN MY AUNT AND METAL BATTERIES. -- FOR BOTH LITHIUM AND METAL BATTERIES.

Actually "For both Lithium-ion and metal batteries."

There is also some good stuff, like this, which pretty well lays to rest all of the speculation about the effect of electrolyte combustion and the contribution of the oxygen liberated within the battery electrode (which is small enough to combust only a very small fraction of the electrolyte):

Quote:

WHICH THEN GOES BACK TO DR. CHIANG'S POINT. IF YOU ENGINEER A SYSTEM THAT HAS NO OTHER AVAILABLE OXYGEN, YOU TAKE AWAY THAT HEAT SOURCE, THAT ENERGY SOURCE, WHICH IS ROUGHLY, IN A GIVEN CELL, THE COMBUSTION ENERGY OF THE ELECTROLYTE IS 1 TO 2 TIMES THE ENERGY THAT IS CONTAINABLE IN THE CELL. IT IS NOT A SMALL AMOUNT. THOSE ARE MY TWO COMMENTS.

So the firebox will reduce the worst case catastrophic energy release by a factor of two or three, in addition to containing it.

Also, a very nice sequence on the choice of Li chemistry:
(ITALIC text is my insertion.)

Quote:

Starting at 319:
>> UNDERSTANDING THAT EVERYTHING THAT WE DO HAS SOME RISK IN IT, ARE THERE CERTAIN LITHIUM-ION CHEMISTRIES THAT HAVE BEEN DETERMINED TO BE UNSUITABLE FOR CERTAIN APPLICATIONS AS FAR AS RISK LEVEL?

>> I DON'T THINK THAT QUESTION LEADS TO A PRODUCTIVE RESULT. TO BAN A CERTAIN TYPE OF THEM ASTRAY. -- TYPE OF CHEMISTRY.

>> NOT NECESSARILY BANNING. CHOICES PEOPLE HAVE MADE FOR A CERTAIN ENVIRONMENT. FOR EXAMPLE, ON A SUBMARINE, ON AN AIRCRAFT CARRIER, OUT ON A SATELLITE, ARE THERE CERTAIN CHEMISTRIES THAT HAVE BEEN RULED OUT THE CAUSE OF THEIR RISK?

>> WHEN WE WERE TESTING MODULES, WE WOULD IT MODULES WITH A " SAFER CHEMISTRY" AND ONES WITH A MORE DANGEROUS CHEMISTRY IN THE CELLS. THE PERFORMANCE OF THE MODULES DIDN'T FOLLOW. THE CELLS THAT WERE DEEMED SAFER AT THE MODULE LEVEL PERFORMED WORSE. SO I WOULD ADVISE A COMPREHENSIVE AND THOUGHTFUL TESTING PROGRAM AND NOT WORRY ABOUT WHAT THE CHEMISTRY OF THE CELL IS.

>> I WOULD COMPLETELY AGREE. I THINK THE IMPORTANT REASON TO SAY THAT IS I CAN BUILD A COBALT, A HIGH CHARGED COBALT CELL INTO A MODEL THAT MAY NOT FAIL AND COULD WEIGH A TON. SO I CAN MAKE THAT BATTERY IN PHOSPHATE AND IT MIGHT WEIGH FIVE POUNDS. SO THE SAFETY REQUIREMENT OF THE APPLICATION, WE WILL HAVE TO GIVE YOU THE LIGHTEST, MOST COST-EFFECTIVE SOLUTION. BUT YOU, THE USER, CAN SAY I WILL NOT TOLERATE THIS. I CANNOT ACCEPT THAT. THIS IS A FAILURE. THE NAVY PROGRAM HAS DEVELOPED A VERY CLEAR YOU CANNOT PUT THIS ON OUR SUBMARINE IF IT DOES THESE THINGS. THAT WILL DRIVE US TO CHOOSE THE SYSTEM DESIGN, INCLUDING CHEMISTRY AND EVERYTHING, TO DELIVER WHAT THEY WANT. BUT TO DECIDE THAT A CHEMISTRY CANNOT WE USED IS LIKE TRYING TO SOLVE A PROBLEM WITH THE FIRST GRAIN OF SAND.

>> WITH RESPECT TO APPLICATIONS, THE CHEMISTRY IS IMPORTANT IF YOU WANT A VERY HIGH RATE APPLICATION. WE WOULD CERTAINLY GO WITH LIKE A SPINNER (spinel?) OR A PHOSPHATE TYPE OF CHEMISTRY. IF YOU ARE NOT LOOKING FOR HYBRID (higher?) PERFORMANCE, THEN WE WOULD GO WITH [INDISCERNIBLE] SO I THINK WE WOULD GO WITH THAT MORE THAN THE SAFETY OF THE CHEMISTRY.

>> LIKE WISE. I THINK THE SAME WESTERN (question) -- ARE THERE SITUATIONS WHERE BATTERIES HAVE BEEN REPLACED BECAUSE OF THE FAILURE RISK BEING TOO GREAT? HE YOU HAVE AN ANSWER TO THAT?

>> NOT WITH RESPECT TO LITHIUM- ION. BUT WE HAVE REPLACED CHEMISTRIES LIKE LITHIUM PCX. WE DID NOT HAVE A GOOD REFLECTION OF WHAT THE ACTUAL ENVIRONMENT WOULD BE. FOR INSTANCE, IN THE ARBITER (orbiter), WE WANTED TO PUT IMPACT SENSORS ON THE WING SO WE COULD UNDERSTAND WHAT WAS GOING ON. AND IF AN IMPACT OCCURRED. SINCE WE DID NOT UNDERSTAND THE ALIGNMENT OF THE TEMPERATURES, WE ACTUALLY REFUSED TO ALLOW THEM TO USE THE BCX CELL BECAUSE OF IT BEING EXPLOSIVE. SO, YES, BUT NOT WITH RESPECT TO LITHIUM-ION.

Some additional test flights?

Arguably this is more relevant to the 787 grounding issue than specifically to the batteries and chargers issue, but I noticed on FlightAware several reported flights reported as 787 flights operating under the ID BOE5 out of San Bernardino International in the last few days.

The FlightAware link for BOE5 is:

Boeing #5 Flight Tracker ? FlightAware

While I've seen seeing a small number of apparently spurious taggings of flights as 787 flights for weeks (mostly presumably false data-entry on ANA Frankfurt-Haneda operations) these KSBD flights seem plausible.

In BOE5 flights listed as of the moment of my posting, there appears to have been a positioning flight from Boeing Field to San Bernardino on April 13, with subsequent daily or more flights out over the ocean in a generally SSW direction. The tracking data seem erratic, possibly partly because of the over-ocean positions.

My guess is that these are real 787 flights. Does anyone know more?

Arch,

Made a few inquiries on BOE05...

ZA005 is in San Bernardino conducting testing to demonstrate the performance of engine improvements provided by General Electric.
GE’s second package of upgrades for the 787’s GEnx-1B engine was certificated by the FAA on April 12. That’s engine-only certification.
This week’s San Bernardino flight tests are working toward the certification of the upgraded engine and plane together.

The NTSB just released the agenda for the April 23/24 hearing on the 787 Battery.

Investigative Hearing Agenda Japan Airlines, JA829J Boeing 787 Battery Fire
April 23-24, 2013

It seems odd that the press is currently reported that the FAA will sign-off on the battery fix today...

Press Release – FAA Approves Boeing 787 Battery System Design Changes

Press Release ? FAA Approves Boeing 787 Battery System Design Changes

The FAA will publish next week the final directive that will allow UA to resume operations of the 787. It is expected other regulatory agencies will follow shortly to allow the 787 to resume services worldwide.

Well, this will certainly make some some entertaining conversations at the hearings next week...

So how reliable is the modified battery expected to be now if there is still no root cause detected?

More reliable than the previous design but how much more reliable will only be revealed after some time in in operation has passed.

Some of this increase in reliability will unfortunately be masked by better working practices on the ground, which seems to have been a major cause of batteries going 'low' and having to be replaced.

SoS

Speed of Sound

Quote:

More reliable than the previous design but how much more reliable will only be revealed after some time in in operation has passed.

Unfortunately, that's not going to do any good. Reliability numbers out around one event per billion flight hours aren't generated by service history. Or we'd all still be flying Wright Flyers. These are based upon analysis of first principles of the physics and engineering involved together with studies of how defects or tolerance errors do or do not lead to subsequent failures.

Unfortunately, a bit of service history can do wonders to :mad: up that original analysis. And waiting for statistical samples to set those numbers right again just isn't in the cards economically.

Boeing (Thales, GS Yuasa, etc.) are going to have to trace these failures back to that mysterious root cause and put in place a plan and process to eliminate it. Only then do they get to go back to a clean sheet of paper, reliability wise.

Yes, there will be an overhaul of the manufacturing process to eliminate contaminants, for example. But until the presence of contaminants in statistically significant samples of existing production runs can be shown, that's just guessing at the cause and the efficacy of the fix.

Well, the hearing is currently ongoing...

from the FAA:

"THERE WAS A REQUIREMENT TO TEST THE BATTERY TO INDUCE THAT CATASTROPHIC THERMAL RUNAWAY FROM MR. SINNETT DESCRIBED TO SEE WHAT HAPPENS. WELL, AN ALTERNATIVE APPROACH, RATHER THAN TO SEE WHAT HAPPENS, IS JUST DECIDE, IT IS CATASTROPHIC, WE MUST PREVENT IT. THERE IS NO NEED TO TEST A CATASTROPHIC CONDITION. YOU ALREADY HAVE ASSUMED IT'S CATASTROPHIC. YOU JUST PREVENT IT."

In a nutshell, it appears that the FAA doesnt care about testing, thermal runaway, or the cause..they assume that all of that is a catastrophic failure, so you dont even really need to test for any of this.
The catastrophic failure simply needs to be contained, hence the lifting of the flight restriction with a better box.

Both the FAA and Boeing said that neither event had an effect on the aircraft...

The venting of the EE bay was an odd response from Boeing. The system has to detect the smoke first (or in their explanation, the 'odor') then the system has to re-configure to vent to the outside, and this takes time to do, so there will be 'odor' into the aircraft.

I know, I know...there was never any fire, there is never any smoke. :suspect:

Airplanes have outflow valves, sink drains, and various other holes that already vent to the outside. All another vent will do is allow the outflow valves to close a bit more...

Just out of interest, whilst carrying out some research on Li-ion cells for EV's last year, i had a couple of occurrences of thermal incidents.

i actually found the root cause to be back EMF spikes from the electronics i was using, and that it could set up a frequency resonance making the cells "pant" until internally breaking down and letting the "odour" out.

Just thought i'd share that with you.

GB.

Bye,

That is interesting because the last speaker was saying that the continued focus on the event would be on the grounding system of the aircraft, how it is isolated and related.

Another good question to Thales was why is the system meant to protect the battery, the BMU, located inside the case with the battery cells themselves.

Query to GS Yuasa:

Quote:

>> OKAY, THANKS. JUST FOLLOW UP ON THAT. HAVE YOU HAD IN THESE PARTICULAR DESIGNS, HAVE YOU SEEN ANY EVIDENCE PRIOR TO THE INCIDENT OF ANY INTERNALLY SHORTED CELLS?

>> NO.

>> THANK YOU.

When asked about the BMU's location, Thales responded that the closer the BMU is to the cells it is monitoring, the better.

When asked if there was any benefit to having the BMU external to the containment vessel, Thales responded that the BMU is isolated somewhat from the cells themselves in the containment vessel (even more so, now, in the new design) and they felt that having the BMU inside the containment box was the logical way to proceed because it prevented a failure risk due to connection problems.

The decision to place the BMU in the containment box was made by Thales and GS Yuasa.

EDIT: Thales is recapping their statement and noted that the BMU has thermal disconnects so it sounds like even if the cells enter thermal runaway and damage the BMU, these disconnects would trip and kills electricity flow to and from the cells in the battery pack.

52 bolts for the lid, 51 more to go..take one down, pass it around...

http://boeingblogs.com/randy/images/AOG-story-2.jpg

EDIT: Dont know about you guys...but since one uses the bolt head to tighten (and measure torque), not the nut...that hes got the bolts in bassackwards....(the ones on the bottom are really going to suk trying to tighten....)

I think there may be a typo in the article "NTSB hearing on 787 batteries reveals Boeing shift on testing", by Stephen Trimble Washington DC, linked below:
NTSB hearing on 787 batteries reveals Boeing shift on testing

Where the article says, "In neither incident did the battery failure prevent a risk to the overall aircraft, ...", I think it should say,"In neither incident did the battery failure present a risk to the overall aircraft, ..."

[I see that this typo has now been corrected.]

I watched the entire proceedings and indeed on multiple occasions testimony was given, including by Mr. Bahrami, that neither NH692 nor JL8 was at risk of hull loss so yes, that is a typo.