787 Batteries and Chargers - Part 2
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NTSB PARTICIPATING IN JAPAN’S INVESTIGATION OF B-787 BATTERY SMOKE EVENT
January 15, 2014
WASHINGTON – The National Transportation Safety Board will participate in the investigation of a smoke event involving the main battery of a Japan Airlines B-787 that occurred while the aircraft was parked at Tokyo’s Narita Airport on Jan. 14.
The investigation is being led by the Japan Civil Aviation Bureau. NTSB aircraft systems investigator Mike Bauer will travel to Japan to assist with the investigation.
All information regarding the investigation will be released by the JCAB.
Latest press release.
January 15, 2014
WASHINGTON – The National Transportation Safety Board will participate in the investigation of a smoke event involving the main battery of a Japan Airlines B-787 that occurred while the aircraft was parked at Tokyo’s Narita Airport on Jan. 14.
The investigation is being led by the Japan Civil Aviation Bureau. NTSB aircraft systems investigator Mike Bauer will travel to Japan to assist with the investigation.
All information regarding the investigation will be released by the JCAB.
Latest press release.
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airman1900: Your post had the correct text form of the link, but the URL behind the text pointed to the previously posted article.
For those who are less agile with their browsers, here is the correct link:
Boeing confirms new 787 battery problem in Tokyo - 1/14/2014 - Flight Global
For those who are less agile with their browsers, here is the correct link:
Boeing confirms new 787 battery problem in Tokyo - 1/14/2014 - Flight Global
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Serious issue pointing to BAD DESIGN
Hi,
Recent incident suggest:
1) Continued problems with battery charging "method"
2) Failure of thermal monitoring of individual cells (was implemented?)
3) Probable failure of voltage monitoring of individual cells (is implemented?)
4) Delay of monitoring. AFAIK smoke was visible BEFORE electronic alarms.
Smoking occur after cell abuse, mostly during charging.
A decent System can ABSOLUTELY avoid cell abuse.
The BAD Thales original design seems still present. "Murphy" is around the corner.
Parallel charging was not implemented? IMHO, would be the best option MAIN/APU Li batt. for airliners.
Recent incident suggest:
1) Continued problems with battery charging "method"
2) Failure of thermal monitoring of individual cells (was implemented?)
3) Probable failure of voltage monitoring of individual cells (is implemented?)
4) Delay of monitoring. AFAIK smoke was visible BEFORE electronic alarms.
Smoking occur after cell abuse, mostly during charging.
A decent System can ABSOLUTELY avoid cell abuse.
The BAD Thales original design seems still present. "Murphy" is around the corner.
Parallel charging was not implemented? IMHO, would be the best option MAIN/APU Li batt. for airliners.
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On "Redesign"
Is a Contained Problem a Solved Problem?
Boeing 787 Dreamliner: Ready for Takeoff...Again?
"But should you rush out to buy a ticket on a Dreamliner? Boeing admits that three months of rigorous testing failed to discover the source of the earlier battery fires. Is containing a problem the same thing as eliminating it?"
Boeing 787 Dreamliner: Ready for Takeoff...Again?
"But should you rush out to buy a ticket on a Dreamliner? Boeing admits that three months of rigorous testing failed to discover the source of the earlier battery fires. Is containing a problem the same thing as eliminating it?"
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Since no battery technology is 100% failure proof, I would have to say that mitigating the potential issues of fire, or damage to other systems in the electronics bay is a big step to making a Li-on battery failure on a 787 a manageable event.
Hopefully, more information as to what exactly the failure mode with this individual cell was in this event, will lead to future improvements in the battery and charging system.
Now I have a question for those with more in depth knowledge of the 787 electrical system. My limited understanding suggests that if the main battery on a 787 were to become unusable, the APU battery can be switched to the 28Vdc bus, providing a backup to the 787's main battery. I'm also under the impression that the APU battery is only used to start the APU on the ground when no other power source is available, and that an APU start when at least one of the main engines is running is done with power from the main engine generators. Am I correct in this thinking?
Hopefully, more information as to what exactly the failure mode with this individual cell was in this event, will lead to future improvements in the battery and charging system.
Now I have a question for those with more in depth knowledge of the 787 electrical system. My limited understanding suggests that if the main battery on a 787 were to become unusable, the APU battery can be switched to the 28Vdc bus, providing a backup to the 787's main battery. I'm also under the impression that the APU battery is only used to start the APU on the ground when no other power source is available, and that an APU start when at least one of the main engines is running is done with power from the main engine generators. Am I correct in this thinking?
No.
The APU battery starts the APU and supplies power to some external lights when towing on bat only.
It cannot connect to any DC bus.
The APU battery starts the APU and supplies power to some external lights when towing on bat only.
It cannot connect to any DC bus.
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Wonderful but critical (Li ion cells)
Indeed, the fix was an overkill. But we must learn thoroughly the issue and kill the causes, not just the consequences.
Certainly something improved in the charging/management of the batteries. The failure rate shows. And the "container" was not necessary. Til this case:
Question: Undetected parameter (electrical and/or thermal and suddenly, smoke and spill?
This sound as an indication of cell abuse. Certailnly when charging the battery.
Very suspicious of additional "room for improvement"
I strongly suspect now:
1) Lack of per cell thermal monitoring
2) Lack of per cell voltage adequate "processing".
My experience with these cells shows they are much more critical than other chemistries. Abuse notably during charging is unacceptable. What kind of?
Not proper thermal and voltage in a "per cell" basis.
Certainly something improved in the charging/management of the batteries. The failure rate shows. And the "container" was not necessary. Til this case:
Question: Undetected parameter (electrical and/or thermal and suddenly, smoke and spill?
This sound as an indication of cell abuse. Certailnly when charging the battery.
Very suspicious of additional "room for improvement"
I strongly suspect now:
1) Lack of per cell thermal monitoring
2) Lack of per cell voltage adequate "processing".
My experience with these cells shows they are much more critical than other chemistries. Abuse notably during charging is unacceptable. What kind of?
Not proper thermal and voltage in a "per cell" basis.
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Ana 787 at Takamatsu
TURIN,
Did you learn what kind of miswiring was detected?
Considering the lights you mentioned could be drive by the busses a miswiring could charge the APU batt bypassing the it´s dedicated charger.
The damage to the battery was impressive. Actually i "modeled" the equivalent circuit and posted the analysis.
I didn´t learn on findings in that case.
Like the Tokyo in the APU batt.
Did you learn what kind of miswiring was detected?
Considering the lights you mentioned could be drive by the busses a miswiring could charge the APU batt bypassing the it´s dedicated charger.
The damage to the battery was impressive. Actually i "modeled" the equivalent circuit and posted the analysis.
I didn´t learn on findings in that case.
Like the Tokyo in the APU batt.
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As every aero-modeller will confirm, when you discharge a Lithium Ion cell in minutes as opposed to hours, ( i.e. at a rate higher than 1xC ) it will get warm. The same applies for fast charging.
As the outside vent from the sealed box is sealed with a rupture plug, Is it true that the whole box has no natural or forced cooling air-flow? I have not been able to find any reference to a cooling system.
As the outside vent from the sealed box is sealed with a rupture plug, Is it true that the whole box has no natural or forced cooling air-flow? I have not been able to find any reference to a cooling system.
Probably a stupid suggestion!
My mobile phone stopped working up the hill today because of sub zero temperature, so I put it inside my jacket until it warmed up. Which made me wonder about possible transient temperature effects on the 787.
Now Li-ion is much less degraded by low temperatures than other chemistries, but it must still be temperature dependent to some extent. Assuming (!!) the charging voltage is adjusted down as the temperature drops, then it would also be adjusted back up as the temperature recovers on descent and landing. But not every area of every cell will be at the same (transient) temperature as the relevant sensor at all times. If this temperature discrepancy exceeded the built in "safety" margins, then over voltage could be applied in some local area(s), leading to damage, and failure becoming apparent after landing.
Of course, the reverse temperature changes occur on take off and climb, but maybe the margins are deliberately greater in that phase, to minimise the probability of an in flight problem.
And I know that I don't know what I'm talking about, so it is more of a question than a suggestion.
Now Li-ion is much less degraded by low temperatures than other chemistries, but it must still be temperature dependent to some extent. Assuming (!!) the charging voltage is adjusted down as the temperature drops, then it would also be adjusted back up as the temperature recovers on descent and landing. But not every area of every cell will be at the same (transient) temperature as the relevant sensor at all times. If this temperature discrepancy exceeded the built in "safety" margins, then over voltage could be applied in some local area(s), leading to damage, and failure becoming apparent after landing.
Of course, the reverse temperature changes occur on take off and climb, but maybe the margins are deliberately greater in that phase, to minimise the probability of an in flight problem.
And I know that I don't know what I'm talking about, so it is more of a question than a suggestion.
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We discussed already some time ago the temperature range recommended by the cell manufacturer compared to the temperature range an aircraft operates in. It looks like nobody has reliable data about the temperature in the electronics bay of a transport aircraft. Especially no data about the regularly experienced temperature cahnges, the extremes when parked in Sibiria overnight or in Dubai on the tarmax at noon with all electronics running is quite predictable, but the temperature range in the electronics bay during a typical moderate climate to moderate climate (via frosty stratosphere) flight seems to be widely unknown.
Which is strange, as other high performance battery applications even have full temperature control (cooling and heating), for example the Antares motorglider or hybrid cars. Typically the energy used for heating is smaller than the increase in battery capacity with temperature, so you win available energy by spending some on temperature control. KISS can sometimes make you keep something too simple...
The 787 Batteries have no cooling system.
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JTSB Final Report on ANA JA804A incident
The JTSB has issued their Final Report on the ANA JA804A battery incident.
