Design Article
Boeing claims new enclosure will stop battery fires
Charles Murray
3/15/2013 2:43 PM EDT
The Boeing Co. took the issue of 787 battery fires head-on last night, definitively declaring that with pending modifications to its lithium-ion battery packs, a "fire can't begin, develop, or be sustained."
Speaking at a technical briefing in Tokyo that was broadcast live on the Web, Boeing executives defended the performance of the embattled 787 batteries in recent overheating incidents, and added that its engineers have strengthened the design of the packs with a number of technical enhancements. Most important, they said, is the addition of a new enclosure that prevents fires.
"I want to be very, very clear on this point," said Mike Sinnett, vice president and chief engineer of the 787 program. "This enclosure keeps us from ever having a fire to begin with. That's the number one job of this enclosure. It eliminates the possibility of fire."
Click to read the rest of this article on Design News.
Speaking at a technical briefing in Tokyo that was broadcast live on the Web, Boeing executives defended the performance of the embattled 787 batteries in recent overheating incidents, and added that its engineers have strengthened the design of the packs with a number of technical enhancements. Most important, they said, is the addition of a new enclosure that prevents fires.
"I want to be very, very clear on this point," said Mike Sinnett, vice president and chief engineer of the 787 program. "This enclosure keeps us from ever having a fire to begin with. That's the number one job of this enclosure. It eliminates the possibility of fire."
Click to read the rest of this article on Design News.
|
|
|
|
|
Navigate to related information
Bert22306
3/15/2013 3:19 PM EDT
When the NTSB had still not finished its investigation or found anything new, on the same day that the fix was going to be described, I guess it isn't surprising that the fix is designed to limit the symptoms rather than to get to the root cause of these thermal runanway events.
Sign in to Reply
SRS Prabaharan
3/20/2013 11:25 PM EDT
Yes, you are absolutely correct. I am sure it takes longer time to test C-rate capability of SAFT supplied Li-Ion batteries. It could be due to internal cell components such as the electrolyte and the anode used. The solution is not a permanent fix to forget the problem. The problem is huge meaning that thermal run away could completely jeopardize the safety. The two batteries (each 32 volt) placed one each for the front on-board control and another one is at the back as auxiliary back-up unit. I believe Dreamliner uses these batteries during taxing and it seems that it over discharges (beyond its DOD capability) and hence the thermal runaway. Hence, the inherent design fault must be identified before being declared “the problem fixed”! The 68kg SS casing is not the absolutely at all. It could be fatal at times even they have a venting in 1.5 sec. Also, the ceramic insulator between cells might be a extrinsic fix to this serious issue.
Sign in to Reply
green_is_now
3/21/2013 3:45 PM EDT
If they are charging to 32 volts instead of 28 volts?
Do these battery charge contollers have overvoltage protection?
Current limit and voltage level control?
If yes why the failures?
Has someone added backup data collection to see if ay on board capture is valid? (or to havef none)
Sign in to Reply
SRS Prabaharan
3/20/2013 11:29 PM EDT
Yes, you are absolutely correct. I am sure it takes longer time to test C-rate capability of SAFT supplied Li-Ion batteries. It could be due to internal cell components such as the electrolyte and the anode used. The solution is not a permanent fix to forget the problem. The problem is huge meaning that thermal run away could completely jeopardize the safety. The two batteries (each 32 volt) placed one each for the front on-board control and another one is at the back as auxiliary back-up unit. I believe Dreamliner uses these batteries during taxing and it seems that it over discharges (beyond its DOD capability) and hence the thermal runaway. Therefore, the inherent design fault must be identified before being declared “the problem fixed”! The 68kg SS casing is not an absolute remedy at all. It could be fatal at times even they have a venting in 1.5 sec (SS metal enlosure). Also, the ceramic insulator between cells might be an extrinsic fix to this serious issue.
Sign in to Reply
Duane Benson
3/21/2013 1:31 AM EDT
All of the items listed seem like reasonably things to do, but they also come off like bandaids being tried out to compensated for a bunch of potential unknowns. I really do hope it works, but it sounds like they are grasping at straws (even if logical and sound straws).
Of course the biggest red flag to me is the statement: "It eliminates the possibility of fire." While it may be accurate, those kind of absolutes are just waiting be be disproved.
Sign in to Reply
green_is_now
3/21/2013 3:20 PM EDT
Burning battery inside of fireproof inclosure that has high pressure strength works fine until it doesn't hold the pressure, then its called something else.
Sign in to Reply
green_is_now
3/21/2013 3:30 PM EDT
Rather what needs to be thought out is:
What conditions are causing an unsafe condition?
What addigtional hardware can mitigate the source of the problem. what if its not the batteries fault?
WHat whachdog, redundant system, or combination failure and/or the intput to both sytems failed.
What recording-data recording is done to capture abnormal conditions?
If not cooked in to design, why not?
If not what data recorders have been used in testing since the grounding of the fleet?
What dv/dt and differential voltages in real time are the batteries seeing?
do the batteries have reverse voltage protection
Wat happens to the battery current and voltage during a lightning strike?
In the air?
On the ground?
without equipment?
with equipment hooked up?
What happens when the batteries are being charged and the plane is hit with lightning?
(With and without equipment hooked up.)
Sign in to Reply
green_is_now
3/21/2013 3:31 PM EDT
Let me make this clear, you start with questions not PR statements
Sign in to Reply
green_is_now
3/21/2013 3:37 PM EDT
If the Boeing plane is locked into 7 year old battery designs via certification...
This begs the question,...Why not use a newer battery design when it reaches a critical level of improvement (may be now.
Or at least start and put in place the plan to use and help develop a better battery.
The DOE is funding better batteries for electric vehicles. There is no reson this is not 100% aligned with the avionics industry needs of a safer, lighter, better battery.
Sign in to Reply
green_is_now
3/21/2013 3:40 PM EDT
If Boeing starts cerifing better available batteries over time then they can be cut in sooner, shortening any potential safety issues with continued use of older technology batteries like being use now on the 787.
They need to put in better safety systems to use the existing batteries to fly now and stop the bleeding.
But it needs to be the right solution.
Sign in to Reply