Electronics & Test
Were the Boeing 787 Batteries Cooled Properly?

An NTSB engineer examines the casing from the battery involved in the JAL Boeing 787 flight in Boston.   (Source: NTSB)
An NTSB engineer examines the casing from the battery involved in the JAL Boeing 787 flight in Boston.
(Source: NTSB)

Return to Article

View Comments: Newest First|Oldest First|Threaded View
<<  <  Page 3/6  >  >>
William K.
User Rank
Re: Don’t jump into conclusions
William K.   1/29/2013 10:16:52 AM
Ervin is quite right! Besides that, any design that required active cooling for reliable operation would be a very poor choice in a situation where reliability and safety are top priority. Just look at the Japanese nuclear plant failure as a verification of that concept! 

In addition it is certain that the folks at Boeing had verified that the design had an adequate margin of safety. So that would put the cause of failure in the supplier quality area, which, as has been reported quite a few times in Design News over the years, has been one of the ongoing problems with the project. Unfortunately, just because we have provided detailed and adequate specifications for items to be provided by suppliers does not assure that those specifications will always be met.

User Rank
Cabin Altitude
Critic   1/29/2013 9:58:14 AM
Cabin altitude (internal cabin pressure at altitude) for the 787 is 6,000 feet maximum.  Plane cabins are not usually pressurized to sea level at altitude because of the stress on the airframe, although there is a trend to increase cabin pressures.  8,000 feet cabin altitude is generally the minimum pressure. 

User Rank
Don’t jump into conclusions
ervin0072002   1/29/2013 8:19:19 AM
I like how everyone is assuming that active cooling is needed (and they seem confident about this.) However nowhere in the article is there a statement of current input or current output. We do not know the amount of power going in or out and cannot make an educated guess if active cooling is needed. I am sure if they were drawing a few W's an hour out of that battery the sheer size alone will handle cooling.  There is a sentence that states that current input and output is controlled which leads me to believe that the battery had sufficient cooling.

Any equipment that goes into a plane is tested for thermal cycles. Not saying this one was only reviews of the reports can prove that. But I will be surprised if it was an engineering flaw and it had anything to do with cooling. If I took a guess it would have to be the rest of the electrical system has a fault. it could be one item or multiple items.

However on a project of this scale and expense and complexity it would be wise to not guess and wait for the investigators to do their job and inform the rest of the world what the problem is.

User Rank
Re: Batteries were bought as off the shelf!! COTS!!!!!
nelso7926   1/28/2013 11:20:35 PM
Paul I am far more optimistic on this one! I simply cannot believe that Boeing who has lived by the  DO 254 credo for the better part of its existence could ever opt for standard COTS without rigourous climatic testing to verify the specs were met or exceeded.  This would constitute a watershed in unacceptably poor risk management and I am not prepared to take away the benefit of the doubt, at least not just yet.  If you are correct then we can both share the same kleenex in a corner, but I simply cannot believe that scenario.

User Rank
Re: Were the Boeing 787 Batteries Cooled Properly
edsparks3   1/28/2013 10:21:17 PM
I've always assumed that large commercial aircraft capable of cruising at high altitudes had some way of boosting cabin pressure, and if so why not go to full atmospheric?  But in my experience, pressure does noticeably increase during a descent (ear problems), so you may be right, it's allowed to drop well below atmospheric.  Even so, vibration is still the logical culprit. 

User Rank
Re: Were the Boeing 787 Batteries Tested Properly
EdParnagian   1/28/2013 10:07:49 PM
Yes, the analysis needs to examine undamaged batteries from the same manufacturer and date code. Preferably samples that have already seen some use. In my own experience with medical devices - yes they need to be highly reliable as well - battery manufacturers want to offer their standard processes even for custom batteries. The problem here is that they want you to take RoHS compliance and No-Clean solder systems. This leads to unreliable circuitry when exposed only to thermal and humidity cycling. Add stress associated with a high vibrational environment and the reliability slips even lower. I'm certain that Boeing did a lot of testing and much of it done in parallel in an attempt to minimize schedule slip. Unfortunately, some problems only reveal themselves when certain of the stressors are tested in series - just as they are experienced in the real world and under electrical load. The other aspect of testing that is critical here is the pass-fail criteria. Simply meeting operating specs isn't good enough at this point. The investigators need to gently disassemble the units and along with everything else examine the circuitry under 20x to 40X magnification looking for the beginnings of electrochemical issues such as surface salts, dendrites and the more difficult to detect, tin whiskers. You will be hard pressed to find a component these days that doesn't have pure tin on the leads. A problem like this rarely has a single cause. To or more corner case conditions must come together in just the right way. This is why serial testing of multiple assemblies under operational load is necessary.

Paul Murk
User Rank
Batteries were bought as off the shelf!! COTS!!!!!
Paul Murk   1/28/2013 7:13:12 PM
From My earlier comment on these Lithium batteries, I want to hear from Boeing that these batteries are not COTS purchased batteries from the CLINTON era for purchase COTS to save money... Off the shelf devices DO NOT WORK ANYWHERE except on earth in a typical building.  Now I want to see evidence that these batteries went through some BOEING testing and was accepted as properly built components worth of aircraft flight for 20 years in service. I bet they dont have that information available and this gets settled out of court with Uncle Sam!!

User Rank
Re: Design Decisions
williamlweaver   1/28/2013 6:40:05 PM
I share your scary thought, Chuck. I will always give Scientists and Engineers the benefit of the doubt, but as we are remembering the 27th anniversary of the loss of the Challenger's Crew today, sometimes margins of risk get bundled together into an "acceptable flight risk". Not suspecting anything nefarious, but with such a complex system, sometimes it is only possible to rank relative risk in hindsight.

User Rank
Re: Design Decisions
bobjengr   1/28/2013 5:18:45 PM
nelso7926, I agree completely.  No injuries and certainly no fatalities.  I'm sure Boeing has tested and retested this system so I would certainly hope the issue is inadequate cooling and not the lack of cooling.    With that being the case, are all of the failures on the ground?  Are any experienced in flight?   Also, can anyone tell me if there are redundant systems for this device?  I don't think so but do not know. 

Charles Murray
User Rank
Re: Were the Boeing 787 Batteries Cooled Properly
Charles Murray   1/28/2013 5:13:22 PM
What is the atmospheric pressure inside a commercial aircraft, edsparks3? I believe I've always heard 2/3rds of an atmosphere.

<<  <  Page 3/6  >  >>
Partner Zone
Latest Analysis
When you think of the DARPA Robotics Challenge, you may imagine complex humanoid contraptions made of metal and wires that move like a Terminator Series T-90. But what actually happened at the much-vaunted event was something just a bit different.
The machine is claimed to be the largest and most powerful electric pipe-bender on the market, exerting nearly 500,000 lb-ft of torque.
Traditional dev kits are based on a manufacturer’s microcontroller, radio module, or sensor device. The idea is to aid the design engineer in developing his or her own IoT prototype as quickly as possible. A not-so-traditional IoT development kit released by Bosch aims to simplify IoT prototyping even further.
This consulting firm has put together a report detailing the growing biomimicry design field in the US and around the world, from naturally bacteria-repelling surfaces to keratin-inspired polymers.
Here's a list of engineering and tech jobs ranked by outlook, work environment, stress, and income.
Design News Webinar Series
1/28/2016 11:00 a.m. California / 2:00 p.m. New York
12/8/2015 11:00 a.m. California / 2:00 p.m. New York
2/18/2016 11:00 AM PT | 2:00 PM ET
2/24/2016 11:00 AM PT | 2:00 PM ET
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Jan 11 - 15, Designing ARM Devices Using Segger Tools
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6 |  7 | 8 | 9

Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2016 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service