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Phil Pearce
User Rank
Silver
Re: A Safe Solution
Phil Pearce   3/21/2013 12:10:08 PM
NO RATINGS
I have not claimed that this is just a new battery management algorithm.

I assume from your reference to 'the system that is already incorporated in the Dreamliner and Chevy Volt etc.' that you are referring to a typical battery management system which at best only monitors voltage, temperature, and current conditions of the battery. These devices although offering some protection are still unable to detect instability at an early stage and are unable to detect  the deformation such as the ballooning or swelling of the battery cells that occurs prior to and during the  condition known as "Thermal Runaway".

The system I refer to is able to detect and protect at an early stage from the potential dangers caused by the volatile nature of lithium-based battery cells by measuring and monitoring any changes, in a 3 dimensional space, the physical dimensions of one or more of the battery cells within the pack.  This dimensional deformation which leads to ballooning or swelling of any of the unstable cells within a battery pack is detected before Thermal Runaway and combustion of any cell occurs.

GuidoBee
User Rank
Iron
Li-Ion battery options
GuidoBee   3/21/2013 12:00:36 PM
NO RATINGS
I am in agreement with VGM's comments on the histories of batteries / battery technologies.  I was involved with USN and USAF aircraft, specifically as an aircraft electrician (AF) and, for a short time, worked in battery charging and testing work centers.  Li-ion was not much on the horizon at that time.  We were using lead acid and Ni-Cad at that time (1966-1970's). Some were large: an 80 lb Nicad is a handfull, even when it is at normal temperatures. 

In our NiCad battery shop we had a large trash can nearly full of water.  The procedure was to pick up an thermal run-away Ni-Cad and drop it in there (also aprons, face shields, and heavy thermal protective gloves).  This was on a USN ship, and ships move, so think about moving around with a heavy battery that is overheating, on a moving deck and possibly a wet floor.  This in a shop full of calibrated test equipment made to evaluate the condition of the battery systems.  If you don't have full control over batteries in that environment in a more sophisticated fashion than a water bath, we need to think acknowledge the risks and reliability and how we deal with them.  The water barrel is not much of an option at FL 380 (38,000' in the air).   And this was not the dark ages, it was 1988. 

For a good link to aircraft related battery issues (mostly they are small batteries, but of pretty much all types), see links:  http://www.faa.gov/about/office_org/headquarters_offices/ash/ash_programs/hazmat/aircarrier_info/media/Battery_incident_chart.pdf

Also:  http://www.skybrary.aero/bookshelf/books/587.pdf 

All battery systems have their problems, plus most of them are heavy and contain aggressive electrolytes and various other toxic materials.  Overheating these compounds does not help the situation, especially in a confined area.

Just my $0.02 worth; it's about learing curves: (1) Boeing and the PR flacks (trying to paint the prettiest face on it) pressured by the accounting department, and (2) would be how we get smarter when newer technologies enter operating environments.  At the bottom of all this is how risk fits into both the discussions: probability of really getting to Zero risk is as unlikely as it will be expensive. 

Sorry for the long-winded post. 

jlawton
User Rank
Gold
Re: "Danger, Danger..."
jlawton   3/21/2013 11:27:53 AM
NO RATINGS
One minor correction, the "more electric" aircraft architecture was really designed to avoid the use of engine "bleed air" which a previous generation of engineers had come to rely on as "free power" particularly on competitive commercial aircraft. If you really get down to splitting hairs though nothing is REALLY free. (The primary reason I'm correcting you is even some of the new aircraft architectures have shaft-driven hydraulic pumps but they're primarily there as a backup in case the entire electrical system were to go down.) Other than that I find that your analysis is pretty much "spot on".

CLBrown
User Rank
Iron
Re: A Safe Solution
CLBrown   3/21/2013 11:09:20 AM
NO RATINGS
Phil,

You can't claim that there's a "new" battery management algorithm which somehow "magically" prevents any risk of what is, frankly, a matter of natural laws.  Batteries, like all real physical objects, do not behave in "binary, digital" ways.

People have been developing battery-management systems (BMS) for as long as there have been batteries.  The BMS is at the core of EVERY battery installation out there.  Your iPhone has a "BMS on a chip" to prevent overcharging of the device (which would result in battery overheating, and thus failure).

To claim that there is a "new" ELECTRONIC MONITORING SYSTEM which somehow can overrule the basic laws of physics is.. naive, at best.  The ability to bypass cell blocks which are showing signs of deterioration is a RISK REDUCER...  and it's one which has been in use for many, many years.  This is a large part of what any BMS system does, after all.

You can "reduce risk" by the use of this sort of monitoring and bypassing scheme.  But every major battery manufacturer already does this, and I doubt, very much, that Boeing bought a battery system without a very robust BMS system as part of it.

And no BMS system can PREVENT failures.  It only reduces the "occurance" number... it can't reduce it to zero.  Severity remains high...  detection risk remains high...  all you can do is handle "occurance" and you do that by having extra banks of cells beyond what you "really" need, and having the ability to switch off banks, or modules, IF you detect electrical or thermal precursors to failure.


And that's something that was already part of the system on the Dreamliner... and on the Chevy Volt... and on and on and on...

ScotCan
User Rank
Platinum
Re: "Danger, Danger..."
ScotCan   3/21/2013 10:52:33 AM
NO RATINGS
No debate needed....you've covered most everything that needs to be said. 

TunaFish#5
User Rank
Gold
Re: Unsinkable
TunaFish#5   3/21/2013 10:45:13 AM
NO RATINGS
@dpccreating:  absolutely.  In fact, the same term came to mind to me, too, and it didn't involve Molly Brown.

I had a post written up to this point right after the article came out, but I killed it (my post.)  There've been so many highly competent & experienced engineers on these 787 threads, I just shied away from being the first.

My angle:

The correct solution is not fire avoidance.  Unless you change chemistry or maybe do a major mechanical reconfig, the best you can do is Fire Control.
  1. Manage risk to increase "probability of no fire" out to so many '9's.
  2. Construct an onboard environment to handle the fire.


ScotCan
User Rank
Platinum
Re: Unsinkable
ScotCan   3/21/2013 10:39:57 AM
NO RATINGS
Having worked for over 30 years with some of the biggest names in industry mostly in startup operations, you're correct. When they are a modest size marvellous engineering happens...it's like one big family forging on to a promising future, then when they get bigger all sorts of cowboys (and cowgirls!) swagger into the organisation and create all sorts of mischief.

There's a recurring theme. At start up even branch plants need engineering people who know something about the product and technology with which they are dealing, then when the company grows a clutter of MBA's comes in throwing their weight around and invariably crowing that they don't need to know anything about the technology they only need to know how to manage people. Some of their braying would make any responsibly minded Engineer's hair curl since an MBA's understanding of the technology is so superficial it amounts to perilous innocence. There are exceptions of course who were engineers before they became MBA's but they are rarities.

Management and spin doctors in big corporations are the company's worst enemies and Boeing suffers mightily from this....just ask any Liaison Engineer who has worked for them at least those who have been on contract since they have experienced other companies as well...unhappily it's not only Boeing.

Phil Pearce
User Rank
Silver
A Safe Solution
Phil Pearce   3/21/2013 10:38:21 AM
NO RATINGS
I, (phil.pearce@ieee.org), have recently been in contact with Boeing with details of a system that is able to prevent thermal runaway by monitoring the cells and detecting any physical instability including swelling or ballooning of one or more of the cells in a lithium-ion battery pack.  By implementing this means of detection we were able to successfully develop a viable solution that is able to prevent the onset of thermal runaway and combustion before it ever occurs. 

bdcst
User Rank
Platinum
Re: traveling with danger
bdcst   3/21/2013 10:11:42 AM
NO RATINGS
The operative word is YET.  True there were no injuries or fatalities from the two serieous battery failures aboard in service 787's.  But there were also comparatively few in service flying hours for the aircraft.  Given more time and other scenarios, combination of unpredictable events, who knows if the current battery design could have contributed to a more severe in flight problem.  Fire and smoke on the ground, even on a taxi-way is bound to be less of a problem than in flight half way across the Atlantic.

To some extent this reminds me of the story about the first production run of the Xerox 914 copier.  The units were fitted with a "scorch guard" pushbutton which, I've been told, was no more than a fire extinguisher trigger.  As the story went, engineering wasn't ready to ship the unit as the toner affixing heater ran hot enough to cause the paper to burn if anything jammed.  But sales and promotions insisted on meeting the announced deadline for starting shipments.  So, the first units were shipped with onboard fire extingishers to buy time until the overheating problem could be solved.  You don't want your new baby blamed for burning down other businesses.  To say the least, you'd never sell another copier.

Ratsky
User Rank
Platinum
Reliability
Ratsky   3/21/2013 9:52:34 AM
The lead-in to this article reminds me that few (it seems these days) engineers have a fundamental understanding of reliability concepts.  To me, the worst terminology ever invented has to be "mean time between failures"/"mean time to failure."  The numbers generated for these reliability measures as generated by the usual methodologies are totally misunderstood unless one appreciates the classic "bathtub curve" of failure rates over life.  The rate starts out relatively high due to "infant mortality" then levels off to a flat rate FOR THE DESIGN LIFE, then begins to rise rapidly after that ("wearout" phase).  MTBF or MTTF is only the failure rate during the flat design life portion of the curve.  Unfortunately, the convention analysis is usually summed up in a report as the MTTF/MTBF, often shown in the misleading form "product life is x million hours" which is patently untrue. Once REALITY sets in, and the product begins to show failures, if the EXPERIENCED failure rate is significantly worse than the prediction, the prediction is shown INVALID, OR (same thing in the long run) there is an unanticipated wearout mechanism in the design.  Those whose training did not include the underpinnings of reliability analyses invariably do not account for wearout mechanisms at all, but only quote the calculated MTTF/MTBF as gospel.

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