787 Batteries and Chargers - Part 1
 

The Washington Post reports:

Quote:

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Overcharging of batteries likely culprit in Boeing 787 fires, aviation and battery experts say

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Here are some details and images of the 787 chargers and batteries:

http://i337.photobucket.com/albums/n...ps460c4d50.jpg

Thales is the power system general contractor for the 787.

The chargers are made by Securaplane (a Meggitt company), who state:

http://i337.photobucket.com/albums/n...ps78dfa924.jpg


The batteries are made by GS Yuasa, and are the Lithium Cobalt variety.

http://i337.photobucket.com/albums/n...ps4e0b43e6.jpg

http://i337.photobucket.com/albums/n...ps0a7c2262.jpg

http://i337.photobucket.com/albums/n...ps393f8581.jpg

Result of overcharge:

http://i337.photobucket.com/albums/n...ps856057b4.jpg

Thank you, Mach

The whole battery thing reminds me of many software and iPhone/Droid folks that always want the latest and greatest apps.

No doubt that the Li-ion batteries have a greater power/density/weight capability than some of the not-so-old batteries like the nickel-metal-hydride ones. Funny, but Toyota sticks with those nickel ones for their Prius.

In a plane that weighs as much as the 787, a few pounds for an "older", but more safe battery seems a good trade-off.

My friends who served in the 'stan and Iraq told me war stories about those "new" batteries. The temperatures and charging systems did not help, so they went back to older batteries.

In my mind, it ain't worth the extra battery capacity to require expensive charging systems and such. Then there's the requirement to have a good fire extinguishing system if one of the suckers goes into thermal runaway.

@gums

I agree with every word.

Nevertheless, the almighty FAA had a different opinion.....

The Thales Li-ion battery unit shown has a mass equivalent to 13.5 two litre bottles of cola. Perhaps restricting the drinks mixer selection and adding a few battery packs might moderate the transient draw of the 1 megawatt load of the aircraft. No doubt the marketing suits would be in high dudgeon regarding this suggestion. I suspect the electrical system weights and redundancy decisions were made by MBA's, which like papal pronouncements in catholicism, are infallible in the corporate religion.

So who else do you give an extra weight allowance to so that you stick with older technology? Hindsight is a nice easy game to play but can you do it prior to the event? And how much extra weight allowance are you going to make for that "good fire extinguishing system"?

What about that new fangled carbon fibre stuff - better make sure they put double the amount of that on or perhaps just stick with aluminium. But heck, where did that aluminium stuff come from!!?? Back to wooden frames and fabric covering I say!!

Progress is progress. Undoubtedly Boeing did their testing and decided the new batteries were safe and yielded significant benefits, primarily weight saving. Now there's a problem. So they will go back and fix it.

That's how progress works.

High tech gear
 

Mach,

Thanks for technical thread. Important issue.

The information you bring us shows there are software involved. :8

And the tracing to the root cause could be more complex and not deterministic in the short term.


May be a tweaking is necessary to the algorithms to allow a safer pass of teething period.

The marketing information make us confident. After reading the caput information we may wonder what happened.

The days difference between similar incidents is just coincidence?

Battery subsystems now have their own FDR.:)

Could you comment something on the graph?

Testability
 

Romulus:

The Testability issue is showed during the products teething phase and even much later, sometimes. Examples in aviation are dramatic.

When designing innovative and complex machines the Testability issue is a big concern. And the plane testing phase may miss important details only detectable by time.

Romulus;
I expect that that question will be part of the investigation prior to re-certification of the B787. From the NYT this morning (Jan 19, 2013 10:54 EST:
The FAA approval of Boeing's use of Li-Ion batteries is in the following document. One would expect that Boeing's testing and results will be examined against the FAA approval.
Special Conditions: Boeing Model 787–8 Airplane; Lithium Ion Battery Installation
AGENCY: Federal Aviation Administration (FAA), DOT.

gums:

The grounding of the 787 fleet an it´s consequences strongly supports your rationale.

It´s unclear to me the size of the gain in using these batteries. We need to understand better the trade-offs and quantify.

The designers probably required to use them in the 787. We need to check why. Which were/are the dominant reasons?

May be the very high peak current of the new batteries (due low internal resistance) were important for the high energy consumption of the 787?

On maintenance aspects and risks it´s clear Boeing heard the promises of the suppliers (Batt and chargers) installing it close to Electronic Equipment without elaborated safety schemes in case of major failures like the ones that occurred.

FAA attitude
 

Hi,

IMO FAA aggravated the problem with this political attitude (e.g. 1000%).

This opens a new front.

The Testability again must be remembered after the problems in BOS and TAK.

Lithium-cobalt, lithium-poly and lithium-ion batteries can be very unstable even under normal conditions; only the power management chip in your laptop battery stops it from bursting into flames when charging. Some have, even when not charging.
Enormous pressure on battery makers to increase energy density and decrease weight/volume, for phones / laptops / tablets etc. (and now for airplanes!) has resulted in increasingly daring & unstable designs being produced. In aerospace, this is all pretty new tech. The massive electric requirements of the 787 compared to other a/c only compound the problem.
Before the 787, I have never heard of any lithum-tech batteries being used for anything mission-critical in aerospace (please enlighten me if I am wrong).

As a previous poster points out:
Yep. Heavy and large by comparison, but well-known, predictable, proven tech.

TNX, boogle

Weight and form factor not a biggie.

It's the charging system and batt monitering system, plus a fire extinguishing system.

I like the Li-ion batts for small stuff, but not big ones for mission-critical power supplies.

Might I suggest switching over to a Plutonium-238 battery, works by means of radioactive decay ,have a very long life, good energy density and at the end of the plane's life-cycle can be sold on the second hand black market for 'alternative' uses.

See, problem solved.

It woul be nuclear flying devices, not very ideal concept to accept...

Securaplane had a major fire back in 2006, there's a discussion about it here it has been suggested that it was due to a lithium battery catching fire while being charged or used. Unfortunately I can find no other contemporary accounts of the fire which destroyed a entire building apparently.

Apparently the International Space Station, the F22 and F35 and the A380 all have LiIon batteries.

The same ones fitted to the 787 have "1.3 million hours of flight time" according the Boeing - so they are used in other places. I would suggest anything on the ISS is "mission critical" as its not easy to land if something goes wrong! ;)

According to Leeham News and Comment:
The Airbus A380 uses lithium batteries to power its emergency lighting system. The US FAA set special conditions when certifying the aircraft. Airbus says “the batteries are small, limited, and are not in a frequently-active charging/discharging function.”

rest of article: A380 has, A350 will have lithium-ion batteries « Leeham News and Comment

(Aviation Week)

So the Main battery as well as the APU battery catched fire..., hhmmm.

Here a small example what to expect....

Interesting charger design
 

The charger manufacturer got a patent Patent US5780994 - Detection of inflection point in secondary-battery charging process, which they claim as per Innovative Inverter Technologies and Main Ship Battery Chargers for Power Conversion to apply with the 787 charger. Last sentence from the abstract: Accordingly, the voltage response is no longer monitored and the time remaining to reach the inflection point is used to complete the fast-charge operation. _If_ they really charge like that, without the monitoring the cell voltage, the problems seen are to be expected, as even a minor mismatch (caused amongst others by aging) of the assumed inflection point to the actual cell would lead to overcharge. Lithium cells will degrade fast with minor (trickle) overcharge and absolutely will not not tolerate any overcharge at fast-charge current. NiCd and Pb cells would be much more tolerant.

words on that graph
 

http://i337.photobucket.com/albums/n...ps393f8581.jpg
I happen to know the man who took the data, made the graph, and presented it to more than one conference--ballpark a decade ago. I discussed it with him extensively a few hours ago.

The graph subject is heat released during a thermal runaway event, with the actual vertical axis being rate of temperature rise observed in a specialized adiabatic test fixture. In the tests, thermal runaway is obtained by very slowly heating a disconnected battery in the test fixture, it taking a couple of days to reach the beginning of appreciable heat release from the battery. This first phase uses externally supplied heat--but when self-heating is detected the test assembly switches to adiabatic mode (i.e. heat is neither added to nor allowed to escape the battery under test). From that point the test progresses up the temperature scale extremely rapidly, as is hinted by the self-heating rate scale.

Obviously different cathode compositions are being compared here. Comparing the curves by essentially integrating the area under them, one can see that the total energy released per unit volume by the lithium cobalt cathode (as used in the Yuasa batteries of interest here) is quite substantially the highest in the comparison.

However, this has relevance to heat released--and thus possibly collateral damage--after the battery has already expired, which in all cases occurs tens of degrees cooler than the beginning of the thermal runaway shown. So this graph has nothing to do with why there was failure, though it does have something to do with the aftermath.

The comparison curves were all measured on 18650 cells--a size and form factor often used inside those black brick laptop batteries we have all seen.

One other point he mentioned: in their automotive application, Tesla uses these very small cells in very large numbers--but they are located in a sort of honeycomb structure. One must either design hoping never to have failure (in reality, extremely improbable), or design in a way so that failure causes acceptable harm. It appears Tesla decided that could not count on their lithium cells never failing, so took good care (it involves both physical and electrical considerations) to assure that the likely failure mode of a single cell would not cascade to adjacent cells. The cells they use are small enough that the energy release from a single one should not endanger crew or vehicle.

Looking at the Thales/Boeing design and the FAA special considerations, it appears that the approach was to assure cell failure would never occur--as it seems self-evident that no serious measures to avert propagation to adjacent cells were employed, nor were serious measures to contain damage to nearby systems.

Even if the specific cause of these events is determined and mitigated, I wonder if all concerned will remain convinced that all other possible causes of cell failure are sufficiently unlikely to make this approach prudent.

I'm not a pilot, and my design and reliability careers were not in aviation, but this all reminds me of the pair of risk mitigation approaches found in, I believe, every modern turbofan engine regarding bits of engine flying away and causing harm when they hit something important. For some parts, such as fan blades, the assumption is that they will indeed fly off sometimes, and an adequate shield is required to protect the rest of the airplane (and a spare engine to keep it aloft). Call this Tesla-like. For other parts, such shielding is deemed "impossible" (which really means too heavy and otherwise expensive), so the approach is to assure it will "never" happen. Call this Thales/Boeing-like. It is awkward when "never" happens anyway, as happened with the IPT disc on a Rolls-Royce Trent 900 on Qantas flight 32, and has happened on these two 787 episodes.

My information is that the batteries are Lithium Manganese. (From Boeing Training Notes). :confused:

cobalt, I think, not manganese
 

I think not.

The GS Yuasa site story on 787 batteries points to GS Yuasa parts LVP10 and LVP65.

GS Yuasa "spec sheets" for the LVP10/65 appear to match characteristics at hand here.

The MSDS posted by GS Yuasa for LVP65 expressly specifies that it is Lithium cobalt dioxide/carbon.

Many, many of the stories on this topic assert that they are Lithium cobalt (as did Machaca in the post starting this thread).

Any more evidence than a recollection of training notes? I certainly don't want to help propagate an error, but I'm not yet convinced of my error here.

Just had a look at that patent. Fwics, at the inflexion point, the remaining time to
full charge is calculated and applied to the battery, but the voltage is not monitored
after that ???. I would have thought that voltage should be monitored continuously,
irrespective of charge or discharge conditions. Also, does the standard reference,
ie: the software battery model, take account of battery aging, where the curve may
change ?. The patent must be only part the story for this application.

Soemone else have more info ?...

As do iPods and Apple Mac laptop batteries!

I took my iPod to an Apple store about 5 years ago to have them check out an intermittent fault. They told me that I hadn't used it for over 18 months and when I asked how they could possibly know that, they told me that prior to a full charge that day, it had not been charged since 3 March 2006 at 18.23.

Apparently every charge/discharge cycle during the life of the battery is logged with the battery itself. :-)

Valuable information
 

saptzae

Welcome aboard; Thanks for important information.

:ok:

Big brother from big corporations in our pocket
 

Speed of Sound.

I hope they could, at least trace voltages of ea. cell in the charred batteries. Next step would be put the memories far from the battery. We may never understand what happened with the BOS and TAK batteries. This would be bad. The FDR analysis probably will not reveal anything useful.

From Boeing land today...

WASHINGTON (Reuters) - U.S. safety investigators on Sunday ruled out excess voltage as the cause of a battery fire last month on a Boeing Co 787 Dreamliner jet operated by Japan Airlines Co (JAL) and said they were expanding the probe to look at the battery's charger and the jet's auxiliary power unit.

Dreamliner probe widens after excess battery voltage ruled out - Yahoo! News


Thats all fine, but one of the batteries was in the front EE Bay, not at the APU...

Patent aplication
 

syseng68k,

Could you provide the link? If so, insert the link instead to paste on the post. To reduce the chance to be edited by the robot. (or PM it)

One of the batteries i used in a Dell mini latched a warning sign that later after investigating the reason i traced to voltage cell mismatch. An important condition that affects the battery performance. And even safety during the charging. For example: You could be able to limit the charging current when a given cell increases it's internal resistance. With higher current one cell can "suffer". (thus increasing it's voltage and consequently overheating)

This may happened in both incidents. A mere cell mismatch.

The outsourcing of new high tech items (capable to ground an airliner) could be well managed (understood, etc.) by a plane manufacturer. This would require experts not working in this environment. The sophistication of the planes and the amount of innovation creates a very difficult situation.

Aggravating the situation?
 

FPO:

This info shows they don't know failure mechanisms of these batteries. The external voltage is just one parameter. There are other 8 VERY IMPORTANT parameters (the voltage of each cell).

I posted this earlier in another thread - really just a bystander here, but I found it quite interesting:


Interesting article from 2008, seems to be saying that the specific type of Li-Ion batteries fitted to customer delivered aircraft differed from those originally fitted to test/certification aircraft:

Boeing looks to boost 787 lithium ion battery service life


Excerpt from above link:

"Boeing will move away from its original lithium ion battery design for its main and auxiliary power units, flight-control electronics, emergency lighting system and recorder independent power supply. Instead, Boeing is investigating the incorporation of manganese inside the lithium ion battery to boost service life.

Boeing has not determined which 787 will be the first to receive the new battery modifications, although multiple programme sources have told Flight's FlightBlogger affiliate that the new battery could be introduced as early as Airplane Seven, the first production 787 scheduled for delivery to All Nippon Airways in the third quarter of 2009."

RR,

I didnt mean anything was fine...far from it...

I agree with you...not only dont they appear to know the failure mechanism...the process of self-cert is in jeopardy...

Longevity?
 

sgs233a:

Important information! :ok:

I havent read every post in this thread. But i know on the 747-400 there is a thermal cut off switch preventing this from happening. I know nothing about the 787 but does the 787 have a thermal cut off switch (im assuming not)?

Machaca : :):ok:Nice Efforts

I assume that they do monitor individual cell voltages though.

From the pics of the damaged battery, we can see that the individual cells are strapped together with steel bars and there is a loom sitting over the top of the cells that sits in a rectangular 'grid' over the top of the cells.

Surely these are the conductors which carry individual cell voltage information to the charging/monitoring system? :confused:

pull-up-terrain

To my knowledge, 747-400s have NiCd batteries.

They behave totally different compared to LiIon types.

NiCd have ONE charge current for all cells.
LiIon are more complex, every cell has to be charged seperately and within certain limits. Don't know if their "runaway temperature" is monitored in 787 chargers/controllers.

Regards

the lab/factory fire was a prologue ...
 

@green granite: The fire that destroyed the Securaplane headquarters is very interesting and relevant for at least two reasons:

1. While under test, the battery assembly being developed for the 787 by Securaplane exploded and caught fire, setting off the three-alarm building fire that destroyed Securaplane's lab and production facility.

2. The technician running the test later became a whistle-blower, asserting the Securaplane battery/charger assembly was unsafe for use in aircraft. He was subsequently fired by Securaplane.

A bit of additional information on the fire is contained on page 2 of the OSHA Administrative Law Judges'
Decision and Order (http://www.oalj.dol.gov/Decisions/AL...3_CADEC_SD.PDF) ,which found the technician's firing to be for valid cause. Given recent developments, looks like the judgement of a tech regarded as highly competent was ultimately ignored as a consequence of his less impressive diplomatic skills.

I'm not a pilot and haven't read the FAA documents cited elsewhere in this thread, but the OSHA findings recounting the circumstances of the Securaplane technician's firing do not encourage me to become a 787 passenger.

hetfield

If as SoS explains, the loom above the cells is sensory, they are connected to each indvidual cell. They are perhaps copper, and appear to be insulated in pretty standard fashion. Once enough heat is acquired, and the insulation fails, don't we have "Inter connectivity"? This eliminates the ability to monitor in isolation, and if the loom also carries the charging current, doesn't this exacerbate the possibility for fire, and explosion? Should the "Loom" be better protected against this type of failure? With diodes, or at least segregated leads?

@Lyman

I'm afraid if the cell temperatur exceeds a certain level (140 deg Celsius?) nothing will stop the internal reaction with known results.

IMHO it would make more sense to have the cells seperated and well canned. So eight small cells instead of one big. They don't :mad: up at the same time.

To make it even more safe I suggest to put a single cell under the bed of CEO Boeing, CEO securaplane and CEO Yoasa.


thermal runaway
"Lithium-ion cells with cobalt cathodes should never rise above 130°C (265°F). At 150°C (302°F) the cell becomes thermally unstable, a condition that can lead to a thermal runaway in which flaming gases are vented."

don't be shy, ask for expertise
 

why should boeing not learn from teslamotors.com
electric cars manufacturers from all over the world ar knocking at their doors.
no, am not working for them nor have I shares but am following them for some time...