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787 Batteries and Chargers - Part 1

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787 Batteries and Chargers - Part 1

Old 20th Jan 2013, 21:49
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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.
My information is that the batteries are Lithium Manganese. (From Boeing Training Notes).
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Old 20th Jan 2013, 22:08
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cobalt, I think, not manganese

Originally Posted by Turin
My information is that the batteries are Lithium Manganese. (From Boeing Training Notes).
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.
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Old 20th Jan 2013, 22:13
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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 ?...
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Old 20th Jan 2013, 22:22
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Battery subsystems now have their own FDR.
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. :-)
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Old 20th Jan 2013, 22:33
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Valuable information

saptzae

Welcome aboard; Thanks for important information.

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Old 20th Jan 2013, 23:46
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Big brother from big corporations in our pocket

Speed of Sound.

Apparently every charge/discharge cycle during the life of the battery is logged with the battery itself. :-)
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.
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Old 20th Jan 2013, 23:56
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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...

Last edited by FlightPathOBN; 20th Jan 2013 at 23:58.
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Old 21st Jan 2013, 00:31
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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.
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Old 21st Jan 2013, 00:44
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Aggravating the situation?

FPO:

Thats all fine
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).
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Old 21st Jan 2013, 00:51
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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."
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Old 21st Jan 2013, 00:51
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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...
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Old 21st Jan 2013, 00:58
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Longevity?

sgs233a:

I found it quite interesting:
Important information!
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Old 21st Jan 2013, 01:25
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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)?

Last edited by pull-up-terrain; 21st Jan 2013 at 01:26.
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Old 21st Jan 2013, 07:27
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Machaca : Nice Efforts
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Old 21st Jan 2013, 10:07
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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.
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?
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Old 21st Jan 2013, 10:17
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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)?
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
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Old 21st Jan 2013, 13:59
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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.
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Old 21st Jan 2013, 14:22
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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?
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Old 21st Jan 2013, 14:49
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@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 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 130C (265F). At 150C (302F) the cell becomes thermally unstable, a condition that can lead to a thermal runaway in which flaming gases are vented."

Last edited by hetfield; 21st Jan 2013 at 15:52.
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Old 21st Jan 2013, 17:18
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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...
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