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787 Batteries and Chargers - Part 1

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787 Batteries and Chargers - Part 1

Old 3rd Feb 2013, 22:06
  #441 (permalink)  
 
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Lyman:

Mr Musk is free to have his opinion, but to use the phrase, his is
just one man's opinion of moonlight. For any design problem, there are
usually > 1 valid solutions and Mr Musk's application is very different
to that of the 787. His application involves high voltages, a much
greater number of cells and much higher power capability, so would
need a very different solution to that required for the 787. Sorry,
but sounds more like a self publicist at work, rather than serious
engineering. Yuasa have been building these batteries for decades,
they've been approved by NASA and the European Space Agency after
some of the most stringent testing. Are all those people and Boeing
really stupid ?.

Anyway, we all know what a certain gentleman said about "opinions"
all those years ago ...
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Old 3rd Feb 2013, 22:24
  #442 (permalink)  
 
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Lyman

If the structure of each plate is continuous, only round (cylindrical) packing is acceptable.
Not if you want to pack more cells into the smallest volume!

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Old 3rd Feb 2013, 22:34
  #443 (permalink)  
 
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B787 battery

Would the aircraft not automatically disconnect the battery if any of the cells went out of tolerance both high or low ? Could someone who knows the B787 aircraft respond please.
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Old 3rd Feb 2013, 23:10
  #444 (permalink)  
 
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Bill, The flight deck crew responded to the SOP for a warning light and an anomalous odour. The information you request is proprietary and to which you are not privy. You may be hearing from the attorneys of Boeing or whatever subcontractor for even asking that.

Last edited by kilomikedelta; 3rd Feb 2013 at 23:14.
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Old 3rd Feb 2013, 23:15
  #445 (permalink)  
 
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kilomikedelta:

My take on that very funny post:

I have the gut feeling that we may be being led by the nose on this
enquiry. There's so much reputation and $ at stake that there may even
be people here who would conveniently steer the discussion off into
the boonies to mask serious analysis and possible discovery of the
truth. (Tinfoil hat aside) .

In fact, any battery of that type must be disconnected from load or charger if
cell voltages are outside high or low data sheet limits, otherwise, you are in
unknown territory. It's that simple...

Last edited by syseng68k; 3rd Feb 2013 at 23:16.
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Old 3rd Feb 2013, 23:16
  #446 (permalink)  
 
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That is what makes non cylindrical unacceptable, trapped heat.

And no space between cells.....

Chris....I think the most powerful of any "scout" is Occam....

Last edited by Lyman; 3rd Feb 2013 at 23:22.
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Old 4th Feb 2013, 00:31
  #447 (permalink)  
 
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KILOMIKEDELTA

Two meltdowns different systems same battery. CRM extends to all sectors of aviation & attorneys are not part of the safety aspect BUT I am safe. (not worth much to any attorney these days & there are bigger fish to fry in this issue!!) & depending on what stage the warning would appear i.e. delayed temp warning requiring crew action V an automatic disconnect with warning is beyond my knowledge of this system hence my question. I would expect auto disconnect for any Li-Ion battery fault under all conditions but if it a problem to answer within this forum then email me. Aviation 25kHrs command & electronics made up all my life before time expired.
Regards
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Old 4th Feb 2013, 01:14
  #448 (permalink)  
 
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Bill, Your initial question was perfectly valid. My cynical response was only to point out that when management is questioned, they call out the legal rottweilers who advise that no further information be released (CoverYourAss). There does not appear to be any high current disconnect device within the Thales battery case and no apparent control signals to activate one. To me, breaking the circuit at a distance from the battery under high temperature/corrosive atmosphere circumstances would not be optimal engineering. Unfortunately CRM is a lucrative field for corporate lawyers to tap but they will ignore you when Boeing has deeper pockets. It's unlikely that anyone will give you a straight answer to your question when $$$$ are involved. Cheers, KMD
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Old 4th Feb 2013, 02:04
  #449 (permalink)  
 
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@kilomikedelta

There is a contactor/breaker in the box, also referred to several times in this thread and visible on the CT scans here and in the NTSB report.

According to recent public info, a NTSB investigator is on the way to France with it.

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Old 4th Feb 2013, 02:11
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Is it at all possible, that as fail safe, there is a fusible link?
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Old 4th Feb 2013, 02:17
  #451 (permalink)  
 
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@syseng68k
... discussion off into the boonies to mask serious analysis ...
No need, we can do that better by ourselves
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Old 4th Feb 2013, 02:54
  #452 (permalink)  
 
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I am sure if there was a short circuit, a fusible link would have worked. I think the APU battery is only used for a couple of things, so a short circuit would have been easy to identify as the problem. There would have been lots of heat damage in a small area. I think anything easy to identifyas the problem, would have already been identified.

I think they will only find it while the entire system is operating, probably in flight. The question is how to do that with a degree of safety that is acceptable.

I don't think disconnecting the battery in flight is enough. Lithium cells can be damaged, but not go nuclear for quite a while later.
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Old 4th Feb 2013, 03:57
  #453 (permalink)  
 
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If we assume the two event aircraft were the only ones that fried their batteries, what was the condition of the two flights where it happened? In cruise flight, both batteries should get little to no use, and little charging.

There were no other system malfunctions.

787's use electric wing and engine anti-ice. Pilots on other aircraft use these sparingly, as they consume a lot of fuel (bleed air). Very occasionally, you have to leave the wing anti-ice on for a long time.

Electric engine and wing anti-ice would use massive amounts of electricity, all of which would have to be dumped into the aircrafts' grounding/bonding system.
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Old 4th Feb 2013, 05:24
  #454 (permalink)  
 
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USMCProbe

Minor point of correction--the 787 does use bleed air from the HPC for engine inlet anti-ice. It's the only bleed air consumer on the aircraft.
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Old 4th Feb 2013, 08:39
  #455 (permalink)  
 
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And another. 777's engine anti-ice is "auto". Not on. You might not know it is turned on. But it was 12 years ago for my last flight on it. I think wing anti-ice was still on/off.

Is this correct on the 787?
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Old 4th Feb 2013, 14:36
  #456 (permalink)  
 
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EAI

Switch positions are OFF, AUTO, ON for each engine
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Old 4th Feb 2013, 19:37
  #457 (permalink)  
 
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Would the aircraft not automatically disconnect the battery if any of the cells went out of tolerance both high or low ? Could someone who knows the B787 aircraft respond please.
Is it at all possible, that as fail safe, there is a fusible link?
APU BAT.
Circuit Breakers between FO's Instrument Bus & Bat Charger and between Bat Charger & APU Hot Bat Bus/Battery.

MAIN BAT.
Circuit Breakers between Captain's Instrument Bus & Bat Charger and between Bat Charger & Hot Bat Bus/Battery.
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Old 4th Feb 2013, 20:01
  #458 (permalink)  
 
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Would the aircraft not automatically disconnect the battery if any of the cells went out of tolerance both high or low ?
Which cells? 1/8 or 1/48?
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Old 5th Feb 2013, 02:50
  #459 (permalink)  
 
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@hetfield
Which cells? 1/8 or 1/48?
For purpose of management, "paralleled" cells count as one.
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Old 5th Feb 2013, 03:02
  #460 (permalink)  
 
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I wonder why they can't just INOP the battery chargers during flight until they find the problem.

Something like this.

1. No APU starts off the battery, must use external power on ground to start the APU. No towing of aircraft without APU being run.

2. Specify a certain battery voltage for dispatch. There already is one, but make it higher, almost fully charged.

3. Before take-off, pull the battery charger CB's.

4. After landing start the APU off the mains, which is normal. Push the CB's back in.


Batteries should never get discharged more than a few percent. Batteries will charged a little bit on the ground, never in the air. Fully charged batteries are connected all the time for their primary purpose, backup.
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