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787 Batteries and Chargers - Part 1

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787 Batteries and Chargers - Part 1

Old 20th Feb 2013, 15:52
  #761 (permalink)  
 
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JTSB today

Hi,

In japanese
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Old 20th Feb 2013, 16:09
  #762 (permalink)  
 
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From the diagrams:

image #3 : showing each battery containing three cells.

image #4 : showing each individual cell, unrolled, at ~ 10 meters in length

image #9 : showing the "breaker" twixt charger and BATT @ 75amps. (?)

RR: Arr EE Got oh...
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Old 20th Feb 2013, 16:18
  #763 (permalink)  
 
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from BoeingLand...

Boeing close to fixing Dreamliner battery

Boeing close to fixing Dreamliner battery: source - Yahoo! Finance

(close is relative....)

I did a quick Google translate on the JTB report..

while very crude, it does give an idea of what happened...

Slide 14 text:
With a record of DFDR, the battery voltage, the sense of a nasty smell in the cockpit
Was the same time, reduced from 31V to 11V in about 10 seconds, and then, on the 10V and name was finally under Repeat , eventually became a 10V
• was recorded every 2 seconds per 1V, the battery voltage is the battery voltage was recorded every 2 seconds per 1V
• In order to be measured by the voltage drop of about 1V lower BDM, DFDR
Converted from the voltage readings, and was originally about 32V conceivable
• Indicates battery voltage, 32V before the occurrence of cases about, the battery Lee Lee believed that almost was almost fully charged state
• For data after the voltage drops, the external device Because it is connected, still ongoing analysis

The overall flavor of all of the slides was they were not able to re-create the failure mechanism, and are going to do much more testing and analysis, including electron scan microscope, further research, and will set up a testing and evaluation methodology in the future...

Last edited by FlightPathOBN; 20th Feb 2013 at 16:44.
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Old 20th Feb 2013, 16:20
  #764 (permalink)  
 
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787 MAIN battery circuitry

Hi,

Finally precise information

Observe the charging current below 75 Amps.
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Old 20th Feb 2013, 16:51
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This appears to show 150A startup...


Last edited by FlightPathOBN; 20th Feb 2013 at 16:52.
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Old 20th Feb 2013, 16:54
  #766 (permalink)  
 
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The 100 replacements were due to the battery shutting down due to being over-discharged. As over-discharging can induce thermal runway, the system is designed to shut the battery down when it reaches a specific level of charge. So in these cases, the battery safety systems were operating as designed.
I wondered how the minimum safe voltage was determined? There might well be statistics involved. eg if the minimum voltage is set to X then the MTBF is Y.

That MTBF calculation might be pretty complicated. It might make assumptions about how frequently the minimum voltage is approached? Perhaps if you approach minimum voltage too frequently the MTBF reduces dramatically?
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Old 20th Feb 2013, 17:06
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LVP 65 cell detail

Hi,

Short to ground (that fused ground wire) "developed" through "hole" at cell side?



See at pg 2 of JTSB report

The opening of the ground wire is showed at pg 10 but not emphasized?
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Old 20th Feb 2013, 17:29
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We may never understand WHY (BOS and TAK)

Hi,

cwatters:

approach minimum voltage too frequently the MTBF reduces dramatically?


Teething phase of batteries in a new aircraft Uncharted waters.

FlightPathOBN:

"Aggressive" marketing specs.: 150 A compared to 16 A of competition.

Where is this page? Source?

I did a quick Google translate on the JTB report..


The overall flavor of all of the slides was they were not able to re-create the failure mechanism, and are going to do much more testing and analysis, including electron scan microscope, further research, and will set up a testing and evaluation methodology in the future...
Confirming my concerns

On Voltages recorded THERE IS A PROBLEM:

If the negative tip of the remaining cells were not SAFELY connected to ground, (AS HAPPENED) the voltage WILL BE LOWER. Will post the equivalent circuit on that problem ASAP.

Fact is:

DFDR is not capable (as configured in 787) to show VALUABLE and NECESSARY information on how battery failed. IMO in teething phase of an a/c, complimentary means should be required for.

Last edited by Jetdriver; 20th Feb 2013 at 17:44.
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Old 20th Feb 2013, 18:16
  #769 (permalink)  
 
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@RR_NDB
We may never understand WHY (BOS and TAK)
Yes, as we see only effects of Tertiary failures, which destroyed all evidence of degradation leading to the Primary failure.

  • 6 Tertiary failure symptoms (heat, fire)
    • 5 Tertiary failure sequence (multi shorts, arcing)
      • 4 Secondary failure symptoms (multi-cell runaway)
        • 3 Secondary failure sequence (electrical or thermal)
          • 2 Primary failure sequence (cell short)
            • 1 Cell degradation
It's impossible to trace back from 6 to 1.

There seem to be no detailed records of per cell voltages around the time of Primary/Secondary failure, which would be the only way to conclusively determine sequence of Primary failure and cause of Secondary failure.

Looking at other in-service, or replaced batteries to find degraded cells is the only way.

Edit
Secondary failure should be reproducible by failing a Cell.

Tertiary failures should be mitigated by better electrical and thermal insulation of individual cells.

Last edited by Jetdriver; 21st Feb 2013 at 00:16.
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Old 20th Feb 2013, 18:47
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RR,

That battery spec was from the website that Boeing has set up for the issue...

Batteries and Advanced Airplanes - Boeing 787 Updates

If the negative tip of the remaining cells were not SAFELY connected to ground, (AS HAPPENED) the voltage WILL BE LOWER. Will post the equivalent circuit on that problem ASAP.
serial bus bars...so if there is a single cell failure....

The opening of the ground wire is showed at pg 10 but not emphasized?
it just states "disconnection"

Last edited by FlightPathOBN; 20th Feb 2013 at 19:05.
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Old 20th Feb 2013, 19:12
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rough translations:
slide 6
Can be seen mark and damage the high temperature in the vicinity of the positive terminal of the cell element 3
○ (arrow), aluminum mosquito melted by heat attached white part Potential can be considered, I need to investigate further

slide 8
Observed by optical microscope and scanning electron microscope inward from the outside of the cell z
Likely open hole investigate the case of cell 6 scheduled to face z
Situation that is transmitted suggests the heat element is diffused into the fan through the hole in the case, I thought the energy was transmitted from the outside to the inside

Slide 11
January 26, on the 27th, the main manufacturer in Fujisawa Survey of the BMU that had been attached to the battery
Damage to the substrate
(1) Intense operation test in the state of being energized I was not able to test
(2)Record the damage condition
(3)Further analysis is being found to damage from the situation, but there is a big difficulty for damage

slide 13
Damage to one of the electrodes. Cells 3
• I considered damaged from heat.
• Why has occurred a trace of damage including damage surveys continue
2 blowout of the current collector.
• blown found in the positive electrode current collector of the cell 1, 2, 3 and 8
• aluminum is high as the positive electrode current collector material is melted, I thought the temperature reached, and was blown
• that a large current flows in the current collector, the temperature reached the cell Allowed, such as the positive electrode current collector that has been heated by thermal runaway in Be considered potential Blown ground wire out of the box
3. Batteries
• is considered likely that the blown current flows through the outer box. In addition,
There was no record of the history of a lightning strike to the aircraft

Last edited by FlightPathOBN; 20th Feb 2013 at 19:12.
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Old 20th Feb 2013, 19:19
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Red 'star' indicates: The positive electrode current collector (Blown)

Red text at upper right states: Safety valve on 7 and 2 open

Last edited by FlightPathOBN; 20th Feb 2013 at 19:21.
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Old 20th Feb 2013, 19:46
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Small advances in JTSB investigation

Hi,

FlightPathOBN:
rough translations:


Thank you!

Red 'star' indicates: The positive electrode current collector (Blown)
Red text at upper right states: Safety valve on 7 and 2 open
The model i constructed in my mind in last weeks is being reviewed in light of this findings.

Anyway:

Can be seen mark and damage the high temperature in the vicinity of the positive terminal of the cell element 3
Damage to one of the electrodes. Cells 3
• I considered damaged from heat.
• Why has occurred a trace of damage including damage surveys continue
2 blowout of the current collector.
that a large current flows in the current collector, the temperature reached the cell Allowed, such as the positive electrode current collector that has been heated by thermal runaway in Be considered potential Blown ground wire out of the box
All this this reinforces my model. A short of cell # 3 tip to battery case (and to a/c ground).

blown found in the positive electrode current collector of the cell 1, 2, 3 and 8
No idea on why blown in # 8

is considered likely that the blown current flows through the outer box.
In addition, there was no record of the history of a lightning strike to the aircraft
Investigators will conclude current from internal short circuit to case blowed aircraft harness ground wire of MAIN battery.

I expected this conclusion from them before. Explanation may be they concentrated on cells analysis.
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Old 20th Feb 2013, 20:16
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My interpretation of a Google translation:-

Slide 15 of the current JTSB report indicates that regardless of switches/CBs in the Nav light circuits being isolated, the Nav lights were on and drawing current from the APU battery. The investigator indicates the subject needs further research.
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Old 20th Feb 2013, 20:39
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Hi,

mm43

...regardless of switches/CBs in the Nav light circuits being isolated, the Nav lights were on and drawing current from the APU battery.
This seems to be a problem not "connected" to the MAIN battery issue.

I did think if the destruction of the MAIN battery ground wire could damage this circuitry or control. Fact (probable) is a high, very high current flowed from battery (MAIN) to ground. Thousand(s) Amps.

They are puzzled and even mentioned lightning strike possibility. And discarded.

A thick ground wire from a battery case doesn΄t open without a reason.
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Old 20th Feb 2013, 21:01
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RR,

Is the fwd EE battery being used as a UPS for the nav system?

EDIT:

News today is saying that because the nav lights were flickering, there was a wiring issue...

What about the IFE re-booting?

Last edited by FlightPathOBN; 20th Feb 2013 at 21:09.
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Old 20th Feb 2013, 21:44
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IFE reboot

Hi,

FlightPathOBN

What about the IFE re-booting?

VERY GOOD QUESTION!

Problem now seems much different than in BOS

Wiring issue?
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Old 20th Feb 2013, 22:14
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Fused ground wire

Hi,

FlightPathOBN:

it just states "disconnection"


Certainly the investigation will look to this fact. They had other priorities.

The things will become more interesting: Circuit analysis.

Last edited by RR_NDB; 20th Feb 2013 at 22:15.
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Old 20th Feb 2013, 23:22
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RR, FPO

Guys, you will recall from another discussion that the IFE will reboot when there is an EE bay smoke alarm. Do try to keep up, will you?
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Old 20th Feb 2013, 23:51
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sb,

Why would the IFE reboot on the EE bay smoke alarm? Does that make sense to you?
The IFE is not even run from the fwd EE bay.

Much the same as the running lights disco...should not be from the fwd EE systems...

Since the issue is being worked on 24/7 by entities all over the world, with NO SOLUTION AND today, the JTSB is stating that the ac was not wired correctly...

So, who is keeping up with what?

Last edited by FlightPathOBN; 20th Feb 2013 at 23:52.
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