Poles spacing
 

Hi,

The battery (high current) is the aviation standard.

This is PERFECT.

Question:

Why Thales decided (together Yuasa) use THE SAME GEOMETRY for the battery?

They had time during 787 R&D to think in other sizes or geometries for the battery.

From the photos in post #1 of this thread, the battery terminals (J3) seem to be about 2 inches apart and about 1/4 inch in diameter. The CT (computerized tomography) scan is an X-ray horizontal 'slice' at about the level of J3. The GSYuasa data sheet http://www.s399157097.onlinehome.us/...s/LVP10-65.pdf for the LVP65 battery seems to suggest that each cell comprises six sub-cells (connected in parallel at top and bottom?) which appear as 'streaks'. The cell anodes and cathodes, I'm sure, are not connected to the cell case.

Recharging time is critical? Why?
 

Hi,

In addiction to the 4 "simple questions" in my post #389 and the one concerning battery geometry i have another:

The recharging time of both batteries is critical in 787? Why? The highly redundant electric power generation is noth enough?

Who said it was critical? I can't find a reference for that.

AFAIK The recharging requirement for the 787 battery is no different to any other.

Except perhaps for emergency brakes in the event of a total electrical failure on takeoff before V1.

So, why we need this critical batteries?
 

Hi,

TURIN,

The most important question (until now UNANSWERED) was posted some days ago by Sandy...(i didn´t find post #):

"Why the insistence on this battery?"

The prolonged grounding of this Dream Craft is to be caused by lack of a DC supply (rechargeable "on the fly") with the electrical specs of the WRONG SELECTED BATTERY?

PS

I am not blaming the cells: The battery CLEARLY was not designed with the reliability and dependability required by the Dreamliner. IMO the problem is: a "nightmarebattery"

The Dreamliner, a technological dream, deserves a Battery. Not a poorly designed one.

URGENTLY.

PS2

A DC SUPPLY IS A VERY BASIC "THING". What is happening is surreal for me.

So NTSB have begun looking beyond the battery, to other possible failure modes.

Boeing replaced as many as one hundred fifty batteries prior to grounding.

Almost enough to upgrade the entire fleet in service.

Until two old batteries lit up.

There has not been a "mystery" from the outset.

"it is inconceivable Boeing would not know what the problem was, since before evidence of it became known".

QED

Occam is being rudely abused, here and elsewhere....

K.I.C.S.
 

Hi,

Probably we are watching one of the best examples of:

Keep It Complex Stupid.

It´s very easy to go to complex situations. You just need to be incompetent. It´s not simple to maintain situations "under control". You need to be competent in Technical and mainly in the "organizational aspects".

I understand that they have replaced 165 batteries. Quite a few of those were lifed items - remember that a lot of 787's have been standing around for a long time.

I also understand that Boeing are hoping to fully instrument an airframe with a view to conducting a series of test flights within the week, with plans in place to regain airworthiness within the month, albeit with certain modifications including measures such as venting to atmosphere and possible enclosing the battery in a welded steel container.

Yes, enough replacements to refit the in-service fleet. They would not have done that without banking on its acceptance by the authority.

Which means an ongoing violation of the letter and spirit of the Certificate.

With people on board, in "commercial carriage"......

(should I have bolded that?) "with people on board".....

Flight test in commercial carriage?

That is an ad hoc and illegal "Airworthiness Directive"

If the "new battery" is different in any way from the OEM, the violation is cut and dried. If it is merely a "fresh OEM" there is still a violation, one a bit more arguable, imo....Plus, how did they "ferry" the "replacement" batteries? A question I posed three werks ago?

Did FAA issue a "Notice of proposed rulemaking"? Seems public comment should have been solicited in allowing "highly dangerous cargo" to fly?

Grant me one (maybe silly) question.

Could the problem be related to the amount of composite materials of the aircraft structure with regards to static charging when in flight or due to insufficient grounding of the cell when on ground after flight? When i get a static discharge in my house, it´s most time asociated with some non metallic material.

As it looks now, a fault in the batteries or in the charging system should have been found some days ago, therefore there could be a greater problem maybe typical for this special built aircraft, which was not considered in testing.

Lyman
 

"Until two old batteries lit up"

Drawing your attention to post 395:

6 months after build and less than 3 weeks in revenue service is not an "old" battery.

I very much respect your writing sb_sfo.

Consider what I wrote, in all its possibilities, and look for where it might be correct, not wrong.

Sorry if this is rude, and I do not think you need an explanation, but if you do, you might not "get" it.

Hint: from the BEACH BOYS, "She's Real Fine, My (#)409"

A general comment. NTSB have "moved on" to look at additional systems.

Where does it say, "The Battery Performs to SPEC". I hope it's there, but I could not find it.

In reading anything, anything issued by the governmental agencies, there is virtually always more in what "is not written".

EMI and EMC considerations
 

Hi,

RetiredF4:

Quote:

---

Could the problem be related to the amount of composite materials of the aircraft structure with regards to static charging when in flight or due to insufficient grounding of the cell when on ground after flight?

---

When you put electric power Systems managed by sensitive electronic circuitry you must look carefully to Electromagnetic Interference and Compatibility. (EMI/EMC).

Grounding and Shielding is another issue in the innovative 787 design. The issue of fuel storage in the plane deserved special attention like "inerting" and carefull structures bonding, etc. The ANA 747 hit by a bolt just after takeoff is an example of what we are subject and the Concorde yaw damper being interfered by HF transmitter keying (as mentioned by Cj in AF447 threads) are to be remembered.

Normally LOW IMPEDANCE circuitry are less prone to be interfered. But:

1) High current and possibly Spikes could interfere in analog and even in digital circuitry.
2) We have inside the battery case more than 500 (estimating) devices and it seems also a high current switch. The two PCB certainly has a "safety role".

I would not consider EMI/EMC in this cases (batteries) as priorities to be looked.

But when investigating, specially when you are in the dark WRT to WHAT and WHY as put by NTSB chief you must look to everything. Even after you find a smoking gun. You may have more than one design problem. The FAA review has this merit. Will spot in other possible issues.

Your comment is pertinent to a new design using "less metal".

Long life batteries diying young
 

Hi,

TopBunk:

I heard this important fact was not considered a safety issue.

I hope Thales, Yuasa and, last but not least, Boeing started to look to WHAT and WHY since the facts started to mount.

@ franzl
 

thinking out of the box here....

I know of 3 airframes [mil and civ over 30 years onthejob] that had circulating current issues along with their associated bond/earth configurations once in service..

2 of them were FBW as well, both with fair % composites construction.....the one left was the F4 in it's final years of service....

....corrosion, intergrannular and especially the less than obvious galvanic, leading to bonds and earthing paths going "high" resistance.....currents finding their "own" way through ex areas...

...just saying...

ref..Corrosion of Aluminum and Aluminum Alloys - Google Books chap 5

Which, Lyman, :) brings us neatly round to our original opening gambits, electrical installation "quality" from that photograph....:hmm:

My patience was wearing thin, waiting for additional support.

:ok:

I am still awaiting some outside interest in "itinerant Polarity reversals"

slippers, pipe, Super Bowl......

When you've seen it, done it, eaten it [and probably shagged it] sometime in your past [and have the T shirts to prove it] you develop that "don't need the sh1t" second sense that gives you that little 10% extra margin that stops issues becoming PROBLEMS.

Nobody wants to employ [or listen to] the old guys anymore. :ugh:

See where it gets you?:}

Eh?
 

I class myself as a simple individual working in a complex industry.

However, this thread and the one running in R & N seems to have been hijacked by philosophers typing in riddles.

No offence but could we please speak plainly for the sake of us simple folk.

Thanks. :\

A cropped image from one recently published by NTSB, showing internal arrangement within a cell.

http://i47.tinypic.com/29fxnip.jpg

Thx mm43

That's very interesting.

Looks like 6 sub-cells are put in parallel to a "master" cell of (1/8) 65 Ah.

Who/what is doing the internal balancing?