Chris,
The 2 batteries are in separate locations. The main ship battery is in the forward EE comp't, and the APU battery is on a rack just inside the door of the aft EE (for easy firefighting access I presume).

sb_sfo,

Are you saying there's only a single main-ship's battery? That would be unusual in my experience. (I know that the APU has its own on the B787.)

Getting winded trying to keep up with the different threads....

I haven't heard back from FPO, but my assumption was that the two batteries in FPO's post were Main, and APU, out of the ANA ship, with their respective covers.

It would be reasonable to think that both batteries would be removed post incident, for inspection.

Just posted that it seems unusual to equip such a generation dependent system with only two batteries. Likewise, my experience with LithIons that they should be charged at one time, and used another, charging a discharging unit used to be prohibited....

1.45 MEGA WATTS.... That is a respectable amount of power, to my inexperienced mind, that value does not compute with (16) 3.7 volts cells.

How can the single Main Battery keep up with a 6000 foot cabin at 41000feet?
Does the 787 have waivered generation? Stored battery power waived? With two beefy gensets per GE, is that how it's done?

Lyman

Don't get hung up on the idea that the battey has to replace ALL of the normally available electrical power. It doesn't.
There are six generators on the 787. Two on each engine and two on the APU. The aircraft only needs a fraction of that power to function. Redundancy etc.
The battery is there to keep insruments and vital computer functions working in the event of main generator failure while the RAT deploys or APU starts.
It's not there to power heavy use electrical motors such as the Cabin air compressors or engine starters.

Chris Scott
Lots of a/c have only one battery, many don't even have a separate APU battery.

A battery charge is a simple operation
 

Bear,

Quote:

---

...charging a discharging unit used to be prohibited....

---

When electrons flows toward the positive terminal the battery is being charged. When they flow out of this terminal the battery is being discharged.

:confused: What you are thinking on this? :confused:

How many MAIN batteries?
 

Quote from TURIN:

“Lots of a/c have only one battery, many don't even have a separate APU battery.”

Yes, but in my limited experience large modern a/c which depend on complex electrical systems have more than one MAIN battery, even if they have a dedicated APU-start battery as well (which many don’t).

The A310 has 3 main batteries, which are also used to start the APU. Each battery has a separate cockpit switch, and separate indicators of Volts, Amps and ON/OFF on ECAM.

The A320 has 2 main (NiCd) batteries, which are also used to start the APU. Each battery has a separate cockpit switch and separate indicators of Volts, Amps and ON/OFF on ECAM.

The A330 and A340 are like the A320, but with the addition of an APU battery. The A380 has two main batteries, but I’m unable to get further details.

Chris

Chris Scott;

Re, "The A380 has two main batteries, but I’m unable to get further details."

Based on this FAA Document, I strongly suspect (but cannot confirm) that the A380's batteries are Lithium-ion.

PJ2

pretty specific that the A380 Li batteries are for emergency lighting only...

the image of 2 batteries, one charred was from the recent ac, the charred being from the forward EE bay, the other the rear.

Chris...there are diagrams in the thread somewhere...one battery is in the forward EE bay, the other in the rear APU bay

Main batteries: A380 uses niCd ; B787 uses LiIon
 

Hi,

787 is the only airliner using Li Ion as main battery. A380 uses it just for emergency lighting.

Ni Cd is the dominant battery type today.

You may verify this looking to suppliers.

The placement of a Li Ion (mature technology?) in a compartment sharing electronic modules, only accessible from outside of A/C, the only source to start the APU (in a plane with very high electric energy requirements), without (AFAIK) measures to contain a malfunction of the charger or the battery is highly questionable, IMO.

The use of (AFAIK) the same battery as the main one differentiates 787 to all other (new/most) airliners flying today. The risks associated to this decision created a very serious adverse fact to the program.

:sad:

Single main battery of Li Ion?
 

Chris Scott:

The use of just one of a new type (all other new/most) airliners use Ni Cd IMHO is highly questionable. The technology is mature yet?

Thanks for that.

How do you feel about carbon fibre for aircraft bodies? That's not a mature technology either. Do you think we should stop that? Or just stuff that you can identify with the benefit of hindsight?

Progress involves change which involves new things. We do stuff and we learn. That is how humanity has not just progressed but survived. We are not the strongest, fastest, toughest or best protected species but we do have the best mental power with the ability to learn and grow. That's what the 787 represents - our ability to improve. Sometimes things don't go as planned so we need to regroup, consider and change. So be it.

Have Boeing accepted your application?

FlightPathOBN;

Thanks for further information. Might we conclude then that risk of battery fire is lower on the A380 due obviously lower battery loads?

Chris, the diagram to which FlightPathOBN refers can be found at: http://www.pprune.org/rumours-news/5...ml#post7621175

PJ2

I am questioning the use of just one!
 

Romulus:

Quote:

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Have Boeing accepted your application?

---

Thanks for that. :mad:

Chris Scott.
Fair points. I was thinking of the older analogue generation of jets. :O

The APU battery is in the aft EE bay not the APU bay. :ok:

FlightPathOBN and PJ2,
Thanks for reminding me about that location diagram. And that, essentially, is all it is. But it certainly seems to suggest that, even if there is more than one MAIN BAT, the two must be mounted in close proximity. On the B777, the best schematic I could find (in the early hours...) shows two batteries, BUT they seem to be treated as a single unit, with only one switch in the cockpit; whereas on Airbuses the separate batteries are connected to different DC buses. So it looks as if Boeing and Airbus have rather different philosophies (surprise!).

RR_NDB,
As a non-electrician I’ve no idea whether having a second battery, in effect boot-strapped to the first (for want of a better description), would give any more redundancy than a larger, single battery. Similarly, I don't know what happens on the B777 in the event of a failure of one of its two main batteries. Can any B777-qualified engineers or pilots comment?

It’s a pity that we don’t seem to have any B787-qualified engineers or pilots to shed light here.

There are a couple but experience on type is VERY low. :{

I think the 777 batteries are connected together to inrease capacity not for redundancy (In parrallel I think. I'm not of the conehead [avionic] persuasion).

The 787 is VERY weight conscious. They even removed the access door from the fwd hold to the EE bay to save weight. :ugh:

Hi TURIN,

Well, basic electrical schematics, panel diagrams, and EICAS pages would be a start. Or have I missed something already posted somewhere?

PS
Just seen your EDIT.
Yes, is the 65Ah provided (I think) by a single battery sufficient, or would they need two in parallel?
Have they replaced the door with a blank, or simply removed it? On the A320, we originally had access from the forward cabin to the forward electronics bay. After a few years, they sealed it up. That was done either to avoid having a trip-risk cut-out in the aisle carpet (!), or more likely to prevent curious pilots from gaining access in flight. (It also removed the option of exiting/entering the aircraft that way on the ground.)

With five threads running here I am catching up slowly.

Regarding posting schematics etc. We were warned by Boeing not to pass on/reproduce training data. Particularly for the GEnEx engine on pain of, well not exactly death but they were very specific.

TURIN,

I did wonder about that...

TURIN...

Howdy. I may have let a muse in when pondering the Batteries' role in the Grounding. I'm pretty sure I was not proposing that sixty pound batteries can keep a flying auditorium pumped up to 6000 feet at altitude :ok:

So some suspense... Boeing has told you not to discuss the GE? That infers a new concept in the word proprietary; how much knowledge can be leaked into the public domain?

Boeing speced a powerplant that is more or less a hybrid. Plugging the bleeds and bolting on Generation? That is not new. The JT-8D supplied multiple megawatts to the power grid in California back in the nineties....

But they were not required to be airborne. So in the interest of discussion, until more data is released by the principals, (I won't hold my bleed air), how do you interpret the turboshaft concept + CFRP?

If it is down to RAT, then Boeing don't have much to offer in the realm of innovation, at least insofar as it applies to "new" technology. imo. (Vis a Vis SAFETY, pardon my "french")

:ok:

No offence meant Lyman, but you tend to talk (type) in riddles. :\

Vis...Sorry, no idea what you are getting at here. It is what it is. The engines are no different really from their predecessors. Two gennies instead of one and no bleed air apart from engine anti-ice.

CFRP is another story. Not new, but the way that Boeing have used it is. How it withstands ramp-rash was one of the major worries. The idea that the aircraft would be grounded due to overheating batteries was certainly not on my list of gotchas when I did the course. The fuselage being thumped by a highloader and the consequent inspection required afterwards was my No.1.

As for the RAT. Well to be honest they get more use in the hangars don't they? No innovation required there except, as I said before, to keep the weight down. :ok:

I was under the impression that 2 separate batteries (which can be isolated separately), are required for ETOPS?

Lithium Battery trials (1980s)

Alarming!



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