FAA Grounds 787s
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Will put my 2 cents in here,
Batts no matter what type are just a storage device.
For example your car, rated at 12 volts, batt is 12 volts, the charging current going into the batt is 13.5 to 14 volts.
Depending on the state of discharge and governed by the voltage regulator.
You would never get a fully charged batt with just a 12 volt charge going into it, has to be higher.
12 volts is already considered 50 percent discharge.
On the 747 batt voltage is 32-36 represents a normal batt charge.
The apu batt is only used during apu start, but has a lower voltage requirement on pre flight.
The main ships batt is always lower because it is wired to the hot battery bus and always has a discharge , clocks etc.
Just wondering if this main ships batt is very low and not being charged as much due to short flights, maybe overheatingtrying to make up for the loss, a sponge even though dry can only soak up so much water a a time will will try to take as much as it can.
If you overcharge or exceed it it will boil over.
Sorry just and old F/E and thoughts.
Thats why the smoke and mirrors replaced us,
They know best.
Batts no matter what type are just a storage device.
For example your car, rated at 12 volts, batt is 12 volts, the charging current going into the batt is 13.5 to 14 volts.
Depending on the state of discharge and governed by the voltage regulator.
You would never get a fully charged batt with just a 12 volt charge going into it, has to be higher.
12 volts is already considered 50 percent discharge.
On the 747 batt voltage is 32-36 represents a normal batt charge.
The apu batt is only used during apu start, but has a lower voltage requirement on pre flight.
The main ships batt is always lower because it is wired to the hot battery bus and always has a discharge , clocks etc.
Just wondering if this main ships batt is very low and not being charged as much due to short flights, maybe overheatingtrying to make up for the loss, a sponge even though dry can only soak up so much water a a time will will try to take as much as it can.
If you overcharge or exceed it it will boil over.
Sorry just and old F/E and thoughts.
Thats why the smoke and mirrors replaced us,
They know best.
Last edited by Earl; 21st Jan 2013 at 06:18.
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Investigation focus 'is now on the battery charger and APU':
BBC News - US widens Dreamliner safety probe after battery finding
BBC News - US widens Dreamliner safety probe after battery finding
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But what's the big deal?Incident: ANA B788 near Takamatsu on Jan 16th 2013, battery problem and burning smell on board The battery is smaller than the car battery. Just put any other type. Will be twice as big but who cares? Can be done in couple of hours.
Last edited by Turbavykas; 21st Jan 2013 at 06:25.
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You're welcome to him in Seattle. We certainly don't want that sort of genius here in Europe. Shame we can't shed these non aviation types, or that they don't care to learn from ppr.
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have to agree also.
stick the old proven types back in and get the airplane back in the air.
Not much difference in the weight, retire a few grandma F/A. at united.
Even lesser weight reduction
Batts weigh less .
stick the old proven types back in and get the airplane back in the air.
Not much difference in the weight, retire a few grandma F/A. at united.
Even lesser weight reduction
Batts weigh less .
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Originally Posted by turby
But what's the big deal?Incident: ANA B788 near Takamatsu on Jan 16th 2013, battery problem and burning smell on board The battery is smaller than the car battery. Just put any other type. Will be twice as big but who cares? Can be done in couple of hours.
I nominate the Baghdad battery. Nothing like returning to old technology to get a tried and tested outcome!
The Baghdad Batteries
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Just put any other type. Will be twice as big but who cares? Can be done in couple of hours
from an earlier post...
They also said a battery fire could not happen in flight because the APU battery was only used on the ground.
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Don't think this was battery related..
Boeing: 787 fire caused by failure in aft electronics bay power panel | ATWOnline
Boeing: 787 fire caused by failure in aft electronics bay power panel | ATWOnline
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- ...First of all the Li Po are not being used in the Av industry.
- ...We are concentrated on li Ion and not Li Po,
- ...We are concentrated on li Ion and not Li Po,
check this
Most Li-polymer packs for the consumer market are based on Li-cobalt.
To my knowledge, the 787 LiIon are cobalt based.
So, the scaring vid I posted is not toooo off...
Regards
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Another relevant article on battery technology:
Boeing’s Dreamliner batteries “inherently unsafe”
Boeing’s Dreamliner batteries “inherently unsafe”
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If it is only battery safety that is concerning the FAA, I wonder if replacing the Yuasa battery with an equivalent SAFT Li-ion unit would work as an interim 'fix' to get the 787 fleet in the air again.
SAFT seem to have a good safety and reliability record in the supply of LI-ion batteries for use in space vehicles. For this application, they must be capable of withstanding mechanical stresses during launch and a wide temperature range during orbit. Safety features on individual SAFT cells include a shutdown separator, a circuit breaker, a vent and a stainless steel outer case. A SAFT battery, comprising a number of individual cells, is then encased in a further stainless steel container.
See link: http://www.saftbatteries.com/doc/Doc...e4af5b011d.pdf
SAFT seem to have a good safety and reliability record in the supply of LI-ion batteries for use in space vehicles. For this application, they must be capable of withstanding mechanical stresses during launch and a wide temperature range during orbit. Safety features on individual SAFT cells include a shutdown separator, a circuit breaker, a vent and a stainless steel outer case. A SAFT battery, comprising a number of individual cells, is then encased in a further stainless steel container.
See link: http://www.saftbatteries.com/doc/Doc...e4af5b011d.pdf
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Any more on the previous report that the APU battery charger takes it's supply off the F/O's Instrument supply bus?
Yeah, I shook my head too when I read it.........they wouldn't would they...
From a post by gas path in http://www.pprune.org/rumours-news/5...arning-12.html
post 224
So the possibility, however slight, of a cascading battery failure [s] dragging down the supply buss[es] for both "sets" of instruments?
that can't be right surely.....
Yeah, I shook my head too when I read it.........they wouldn't would they...
From a post by gas path in http://www.pprune.org/rumours-news/5...arning-12.html
post 224
The four engine driven generators supply the 235v variable freq. That goes to the aft and fwd EE bays. The aft EE bay Auto TRU's convert to +/-270vDC.
The DC is for driving the cabin air compressors, centre hyd. pumps. O/Jett pumps, the ram fans, and the NGS compressor.
The APU battery located in the same bay supplies the APU Hot Batt Bus its charger is supplied from the F/O's instrument bus. APU starter 235vac from the ATRU.
The main a/c battery located fwd. is charged (via a charger) from the capt's instrument bus. This is the only one with a diode pack to prevent the Hot batt. bus from back feeding the battery.
The PMG's only power the eng. EEC's
Windmilling engines will provide some hydraulic power. Enough for flight controls.
The RAT will supply hydraulic power to the centre hyd. system.
The RAT will supply electrical power to the ac busses (with some serious load shedding!) but primarily the backup bus, flt. instrument busses, brake system controllers (130VDC)
I'm tired its getting late..so apologies if I've got something wrong.
The DC is for driving the cabin air compressors, centre hyd. pumps. O/Jett pumps, the ram fans, and the NGS compressor.
The APU battery located in the same bay supplies the APU Hot Batt Bus its charger is supplied from the F/O's instrument bus. APU starter 235vac from the ATRU.
The main a/c battery located fwd. is charged (via a charger) from the capt's instrument bus. This is the only one with a diode pack to prevent the Hot batt. bus from back feeding the battery.
The PMG's only power the eng. EEC's
Windmilling engines will provide some hydraulic power. Enough for flight controls.
The RAT will supply hydraulic power to the centre hyd. system.
The RAT will supply electrical power to the ac busses (with some serious load shedding!) but primarily the backup bus, flt. instrument busses, brake system controllers (130VDC)
I'm tired its getting late..so apologies if I've got something wrong.
So the possibility, however slight, of a cascading battery failure [s] dragging down the supply buss[es] for both "sets" of instruments?
that can't be right surely.....
Last edited by glad rag; 21st Jan 2013 at 12:02. Reason: more info re charger power supplies
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Can I just clarify some confusion in my head? There are two batteries per plane, is that right? One for the APU and one for the rest of the plane's electrical requirements? The various battery problems encountered in the 787 involve both the APU battery and the main ship battery, yes? Are these both Li-ion and made by Yuasa? And are they both physically in the same electronics bay?
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There are two batteries per plane, is that right?
Yes
One for the APU and one for the rest of the plane's electrical requirements?
Yes
The various battery problems encountered in the 787 involve both the APU battery and the main ship battery, yes?
Yes
Are these both Li-ion and made by Yuasa?
Cells (Li-Ion) are made bei Yuasa, Batteries are labled "THALES"
And are they both physically in the same electronics bay?
No, main batt in fwd E/E, APU batt in aft E/E compartement.
Yes
One for the APU and one for the rest of the plane's electrical requirements?
Yes
The various battery problems encountered in the 787 involve both the APU battery and the main ship battery, yes?
Yes
Are these both Li-ion and made by Yuasa?
Cells (Li-Ion) are made bei Yuasa, Batteries are labled "THALES"
And are they both physically in the same electronics bay?
No, main batt in fwd E/E, APU batt in aft E/E compartement.
If this is a repost, please erase. Look at pic #2, about 1/3 down this page:
Dreamliner Fire: Investigation Widened
Dreamliner Fire: Investigation Widened
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So the possibility, however slight, of a cascading battery failure [s] dragging down the supply buss[es] for both "sets" of instruments?
Don't worry, if a battery
up, the relevant charger will not affect its supply bus.