Posted on 02/13/2013 9:20:08 PM PST by rawhide
Two test flights of Boeing Co's (BA.N) 787 Dreamliner have not revealed the cause of the battery malfunctions that grounded the jets, leaving it to focus on low-tech interim fixes, the Wall Street Journal said, citing government and industry officials.
More test flights are planned, including efforts to assess potential fixes, although no significant new clues emerged to help pinpoint the cause of the problem, the Journal said.
Boeing is now considering putting the lithium ion batteries in a sturdier container to stop heat, flames and toxic chemicals from escaping if the power packs overheat, the newspaper said.
People familiar with the design of the container told the Journal that titanium is a possible material for its construction.
(Excerpt) Read more at reuters.com ...
But the charging circuits are charge rate limited and quad-redundant and if one malfunctioned the others would be lighting up warning blinkers like a Christmas tree. There are current and thermal sensors embedded in the systems. I think it is much more likely that an internal short developed in these batteries.
” I think it is much more likely that an internal short developed in these batteries.”
I think you are right...
These batteries are said to work well in other vehicles, even in those that experience considerable vibration. Ther must be something unique to 787 that causes the problem. Could be pressure change, could be vibration at certain frequencies, could be stray charged particles (those can impact not just the battery, but the controller too. Is the controller fault-proof?)
One bad cause would be defects in manufacturing of those specific batteries that failed. The fire destroys all the evidence (the microstructures that can short the terminals.) You can stare at the good batteries until the cows come home, and you will see nothing and the tests will show nothing. You have to test *bad* batteries - perhaps a large number of batteries, to find those that are bad.
If Boeing cannot find the trigger then they might just as well start designing these batteries out. You cannot sell 50 airplanes for $200M each and then tell the happy owners that they cannot fly them. It's serious money, and there is serious interest on those credits. I'm sure Boeing does everything they can to mollify the customers; otherwise the very first lawsuit will bring Boeing to their knees - and it will be an open and shut case in any court of the world.
http://www.youtube.com/watch?v=JdCYeGrdhE8
So make the battery manufacturer be made to replace them every 10,000 flt. hours(or much less) until they solve the problem(assuming it really IS a "battery" problem).
Make a mandatory(pre-flight)check for battery condition daily/other with internal monitoring systems galore.
(no-bleed system...gutsy call or ???)
If it were a Republican administration pushing(unproven/green)battery technology...the media would have a field day throwing these type stories back in their face.
“Far exceeds the life and strength of aluminum!!!”
Yeah, I’ll just bet “kennyboy” still drives a horse-drawn buggy. Composites are amazing structural materials.
“I understand, from very knowledable family sources, is that the Dreamliner is an electrical hog, as all normally hydraulic systems have been replaced by electric motors.”
If I remember correctly, the batteries involved are used to start the APU, which provides ground power and the means to start the engines. So It’s doubtful that the problem is related to in-flight electrical power which is normally provided by the generators on the engines. BTW, if you have a really new car, you may find that the hydraulics that used to power the power steering have been replaced with an electric motor as well. Much simpler, more reliable, and a whole lot lighter.
these batteries are needed when the airline
is too cheap to run the APU, or not.
please enlighten me.
So the battery is overheating and the solution is to put it in an enclosed metal box???!!!
LOL, more like unlocked cargo door failure and a payoff.
Folks, you have the wrong impression of what these batteries are for. They are not used to run the entertainment and hospitality equipment. They are used to start the APU’s and in emergencies, the avionics.
They are the size of an old desktop PC.
With that said, from the photographs I’ve seen, these packs are poorly designed for use in aircraft:
1) The cells are not partitioned with a cooling system - Air or water jacket around each cell to prevent over or under heating.
2) The electronics in the pack are incorrectly supported for aerospace use - They are held via posts instead of frames and slots.
3) If dedrite growth is the issue, 2 - 3 hour flights will not cause a failure in the short term. Repeated, rapid charge and discharge cycles on a bench will cause the dendrite growth which will eventuall pierce the inter-layer membrain of an individual battery leading to thermal runaway.
Also, there’s way to much speculation being taken as fact here. Go to the NTSB web site and read the investigation reports for facts.
Also, let the engineers do their job. Time more than anything will find the source of this problem.
As an interm, Boeing can probably retrofit nickel metal hydride packs. This will require a recertificaiton of the aircraft however. Which can take months.
Yes, But its a sturdy box. Plan B is to have the flight attendants pour ice into the box every hour.
Aircraft batteries serve several purposes. One is to start the APU, another is emergency power in the event of total generator outage (flameout of all engines like Sullys Hudson crash), aircraft need a power source for relays etc so that you can hook up external power.
Airlines use gate power, APU or external power carts when on the ground. The only time they use APUs on the ground is when parked away from a gate or during wait times for taxi, etc. There is a fixed fee for using electrical carts, tow bars, etc.
APUs are very fuel efficient. On the DC-9 we would add an extra 500 pounds of jet fuel to accomodate APU usage. We ran the APUs all night.
I’ve seen the result of a lead battery explosion on an aircraft. The battery was enclosed in an armored box that was perfectly round after the explosion. One of the cells had shorted out. No idea how it happened because the bird was parked for the night with no systems left on.
>>> Far exceeds the life and strength of aluminum!!! <<<
We will see what problems the plastic tube encounters.
You may remember the Comet disaster.
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