Dreamliner: Boeing 787 Aircraft Battery "Not Faulty" 184
A reader writes "Airline safety inspectors have found no faults with the battery used on Boeing's 787 Dreamliner, Japan's transport ministry has said. The battery was initially considered the likely source of problems on 787s owned by two Japanese airlines. The world's entire fleet of 50 787s has been grounded while inspections are carried out. Attention has now shifted to the electrical system that monitors battery voltage, charging and temperature. Transport ministry official Shigeru Takano said 'we have found no major quality or technical problem' with the lithium-ion batteries. Shares in GS Yuasa, which makes the batteries, jumped 5% on the news. 'We are looking into affiliated parts makers,' he said. 'We are looking into possibilities.'"
Which way will it go? (Score:5, Interesting)
The 787 is a revolutionary aircraft on many levels, from features to construction technology to production methods. I would expect there to be unforseen issues resulting from interaction between different systems. What I'm curious about is whether Boeing will get them all sorted out quickly enough...in which case they will be superbly positioned to compete, having mastered the many challenges around making the 787 what it is. If they don't, then they will be in terrible trouble. I feel like I'm watching aeronautical history playing out before my eyes.
I hope they get it all fixed in time, personally. The 787 is a hell of a plane. Check it out here: http://www.newairplane.com/787/ [newairplane.com]
more conventional batteries add few hundred lbs (Score:5, Interesting)
A Bit of a Deceptive Statement (Score:4, Interesting)
Driving into work this morning, I heard this same quote on NPR:
"Airline safety inspectors have found no faults with the battery used on Boeing's 787 Dreamliner, Japan's transport ministry has said."
Worded as such, I think most people would get the wrong impression. They're defining the battery as if it's sitting in someone's pocket, detached from any relevant system & unable to charge or discharge; I didn't think of it that way, and I'd suspect most others didn't either. Most news outlets could use the clarity (albeit, only eventually) provided by the BBC article. The battery *itself* is not the culprit, but investigators essentially *do* still suspect the battery *system,* including the batteries themselves.
Re:Which way will it go? (Score:5, Interesting)
I'm not surprised by unforseen issues from the new technology and design (like the fuel leaks that have been reported), I'm quite surprised to see battery problems since they must have already run the batteries and charging system through many thousands of simulated takeoff/landing cycles both in bench tests and while installed in a test airframe.
This. They knew the batteries were problematic. The Boeing engineers and subcontractors aren't idiots. Even if the snarky NYT opinion piece which suggests that Japanese firms were preferentially picked for financial rather than technical reasons is true - those said Japanese firms aren't exactly slouches (GL-Yeasu (sp?) makes Lithium ion batteries for spacecraft.
Sounds like a production issue. But these things are complicated. Look at the F22. That's why it's called the bleeding edge.
Logs indicate no overcharging (Score:5, Interesting)
The battery charging voltages and currents are logged, the logs go to the flight recorder, and they don't indicate overcharging. [aero-news.net] There are monitoring circuit boards in the battery case, separate from the charger, which report this data. Either the charger failed in some way that caused an overcharge without the voltage sensing detecting this, or the battery itself failed.
The NTSB says they haven't found anything defective yet. The burned battery is enough of a mess that it's hard to extract much info, but they're using spectroscopy to check that the composition of the components was correct.
The grounding is necessary. The JAL aircraft at Logan only had 22 takeoff/landing cycles on it, and this has now happened twice, so the odds of further trouble are high. Over the next few days and weeks, batteries and chargers will probably be pulled from other aircraft and cycled through pressure chambers, shake tables, and hot/cold cycles in attempts to induce the failure.
Meanwhile, I suspect that there are frantic efforts at Boeing to design a replacement that doesn't use lithium-ion batteries.
Re:Oxygen is usually the culprit in most fires (Score:4, Interesting)
OMG, so THAT'S what Uncle Sam meant when he trained me to fight Class Delta fires!! Well, just push the damned thing overboard, and let the giant squids at the bottom of the sea worry about the fire!
Which reminds me - I saw a video one time - wonder if I can find it again . . . .
Can't find that particular video now, but this one gives you the idea:
http://www.youtube.com/watch?v=95O-bQo04Ok [youtube.com]
A fire department arrived at the scene of a cargo fire on board a tractor trailer. They proceeded to hose the fire down, and before they were done, a dozen other trailers had caught on fire. The fire would burn merrily along, the firemen would turn a hose on it, it exploded, they ran, and when the flames started to die down some, they would repeat. I wanted to laugh - but I've stood to close to the fire to many times to laugh, I kept expecting the fools to kill themselves.
Brakes and wiring (Score:4, Interesting)
You can take it for what it's worth but the wide array of problems plaguing this plane right now, the wire harness does make sense. Though bad design or bad manufactoring is yet to be seen.
Re:Japanese covering their butts? (Score:5, Interesting)
The cells do not have identical leakage, so some cells tend to overcharge to compensate for the other cell in the stack which leaked its charge away.
This phenomena shows up after the cells have been in service for months to years.
The older chemistries I have worked with have been relatively tolerant of overcharge, converting the excess energy either to heat or hydrogen gas, which was silently vented. Lithium ion cells are not nearly as tolerant to overcharge as NiCd, LiMH, or Lead-Acid cells. Overfilling a lithium ion cell seems like overfilling a propane tank. Once it tops off, there is nowhere for the excess energy to go and POP goes the weasel.
If you are charging based on stack voltage, you will overcharge the hell out of a good cell as you try to bring the terminal voltage of a weak cell up. You will detonate your good cell in the process.
I am currently playing around with a lithium battery pack monitor with which I have individual chargers for each cell. There is no way I would consider charging all cells in series as is commonly done in the earlier packs. With the DC isolation I can easily get from high frequency inverters, it is quite easy for me to get matched voltages from multiple windings. I use supplemental converters to additionally charge individual cells that leak a bit more than others in the pack. I also have switched cell monitors which rapidly switch each cell onto a measurement buss along with three tightly controlled reference voltage sources. This results in a signal stream which indicates terminal voltage of every cell in the pack, cell by cell. This feeds a digitizer which constantly tracks each cell voltage and is instructed to terminate battery function if any cell shows over or under charge. If a cell simply needs a little help, the individual cell inverters kick in to boost the weaker cell and such activity logged.
A supplemental benefit of the serial analog data stream is that I can use any oscilloscope to see all the cells at once... I can sync to cell 0 which is the reference voltage. ( three references because this is so critical that if I have a reference drift I will have two others that hopefully are providing reliable data. Bad data = explosion; false trip=expensive downtime ).
Lithium batteries have a lot to offer, but they are also quite a bit more volatile than other chemistries I have worked with. Even YouTube has quite an assortment of videos of overcharged lithium cells igniting. Like a propane tank, they are quite useful if not mistreated, but can really take you to the cleaners if you do.