"Transportation Secretary Ray LaHood has said he wants to personally conduct a thorough review of the 787 battery situation. Satisfying LaHood would be critical, since the US Department of Transportation oversees the FAA.
I wouldn't hesitate to fly on an airplane that had this battery in it. After all after Ray La Hood (a career politician) who knows everything about engineering aircraft systems, batteries, etc. is finished with his "review" everything will be fixed. Too bad that he didn't fix the Toyota acceleration problem-- Oh wait he DID.
May be we can get the Navy Admiral who thinks global warming is his biggest problem he has to work with La Hood.
Clearly the cause of over heating needs to be discovered and solved. I' m sure that there are solutions that exsist. I did run across a project where a system was submerged in 3M™ Fluorinert™ Electronic Liquid. What are your thoughts on it or similar products heat transfer and fire suppression abilities?
I'm sure that I read somewhere earlier that the 787 requires two of these new style batteries at approximately 65 pounds each. I think the same article indicated that equivalent batteries of an already proven design type would weigh 20 to 25 pounds more. Since I work in aerospace, I understand the importance and desire to cut weight, but it woud seem that for approximately 50 pounds in weight savings there should be other alternatives. NiCad has been used for years in aircraft without the same risk level as NiMh. Since this is a totally new design aircraft, I would have to think that it includes all the latest levels of EMI sheilding and protection. Since the FAA is re-evaluating the use of on-board electronic devices, maybe Boeing could work with the FAA a bit to get the use of electronic devices approved in the 787 and then they could do away with things like the hundreds of copies of newspapers that get carried on board evey flight. That alone would probably make up for any weight penalty imposed by using proven battery technology, would probably help to improve consumer confidence in the safety of the aircraft and should helpt to get the program back in the air again.
The theoretical upper stability limit of water, above which oxygen should evolve, is 1.23 V and is also pH-dependent. Li-Ion battery works at higher voltage.
The triggering mechanism that induces thermal runaway is directly related to the extent of the cathode thermal instability, and increased oxygen generation Heat generation from the cathode is 3 - 4 times greater than from the graphite anodes at fully charged states because of oxygen that evolves from the cathode lattice above 200 deg C.
I don't think that aqueous cooling will be used to cool direct the electrodes, but there are non-aqueous liquides able to replace the water.
Possibility to implement water in electrode cooling <1%... the risk is to high for this type of Li-Ion battery
But isn't that the key point, Charles? Any peak temperature the battery hit during the combustion is not relevant; once thermal runaway starts, the cell heats itself. The key point is, was the cell running at a temperature high enough to start the thermal runaway, before it got started, and due to some external load or charge condition, such that a cooling system could have kept the cell temperature below the ignition point. If so, some cooling system enhancement is needed. If not, it would not be.
My understanding, which may be wrong, is that once thermal runaway starts, no external cooling will help, the cell just flames itself.
I suspect that the respondents here who are dumping on Boeing are barking up the wrong tree. I think enough testing was done to assure that operation and charging never drove the cells anywhere near the temperature thermal runaway point. This would make speculation about extra cooling systems pointless. And this is what has made the problem so difficult.
I suspect that the problem is in fact in the cells - not necessarily that GS Yuasa "screwed up", that is, permitted a flaw that was known to be wrong, but that some unknown, and therefore uncontrolled and uncontrollable, aspect of production or materials changed.
More interesting than the solution is how can an aircraft go thru nearly 2 years or rigors testing, knowing that the batteries are new technology with specific pitfalls, go into service for less than a year and have several of these dramatic failures. Who is minding the store?
IMHO these batteries failures are inexcusable engineering failures. Could these failures have happened in the air as easily as they did on the ground? Do some people need to be fired?
Republican In Name Only! And he works for the current administration, so...
If the FAA does approve a corrective action plan (understanding that this is an unknown time variable), how long do you think it would be for the 787's that are grounded to be flying again? I assume that the existing fleet would get priority fixes, but would they be fixed where they sit, or would they have to get waivers to fly back to Boeing?
In my mind, even after an approved corrective action, this could be a while before these are seen in commercial use again!
Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.