Japan 787 probe finds thermal runaway in battery

There was thermal runaway in the battery? Well state the obvious!

So basically, what they are saying is that, these planes won't probably be in the air this year, this just the tip of the ice berg, betcha, that won't be the only thing they'll find methinks. Even if they might, don't expect the 787 to sell out seats.

Finally we can clearly see what caused the loss of billions of dollars = Poor Japanese design.

Investigators earlier said they found no evidence of quality problems with production of the 787’s batteries

Of course there's nothing wrong in the production systems of a world-class company like GS Yuasa. But there may be problems in terms of design.

It's not the battery that is at fault. I bet what the problem is the battery charging circuit. Lithium-ion batteries cannot be charged the same way as NiCAD or Lead Acid. They have specific charging requirement and are prone to thermal problems (like catching on fire or exploding) when charged incorrectly.

Pictures of battery are showing that 787 may have more problem then just batteries because with out overload they would not blow up and burn .

The temperature rose up to 600 degrees celsius causing the damage.

Still no definitive results. What caused the thermal runaway ? Poor design ? Improper operation of the charging circuit ? They made it a point of saying the quality of production with these batteries is not the cause this nome but failed to point out whether it is a definite design problem either with the battery or the circuits involved controlling the usage of these batteries

Whatever the cause of the fires is ultimately found to be, I suspect that there will be a quick fix in the form of changing back to a more proven battery. Ni-CD and Ni-MH have logged millions of hours in aerospace applications and evidently do not have a risk of thermal runaway. Looking at the small size of the battery that burned, it seems like only a small weight savings was achieved by using Li-ion, and I think everyone will gladly accept a few kilos more for the sake of safety. Boeing engineers just over-reached in the cause of saving weight.

Steve, I doubt that switching to Ni-CADs or others would be a "quick fix." A fix yes, but all Dreamliners would then have to be modified and then re-certified.

Elon Musk says that the lithium-ion batteries used on Boeing's 787 are inherently unsafe, due to its design. "Large cells without enough space between them to isolate against the cell-to-cell thermal domino effect means it is simply a matter of time before there are more incidents of this nature," he adds.

Both Boeing and Tesla (the electric car company by Musk) use batteries fueled by lithium cobalt oxide, which is among the most energy-dense and flammable chemistries of lithium-ion batteries on the market. While Boeing elected to use a battery with a grouping of eight large cells, Tesla's batteries contain thousands of smaller cells that are independently separated to prevent fire in a single cell from harming the surrounding ones.

"They [Boeing] believe they have this under control, although I think there is a fundamental safety issue with the architecture of a pack with large cells," writes Musk in an email. "It is much harder to maintain an even temperature in a large cell, as the distance from the center of the cell to the edge is much greater, which increases the risk of thermal runaway."

"Investigators earlier said they found no evidence of quality problems with production of the 787’s batteries by Kyoto, Japan-based, GS Yuasa, whose own aerospace ambitions are on the line."

Of course they didn't! vested interests and all that. So now that they know it's the battery and Yuasa, is ANA going to stop demanding money from Boeing? Are they going to redirect their lawsuits?

Lithium ion batteries are more susceptible to catching fire when they overheat or to short-circuit than other types of batteries.

This isn't even proper english, let alone correct. When a battery overheats, it can catch fire, regardless of the type, aviation grade lead-acid ones are just a bad even.

Photos distributed by the Japanese investigators show severe charring of six of the eight cells in the ANA 787’s battery and a frayed and broken earthing wire — meant to minimize the risk of electric shock.

The earthing wire isn't there for electric shock, and theoretically should have nothing to do with a short since it isn't "part of the circuit" for normal operation. If it does, then they have some serious design flaws in those batteries.

The Japanese probe is focusing on flight data records and on the charger and other electrical systems connected to the damaged battery.

Of course they are, because the charger is american (with Yuasas specifications) and the controls are french (with a good chunk of british engineering). No Japanese company could ever make bad batteries... after the first Sony incident in 2000... and then the second one in 2005 (nikon branded)... then a third in 2006-2008 (practically half the laptop batteries from that time)....

Steve FabricantFeb. 06, 2013 - 10:07AM JST

I suspect that there will be a quick fix in the form of changing back to a more proven battery. Ni-CD and Ni-MH have logged millions of hours in aerospace applications and evidently do not have a risk of thermal runaway.

False, NiCd batteries also have thermal runaway, and worse yet, they can just fail for no reason. Lithium batteries can be just as safe, though not all types of li-ion are built the same. And li-ion batteries have also logged at least hundreds of thousands of hours in space, if not millions. No failures to date.

Looking at the small size of the battery that burned, it seems like only a small weight savings was achieved by using Li-ion,

no less than 30% weight savings, up to 40% (http://www.ainonline.com/aviation-news/ainalerts/2013-02-05/eaglepicher-li-ion-aircraft-battery-nears-certification). In aviation, that's huge considering the 12 or so battery packs would weigh a ton (literally) if they were flooded lead acid like on older aircraft.

@FPSRussia

"Finally we can clearly see what caused the loss of billions of dollars = Poor Japanese design."

Wrong. But we can clearly see that you can't read.

If I read the earlier articles correctly, this battery is the starting battery for the APU. It does not need to be a large bank, I would think a comparable bank of AGM (absorbed glass mat) batteries would do the same job and not be a safety hazard.

Instead of changing the Batteries, they prefer to keep saying 'Its not the Batterys fault' and keep the Flights grounded! Its cheaper to replace these stupid so-called cost saving batteries than to ground all the Airlines fleets. Arrogant really.

Droll QuarryFeb. 06, 2013 - 01:19PM JST

If I read the earlier articles correctly, this battery is the starting battery for the APU. It does not need to be a large bank, I would think a comparable bank of AGM (absorbed glass mat) batteries would do the same job and not be a safety hazard.

Correct and incorrect. The mainship batteries are identical make to the aux batteries, just in different places. And between batteries there's plenty of cooling in place, which is why one battery won't cause fires in adjacent batteries. The 8 cells per battery though is mandatory, since each cell is 3.7v and they need 30V total.

As for AGM, I've already stated that lead acid batteries are both heavy and still perfectly flammable. Of course, if you don't mind your luggage charge doubling you could replace them, but it's not really a good idea.

humanrightsFeb. 06, 2013 - 01:52PM JST

Instead of changing the Batteries, they prefer to keep saying 'Its not the Batterys fault' and keep the Flights grounded! Its cheaper to replace these stupid so-called cost saving batteries than to ground all the Airlines fleets. Arrogant really.

To replace them with properly manufactured versions of what they already have is cheap, to replace them with outright new ones is not, and it'll require them to be grounded for 8-12 months while the batteries are certified. As I stated, eaglepicher is in the process of certification right now, but they still have a long way to go.

Due to the number of new technologies in these planes I wouldn't be surprised if some interaction between them is causing these issues rather than the batteries themselves. The damage to the grounding wire is particularly interesting. I wonder if the issue could be related to static buildup on the carbon fiber fuselage leaking into the battery via the grounding system.

AinTsFeb. 06, 2013 - 03:36PM JST

The damage to the grounding wire is particularly interesting. I wonder if the issue could be related to static buildup on the carbon fiber fuselage leaking into the battery via the grounding system.

That wouldn't fray it, only real causes for that are fire, improper handling, improper design (they used braided cable rather than solid when the design was originally for solid), or manufacturing error (someone accidentally left out a sleeve somewhere).

Static shouldn't really matter in this case because the issues are the same as in a regular metal skinned craft, and both still have metal frames.

@basroil the same batteries are not all used by other countries, they already approve different batteries. The JP refuse to acknowledge other coutries Certifications, its a plot to stall like everything else in JP, 'Waste the time' 'Waste the Life!' Ridiculous and ignorant.

No other Airlines has Grounded its Planes for so long over a simple Battery issue. JP impossibility for decision making and accepting responsibility is evident here!

humanrightsFeb. 06, 2013 - 06:26PM JST

the same batteries are not all used by other countries, they already approve different batteries

Absolutely false. The only battery approved for use in 787s is the pack manufactured by GS Yuasa using their LVP line of lithium ion cells. No other battery was approved for use in 787s by either Boeing or FAA, and to ship a plane out with alternative batteries you need both.

That wouldn't fray it, only real causes for that are fire, improper handling, improper design (they used braided cable rather than solid when the design was originally for solid), or manufacturing error (someone accidentally left out a sleeve somewhere).

I suppose the wire is rather thick and the temperature of the burning batteries (I remember that I read about 600~700C somewhere) is probably not enough to melt them, even when it is braided cable.

Static shouldn't really matter in this case because the issues are the same as in a regular metal skinned craft, and both still have metal frames.

I wouldn't dismiss static electricity easily, as it could destroy the protection circuits in the battery which then causes the battery e.g. to overload or to short as a secondary effect. The fact that Boeing has asked for the authorization of test flights indicates that they are looking for something which can only happen during operation and the build up of static electricity or other high voltage spikes on the power lines are prime candidates. I can't see how the plane having a metal frame should change anything?

I don't understand why people here consistently give thumbs down to your comments. You have a strongly biased opinion, but that's fair as long as you support it by facts and other facts don't contradict you.

Question for the knowledge base: what level of change would NOT be considered to require re-certification? Let's assume that we stick to Li-ion because alternative battery types are also potentially catastrophic failure-prone (and let's ignore the disingenuous weight comparison with lead-acid). I am partial to Elon Musk's explanation that a higher cell density is the answer, but also think it likely that Yuasa had excellent quality control on what must be a small but intensely monitored production line, and that Boeing production does not allow stupid mistakes like using the wrong kind of wire and absent insulation to happen. So wouldn't going to more cells per Li-ion battery be subject to re-certification? What about a software fix for the charging unit(s)? It's crazy to keep hoping that investigation of the Yuasa batteries will turn up some metal shavings or Monday-morning cigarette butts in the cells.

gonemadFeb. 06, 2013 - 08:55PM JST

I suppose the wire is rather thick and the temperature of the burning batteries (I remember that I read about 600~700C somewhere) is probably not enough to melt them, even when it is braided cable.

Not enough to burn them sure, but then again I was leading towards manufacturing errors.

I wouldn't dismiss static electricity easily, as it could destroy the protection circuits in the battery which then causes the battery e.g. to overload or to short as a secondary effect.

Could, if it wasn't that no such errors were seen in the data, nor would it explain two fires in such a short time with two planes that had nothing else in common other than new batteries, and why it hasn't shown up in any other hull.

No other Airlines has Grounded its Planes for so long over a simple Battery issue. JP impossibility for decision making and accepting responsibility is evident here!

??? ALL airlines with this model aircraft have grounded their 787 planes since the second incident with the battery. ANA and JAL are not being irresponsible in doing this. Two catastrophic failures within a week of each other resulting in smoke and fumes entering the cabin is going to get ANYBODY'S attention. Boeing is taking this seriously and will not be satisfied until a reason for the failures can be determined. With all the money that they are losing with this grounding, it's STILL cheaper than what would happen if they got the planes in the air and one subsequently crashed due to an on-board fire.

Question for the knowledge base: what level of change would NOT be considered to require re-certification?

Any change from the currently-approved battery requires certification. If a different manufacturer wants to make the exact same design, they have to show that their product is identical to the already certified product. The certification process does this.

Could, if it wasn't that no such errors were seen in the data, nor would it explain two fires in such a short time with two planes that had nothing else in common other than new batteries, and why it hasn't shown up in any other hull.

I don't think we can rely on the data from the on-board voltage monitoring circuits. It depends on how they are designed, but their sampling will be rather slow while discharges of static electricity are very fast. Probably you need specialized equipment to detect the spikes. The reason why the problems haven't shown up in any other hull is that they depend on a unique combination of equipment, wiring and physical placement. Small changes can show completely different behavior. Actually, these things can become nightmares even for experienced engineers.

We can't rule out manufacturing defects. But there are still so many other possible explanations, the above being just one.

Wouldn't the primary questions be 1 - Why are these batteries overheating? 2 - What is drawing so much current as to cause this reaction? 3 - Is the aircraft's electrical system undersupplied so much by these batteries? 4 - If so, why?

SperryFeb. 07, 2013 - 01:58AM JST

Wouldn't the primary questions be 1 - Why are these batteries overheating?

Only one reason, a chemical reaction that takes place when charging and discharging. Batteries are imperfect, so heat is produced. That's not really a question.

2 - What is drawing so much current as to cause this reaction?

That is unknown, and can possible be completely internally created shorts. Doesn't have to draw current from outside, and in fact, leading cause of battery failure is internal failures.

3 - Is the aircraft's electrical system undersupplied so much by these batteries? 4 - If so, why?

Absolutely not. The batteries are backup, primary power comes from the engine's generators and a secondary electrical generation system. These packs are actually rated for lower power draw and charging rates than most large hobby batteries.

Would a better headline be: Thermal Battery Can't Leave Runway?