Boeing 787 Dreamliner & Battery Issues

[stopcrazypp]

There is rarely just one cause. The box probably saved many lives. If as Elon says the cells aren't sufficiently isolated then they missed an opportunity to stop the failure earlier. There's another cause on top of that, probably an issue with the charging system (since they have exonerated the cells what else is left?).

The thing is if the cells have no issues and the issue was the charging system, then it's quite possible for it to cause damage to all the cells at once (for example by overcharging), in which case isolation probably wouldn't have helped. Isolation would help if the damage started in one cell or only a couple of them.

[aaronw]

Actually with Tesla there's a much lower chance of overheating and fire since each individual cell has its own protection circuit to prevent overcharging, overdischarging and overcurrent conditions.

[brianman]

If they're seen as inferior to Tesla by accepting their help, it could be more likely that Tesla will be awarded contracts over Boeing.

If it's the case, it's pride leading to bad decisions.

I would argue they are inferior because they would be rejecting such help. Further, it's arguably negligent (as hinted by others) to not at least entertain all possible solutions to their technical problems that put human lives at risk -- regardless of the source.

[Norbert]

As I understand it the cells have been cleared of defects.

What kind of defects have they been cleared of? Individual manufacturing defects? That wouldn't necessarily mean that it is a safe design to use a pack design with large cells of that specific chemistry, and additionally, to do so without sufficient isolation between cells. Regardless of whether that was the specific cause in any of these two cases, or not.

[AnOutsider]

If it's the case, it's pride leading to bad decisions.

I would argue they are inferior because they would be rejecting such help. Further, it's arguably negligent (as hinted by others) to not at least entertain all possible solutions to their technical problems that put human lives at risk -- regardless of the source.

First, I realize now my post should have read "...likely that SpaceX will be awarded contracts over Boeing."

In any case, I agree with you re: them saving lives. From a business standpoint though, if two technology companies are vying for your dollars, and one of the companies ends up helping the other out on something that's not directly related to your business, but close enough, you might pick the more knowledgeable one (barring other factors like the other clearly having superior tech in your specific field, or bid half what the other guy bid or something along those lines).

[JRP3]

What kind of defects have they been cleared of? Individual manufacturing defects? That wouldn't necessarily mean that it is a safe design to use a pack design with large cells of that specific chemistry, and additionally, to do so without sufficient isolation between cells. Regardless of whether that was the specific cause in any of these two cases, or not.

Similar cells of the same chemistry have been successfully used in rockets and satellites for years. I'd guess that either external controls failed to keep the cells within design parameters, or as you suggest this application as designed excessively stressed these cells by subjecting them to constant C rates that were too high, causing premature cell degradation.

[Suzieq]

Boeing Lithium-ion Batteries are Inherently Unsafe, Says Elon Musk

Here's the link:Boeings 787 Lithium-ion Batteries are Inherently Unsafe, Says Elon Musk : TreeHugger

From the article:
"Unfortunately, the pack architecture supplied to Boeing is inherently unsafe," writes Musk in an email to Flightglobal.

"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. [...]
"Moreover, when thermal runaway occurs with a big cell, a proportionately larger amount of energy is released and it is very difficult to prevent that energy from then heating up the neighboring cells and causing a domino effect that results in the entire pack catching fire," says Musk.

[Martini]

Will a smaller cell always be statistically safer, independent of control electronics?

[JRP3]

It seems like a trade off to me. Smaller cell, less potential damage per cell, but more cells involved, so more potential failure points.

[Doug_G]

The thing is if the cells have no issues and the issue was the charging system, then it's quite possible for it to cause damage to all the cells at once (for example by overcharging), in which case isolation probably wouldn't have helped. Isolation would help if the damage started in one cell or only a couple of them.

If you connect ten balloons together and then over-inflate one will pop first. This is no different; one of the cells will fail first. The control system should recognize the irregularity and shut down the system. In that case the problem is unlikely to propagate IF the cells are isolated. The resulting damage would be much less significant as there would be less fuel for the fire.