

Investigation continues focusing on battery certification




Boeing 787 production line [Image Source: Boeing]



Sources: Boeing, NTSB

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propagation of fire to adjacent cells??


RE: propagation of fire to adjacent cells??


RE: propagation of fire to adjacent cells??

RE: propagation of fire to adjacent cells??




RE: propagation of fire to adjacent cells??





Power cells:
Electronic Cool Liquid:




* A small cell is much easier to cool.
* Extra redundancy by using parallel cells.





RE: propagation of fire to adjacent cells??

RE: propagation of fire to adjacent cells??



RE: propagation of fire to adjacent cells??






They wouldn't take his help...
By Daneel_ on 2/11/2013 11:03:25 AM , Rating: 5
Elon Musk must be feeling pretty smug right about now.

RE: They wouldn't take his help...
i think he feels that way most of the time anyway.

And in most cases, justifiably so.

RE: They wouldn't take his help...
By Sazabi19 on 2/11/2013 12:02:35 PM , Rating: 2
But aren't the drivers of hybrids and alternative energy cars the leading cause of smug?

RE: They wouldn't take his help...
By mrwassman on 2/11/2013 12:28:17 PM , Rating: 1

By seamonkey79 on 2/11/2013 6:01:05 PM , Rating: 2
I heard the smug in LA was so bad they had a news report about it and it blanketed the city in smug clouds 0_0

The hair trigger.
By drycrust3 on 2/11/2013 4:38:29 PM , Rating: 2

I think the investigators have got the wrong end of the stick. They are saying the battery cells are the problem, not the environment, but I think the environment is the problem, not the battery, or rather, the battery isn't the right one for the environment.
As I understand it, this battery has a nominal voltage of 30 volts, and each cell has a nominal voltage of 3.7 volts, meaning the entire battery consists of just 8 cells, so all cells in the battery showed the same signs failure.
According to one media report, Japanese Transport Safety Board investigator Hideyo Kosugi said "I'm sure that too much current or too-high voltage has gone to the battery".
(Link removed to avoid spam detection)
According to the Yuasa spec sheet for this battery, the maximum "operative ambient temperature" for each cell is 65 deg C. (See their spec sheet here: (link removed to avoid spam detection))
As I see it, as the internal temperature goes up, so the resistance of the internal insulation drops, thus the internal leakage current increases within each cell. Normally the heat generated by the internal leakage is so small that the battery as a whole can dissipate it happily, and there isn't a problem.
If, however, due to some environmental factors the battery cells aren't able to dissipate the internal heat as fast as it is generated, e.g. an alternating high discharge current and then a high charge voltage are applied to the battery, or the battery cells are tightly packed in a poorly ventilated area, so the internal temperature rises above 65 deg C, then you could one of those endless loop problems.
For example, say a sustained cycle of load and charging is placed on the battery and the raises the internal temperature rises above 65 deg C, so the leakage current also rises to the point the heat generated by it is faster than the battery can dissipate, then you would have a cascading effect, where the rising temperature allows more the leakage current, and the increasing leakage current raises the internal temperature, and you would get an almost impossible to stop situation.
It may well be this battery could, in just seconds, go from being "a bit hot" to erupting like a volcano.


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