NTSB chairman Deborah Hersman said last week that investigators have concluded that a short circuit occurred in cell number six of the pack's eight cells. (Source: NTSB)
We all know that lithium batteries are not the state of the art.Funny is that I have an old Samsung 225 with ORIGINAL battery for 10 years. Lithium batteries are bit strange.They should not be discharged completely like SOME others can.I found out that NiMH are also praclically trash if you discharge them fully.So, some kind of trickle charge is a good idea.I am onot a chemist, but I suspect that once the chemistry of a battery goes to extreme ,be it under , or over limits , that battery is unuseable.As far as temperature goes lithium batteries have been used on ships for many years with a great success.Cooling(or in case of airplane ,sometimes heating) and stable pressure is a key here.Unfortunately planes have no natural constant cooling and experience huge changes in an air pressure.
The best thing is this - We will create a battery technolgical leap with this issue. If the analysis is correct the solution has already solved itself -fix the initial or isolate the components of the battery so a small section at 500 degress will not ignite more of the battery or surrounding componets and the issue cannot migrate to the rest of the battery. I commend Boeing for using this technology. If every issue they ran into was solved by adding a cooling system (weight) and revering to the tried and true the plane would be a 707 with lipstick on it - just like a typical marketing department requested. Engineering is not for the faint of heart. In ten years we'll look back at the 787 as a relic that pushed us forward. It will create battery powered cars that actually make sense and cents.
When I wore a military uniform (never mind which color) I remember we had some communicaion equipment which had lithium batteries installed. The equipment was labeled "Do not airlift" because no one trusted the batteries to behave themselves in the air. Nevertheless, I don't remember ever seeing one of these boxes damaged by battery failure. Maybe the correct fix is to switch to a safer battery technology (LiFePO, fof example). Less energy density, but the airlines can make up for it by charging obese passengers a surcharge (they are a prime example of low energy density). Sorry for not being politically correct.
It's been previously reported that the battery was not factory-original, that the battery that burned was replaced by the airline as part of maintenance.
The first 787 is barely one year old, and airlines are replacing batteries? Can you draw a parallel between 787 and a smart phone?
Experts Sadoway and Elton Cairns "suggested that an active cooling system would provide an additional layer of safety for a cost that would be miniscule compared to other 787 sub-system costs. Sadoway again said last week that the Boeing batteries would be safer with active cooling. "That's what GM does in the Chevy Volt," he told us."
My first thought was weight. The Chevy Volt is a grounded vehicle that must generate enough electrical power to propel itself over pavement at a reasonable rate of speed...relatively slow compared to the 500+mph (ground speed) of a large commercial airline.
Like most other mechanical contraptions we've invented, turning electricity into power and power into motion is a big issue. The heavier the machine, the more power it takes to make it move. And thus more electricity. More batteries. More weight.
Wouldn't adding an active cooling system add considerable weight? And take up precious space?
Yes, did it short due to poor construction, being deep cycled too often or being baked too long in that sealed box with no active cooling?
It's almost like having a murder case where the victim was poisoned, shot and stabbed by three different people and the coroner's report states that the victim died due to cardiac arrest.
If it's a manufacturing flaw, then Boeing is off the hook and they look good due to the limited damage caused. If it's an external problem, where the batteries are being utilized more than intended, then it indicates insufficient testing and/or new model growing pains and doesn't really indicate a significant problem at Boeing. If it's an overheat problem due to ignorance or post-testing/pre-production design changes, then it tends to reflect poorly on Boeing.
I guess we will only find out if Boeing volunteers the information.
Yes, it does raise more questions. Because they've isolated the short circuit to cell number six, they should now be in a better position to track down the reason for the short. Hopefully, we'll be getting more news soon.
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