By George S. Bower
We all know that the batteries involved in the Boeing 787 fires are lithium-ion batteries like in the Volt.
How big is the battery?
Is it liquid cooled?
Where and what is the battery management system?
What is the battery chemistry?
Who makes the cells and what are the cell specs?
And of course:
What was the cause of the fires?
We can see from figure 1 that the battery has 8 cells. Also we can see some circuit boards in the battery case that are presumably the battery management system.
The cells are produced by Yuasa. Yuasa cell specs are shown in figure 2 along with some calculated specs for the pack in total.
The battery box is APPROXIMATELY 11 inches wide by 10 inches tall by 14 inches long and has a stored energy of 1.9kwh. There appears to be no liquid cooling in the battery.
Yuasa cells are a different chemistry than the Volts cells. Yuasa cells are LiCoO2while Volt cells areLiMn2O4. The Yuasa cells are high energy density cells as we might expect in aircraft in order to minimize weight. The Yuasa cells also tend to have a higher combustion rate that the Volts. The CoO2 cell chemistry was used in the Tesla roadster.
“LiMn2O4 [Nissan LEAF / GM Volt] reaches a peak combustion rate of 2.5C/min, while LiFePO4 reaches a peak combustion rate of 3.4C/min. Contrast those to the combustion rates of the batteries that Tesla uses — in the Roadster, LiCoO2 reaches a peak combustion rate of 360C/min, and in the Model S, LiNi.8Co.15Al.05O2 reaches a peak combustion rate of 280C/min…”
Safety Board Rules Out a Cause for 787 Battery Fire
“Federal investigations said Sunday that they had ruled out excessive voltage as the cause of a battery fire on a Boeing 787 in Boston this month, widening the mystery into what led to the grounding of the world’s most technologically advanced jet after a second battery-related problem last week.
With investigators focused on the plane’s lithium-ion batteries, the National Transportation Safety Board said an examination of the data from the plane’s flight recorder indicated that the battery “did not exceed the designed voltage of 32 volts.”
So as of this point in time we don’t know the cause of the fires. We can only speculate.
What we do know is:
There are a lot of tired engineers sleeping on cots at Boeing.
This entry was posted on Tuesday, January 22nd, 2013 at 5:55 am and is filed under General. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.