On 20/01/13 00:38, wrote:
On Tuesday, January 15, 2013 10:01:51 PM UTC-5, Vaughn wrote:
I still think it's silly to use the word "failure" but there is more bad

news. "All Nippon Airways has grounded its fleet of 17 Boeing 787

aircraft after one was forced to make an emergency landing because of

battery problems."





Vaughn

1. In no way can one call this ship a failure. It
is simply still "teething".

2. Lithium batteries are safe and appropriate.
Anything will catch fire, including a rock, if
you put enough voltage to it. The industries
are still learning how to integrate their BMS
with their batteries without having to learn it
empirically.


"The BMS designers may have used Mosfets or Relay contactors. Where the BMS control elements are Mosfets they require sizing for load current and thermal management. If the designers got that wrong, the N Mosfets could burn out with collateral damage to the PCB, possibly causing a short circuit on the board. Relay contactors are more robust and generally the power path is not through the BMS PCB.

BMS design for large format batteries such as those on the Dreamliner requires a conservative approach including secondary cell-by-cell overvoltage protection. According to Ken, this requires an understanding of the full aircraft system, something that may have been tough to come by before the aircraft was operational."

http://www.engineering.com/Electroni...reamliner.aspx


And there are those who want electric powered C172s