On Saturday, January 19, 2013 2:16:17 PM UTC-5, george wrote:
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

Ah, that's easy compared to designing
a dreamliner from scratch. One must manage
the heat sink.

Just think if everything had always been electric
(Henry Ford's wife drove an electric car), and now
all of a sudden we discovered gasoline and jet fuel
but knew little about volatility management.

You think there might occur a fire or two? LOL,
in fact, there still is.

--
Mark