On Mon, 15 Jan 2007 14:31:16 GMT, "Neil Gould"
wrote in
:

Recently, Larry Dighera posted:

On Wed, 10 Jan 2007 15:39:17 -0000, Dylan Smith

It would be totally and utterly impractical to charge these
batteries at this rate. I'll let you do the calculations for the
equivalent in electricity that filling a Cessna 150 with avgas in 4
minutes (the typical time to do it at a self serve pump) would be.

The issue of high charging current is true, of course.

After studying the information available on the Altair web site
http://www.altairnano.com/markets_amps.html, it has become apparent
that their battery technology trades energy density for low internal
resistance. So their product is probably not the best choice for
aircraft due to weight considerations.

According to their W/kg chart, their batteries trade a lower specific
energy (W hr/kg) for a considerably higher specific power, but I would
think that Altair's operating temperature range would be a more important
factor w/r/t aviation, as the other batteries' performance suffers badly
in low-temperature environments. I doubt that a typical Li-ion battery
would deliver the indicated specific energy in aviation temperatures, so
any weight benefit would be compromised.

Battery temperature is important. However it's important to realize
that batteries with a higher internal resistance will generate more
heat under load than those with lower internal resistance, so I doubt
low temperature would be an issue with conventional LiIon batteries.
In fact, the Tesla car needs a liquid cooling system to remove battery
heat, and I would suspect that some sort of cooling system would be
required for aviation applications also.

If it is the weight of the batteries that preclude the use of electric
power for airplane use, using the Altair batteries, with half the
energy density of conventional LiIon cells, wouldn't make very good
sense. The A123Systems M1 cells, with their claimed "the highest
commercially available power density of any Li Ion chemistry" may be
an enabling technology for electrically powered airplanes:
http://www.a123systems.com/html/home.html