Can Aircraft Be Far Behind?

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

On 2007-01-09, Larry Dighera wrote:
Charge time for the Altair batteries is only a few minutes as I
recall.

I'm extremely skeptical - if these batteries are not snake oil, consider
this. Let's call "a few minutes" 10 minutes, and let's say the battery
pack stores 70kWh (enough to run a motor producing 94 hp for 1 hour).

To put 70kWh's worth into a battery pack in 10 minutes would require a
charger capable of putting out 420kW.

At 120 volts, 420kW would require a current of 3500 amps. Look at the
massive thick wire coming into your house (which maybe is rated at 80
amps).

Now let's say these batteries give three hours worth at 70kWh, and
charge in 10 minutes - now you're up to 10,500 amps at 120 volts. YOU
CANNOT AVOID high voltage, high amperage controls in a vehicle like the
Tesla, regardless of the battery technology. You are moving around
tremendous amounts of current. If this mythical charger was 99%
efficient, the 1% emitted as heat could heat an entire office building
in the dead of winter in central Canada. To consider this new battery
technology a silver bullet is to ignore the well established laws of
physics. Now imagine if *everyone* is charging their mythical car. No
practicable electricity distribution network that's feasable in the near
term could cope.

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.