Robin, your calculation is right: we don't need 500 kWh stored in the
battery, but only 100 kWh. Even 50kWh would be enough for most purposes (the
EEstor "battery" stores 52kWh).
You're also right that a few hours recharge is fine at home, but this is not
true on the road, where you will be happy not to spend several hours at the
filling station, that's where fast recharge ability shines.
The alternative is battery swapping as was mentioned, but this may not be
very practical: batteries are heavy and bulky, not necessarily easy to
access, and cost a lot so one may be reluctant to swap a brand new battery
pack with one in an unknown state.
Michel
----- Original Message -----
From: "Robin van Spaandonk" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Wednesday, May 03, 2006 12:15 AM
Subject: Re: "Fully Charged in About 8 Minutes"
In reply to [EMAIL PROTECTED]'s message of Tue, 02 May
2006 15:48:58 -0400:
Hi,
[snip]
My car has a 40 L gas tank (only 1500 cc engine). At 14 kWh/kg for
gasoline that equates to 420 kWh. However an ICE probably uses on
average no better than 20% of this, hence for the purposes of
comparison, we get 84 kWh. Since electrical systems can be much
more efficient, let's say 75%, we would only need 112 kWh stored
in the bettery.
At 24 kW mentioned in another post, total recharge is accomplished
in 4.7 hours.
IOW during the early hours of the morning while you sleep...and
you start each day with a full "gas tank", which certainly isn't
the case currently (no pun intended). Perhaps more to the point,
since cruising requires less than 24 kW of power, one needs to
recharge less hours each day than one drives.
A simple rule of thumb, taking inefficiencies into account would
be recharging time = driving time.
Hmmm, to deliver 500 kWhr in 8 minutes at 240 V . . .
500 kWhr x 60 = 30 MWmin
30 MWmin / 8 min = 3.75 MW instantaneous
15,625 Amps?
[snip]
Regards,
Robin van Spaandonk
http://users.bigpond.net.au/rvanspaa/
Competition provides the motivation,
Cooperation provides the means.
