"Electric car range anxiety to be cured by battery that chargesin five minutes"
On 19/05/2021 13:47, GB wrote:
On 19/05/2021 09:53, NY wrote:
My (diesel) car has a range of about 700 miles on a 60-litre tank.
Diesel has an energy density of about 38 MJ/litre.
The fact that your car can drive 700 miles without a fill-up does not
mean that you can drive it that far without a break.
I've done 900 miles with just a driver switch and 1200 miles with a 45
minute break half way
Plus cross channel ferry of course
For me, a practical use case is to be able to drive 1-2 hours between
breaks. I have a petrol car, but if I had an electric car, I'd just plug
it in at each rest break.
nah. I tend to do 4 hours a stint
Suppose the charging process is 99% efficient - ie only 1% of the
electricity is wasted as heat. That's still a power of 1/100 MW or 10
kW. So the batteries and the charger have got to dissipate waste heat
equivalent to three 3-bar electric fires. Gulp!
But, they only have to do that level of charging for 5 minutes. So,
that's not going to heat the car up appreciably?Β* Perhaps the charging
station will incorporate fans to help dissipate the heat? Current
charging stations don't need that, as they are only charging at a
fraction of the rate.
I think people don't realise just how much heat you can simply blow away
- getting rid of 10KW is a piece of ****. Getting it out of the
batteries while keeping them less than say 60C is more challenging BUT ...
....that's what a fast charge battery is all about - better heat dump
capability You can build thin flat cells with air spaces between, fin
them and fan blow them.
In model plane circles we can now safely *discharge* a lithium battery
in 3 minutes or less. That's the same sort of power dissipation as
charging it in 3 minutes or less. There are other reasons why we don't
charge that fast however.
Fast charge cells would of course have internal voltage and temperature
sensing built in, to tell the charge to slow down a bit, or if it didnt,
to disconnect themselves from it - or such smarts might be built totally
into the car itself.
This is a very soluble problem. At a weight and complexity cost. But do
you want the 300 mile car that needs an hour to charge, or the 150 mile
car that you can charge in 5 minutes?
Your Mileage May Vary...;-)
--
It is hard to imagine a more stupid decision or more dangerous way of
making decisions than by putting those decisions in the hands of people
who pay no price for being wrong.
Thomas Sowell
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