On Tue, 17 Jul 2018 11:46:47 +0000 (UTC), wrote:

On Tue, 17 Jul 2018 11:50:18 +0100
The Other Mike wrote:
On Mon, 16 Jul 2018 08:59:01 +0000 (UTC), wrote:

It seems to me the whole charging problem of mass ownership of electric cars
has been kicked into the long grass. As usual politicians will only react
when
they have to when the load on the grid either local or national becomes
critical
whereupon headless chicken mode will be engaged.

We've already been here before and there is NO problem.

The additonal supply requirements are negligible if you take your head out of
the sand, forget this idea of a two minute charge because thats how long it
takes for your hydrocarbon car to refuel to do 600 miles to the back end of
nowhere without stopping for urinating or whatever and realise the average car
is, with absolute certainty, sat doing absolutely nothing but depreciating for
many thousands of hours a year. Around half of that almost certainly at home.

So what? Its the energy that it uses when it is moving thats the issue.

Really?


When I last commuted to work by car it was a round trip of about 40 miles, say
2 gallons of diesel which is approx 300 million joules of energy.

20mpg from a diesel 'car'? I could nearly get that from a UNIMOG

Assuming
for ease of calculation my car is around 33% efficient that'll be 100M joules
used for moving. Electric cars are (according to google) around 50-60%
efficient from grid to wheel so say an electric car needed 200M to do the
same job. With a 30 amp supply that'll take 200,000,000 / (240 * 30) = 27777
seconds = 7.7 hours to charge.

Now I don't know about you, but I suspect an extra 240 * 30 = 7.2KW load
multiplied by however many houses have electric cars multiplied by 7 hours
will be quite a bit extra for the local substation to cope with.

How about using real world kWh/distance travelled published for all commercially
available electric cars rather than 'guessing'?

Plus get this idea out of your head that everyone today drives around with a
near full tank of hydrocarbon fuel and/or they all need to do x hundred miles a
day and they need to emulate anything even remotely resembling your declared
'charging' regime

27kWh spread across 100 hours per week 'at home', or just 270W when on charge is
enough to power most of todays electric cars (Nissan Leaf, BMW i3 etc) for the
mileage of the average motorist. 1.4MWh per average private vehicle per annum,
or aroumd 28TWh for 20 million vehicles on a total current annual supply of
around 330TWh. 28 TWh is only very slightly more than the expected annual
output of Hinkley Point C.


This is from my other posting today in reply to Roland Perry

==
So with a 35 mile round trip, maybe averaging 35mph, that's one hour per day, or
five hours usage a week, add on another hours usage for bit for shopping etc and
a day off on sunday and that leaves some 162 hours a week for a charge to take
place. 210 miles in a week is just under 11000 miles a year which is high by
average private motorist standards (see below)

At 18kWh/100 miles for a Nissan Leaf (BMW i3 is similar as is the claimed
performance for the Tesla Model 3) then it needs some 1980kWh per annum of
charge.

If 100% of that charge takes place at home then it can take place spread across
100 hours a week (12 hours a day weekdays + 24 hours sunday + 16 hours on a
saturday)

It needs 38 kWh per week to do those 210 miles

Ignoring charging losses that equates to an average mains supply load when on
charge of around 380W, or 1.6A at 240v

As it is the average UK private mileage is (was) 7900 miles in 2013, down from
9200 miles in 2002

https://www.bbc.co.uk/news/uk-england-28546589

So for the 'average private motorist' the average mains supply load when on
charge, for charging purely at home, drops to around 270W or 1.125A at 240v
==

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