In article , Andrew Mawson
wrote:
"Tim Lamb" wrote in message
...

In message , Clive Arthur
writes
On 20/01/2018 17:45, Tim Lamb wrote:
Smart meters will be able to identify electric cars and charge the
missing fuel duty, VAT and climate change levy (from the coal-
fired powerstation) to your leccy bill. Ha Ha

No they won't.
Hmm.. something might. Assuming full wave rectification, the battery
will only draw current when the supply voltage exceeds that of the
battery. I doubt it would take much electronics to spot that.

That could work with a very old-fashioned car battery charger, but an
EV charger will be a sophisticated switch-mode unit with power factor
correction.
I'm a very long way out of touch Clive and my maths have always been
suspect. However, my assumption is, for a domestic single phase supply,
there will be a number of milliseconds where the voltage is insufficient
to provide a charge.

Now you can store energy in a capacitor or an inductor but these would
need to be high capacity in view of the charge current needed.

I doubt much of this current draw is going to be sinusoidal so probably
identifiable with respect to conventional domestic loads.


And how could it possibly differentiate between an electric vehicle used
on the public road, and one used (for instance) at a private golf links
or an electric off road farm vehicle, fork lift etc ... it couldn't

and how do you differentiate between the users of petrol? I object to
paying road use tax on fuel for the lawn mower.

--
from KT24 in Surrey, England