EV charge times

According to the Sunday Times, this was (and may still be) draft legislation: https://www.driving.co.uk/news/environment/ev-chargers-switch-off-peak-times-blackouts/

It seems to make good sense, but if the energy companies want to encourage off-peak use, then favourable tariffs are probably the best approach.

That sounds a good idea, hopefully there would be an override facility that operates ONCE ONLY and does not permanently alter the preset times, which should be fine for most people under most circumstances.

By “once only” I mean that the user has to select this when ever required, every day if they really want, but most people wont bother.

The other facility I would like to see would be an EV charger that “talks” to the grid tied PV inverter in homes so equipped. Could be set to charge only to say 50% when buying power from the grid, but to 100% when solar is available.

I also believe that the default limit to the size of domestic grid tied PV systems should be increased, perhaps to say 6 Kw. In order to help with daytime charging of either the owners EV or others nearby.

Chris Pearson: 
 

According to the Sunday Times, this was (and may still be) draft legislation: https://www.driving.co.uk/news/environment/ev-chargers-switch-off-peak-times-blackouts/

It seems to make good sense, but if the energy companies want to encourage off-peak use, then favourable tariffs are probably the best approach.

Indeed, if preferential tariffs are to be offered then I would favour a simple to understand charge controller with three colour coded push buttons.

RED button to charge as quickly as possible, but be aware that this carries a cost penalty.

ORANGE button to fully charge within the next 12 hours.

GREEN button to charge to at least 70% with the next 12 hours.

NOTE that if no button is pressed, the vehicle will eventually charge FOR FREE but this might some several days. Select this option for lightly used vehicles.

A similar system could be applied to washing machines for example

RED, washes straight away, but this costs more.

ORANGE, Cheaper and will be completed within 12 hours.

GREEN, Cheapest and will be completed with 30 hours.

Given all the clever electronics inside it would be a modest change to make the EV charger load shed or throttle back to a reduced rate when the nominal 50Hz frequency dropped below some limit, thus reducing stress on the grid at any time of day, and far less dependent on the correct setting of network time and standardised load schedules. After all, a grid tie inverter knows to throw itself off-line if the mains frequency strays out of bounds for more than a few cycles, so no-one can argue the technology does not exist or is too difficult. If we are to make more use of wind power and other less than constant sources, that do not respect the time clock, then the ability of loads to detect times of grid stress and wind their necks in automatically will become more important.

Mike.

Absolutely, but is our government capable of such joined up thinking ?

Absolutely, but is our government capable of such joined up thinking ?

And there's me thinking that they would find a way to tax the kWh used for EV charging to replace the lost revenue from road fuel tax and reduced revenue from lower road fund licence for EVs……….

Regards

BAD

BOD/BAD, you know fine well what is inevitable. ?

There is a huge misunderstanding going on here. The real charging rate is controlled by the vehicle, not the charge point. The range of charge rate options depends on the vehicle and they are not all the same and some are quite simple. Reducing the mains voltage for example does not reduce the charge power, it just increases the current. Charge points do provide communication with the vehicle, but this is not usually on a completely “sliding scale” as this makes the charger (in the vehicle) much more complex.

It is a difficult problem, because changing the mains waveform to a lower average, say chopping it up into a high frequency chopped sine wave has huge snags although it is done for power factor correction, and impacts the supply system as a whole, particularly the EMC. It can be overcome by rectifying the mains and smoothing the resulting DC, but this needs large, heavy, and expensive smoothing capacitors in the car, which is a problem. 

The underlying difficulty is that the car charging specification has never been satisfactory, and we are now stuck with a system that is unsatisfactory in several ways, particularly that cars should be class 2 appliances. You will note that all the problems are passed over to the fixed installation, and some of these are very difficult and expensive to work around, typically type B RCDs and the TT supplies, and neutral loss detection.

The charging rate is set by the vehicle, bit the vehicle takes more or less up to a max limit set by the mark to space ratio of the tone emitted by the charger.

It would be a relatively easy change to make this a variable parameter.

Mike.

AFAIK, There is already at least one EV charger that modulates the charging rate in order to avoid operating the cut out fuse. It measures the total load by means of a current transformer on a meter tail. 

And anyway the proposal described in the O/P does not involve variable rate charging, it is a simple time switch, that inhibits charging at certain times, and permits of charging at the usual rate at other times.