Electric vehicles involved in RTAs

[gyvespa]

Sorry Nighthawke

“Does the sub still trip out? If so then there must be a fault other than overload”

Our road was built in the 60’s, at least 2 phases of building. All the houses uphill from us still run from cables slung from a pole then draped across the road. Ours was built at a later stage and runs from a substation connected to the houses on the street behind, using cables under the ground (progress).

In the first 10 years of our residency the power used to go off about once a month on average, possibly more. Uk Power Networks or whoever, replaced the controller/switchgear which improved the odds somewhat.

Years 11 to about 13 it was better, then one Thursday afternoon off it went, a cable fault.
Anyway, Special Forces got mobilised and they sorted it out, off for a total of about 8hrs.
It was hell, couldn’t cook, had to go out, eat steak and drink beer !

Since then, the Traffic Lights on the main road have been replaced and for some reason they are now on our phase (blue). So now when the power fails it gets flagged much quicker.
I worked from home for a while and regularly chatted with the engineers so I know the history of our substation, I’ve even seen the notes for it, which one engineer described as ‘War and Peace’.
It was only ever the blue phase that tripped. If anyone is thinking there might be a weed growing operation locally, yes there was, not far away, but on the other substation !
If some of this is a bit vague it’s because I can’t remember the exact terms used. All due respect to anyone who works with ‘grid’ voltages.

HOT TIP
if your power goes off, ring them up !
They won’t investigate until they have more than one report from an area. Ourselves, next door but one and the local shop are on the same phase so we all have the number and ring it right away.
And don’t swear at them, it’s not their fault, it’s the creaky network.

[Nighthawke]

Glad to hear you've jgot contact number and have a rapport with the field staff. Quite right about not swearing or even being unpleasant ad the person on the other end is usually not to blame and is there to help. Much of the network is in good condition but it is a huge amount if infrastructure, and it will never be perfect.

[gyvespa]

Anyone interested in EVs give the Guy Martin Worlds Fastest Electric Car program a look.
I would describe it as pro EV but I couldn’t help sniggering when he said that one of the charging points was priced at 70p a unit nearly 5x what it’d cost to charge at home (assuming home tariff was 15p).
And
The cost of his road trip was £240 when it would have cost half of that in a diseasel.
That’s why the manufacturers are promoting EVs :-)
Give it a look
CH4 or catchup.
Note. I do like that Beetle !

[gamecock]

Saw the last half hour or so. His journey wasn’t exactly representative of the average was it? I agree electric cars still aren’t viable due to the poor infrastructure and cost of the cars themselves, but he was comparing apples with oranges.

[Malcolm]

Saw the last half hour or so. His journey wasn’t exactly representative of the average was it? I agree electric cars still aren’t viable due to the poor infrastructure and cost of the cars themselves, but he was comparing apples with oranges.

Averages are irrelavent in this context. My daily commute to work and back is only about 30 miles, so easily done in an EV with charging at home overnight. However, I also do 15-20 long distance trips a year - the next one might be Yeovil to Waddington for the Canadian Hornets (if they bring any good ones). A return trip via Marham, Coningsby, Mildenhall, Lakenheath (depending on which day of the week we go) could easily be 600 miles. Given that it's mostly high speed Motorway/Dual Carrageway it would probably need at least 2 charging stops, and that's at least 40 minutes, and potentially 2 hours stationary somewhere miles from an airfield.

When they install fast chargers at the WAVE or Lakenheath gen pen, then perhaps, but at the moment I'll use the gas guzzler. 400 miles on a tank and sub 10 minutes to refill at any number of petrol stations.

So yes, on average I could use an EV, but the 10-20 exceptions a year mean I also need a long range petrol car, and I'd rather stick with one car that can do everything. Pretty sure that was Guy Martins conclusion too.

[gyvespa]

The thing I thought odd was what they said about motorway mileage.
I’d have thought that a steady 60+ mph would use less power than driving on A roads where acceleration and deceleration would sap the batteries more.
The bulk of the power is surely used to move the vehicle from rest and to accelerate it up to speed. Once it’s up to speed you are only fighting frictional and aerodynamic losses.
Am I missing something ?
Or is it just dumbed down TV science.

[Malcolm]

The thing I thought odd was what they said about motorway mileage.
I’d have thought that a steady 60+ mph would use less power than driving on A roads where acceleration and deceleration would sap the batteries more.
The bulk of the power is surely used to move the vehicle from rest and to accelerate it up to speed. Once it’s up to speed you are only fighting frictional and aerodynamic losses.
Am I missing something ?
Or is it just dumbed down TV science.

Acceleration turns potential energy (battery power) into kinetic energy (mv^2). Deceleration on a normal car turns kinetic energy into heat (in the brakes) - and that's all lost very quickly to the environment (otherwise the brakes overheat!). An EV can recover some of that kinetic energy and convert it back into potential energy (re-charge the battery) although I've not seen what percentage is recovered that way versus being wasted in getting the brakes hot. So an EV will always be more efficient in pure conservation of energy terms than an ICE car - sadly an ICE car can't convert kinetic energy back into petrol.

The power required to overcome Aero losses go up with the cube of velocity. Rolling losses (bearings, gearboxes, differentials) go up with either the square or cube (can't remember - uni was a long time ago). Anyway, although most MPG figures are given at 56MPH, that is rarely the most economic speed in any car - its often much closer to 35-40MPH on a flat road. Traveling at 60 rather than 40 increases the aero losses by a factor of 3.5, and rolling losses by something like 2.5 times.

Stop/start in towns is very bad for ICE engine economy because it isn't being used in its most fuel efficient mode. That's less of an issue for an EV since when you're slowing down or stationary you're not using any leccie, and when you're accelerating/cruising the electronics can modulate power delivery to keep things as efficient as possible.

[Tooks]

I would describe it as pro EV but I couldn’t help sniggering when he said that one of the charging points was priced at 70p a unit nearly 5x what it’d cost to charge at home (assuming home tariff was 15p).
And
The cost of his road trip was £240 when it would have cost half of that in a diseasel.

I’ve used those same chargers and with the VW We Charge card that came with my ID.3, they cost nothing.

Even when that expires, membership will cost 29p per kWh. Typical rapid charge cost per kWh outside of membership is in the range of 30-45p per kWh. Those Ionity ones are priced to discourage casual use.

It’s a bit like coffee at Costa/Starbucks etc, it’s many times more costly than making one at home, but it’s for when you’re out and about and you’re paying for convenience and a service.

I drove my ID.3 from home in Lincs to Lossiemouth in June (485 miles), total cost was around £7, and that was the electricity I charged with at home before I set off.

Even when I have to pay for the rapid chargers at full price, I’d be looking at less than £30 in electricity for the trip. I think that compares pretty well to diesel.

I do agree though that we need more and better charging infrastructure, especially if we get the exponential growth in electric cars that we’re expecting.

If you’ve got access to home off road parking and a means to charge, then EVs make a lot of sense. If you’re going to be relying on public charging for your electricity, then I wouldn’t be doing it yet. I also wouldn’t be looking to change until my car wore out/was end of life either, unless legislation forced me too.

[gyvespa]

Malcolm
Thanks for you excellent reply.
Technical but clear.

In our random pub conversations over the last few years the idea of electric aircraft keeps popping up. Things of a Jumbo size.
It’s surprising what hurdles there are to doing this stuff, one thing that’s stuck with me is the amount of thrust that’s needed to accelerate a plane up to speed. To provide that with batteries and motors would be a real challenge. I pointed out that the plane would need to be charged and at a reasonably high rate, then we realised that this charger couldn’t easily be mobile because of the capacity needed. Then cabling was discussed, then we realised that we would need multiple chargers because planes aren’t easy to move about and you probably couldn’t charge them with passengers aboard, especially until the technology was proven safe. Then there was the supply problem to power all of this.
Just how many Watts would somewhere like Heathrow need to power all those long haul flights ?
After many weeks I had a thought. A plane usually takes off with just enough fuel for the journey plus a buffer. If you have an electric plane the batteries will have to be fitted to the airframe so logically it will always be carrying the equivalent of full tanks even when that capacity isn’t needed. This sparked a thought about EV cars, they too are always carrying a full fuel weight, even if it isn’t charged it still weighs the same, something none of us had thought about. With a car it’s probably insignificant but with an airliner that must be a lot of extra weight they’d rather not have to carry. This also means that the undercarriage would have to be stronger as the landing weight will be about the same as the take off weight, then there’s the brakes.
There really is a lot to consider.

Also the 56mph thing, I’ve often wondered if that was attempt at a psychological prompt to get people to drive at a sensible speed. Or perhaps ALL cars, everything from a Trabant to a Veryon all work most efficiently at this exact speed. Who knows :-)

[Malcolm]

There is a reasonably good, if a little dated, piece on vehicle fuel economy on Wikipedia here : https://en.wikipedia.org/wiki/Fuel_econ ... utomobiles

Half way down on the right hand side there is a graph for various mid 1990's American cars' optimum speeds.

As for planes, particularly ones the size of a B747 - IMV no chance. You just have to calculate the amount of energy extracted from the hundreds of tons of fuel a Jumbo takes off with, convert that into KWh, and then work out how big/heavy the batteries would need to be to realise it's a non starter. Stuff like Hydrogen or Bio-Ethanol is (again IMV) the way to go, although there is a question over how green these can ever be as well.

[iainpeden]

Slightly off topic but I was reading the introduction booklet for my new car today, Petrol but it also comes as pure electric.
There’s a very clear warning that if you have a pacemaker do not sit in the car if it is charging from a domestic supply, and a very, very clear warning to be no where near it if charging from a fast charger at a garage/service area - not even to just plug it in and run.