Cost to charge Electric Vehicle - a question

merchcon55

I have just been reading an article regarding the cost of charging EV both at home and quick charge. Could someone please confirm I am doing the calculations correctly.

The article states, to charge at home, the cost per mile is 9p (average size EV, driven reasonably efficiently) - and that an 80% charge is just under £18.
So that's 200 miles (1800/9) for this example.

To charge at a public facility, the same 200 miles costs nearly £33.00

If you have a petrol car that gets 10 miles per litre, at £1.70 per litre, you need 20 litres for 200 miles, which costs £34.00

So if I understand the figures quoted, no question EV vehicle is cheaper to run, provided you can charge at home - and I am guessing cheaper than 9p per mile if you have for example one of the Octopus special tariffs.

But "on the road" charging costs seem very similar to using Petrol.

I'm not wanting to debate pros and cons of EV vs Petrol - I just want to confirm I have interpreted the figures correctly. Thanks

[Deleted User]

EV range varies throughout the seasons. For example, I get 3.7 miles/kWh in the summer but when it is very cold and wet outside this range may fall to c.2.5 miles/kWh. 

The energy that you use to put into an EV is not the same as you get out of it. When charging, batteries heat up and this is a loss.

https://www.caranddriver.com/features/a36062942/evs-explained-charging-losses/

Octopus Go Offpeak is now 12p/kWh. Yes, you are correct: public charging has become very expensive. Generally, the faster the charger the more it costs. Some high speed public chargers were charging £1/kWh. My local Ionity 120kW charger is 66p/kWh.

Octopus’ favoured tariff at the moment is Intelligent. They choose the slots based on your EV’s charging requirement. Not all EVs or EVSEs are compatible with it. The rates for my area are:

https://octopus.energy/intelligent-octopus/

ariarnia

when talking energy numbers in pounds and pence are a bit meaningless. you havent said (i'm guessing its not in the article) what unit rate the people writing that article were paying so we can't say if its still 9p a mile. and a lot of people who do those calculations seem to not mention that most people charge some at home and some at public points (so the calculation should really be more like the one for e7 where you look at how much of your use is at the different rates over a month) the losses from charging or about ageing batteries and replacemnt costs and so on. .

ev cars are generally considered cheaper to drive than petrol. but thats based on historic prices of energy and petrol. i think its still the case now (especially if you can charge at cheap overnight rates at home) but what you really need is someone who actually has an electric car that they charge and home and out and about to tell you how many units there ev uses and how many miles that gets them. then you can use YOUR unit figures to work out what it would cost you (at least until april when the cap goes away). luckily theres more than a few people with ev cars on the forum who might be happy to help

[Deleted User]

EV driving for range is all about technique. Maximum range is achieved by adopting a technique of ‘lift and coast’ rather than ‘accelerate and brake’. This was much discussed on forums when I bought my first EV with a 80 mile range in summer some 7 years ago. I am now on my third model.

Speed is also a key factor when it comes to EV range: the aerodynamic drag at 60mph is 4 times higher than it is at 30mph. It follows that if you ask a group of EV drivers who own the same model of EV about range, you will get as many ranges as people. The same considerations apply to ICE vehicles but not many ICE drivers take much notice of the remaining range of their cars.

[Deleted User]

If you filled up your petrol car at a motorway service station then you wouldn’t be paying £1.70 per litre.  Pretty sure the fuel economy would change a lot between a mini and a Range Rover.

 Pick any figures you like, they will tell the story you want to tell or be so far from representative to be meaningless.

Apodemus

[Deleted User] said:

If you filled up your petrol car at a motorway service station then you wouldn’t be paying £1.70 per litre.  Pretty sure the fuel economy would change a lot between a mini and a Range Rover.

 Pick any figures you like, they will tell the story you want to tell or be so far from representative to be meaningless.

Quite so, although the figures that Dolor quotes (12p at home 66p at a fast charger) suggest a lot higher price difference than between supermarket petrol and Motorway (but please don't suggest to the Motorway guys that they could get away with a 550% mark-up and sell petrol at £9.35!)

[Deleted User]

Apodemus said:

[Deleted User] said:

If you filled up your petrol car at a motorway service station then you wouldn’t be paying £1.70 per litre.  Pretty sure the fuel economy would change a lot between a mini and a Range Rover.

 Pick any figures you like, they will tell the story you want to tell or be so far from representative to be meaningless.

Quite so, although the figures that Dolor quotes (12p at home 66p at a fast charger) suggest a lot higher price difference than between supermarket petrol and Motorway (but please don't suggest to the Motorway guys that they could get away with a 550% mark-up and sell petrol at £9.35!)

Yes, there is a bigger difference between domestic off-peak electricity rates and commercial EV charger rates than there is between different petrol stations.  At least part of this is the domestic/commercial difference - that's 5% VAT changing to 20% - and the EPG keeping domestic prices artificially low.  There's also no off-peak on the commercial chargers (just like there's no off-peak petrol).

If you compared what the non-EPG single rate domestic price was likely to be (just over 50p) with your 66p, and include the VAT change, it's a lot closer.

si_74

merchcon55 said:

I have just been reading an article regarding the cost of charging EV both at home and quick charge. Could someone please confirm I am doing the calculations correctly.

The article states, to charge at home, the cost per mile is 9p (average size EV, driven reasonably efficiently) - and that an 80% charge is just under £18.
So that's 200 miles (1800/9) for this example.

To charge at a public facility, the same 200 miles costs nearly £33.00

If you have a petrol car that gets 10 miles per litre, at £1.70 per litre, you need 20 litres for 200 miles, which costs £34.00

So if I understand the figures quoted, no question EV vehicle is cheaper to run, provided you can charge at home - and I am guessing cheaper than 9p per mile if you have for example one of the Octopus special tariffs.

But "on the road" charging costs seem very similar to using Petrol.

I'm not wanting to debate pros and cons of EV vs Petrol - I just want to confirm I have interpreted the figures correctly. Thanks

I did the workings out for this when my energy contract ended and yes your calculations are about spot on for an efficiency of 3.8-4 miles per kw which is what I get on mixed driving (urban, country, motorway). Maybe a bit more in summer and a bit less in winter.

The prices of the public charges has obviously risen a lot this year, up to 65p/kwh for a rapid charge. So I only do this when absolutely necessary.

Also correct to my calculations that EV's are still cheap to run on domestic energy prices, but comparable to conventional engines once out on public chargers. I don't have cheaper night time EV charging.

pcgtron

I charge at home on octopus intellgent @ 7.5 ppkwh

I put 30kw into the car most days when I'm working 

After just over 1 year of ownership, the car averages 4 miles per Kwh over that period 

30 kwh at 7.5 pence = £2.25 
4 miles per Kwh = 120 miles 
That then equals 1.875 pence per mile charging at home