Calculating cost of home charging an EV
Calculating cost of home charging an EV
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Discussion

Itsallicanafford

Original Poster:

2,890 posts

180 months

Saturday 2nd October 2021
quotequote all
Can somebody assist me with calculations on this.

We are with Scottish power and they cannot at present install a smart meter at our property due to some signal issues or somewhat.

Our over night unit rate is at 10.79p. Currently we are charging only my wife 120ah I3 on this rate.

How much is this costing us per charge? I have a feeling it might be an easy calculation but would be good to get confirmation.

At present i don't think this rate will be an issue as it looks like we will be Charging the i3 once a week at most but soon we will also be charging a Model 3 long range for frequently so this rate will start to have an impact.

Any advice would be appreciated.



SWoll

21,621 posts

279 months

Saturday 2nd October 2021
quotequote all
Assuming all charging done within the window mentioned then 38kWh x 10.79 = £4.10

The LR has a battery twice the size so £8.20

There will be some losses but should be about right.

You're looking at 2 to 3p per mile for the i3 and 3 to 4p per mile for the Tesla dependent on driving speeds and time of year.

Edited by SWoll on Saturday 2nd October 08:15

Itsallicanafford

Original Poster:

2,890 posts

180 months

Saturday 2nd October 2021
quotequote all
Ah thanks, as easy as that then!

Still pretty cheap compared to ICE.

thanks again for your help!

CinnamonFan

1,007 posts

217 months

Saturday 2nd October 2021
quotequote all
Timely thread this.

I commute 110 miles a day from central kent to outer london. Mostly motorways.

My toyota tells me it does 55mpg so £12.45 a day for fuel. Its a shed with 212,000 miles and i sort of love it. Its £160 to tax which id of course save. The ULEZ expansion doesnt affect me as my place of work it well outside it.

Would running an electric car save me enough to make the outlay worth it?

Currently Bulb charge me 18.65p per kwh for electricity. So with a 40kwh battery. Is it as simple as multiplying it to give £7.46 per day.

Annually £1197.60 electric. Although i hope i could get the kwh price down. £2988 for diesel.

Saving me £1790 per year. 8 years to pay off the car purchase assuming the EV costs £15k.

Not factored in having a home charger installed though. No idea what these cost, but id need it to charge overnight. I have the space & a driveway.

As a back up i could use the train, or take my wifes car. Not a fan of monthly costs, id rather own it outright and have the freedom to leave a job at anypoint if needed.

Have i thought of most things? Is the maths right? Or am i forgetting or overlooking something important?

Sorry for the thread hijack, seemed better than making a separate one.



anonymous-user

75 months

Saturday 2nd October 2021
quotequote all
Itsallicanafford said:
Can somebody assist me with calculations on this.

We are with Scottish power and they cannot at present install a smart meter at our property due to some signal issues or somewhat.

Our over night unit rate is at 10.79p. Currently we are charging only my wife 120ah I3 on this rate.

How much is this costing us per charge? I have a feeling it might be an easy calculation but would be good to get confirmation.

At present i don't think this rate will be an issue as it looks like we will be Charging the i3 once a week at most but soon we will also be charging a Model 3 long range for frequently so this rate will start to have an impact.

Any advice would be appreciated.
Use the charging history facility on your BMW app. Just type in your tariff price and it shows how much you use each charge (or per month) in kWh or pounds. Simples!

kambites

70,372 posts

242 months

Saturday 2nd October 2021
quotequote all
CinnamonFan said:
Currently Bulb charge me 18.65p per kwh for electricity. So with a 40kwh battery. Is it as simple as multiplying it to give £7.46 per day.
Only if you use all 40kwh every day. Better to make a rough guess at your miles/kwh and go from that; so 110 miles at maybe 3.5m/kwh on the motorway (obviously depends on the car) would mean 31.4kwh, which at 18.54p would equate to £5.86 per day.

Knock_knock

608 posts

197 months

Saturday 2nd October 2021
quotequote all
kambites said:
CinnamonFan said:
Currently Bulb charge me 18.65p per kwh for electricity. So with a 40kwh battery. Is it as simple as multiplying it to give £7.46 per day.
Only if you use all 40kwh every day. Better to make a rough guess at your miles/kwh and go from that; so 110 miles at maybe 3.5m/kwh on the motorway (obviously depends on the car) would mean 31.4kwh, which at 18.54p would equate to £5.86 per day.
Octopus are still offering Go, which gives you four hours at 5p/kWh. You wouldn't get all 32kWh on that rate, maybe about 28kWh. So about £1.40 super cheap and another £1 at the higher rate. About £2.50 a day.

LaserTam

2,181 posts

240 months

Saturday 2nd October 2021
quotequote all
CinnamonFan said:
Timely thread this.

I commute 110 miles a day from central kent to outer london. Mostly motorways.

My toyota tells me it does 55mpg so £12.45 a day for fuel. Its a shed with 212,000 miles and i sort of love it. Its £160 to tax which id of course save. The ULEZ expansion doesnt affect me as my place of work it well outside it.

Would running an electric car save me enough to make the outlay worth it?

Currently Bulb charge me 18.65p per kwh for electricity. So with a 40kwh battery. Is it as simple as multiplying it to give £7.46 per day.

Annually £1197.60 electric. Although i hope i could get the kwh price down. £2988 for diesel.

Saving me £1790 per year. 8 years to pay off the car purchase assuming the EV costs £15k.

Not factored in having a home charger installed though. No idea what these cost, but id need it to charge overnight. I have the space & a driveway.

As a back up i could use the train, or take my wifes car. Not a fan of monthly costs, id rather own it outright and have the freedom to leave a job at anypoint if needed.

Have i thought of most things? Is the maths right? Or am i forgetting or overlooking something important?

Sorry for the thread hijack, seemed better than making a separate one.
Road tax is zero (currently) on an EV so another saving.
Charger costs - I am getting one installed shortly £600 which includes £350 government grant towards the cost. Its a very simple installation, something more complicated could be more.

annodomini2

6,959 posts

272 months

Saturday 2nd October 2021
quotequote all
Knock_knock said:
kambites said:
CinnamonFan said:
Currently Bulb charge me 18.65p per kwh for electricity. So with a 40kwh battery. Is it as simple as multiplying it to give £7.46 per day.
Only if you use all 40kwh every day. Better to make a rough guess at your miles/kwh and go from that; so 110 miles at maybe 3.5m/kwh on the motorway (obviously depends on the car) would mean 31.4kwh, which at 18.54p would equate to £5.86 per day.
Octopus are still offering Go, which gives you four hours at 5p/kWh. You wouldn't get all 32kWh on that rate, maybe about 28kWh. So about £1.40 super cheap and another £1 at the higher rate. About £2.50 a day.
Day time rate has shot up though ~25p/kWh, would look very carefully at that before switching

JD

3,081 posts

249 months

Saturday 2nd October 2021
quotequote all
annodomini2 said:
Knock_knock said:
kambites said:
CinnamonFan said:
Currently Bulb charge me 18.65p per kwh for electricity. So with a 40kwh battery. Is it as simple as multiplying it to give £7.46 per day.
Only if you use all 40kwh every day. Better to make a rough guess at your miles/kwh and go from that; so 110 miles at maybe 3.5m/kwh on the motorway (obviously depends on the car) would mean 31.4kwh, which at 18.54p would equate to £5.86 per day.
Octopus are still offering Go, which gives you four hours at 5p/kWh. You wouldn't get all 32kWh on that rate, maybe about 28kWh. So about £1.40 super cheap and another £1 at the higher rate. About £2.50 a day.
Day time rate has shot up though ~25p/kWh, would look very carefully at that before switching
They have a new tariff on the way, 6 hours at 5p.

paul chocks

77 posts

184 months

Saturday 2nd October 2021
quotequote all
Big price rises coming though. Just received an email from Ecotricity saying unit rate going up from 18p (per KWh) to 27p in November. Fifty per cent increase! Would be surprised if others aren't about to do similar.

georgeyboy12345

4,152 posts

56 months

Saturday 2nd October 2021
quotequote all
paul chocks said:
Big price rises coming though. Just received an email from Ecotricity saying unit rate going up from 18p (per KWh) to 27p in November. Fifty per cent increase! Would be surprised if others aren't about to do similar.
Even at that rate, still only around £11 to charge a 40 kwh BMW i3.

I just took out an EV tariff from EDF the day before the price increases, 18 p/kwh and 4.5 p/kwh between midnight and 5 am, fixed until mid 2024.

so called

9,157 posts

230 months

Monday 4th October 2021
quotequote all
I've just moved from Octopus Go to Octopus Go Faster.
5 hours at 5.5p / kWh - 20:30 to 01:30.
Day rate is 16.67p / kWh.

Edited by so called on Wednesday 6th October 11:44

BIG DUNC

1,919 posts

244 months

Monday 4th October 2021
quotequote all
CinnamonFan said:
Timely thread this.

I commute 110 miles a day from central kent to outer london. Mostly motorways.

My toyota tells me it does 55mpg so £12.45 a day for fuel. Its a shed with 212,000 miles and i sort of love it. Its £160 to tax which id of course save. The ULEZ expansion doesnt affect me as my place of work it well outside it.

Would running an electric car save me enough to make the outlay worth it?

Currently Bulb charge me 18.65p per kwh for electricity. So with a 40kwh battery. Is it as simple as multiplying it to give £7.46 per day.

Annually £1197.60 electric. Although i hope i could get the kwh price down. £2988 for diesel.

Saving me £1790 per year. 8 years to pay off the car purchase assuming the EV costs £15k.

Not factored in having a home charger installed though. No idea what these cost, but id need it to charge overnight. I have the space & a driveway.

As a back up i could use the train, or take my wifes car. Not a fan of monthly costs, id rather own it outright and have the freedom to leave a job at anypoint if needed.

Have i thought of most things? Is the maths right? Or am i forgetting or overlooking something important?

Sorry for the thread hijack, seemed better than making a separate one.
The cost of the electric car is the capital cost.
As someone else said, road tax is zero.
Servicing is much cheaper.
Insurance is about the same.
You will be able to get a much better rate for electricity if you are prepared to shop around.
If you can afford the capitol cost it is a no brainer.
It "should" be more reliable than your current shed.

I know what you mean though. While my wife has an electric car, I have an old diesel estate with similar mileage. It will be replaced at some stage with an electric car, but I want to see how long I can keep my shed going first.....

BIG DUNC

1,919 posts

244 months

Monday 4th October 2021
quotequote all
To those with Octopus, I would be interested in the new tarrif at 6 hours cheap rate. One of the main reasons that I have not moved to Go is that we currently get 7 hours off peak and 4 hours seems a bit mean. Also, the Octopus standing charge is over double what I currently pay, which does make a significant difference to the bill.

Like someone said, I expect all suppliers to be increasing rates several times over the coming months so it will be a moving target trying to keep track of the cheapest.

so called

9,157 posts

230 months

Tuesday 5th October 2021
quotequote all
BIG DUNC said:
To those with Octopus, I would be interested in the new tarrif at 6 hours cheap rate. One of the main reasons that I have not moved to Go is that we currently get 7 hours off peak and 4 hours seems a bit mean. Also, the Octopus standing charge is over double what I currently pay, which does make a significant difference to the bill.

Like someone said, I expect all suppliers to be increasing rates several times over the coming months so it will be a moving target trying to keep track of the cheapest.
As I mentioned above, I've just move from Octopus Go to Octopus Go Faster.
Go was 4 hours 12:30 to 04:30 at 5p/kWh and 15.67p/kWh day rate. 25p/day Standing charge.

Go Faster offers 3 hours @ 4.5p, 4 hours @ 5p or 5 hours @5.5p. Day rate is 16.67p / kWh. 25p/day Standing charge.
Additionally, you can choose/ask to start your Faster rate from 20:30, 21:30, 22:30, 23:30 or 12:30.

Makes it easier to run other appliances, dish washer etc., at the lower rate.

JD

3,081 posts

249 months

Tuesday 5th October 2021
quotequote all
BIG DUNC said:
To those with Octopus, I would be interested in the new tarrif at 6 hours cheap rate. One of the main reasons that I have not moved to Go is that we currently get 7 hours off peak and 4 hours seems a bit mean. Also, the Octopus standing charge is over double what I currently pay, which does make a significant difference to the bill.

Like someone said, I expect all suppliers to be increasing rates several times over the coming months so it will be a moving target trying to keep track of the cheapest.
The new tariff (in the SE anyway) will be :

24.01p standing charge
24.25p /kWh day rate
5p /kWh 23.30-05.30

SpeckledJim

32,285 posts

274 months

Tuesday 5th October 2021
quotequote all
CinnamonFan said:
Timely thread this.

I commute 110 miles a day from central kent to outer london. Mostly motorways.

My toyota tells me it does 55mpg so £12.45 a day for fuel. Its a shed with 212,000 miles and i sort of love it. Its £160 to tax which id of course save. The ULEZ expansion doesnt affect me as my place of work it well outside it.

Would running an electric car save me enough to make the outlay worth it?

Currently Bulb charge me 18.65p per kwh for electricity. So with a 40kwh battery. Is it as simple as multiplying it to give £7.46 per day.

Annually £1197.60 electric. Although i hope i could get the kwh price down. £2988 for diesel.

Saving me £1790 per year. 8 years to pay off the car purchase assuming the EV costs £15k.

Not factored in having a home charger installed though. No idea what these cost, but id need it to charge overnight. I have the space & a driveway.

As a back up i could use the train, or take my wifes car. Not a fan of monthly costs, id rather own it outright and have the freedom to leave a job at anypoint if needed.

Have i thought of most things? Is the maths right? Or am i forgetting or overlooking something important?

Sorry for the thread hijack, seemed better than making a separate one.
110 miles a day is about £1.50 per day at 5p per kWh on Octopus Go. So about £375 a year assuming 250 days in work. Your energy savings would be significant.

The cost of the car is different consideration. You need to find the money to buy it, but running costs are extremely low, as is depreciation on a used EV.



BIG DUNC

1,919 posts

244 months

Tuesday 5th October 2021
quotequote all
Thanks for the info on Octopus, chaps.

CinnamonFan

1,007 posts

217 months

Tuesday 5th October 2021
quotequote all
SpeckledJim said:
110 miles a day is about £1.50 per day at 5p per kWh on Octopus Go. So about £375 a year assuming 250 days in work. Your energy savings would be significant.

The cost of the car is different consideration. You need to find the money to buy it, but running costs are extremely low, as is depreciation on a used EV.
I have around 20k sitting in cash at the moment, was ear marked to be added to our budget for house move.

The only cars sub 15k appear to be Renault Zoes. Anyone have any experience with these? Most are leased batteries too, cant find any reliable sources to work out the lease cost for 25k per year, apart from justevs website suggesting £110 a month for unlimited miles. Other brackets are 15k miles or lower.

Only battery owned model i could find, admittedly brief search.
http://www.autotrader.co.uk/car-details/2021090670...

Edited by CinnamonFan on Tuesday 5th October 21:55