Home Charging Costs

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s-x-i

Original Poster:

194 posts

56 months

Tuesday 29th October
quotequote all
Quick question with regards to home charging costs and working out the pence per mile (PPM) rate.

I have a PHEV company car and up until now there has been no benefit/incentive for me to charge it as company car tax is based on emissions regardless of how the car is fueled.

A recent company policy change means that I will now need to personally pay for all fuel and claim back business mileage at £0.15 PPM.

I have worked out the PPM running the car solely on Petrol and I would need to get a minimum of 42 MPG to break even. This can be a struggle at times even when driving carefully.

What is the best calculator to use to work out PPM when charging a car from home using a 3 pin socket?

My thoughts are that it would now be cheaper to charge the car overnight and use its 40/45 mile real world range but would like to work this out as accurately as possible.

Paul_M3

2,417 posts

192 months

Tuesday 29th October
quotequote all
How much do you pay per kWh for your electricty at home?

What is the efficiency of your vehicle in electric mode (in terms of miles per kwh)

Once you know these two numbers it's simple to calculate.

off_again

13,043 posts

241 months

Tuesday 29th October
quotequote all
s-x-i said:
My thoughts are that it would now be cheaper to charge the car overnight and use its 40/45 mile real world range but would like to work this out as accurately as possible.
^ This

Charging at home is pretty much always going to be the cheapest way to get distance at the cheapest ppm. Of course, if you get free public charging, thats going to be the best option, but off-peak, discounted rates and alternative services will be the best way to drive down the charging costs.

PHEV cars make a lot of sense for a lot of use cases. If a lot of your driving which will be within the 40 miles range, EV mode will be the best. And if you need to go more, the combined MPG will be great because of the initial 40 miles on EV. I still think that a decent range PHEV makes a lot of sense for a lot of people, even if they are heavy and expensive.

clockworks

6,135 posts

152 months

Tuesday 29th October
quotequote all
As above, unit price and efficiency needed.

For example, my XC40 plug-in does a shade under 3 miles per kilowatt hour.
I pay 8.5p per kilowatt hour off-peak on Octopus Go.

It costs me just under 3p a mile.
(8.5 divided by 3)

My daytime rate is,I think, around 26p, so it would cost around 9p a mile
(26 divided by 3)

Charging at night is the cost equivalent of 200mpg on petrol

s-x-i

Original Poster:

194 posts

56 months

Tuesday 29th October
quotequote all
OK, a bit more information.

The car is a Volvo V60 T6 PHEV. 18.8kwh battery which is believe 14.9 are usable. Average range would be 42 miles so 2.8 miles per KWH???

Cost of electricity is 21.83p per KWH (Octopus 12M Fixed), so 21.83 divided by 2.8, £0.07 pence per mile???

Whereas fuel at 130.9 per litre and 42mpg would be £0.14 pence per mile.

samoht

6,284 posts

153 months

Tuesday 29th October
quotequote all
That sounds about right, yeah. Maybe ~8p including 10% charging losses.

If the dashboard has the option to show electric efficiency, you could check the efficiency you're actually getting against the assumed 2.8 m/kWh, but it feels about right.

On a longer trip if the car lets you choose when to run in electric mode it may be worth using it for the lower-speed town sections, and running the engine on the motorway, as petrol engines are less efficient in stop-start traffic.

clockworks

6,135 posts

152 months

Tuesday 29th October
quotequote all
samoht said:
That sounds about right, yeah. Maybe ~8p including 10% charging losses.

If the dashboard has the option to show electric efficiency, you could check the efficiency you're actually getting against the assumed 2.8 m/kWh, but it feels about right.

On a longer trip if the car lets you choose when to run in electric mode it may be worth using it for the lower-speed town sections, and running the engine on the motorway, as petrol engines are less efficient in stop-start traffic.
This is what I do - battery power for the slower stuff, petrol (with battery assistance) for faster roads.
I leave the car in "hybrid" mode, and use the "battery hold" function to switch on the petrol engine.

Despite only having around 100bhp running purely on the battery, the car keeps up nicely in normal driving, happily doing 70+mph.

s-x-i

Original Poster:

194 posts

56 months

Tuesday 29th October
quotequote all
Thanks for confirming the calculations are there or thereabouts.

clockworks said:
This is what I do - battery power for the slower stuff, petrol (with battery assistance) for faster roads.
I leave the car in "hybrid" mode, and use the "battery hold" function to switch on the petrol engine.
Yes, the drive modes are handy. Hybrid most of the time but 'Hold' anything above 45/50mph. I also find that using the Sat-Nav aids with battery consumption