How much is a litre of EV charge?

Within this decade, electric vehicles will cost the same or less than petrol cars. However, in 2022, EV early adopters are paying more upfront and then saving on the running and fuel costs over time.

Despite owning an EV for over a year now, there are a few simple questions which I still don’t know the answer to:

  • How much does it cost to charge an electric car from empty to full?

This post is an attempt to answer those questions, which I hope may be useful for anyone considering an EV.

  1. How much does it cost to charge an EV?

I have a practical reason for wanting to know this one. I occasionally plug in at friends or in-laws houses. It is awkward, but that’s what I get for dipping my toes in at the lower end of the EV world.

The etiquette around charging at friends and family still needs to be settled — right now we seem to be bartering electrons for bottles of wine. So how expensive do those bottles of wine need to be? Châteauneuf-du-Pape or Château-du-Sainsbury’s?

There is a simple formula for calculating the cost of a charge:

Battery size (kWh)x unit cost of electricity (£/kWh)= cost to charge (£).

My beginners EV is a Nissan Leaf with a 28 kWh useable battery. And my current unit rate of electricity is 16p per kWh during the day.

28 x £0.16 = £4.48 for a full charge.

If you add a hassle premium, we’re still in the Sainsbury’s middle-shelf.

What about the cost of charging away from home?

In my somewhat limited experience of public charging, £5 — £15 seems about the price range depending on the duration of the charge and the speed of the charger. Last week, I used a Gridserve fairly-flipping-rapid (50kW) charger on a motorway service station and got a ‘full tank’ for £9.35.

What if you have a bigger battery?

Taking the VW ID.3 and Tesla 3 as examples, their batteries come in the 45–77kWh range. That’s currently about £7 — £12 per charge.

2. How do the fuel costs stack up against a petrol car?

A full battery isn’t quite the same as a full tank of petrol. You need a specific mileage to compare the two.

Our Leaf gives roughly 100 miles of range, which conveniently for me and my mathematics ability, is a nice round number. Range actually varies a lot more than this due to speed and temperature but that is a story for another day. For now, a basic EV will get you 100 miles, on £5 of fuel.

A Volkswagen Golf is a similar sized petrol car. The fuel cost of a Golf is 12p per mile, therefore driving 100 miles in a Golf costs around £12 in petrol.

For every 100 miles, an EV driver, in a compact car, would save roughly £7 against a petrol equivalent.

What about over a year?

If we take the average UK driver’s mileage over the past two years at 7000 miles, you would save around £500 per year on fuel costs by going electric.

If you drive more than 7000 miles, the savings will be greater, and vice versa.

Other factors to consider are:

  • There is no road tax on EVs (another ~£150 to £500 annual saving).

3. What are your additional electricity costs over a year?

I’ve never looked into the detail of this one - I just assumed that the increase in electricity would be offset by even bigger savings at the petrol pump. It would be good to know the facts.

Unfortunately for this comparison, I moved home as I got an EV so I don’t have a before and after snapshot on my bills. Instead, I’ll use back of the envelope calculations. Driving the UK average of 7000 miles per year in a 100 mile range car requires 70 full battery charges. Just over 1 full charge per week.

70 full charges * 30kWh (battery size) = 2,100 kWh of extra electricity.

At 16p / kWh, that means the average driver would add an extra £336 on their annual electricity bills. That’s fairly reasonable, but..

4. What’s going to happen with electricity prices?

You will have seen the headlines about energy prices rising. The increase is driven by a record rise in global gas prices, with wholesale prices quadrupling in the last year. Those hikes will kick in on energy bills from April 2022. As a result, electricity prices will increase by 54%, for the next 6 months.

Meanwhile, petrol prices have also been on the rise. In August 2020, pump prices were 114p per litre. A year later, in September 2021, the price had climbed to 135p. Today they are up at 146p per litre — a 28% increase over the past 18 months.

Electricity prices still have a long way to climb before the fuel costs between petrol and EV are in some sort of parity. Using the Leaf vs Golf example above, electricity prices would need to increase by 240% in order for an EV’s fuel costs to reach £12 per 100 miles. That’s assuming petrol prices stay the same.

In short, EV drivers will still save compared with a petrol equivalent. However, until global gas prices settle down, the savings won’t be as great as before.

Perhaps time to upgrade my wine supply.

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