How much should it cost to charge a car?

Back when nuclear power stations were first proposed, we were promised "energy which is too cheap to meter". That is, the cost of electricity would be so low, invoicing for its use would be prohibitively expensive.

Well, that didn't exactly turn out that way! But as our electronics have become more efficient, the cost of processing payments begins to outweigh the cost of providing electricity. How much would you pay to fully charge your smartphone? A quid? 50p? If you're desperate, a fiver?

A modern phone battery can hold about 22Wh (Watt-hours) of electricity. My domestic power provider charges about 13p per kWh (kilowatt-hour). So the energy in your phone costs less than half a penny.

If you have the latest Tesla, with the biggest battery - 100kWh I think - the total cost of electricity will be around £13. My car, the slightly more modest Soul EV, has a 30 kWh pack - less than £4 to fill from empty.

Given that most people won't be charging from 0% to 100% - and most merchants won't let you use a credit card for anything under a fiver - we can safely say that electric cars are too efficient to meter :-)

Except, that's not how the real world works. Use a litre of water at home and it'll cost you less than a penny - but buy a litre of water from a supermarket and you'll pay considerably more.

Why? Partly the infrastructure to supply you, partly the plastic bottle. Add in the advertising costs, staffing costs, insurance, and goodness knows what else - and you can see how expensive shop-bought water can be.

The same applies to supplying electricity for someone to consume. Even if you're just fitting a domestic plug socket, there's a labour cost involved, and the cost of periodic checks, and the cost of advertising that it is available. If you're supplying a rapid charger - 50kW as opposed to a domestic 7kW - there are some huge costs for equipment and supply.

For example, Electric Highway charges 30p per kWh to use their rapid chargers. But, even so, filling up from 20% to 80% is only going to cost a fiver. Once you factor in credit card fees, it's hardly worth collecting the cash. (And anyone who mentions a dodgy cryptocurrency being able to transfer funds instantly and for zero cost gets permabanned from this blog!)

So what are companies supposed to do? Broadly speaking, public car charging schemes fall into four categories.

1. Pay-as-you-go - with an inflated cost per kWh.
2. Pay-per-minute - sort-of makes sense if you're also paying for parking.
3. Pre-pay - top up your account by £X and pay per kWh from there.
4. Membership - pay £Y per month for unlimited charging.

For me, PAYG using a credit card makes the most sense. I mostly charge at home and don't regularly stop at the same charging station. I've used dozens of different charging schemes - here's a quick comparison.

Free! (ish)

I already had a standard 220V socket in my garage. My car came with a domestic charger. I plug it in when our solar panels are generating delicious free-range electricity from the sky gods.

Some public chargers are set to free vend. Usually in supermarket car parks. Electricity is a loss-leader; like cheap baked beans.

PAYG

This is the simplest method. Unfortunately, some schemes require you to pay using their app rather than just having a contactless credit card reader.

• 30p (15p if you're an Ecotricity customer) - Electric Highway
  • Uses a pretty rubbish app, but works fairly well.
• 33p - On street lamppost charging from Chargy
• 39p - Shell Recharge / Smoov
  • Tap to pay with credit card. Nothing could be easier! Read my review
• 30p + £1.80 connection fee - GeniePoint
  • prices vary depending on location and speed of charger

Pay by time.

I think this is a hangover from the cost to park usually being in time-based increments.

Pod Point have an excellent app, but a weird charging structure. Some are free, some cost 25p/kWh, some are £1 for 3 hours, and some change their cost throughout the day.

Pre-pay

A fairly annoying option - unless you always use the same charging network. I have a bunch of credit with various apps which I doubt I'll ever use again - and there's no way to reclaim.

• Polar Instant. £10 minimum top up, £1.20 connection charge. Some chargers are free, some cost £1.00 per hour, others are £6.00 for 30 minutes.
  • Verdict? Confusing, complicated, expensive. And the app is crap.

Membership

Are you a member of your local petrol station? No! The idea is ridiculous. You might collect bonus points from them, but why would you ever subscribe to them?

• £39 / month for up to 200kWh - On street lamppost charging from Chargy
• £68 / month for unlimited - On street lamppost charging from Chargy

If you have no charging at home, and can reliably use a lamppost near your home, this could be a decent service.

Worst of both worlds

Source London have a truly user hostile scheme. £4 per month, and then charging per-minute between 3.6p - 9.5p per minute - plus a surcharge in certain parts of London. Or you can pay a one off fee and the pay more per minute. Or PAYG.

Given the PAYG rates are only about 5p a minute more, you'd have to spend 80 minutes a month on charge to make it worth paying the monthly fee.

Confused? I think that's the idea!

What a mess!

Customers, mostly, don't want to interact with competitive capitalism. We aren't Homo Economicus constantly adjusting our behaviour to find the cheapest deal. We just want reasonable service at a reasonable price.

The infrastructure for charging electric cars is mostly here - but the infrastructure for charging money has a long way to go.