Thinking about an EV? Part 1 – How Does an EV Work?



While many countries are encouraging motorists to embrace electric vehicles (EVs), there is a massive amount of FUD (fear, uncertainty and doubt) regarding the new vehicles. Some of it comes from vested interests, some of it from ignorance, but I’ve had an EV for over 10 years now and I think they’re great. My first two cars were plug-in hybrids (PHEVs) – that’s where there’s a smaller battery backed up by a petrol engine – but my current car of nearly three years is completely battery powered (BEVs).

Now, I’ll be the first to admit that the automotive industry and general society is in a period of change. We’ve been used to mass ownership of cars fuelled by petrol for about 70 years and switching to electricity doesn’t happen overnight. However, I’ve seen the change over the past decade and while EVs might not be for everyone, they can be right for many people.

Today’s discussion will focus on what makes an EV go, Obviously, EVs use electricity to power the vehicle rather than petrol (gas) and diesel. It’s potentially a clean source of power both when generated from renewable sources and when used in the vehicle – there are no nasty noxious fumes or particulates emitted from the exhaust. Simplistically, a large battery stores the electricity which is then used by motors to make the wheels go round. On the whole, it’s all straightforward but let’s answer a few of the common questions about EVs and driving one.

Do I need to pass another driving test or get a special driving licence?

If you are worried about being able to drive an EV, don’t be. If you have a driving licence that covers cars, you can drive an EV. It’s basically the same as driving a petrol or diesel vehicle with an automatic gearbox, only much quieter and cleaner. If anything, it’s a great deal simpler. Turn on the ignition to start the car…put a foot on the brake and put the car into Drive…press the accelerator…the car goes forward. Exactly the same as an automatic.

How is electricity stored in the car?

Electricity is stored in a battery that’s quite similar to the battery in your smartphone or tablet, only much, much bigger. The liquid fuel tank in your petrol or diesel vehicle is normally described in terms of volume – say, 30 gallons or 80 litres. In an EV, the battery is the equivalent of the tank and it’s measured in kWh – kilowatt hours – so you might see cars with 50 kWh batteries or 80 kWh batteries. As with a fuel tank, the bigger the battery, the further the car will go, though bigger batteries are heavier and do cost more, which is a downside.

How do I charge the battery?

Fundamentally there are two options. You charge slowly overnight at home or quickly at a commercial charge point or charging station. If you are able to charge at home, you can usually take advantage of cheap overnight electricity rates for lower cost motoring.

Hold on….I can charge at home?

Yes. While there are some solutions for people who park in the street, it’s best if you have a driveway and you can have a home charger (aka wall box) installed by a professional electrician. Costs will vary depending on the features of the charger and the ease of installation. There are sometimes grants to help cover the costs but expect to pay £500-£1000 for the unit and the installation.

The good news is that the charger will work with many different cars so you are very unlikely to have to change anything when you switch cars. I’m still using the same charger three cars on.

My car gives me 45 miles per gallon. What’s the equivalent with an EV?

With EVs people talk about miles per kWh. My car averages 2.9 miles per kWh though it’s a big SUV. A smaller, lighter car might do 4 miles per kWh.

Does that make an EV cheaper to run?

If you can charge at home, almost certainly. Let’s do the maths and work out the cost per mile based on fuel only.

Using my SUV model as an example as it comes in both petrol and electric versions, the petrol version gets about 37 mpg at best. Petrol is about £1.30 per litre here in the UK, so that’s £1.30 x 4.55 (litres in a UK gallon), giving £5.92 per gallon. Dividing that by the 37 mpg gives a cost of 15.9p per mile.

Taking the electric version, overnight I pay 18.4p per kWh to charge the car. I get 2.9 miles per kWh when I drive, so 18.4 / 2.9 gives 6.3p per mile.

(For the Americans, the calculation is similar, though I suspect you still buy gas per gallon. Yes, I know US and UK gallons are not the same but it doesn’t matter as long as you use US mpg figures.)

Whoa! That’s quite a saving. What if I can’t charge at home?

If you have to use a commercial charge point, it can cost anything from 30p to 70p per kWh, depending on the supplier, the power of the charger, whether you use an app and so on. This is not such good news and part of the extra cost is the VAT or sales tax. At home, the tax on electricity is 5% but at a charge point, it’s 20%. Don’t blame me, blame the Government. And obviously, the charge point operators are wanting to recoup their investment costs and they need to make a profit. If you can’t charge at home, do take this extra cost into consideration. Check the cost at your nearest commercial charge point.

If you don’t have a driveway, there are some options for cutting a groove in the pavement (Charge Gully) but you’ll need to consult with your local council as to what’s permissible.

How long does it take to charge?

It depends….the main factor is the power of the charger. If you are charging at home, it’s likely to be a relatively low power charger, say, 7 kW. This means that if the car has an 80 kWh battery, it will take a little over 11 hours to charge from empty. In reality, you rarely run the battery down to nothing but instead top the battery up every few days, maybe from 50%. I’m charging every third or fourth day based on my daily mileage.

If you go to a commercial high power charger, these can often deliver power in excess of 100 kW, which in theory means an 80 kWh battery charges in under an hour. This is dependent on the capability of the car to receive the power but most recent vehicles will be fine. Charging does slow down as the battery gets closer to 100% so often it’s best to only charge to only 80% or 90% to save time.

Is it easy to use a charger?

Yes. It’s a bit like using a petrol pump but with a big electrical plug on the end of a cable instead of a fuel nozzle. In Europe, most chargers will use the CCS and CCS2 connectors. There’s an older connector type called CHAdeMO but it’s gradually disappearing.

Here’s the socket on my car. The CCS part is on the top, with the CCS2 extension on the bottom. The CCS socket can be used on its own with low power chargers such as when you are charging at home. High power chargers use both connectors.

In terms of paying for the charge, it’s getting easier. There are lots of suppliers on the market so you’ll probably end up with a clatter of apps on your phone, but recent legislation says that all high power chargers have to support swiping a credit or debit card without the need to sign up. Personally, I find that the chargers which use RFID fobs or cards are the easiest and quickest to get started.

Watch out for overstay fees. To stop people hogging chargers, some suppliers will make you pay extra if you stay too long, particularly at the high power chargers.

What about charging when I’m away from home?

Broadly, there are two categories of chargers that you are looking for when you are away from home. The first are the chargers that you need en route to get to where you are going. These are typically high power chargers and are usually found close to major routes. Ideally you want to spend a short amount of time at these, preferably less than an hour.

Destination chargers are chargers often offered by hotels and other facilities where you might be spending more time. These chargers won’t be as powerful but you’ll leave your car connected to these longer, perhaps overnight. Contact the hotel to see what they can offer.

There are several good apps and websites such as Zap Map and PlugShare that show both the location of chargers and if the charger is in use. This is great if you are heading to a charger and you want to be reasonably confident it’s going to be available when you get there. I’ll talk more about travelling away from home in my next article about EVs, “How Far Does an EV Go?”

That concludes the first post in the series and I hope it helps some of the “EV curious” understand EVs a little bit better. If you’ve any further queries, drop them in as questions below.