► Today’s reality of EV charging
► It’s come a long way in a short time
► Battery tech is on the cusp of an overhaul
Along with range, EV charging time is one the main barriers to stopping people moving from fossil fuel to electric. On this page, we’ll explain how long it realistically takes to re-energize electric cars these days, because it has changed quite a bit since the first-generation Nissan Leaf.
Calculating charging time
The time it takes an electric car to charge is entirely dependent on the car’s battery size and the charger’s power output.
The way to calculate how long an EV will take to charge is very straightforward:
Battery size ÷ charging power = charge time.
For example, a Jaguar i-Pace’s 90kWh battery will take about two hours to fully charge using a rapid 50kW charger.
Types of chargers
Throughout the UK’s public network of over 22,000 chargers, there are three categories.
Rapid charging (up to 350kW)
Rapid chargers are those that have a power output of 50kW or more. There are over 4000 of these around the UK – a number that is ever-growing. Rapid chargers (including Tesla’s Superchargers) have their own tethers and can have an output of up to 350kW. The number of rapid chargers over 100kW is growing too; this is the new generation of ultra-fast EV charging.
Most EVs use the rapid chargers via their Type 2 alternating current (AC) or CCS direct current (DC) plugs, with a few models such as the Mitsubishi Outlander and Nissan Leaf that use the mouthful abbreviation CHAdeMO plugs. Teslas are the only cars that can use the company’s chargers, but they are also supplied with adaptors that allow them to use regular charging stations too.
Fast charging (7kW and 22kW)
Used both at public charging points and at home, fast charging refers to 7kW and 22kW chargers. A home charger tends to be the former because that’s all a regular single-phase domestic power supply can manage (we will cover charging at home in moment).
The majority of public chargers are classed as ‘fast’, and many of these are untethered, meaning you use your car’s supplied cable to plug in with. In terms of charging time, use the equation above.
For example: 90kWh battery ÷ 22kW charger = four hours to fully charge your car.
Slow charging (5kW-3kW)
Slow charging is done with either the Type 1 or 2 plugs, or a familiar three-pin house plug. Public slow chargers usually have around a 5kW output, but using a regular home plug you will only get 2-3kW. Slow chargers are mostly used at home by people who charge their small EVs overnight.
How much does it cost to charge an electric car?
Methods of charging
This is what people generally do when using the public chargers. Sticking with the i-Pace and 50kW rapid charger scenario, let’s say you wanted to know how much range you would get from plugging in the Jag at a motorway service station for 30 minutes. In that time, using that charger, the i-Pace would gain about 90 miles of range. If using a 22kW fast charger, that would drop significantly to about 12 miles.
Therefore, it largely depends on the charger. Unlike the earlier generation of plug-in cars, modern EVs can cope with rapid charging.
The overwhelming majority of EV owners charge their cars at home overnight. As we mentioned, the easiest but slowest means of domestic charging is by plugging an EV into a regular home socket. However, 7kW fast chargers are easy to get installed, and affordable thanks to the government’s Electric Vehicle Homecharge Scheme. The EVHS grant contributes up to £350 per charger installation, covering a maximum of two chargers per property.
With charging and electric car at home, amps, volts and watts are useful in working out how long it takes to charge a car with a given charger. Chargers give you a power output figure, but it helps to understand how it has reached that figure.
Amps measures electrical current, the amount of electricity flowing through a circuit. Voltage is the muscle; it determines how much current can be shoved through and electrical circuit. And Watts are the unit of measurement for the power that results. The relationship between these three is represented by this equation (remember it from your physics schoolwork?):
Power = Current x Voltage
Therefore, a 7.4kW home charger has a voltage of 230V (standard home voltage) and current of 32 amps (230 x 32 = 7360 watts/7.4 kilowatts). 7.4kW chargers are ideal for overnight charging, even for EVs with big batteries. Plus they only require a single-phase power supply like domestic properties tend to have.
You can upgrade to a 22kW charger at home if you really wanted to, but it demands installing a three-phase power supply. The 3kW slow chargers are hardly worthwhile. For any EV with a large battery, such as a Ford Mach-E or any Audi e-Tron, for example, you’ll be waiting for eons to reach full charge.
There are a number of companies that offer home chargers such as Wallbox, Pod Point, BP, and Rolec. Additionally, car manufacturers such as Tesla and BMW offer its own domestic units.
While home chargers are undoubtedly useful and easy, they ideally require a garage or at the very least a driveway. Those of us whose cars live outside our houses, sometimes a little down the street if a visitor has nicked our spot, struggle with practical issues of draping a charging cable out to the car.
Watch out for the cold
The weather can seriously tamper with some of the theories above: colder temperatures can slow the charging rate and reduce the overall range of an EV. A study conducted in 2018 by the Idaho National Laboratory looked at the effects of temperature on a fleet of Nissan Leaf taxis. They found that the cars being charged at 25°C for 30 minutes gained 36% more charge than those being charged at 0°C for the same length of time.
The future of EV charging
While chargers are getting better, current battery tech is holding some EV buyers back. For many, it still takes too long to charge an EV compared to a petrol or diesel car. But things are changing.
Israeli company StoreDot has begun production of its extreme fast-charging (XFC) batteries. StoreDot’s aim is for these batteries to be able to gain 100 miles worth of charge in five minutes by 2025 – that’s twice as fast as a 150kW charger can manage. It’s serious business too, having attracted investors including Daimler and BP. StoreDot’s batteries are still lithium-ion, which means they still bear the issue of range and particularly weight. Nevertheless, it represents a promising intermediary that will make EVs more attractive to buyers while a better battery solution is developed.
StoreDot is far from alone in its quest for improved battery technology. All the world’s car makers are reorganising themselves to focus on EV R&D. In addressing people’s environmental and humanitarian concerns over the use of cobalt in lithium-ion batteries, Panasonic revealed its new low-cobalt batteries earlier this year, with the intention of not using the rare mineral at all in its batteries within the next couple of years. This will make car batteries not only more eco-friendly, but cheaper too. New and improved batteries are case of when, not if.