For anyone that has plugged in an electric car, they will know that working out exactly how fast your electric car will charge is a bit of a dark art. This is because there are so many variables, it’s almost impossible to accurately work it out. Often, it is simplest to leave it to the car’s countdown, which appears when it is plugged in to a charger, but even this can be a little out.
So what are the essentials that you should know, and what impacts charging speeds? We take a look in this handy guide.
EV charging basics
At its most simple level, charging times can be calculated by dividing the battery capacity by the charger power. For example, a 70kWh battery would take 10 hours when plugged in to a 7kW charger - divide 70 / 7. The same applies if it’s a 35kWh battery being charged by a 7kW charger, the time will be five hours.
Except this is the theoretical charging time for a 0-100% charge… and nobody really charges from “empty”. So the first variable is to calculate the remaining battery capacity that you need to charge. For example, if you charge the same 70kWh battery from 30%, you have 49kWh to charge to 100%, which will take seven hours… you get the gist. Secondly, charge points and vehicles will have different power ratings. An EV can be plugged in to any charge point that has the right cable/plug to fit the car, but how fast it charges depends on the lowest common denominator. A car/charge point can always take/deliver less power, but never more.
So a car that can charge at 7kW from a 7kW charger will see the maximum potential reached for both vehicle and unit. Some cars can only charge at 3.6kW, so on the same 7kW charger, will take about half the time to charge, since it can only draw half the charger’s maximum rate. Alternatively, some cars can charge at 22kW, but still, on the same 7kW charger, it will only have 7kW an hour delivered. When calculating charging times, it’s important to base it on the lower of the two ratings.
Advanced EV charging
Following on from the relatively simple maths above are the unknowns - just to throw some confusion into the mix. Each charger’s power rating is the average power possibly delivered over the course of an hour, but it might not be able to deliver that. Demands on the grid may restrict it, but most commonly, rapid and ultra-rapid DC chargers can sometimes share a single power supply. Tesla’s Supercharger network is built on this principle, with each charge point capable of charging at more than 200kW - but we’ll use this nice round figure for the sake of simpler maths.
Supercharger points are always built in pairs, because they share a common power supply, which means when a single EV is charging on the pair, it gets the full 200kW. Park an EV next to it and plug it in, and the power is split, so each car would get a maximum of 100kW.
There are variances here, such as if one car was charging with a battery more than 80% topped-up, it would draw less than half the power and the other car would get more, but essentially the 200kW is shared between two chargers. And some other networks use the same principle in places - it’s not just Tesla.
As mentioned, cars charge along a curve, and the closer the car gets to 100% charge, the slower the charging rate. This is particularly noticeable on rapid chargers, which always have times quoted to 80%, as after this, the charging rate slows down dramatically. The slower the charger, the flatter the charging curve, so a reliable time is easier to calculate from non-rapid chargers.
There are other factors too, such as temperature - both the car’s battery and the outside air. Batteries don’t like being cold, but also don’t like being too hot. If you plug a car in when it’s not been driven far and there’s snow on the ground, it will take longer to charge than if it’s a clement spring day.
Likewise, if it’s been driven hard for hours and it’s the middle of summer, it will not charge as fast as it could, because it’s too warm. This sounds extreme, and there are battery management systems to help mitigate this impact, but broadly speaking, temperature can make a difference.
Ultimately, you will get used to how fast your car can charge with time, but by using the above principles, you will have a good ballpark idea.
Fastest charging EVs
The only real way to get a good handle on how fast an EV charges is to test it out by charging it. Fortunately, there are results in the open space that show the fastest charging EVs on the market, with research carried out by EV Database. Based on the maximum charge rate available from public high-power chargers, the fastest charging models in the UK are:
|Make-model||Max DC rate||Min charging time|
|Hyundai IONIQ 6||233kW DC||16min|
|Kia EV6||233kW DC||16min|
|Genesis GV60||233kW DC||16min|
|Porsche Taycan||268kW DC||17min|
|Audi e-tron GT||268kW DC||17min|
|Genesis GV70||233kW DC||17min|
|Genesis G80||230kW DC||21min|
|BMW i4||207kW DC||27min|
|Mercedes EQS||207kW DC||28min|
|BMW i7||200kW DC||28min|
The fastest charging versions from each model range are highlighted.
As you can see, even though the Porsche and Audi have a higher maximum charge rate, they are fitted with larger batteries, so take slightly longer to charge than the Hyundai, Kia or Genesis above them. These three models - as well as the two Genesis models lower down the list - use the same charging system, and the Porsche and Audi share one too.
Where times are shared, models are rated in order of how many miles can be added to the range in that time, so more efficient EVs are higher placed than less efficient versions.
If you would like to lease an electric car, then we have a range of models available at different lease price points - and, of course, different charging speeds!
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