I’ve heard a lot recently about superfast charging times, so how long does it actually take to charge up an electric vehicle (EV), and will it ever really match the convenience of fuelling up with petrol or diesel?
Annoyingly, this is one of those questions, for which the answer is directly proportionate to the length of a random piece of string.
The speed at which a petrol or diesel car can be refuelled is a known and familiar quantity – fuel from a fuel pump flows at about 30-40 litres per minute, so an average family car can be topped-up in about two minutes at most (plus time spent queuing to pay or using the pay-at-pump service).
When it comes to recharging an electric car, you have to deal with a number of variables. The first is the power of the charging point.
Charging points basically come in three broad flavours. There’s a home charging point, which for most of us will be able to input energy into our electric car’s battery at a rate of 7.4kW on alternating current (AC) charging.
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Taking, as we usually do on these pages, the 77kWh battery of a Volkswagen ID.4 electric SUV – the bestselling EV in Ireland – as a useful average, that means that at home, assuming you plug in with 10 per cent charge left in the battery, you’re going to need 9 hours 20 minutes to recharge a full charge.
What if we use more power?
A kerbside charger – the boxy ones used by ESB e-Cars, for instance – is the second main flavour of charger, and can offer as much as 22kW of charging power on AC.
So that means you can charge really fast?
Not quite, as most EVs will only accept a maximum charge power of 11kW on AC power. Now, that is faster, and it means our notional VW ID.4 will charge from 10-100 per cent in 6 hours and 20 minutes.
Can you charge at 22kW on AC Power?
Yes, but not in all EVs. Renault has traditionally been the best at offering faster AC charging, so at 22kW its Scenic E-Tech will do a 10-100 per cent charge of its 87kWh battery in 3 hours 30 minutes.
Although it might not. You see, a 22kW AC charger will only provide its full 22kW of power if only one car is plugged in. If someone else comes along and plugs in too, then the 22kW is divided between the two cars, so you get 11kW of charging power each.
Okay, what if we use even more power?
Now, we’re into the realm of DC – Direct Current – power, and you’re talking about the big, hefty rapid chargers found mostly at service stations. These use the larger “CCS” connector – the double-decker shape – and can charge at anything from as little as 50kW (which hardly even counts as rapid charging any more) up to a whopping 400kW, depending on the charger. Most chargers in Ireland will manage a maximum of 150kW.
Now, your car might not be able to accept all that power. Each EV model’s battery has its own maximum charge rating, so the battery in a Renault 5 E-Tech can charge at a maximum power of 100kW, while that of a Kia EV4 can cope with 128kW, and an Audi A6 Sportback can cope with a massive 270kW.
For the most part, with most cars, car makers are working to an average charging time of about 30 minutes for a 10-80 per cent charge when you’re using a DC high-speed charger. So the Renault 5, with its low charging power, can charge in about the same time as the Kia EV4 because its battery is actually smaller.
Things get more interesting when you ramp up both the power of the charger and the power the battery can accept. So that Audi, with its 270kW charging power and a 94.9kWh battery, can do its 10-80 per cent charge-up in as little as 20 minutes.
There are cars that are potentially faster than that, though. The incoming update of Xpeng’s G6 electric SUV, for instance, has a maximum charging power of 451kW, cutting the potential 10-80 per cent charge time to just 12 minutes.
Still not down to petrol/diesel speeds, but getting there.
Of course, there are more variables with which to contend here.
There are outside forces that can affect your fast-charging times, and those include the amount of power actually reaching the charging point (which can vary dramatically depending on where in the country you are), the number of other cars plugged in at the same charging hub, the ambient temperature and the condition of your battery.
It’s critical, if you want to get the best charging speeds, to make sure that the battery of your car has been preconditioned (essentially brought to the optimum temperature) before plugging in.
Most EVs will do that automatically once you input a fast-charging point as a sat-nav destination, while many will also allow you to turn on the battery conditioning system manually. If you don’t do either, then the battery might be too cold or too hot for optimum performance, and you’ll get slower charging.
Incidentally, you’ll still have to pay the same (often expensive) price for fast charging, even if you’re not getting the maximum rate advertised. We’ve been asking the charging operators for some time now for dynamic pricing based on the actual, real-time charging rate, but no dice, it seems.
So, rule of thumb time – how fast can you charge an EV?
In about 10 hours overnight at home, in three-to-six hours on a kerbside charger, and in 30 minutes or less (to 80 per cent charge) at a public DC fast charger. However, that thumb comes with a lot of caveats.
And will EVs ever actually match petrol and diesel cars for refuelling times?
Well, possibly. BYD – the gigantic Chinese car maker – has this year shown off a megawatt charger (yes, that’s 1,000kW of charging power) that it plans to roll out across China and Europe in the coming years.
In theory, one of its EVs strapped to that charger will be able to add as much as 400km of extra range in just five minutes of charging. So closer again to petrol or diesel refuelling and, possibly, eventually, solid-state batteries might get us closer again.
Of course, there’s an important point we’re missing here, which is that ultimate 10-80 per cent charging speeds don’t really matter.
In theory, anyway, people don’t charge their cars like that; they just top up enough extra range to get home so that they can charge on cheaper home electricity rates, rather than paying through the nose for DC charging.
