How long does it take to charge an electric car?

How long does it take to charge an electric car?

How Long Does It Take to Charge an EV?

How long does it really take to charge an electric car? This is a question that often comes up when considering making the leap from fossil fuels to electric. We hope this guide to charging times provides you with a better understanding of how EV’s operate.

What You Need to Know:

  • There are three types of charging
    • 3-pin plug (slow and time-intensive)
    • Dedicated home, workplace or public charging devices (range from slow (3kW) to fast (22kW)
    • Fast and rapid charging stations (range from 50kW to 150kW)
  • You will rarely need to charge from 0% to 100%. Instead, it is more realistic to look at timings from 20% to 100% at home and 80% for public charging.
  • Charging and range efficiency can fluctuate depending on the temperature. EV’s typically average slightly better mileage during warmer months, whereas energy is taken away from range to heat the cabin and battery during colder months.
  • A basic calculation to work out charging times:
    • Required kWh/Charger Output = Hours to Charge

Getting accustomed to the idea of not being able to swing by a petrol station to refuel can seem unnerving at first. Still, the on-going advancements in rapid charging stations, alongside larger battery capacities are leading to faster charging times and less frequent charging sessions required overall.

It is also worth noting off the bat that the majority of EV charging takes place at home, in comparison to the current refuelling process of traditional fossil fuel vehicles. The advantage of this means that even if your car takes hours to charge fully, you can simply leave it overnight – much like you would charge a mobile phone. The nightmare visions of having to spend hours of your day at service stations to get anywhere are not the reality for many EV owners. Instead, they often boast of time saved by not having to queue up for petrol/diesel.

So, what you can expect as an EV owner.

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Charging Variables

These are the factors that will determine how long it takes your EV to charge, note that some are within your control (such as your selected home charging device), some are not (the weather for example).

  • Type of charging device
  • Size of your EV battery
  • How empty/full (depending on your philosophical outlook on life) the battery is
  • Outside temperature
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Types of Charging

Let’s begin with AC and DC chargers. Without deviating into a science lesson, for the purpose of EV charging, you simply need to know that AC (alternating current) is the type of electricity pulled from the National Grid and will be the source of energy for all home and many public charging devices. DC (direct current), on the other hand, is used by fast and rapid public charging stations. Not all EV models are equipped to charge with DC, so if using rapid chargers on long commutes is something you will need, it’s worth checking the EV model you want is compatible.

There are essentially three types of charging. The first ‘level’ so to speak, would be your three-pin plug, which often comes as standard with many EV’s, enabling owners to get started and/or keep as a back-up. The problem with this option is that charging time can be extensive, given the limited power supply. Typically, a three-pin will operate at 2kW, providing roughly 8 miles per hour; if for example, you owned a Kia e-Niro with a battery size of 64kWh, it will, therefore, take approximately 32 hours to fill your battery from empty to full. Additionally, the 3-pin chargers are not designed to withstand high loads for long periods, posing a potential safety hazard.

Level 2, as we’ll call it, is a dedicated home or public charging device. These devices start at 3kW and go up to 22kW. The average EV owner will opt for a 3kW or 7kW, as 22kW requires a three-phase power supply, which isn’t common and can prove costly to implement. Nevertheless, you can find 22kW chargers available in public locations. Charging times will vary depending on the output of the device, battery capacity, and whether the car can pull the highest load. Some EV models are only capable of charging at 7kW or 11kW when using AC, this means that your car will charge at its peak power, regardless of the type of charger you use. For example, if you own a Nissan Leaf which can charge to a maximum of AC 6.6kW, then despite being plugged into a 7kW or 22kW fast charger, your EV will charge at 6.6kW.

Lastly, level 3, which is the DC fast and rapid car charging devices, often situated at service stations for those on-route. These are powerful, typically ranging from 50kW to 150kW. Further still, these outputs are only increasing with Tesla boasting an impressive 250kW charging station (although this output is only available when the device isn’t being shared).

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Topping Up

This is perhaps the most crucial point to make when discussing charging times. You will rarely be charging your battery from 0% to 100%. Just as you don’t let your petrol tank run dry (although if we’re being honest, we’ve definitely pushed our luck with that a few times), you wouldn’t completely drain your EV battery.

Typical charging sessions are merely top-ups and will often coincide when the vehicle is out of use; when you’re working, shopping or at home binge watching Netflix when you should be sleeping. We have a tendency to overestimate how often we use our cars, when in fact they are parked up for well over 90% of the time. That’s a lot of charging opportunities.

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Charging Times at Home and the Workplace

Home charging devices often rated at around 3kW to 7kW. Given the increasing size of EV batteries and the growing popularity of EV friendly energy tariffs, a 7kW device usually is more beneficial. Given you’re in the comfort of your own home, charging time isn’t as much of a concern, you can simply plug-in overnight to wake up to a 100% full battery, ready to hit the road.

Let’s take our BMW i3 driver as an example. You’ve had to travel for work, and you’ve arrived home with a near-on empty tank. You need to load up a full 42kWh to be back at 100% by 6am tomorrow morning to make your first meeting. With a 7kW charging device, this will take roughly 6 hours (required kWh / kW charge), meaning you’ll need to be plugged in and charging by 12pm.

How about if the battery isn’t completely dead? It’s a Saturday afternoon, you hit the gym in the morning, taken the dogs out and ran some errands during the day. You arrive home, and you’ve used roughly 30% of your battery. It’s your brother’s birthday that evening, and you need to make a long drive up north to join the celebrations; you need to top-up what you’ve used. This time we’re going from 70% (29.4kWh) to 100% (42kWh). That’s a deficit of 12.6kWh. With your 7kW charger, this will take just under two hours of charging.

Workplace charging stations are often more powerful than home devices as they’re serving multiple EVs in one day. In this example, we’re going to assume your company has invested in a 22kW charger. You forgot to charge overnight, but you had enough range to get into work for 9am. The battery in your i3 is now at 8% (3.4kWh), you need to travel that evening for a client presentation the next day; to comfortably make the drive you need to top your battery up to 100% before you leave at 3pm. The i3 has a max AC 3-phase rate of 11kW, and you need 38.6kWh added, this will take just over three and a half hours.

Note here, that although the example used a 22kW charger, the output maxed out at 11kW, limited by the vehicle’s onboard capabilities. If, however, you owned a Tesla Model S that is capable of pulling 16.5kW on AC, topping up the same amount would take just under two and a half hours.

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80% Rule

So far, we’ve discussed charging up to 100%; however, it is worth noting that car batteries will charge quickly for the first 80% of its capacity and slow down for the last 20%, taking almost as long as the first portion. To wrap your head around this, think of it like filling up a bathtub, in the beginning, you have the tap turned to full capacity to fill the tub as fast as possible, and when you get to the last 20%, you turn the faucet down to prevent the water spilling out. The same occurs with your battery charger, and this is why you will often see manufacturers quote charging times to 80%, rather than the full 100%.

Perhaps more importantly for EV owners is the 80% rule when charging at public stations. If you consider that the last 20% takes just as long as the previous 80%, then you may not have the luxury of time to wait for a full charge, and in many cases, an 80% capacity will get you to where you need to go.

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Public Charging Times

Let’s just dive into this with another example. The BMW i3 has a CCS connector making it compatible with rapid charging devices up to 50kW. Using the case above, let’s assume all the charging bays at work were occupied for the first half of the day, so you didn’t achieve a full charge. Halfway through your trip, your battery is at 30% (12.6kWh), so you stop off at the service station for a bite to eat and a top-up, this time to 80% (33.6kWh). The 50kW provides 50kWh every hour, and you only need 21kWh to be on your way. How long do you have to grab a tea and something to eat? 25.2 minutes. How did we get there? Divide the amount of kWh you need (21kWh) by the charger rating (50kWh), giving you 0.42 or 42%. That’s the percentage of 60 minutes you will need to charge for.

If you had a Tesla Model S and were able to use a rapid charger at 145kW, then to top up the same amount would take just under 9 minutes! Given the range on the Tesla’s you’d likely be filling up a little more, nevertheless, how long it takes to charge is heavily dependent on the capabilities of your vehicle and the charge point in use. It is worth pointing out here that Tesla has its own rapid charging network and come with their own type of connector; however, Tesla owners can use adaptors enabling access to all fast chargers.

Calculation Formula based on Load and time

Converting Time to Mileage

Okay, by now, you get the gist on how to calculate charging times using battery size and charging power output. A more meaningful conclusion, however, maybe how long it takes to add a certain number of miles. For example, a 50kW charger is estimated to provide up to 100 miles in 30-35 minutes and a 150kW charger up to 200 miles in 30 minutes.

This is a different take on the MPH (miles per hour) than we are used to. Of course, MPH still relates to how fast a car can go, but EV drivers are now switching to thinking about MPH or RPH (range per hour), in terms of the mileage accumulated for every hour of charging.

Smaller, lighter cars are typically the most efficient in terms of RPH, with a Renault Zoe achieving 30 miles every hour using a 7kW charger. Heavier vehicles such as Audi e-tron average around 20 miles with the same charge point.

In addition to the car itself and environmental factors like temperature (EV’s will achieve slightly better range in warmer months), you will need to factor in driving styles. This makes range per hour more individual and as a result, quite challenging to quantify, but not impossible. As you become accustomed to driving electric and collect your own data, you’ll be in a much better position to calculate how far you get with every kWh added and eventually will have your individual ‘averages’ to go by.

Hopefully, you found this guide helpful, and it answered some of your questions. For more EV info and what you can expect as an EV owner take a look at our other guides, here.

For any other charging queries, please feel free to get in touch, we’re always happy to help.

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