Charging an EV can take anything from mere minutes to more than 24 hours. It depends on everything from the type of charger and the model of EV to the ambient temperature and even the length of the charger cable.
How to calculate EV charging time
There are lots of different factors that influence charging speed, but the two most significant ones are the battery capacity of your EV and the charging power. Once you determine these, the calculation is very straightforward:
Let’s look at both in more detail below:
🔋 Battery capacity
The battery determines how much energy can be stored and, therefore, plays a big part in how long it will take to charge.
The battery capacity differs for each car. The Nissan LEAF, for example, has a battery capacity of 30 kWh, while the Tesla Model S has a capacity of 100 kWh.
⚡ What is charging power?
Charging power is the amount of energy that can be introduced in the battery per hour. It’s made up of three factors: the connection to the electric grid, the onboard charger of your car and your Wallbox charger.
The weakest link determines the charging power. Let’s look at the example below.
In this case, the charging power is 4.4 kW, because it’s the lowest value of the three.
⏲️ Calculating your EV charging time
Now, let’s put all the pieces together (for this example we assume the battery capacity is 30 kW).
So, 7 hours is the amount of time your car needs in order to be fully charged (from 0% battery).
How much range do you get from one hour of charging?
The amount of range you can get from one hour of charging depends on the type of charger you use and the EV you drive.
Let’s take the most popular EV, the Nissan LEAF, as an example.
The full capacity of its battery is 40kWh and its maximum range is 270km.
A level 2 charger, which offers up to 22kW of charging power, would still only be as fast as the Nissan LEAFs onboard charger, which is 6.6kW. This would take 6 hours to charge the Nissan LEAF to its full capacity.
So, to get the hourly range, we divide 270 by 6 = up to 45km per hour of charging.
Other factors that affect charging time
Here are some of the other variables that affect your EVs charge speed:
- 🌡️ Ambient temperature – as cold batteries have a greater resistance to charging, cold weather can affect your EV’s charging speed considerably. It can also affect the battery’s range.
- 🕑 Hour of the day – charging your EV during peak hours will result in a slower charge, as more energy is drawn from the grid.
- ⚡ Number of EVs connected – this is something that affects public-use EV chargers, rather than household chargers. If the accumulated maximum charging power of the EVs and chargers exceeds the maximum amount of power delivered by the charging station, the charging speed will be affected
- 🔋 EV’s battery level – if an EV’s battery is below 20% or above 80%, the charge speed may be half as much as usual. This is an in-built feature by EV manufacturers to optimize battery life and prevent overcharging.
- 🔌 Type of charge cable – different types of charge cables include Type 1, Type 2 and CHAdeMO, all of which charge at different speeds
- 📈 Avoid dropping below 20% – letting your battery get too depleted can also affect its longevity. Using a smart charger will enable you to make sure your EV battery never drops below 20%.
- 🚗 Use it! – EV batteries aren’t affected by overuse. In fact, they are more likely to be affected by sitting in a garage for long periods of time. So, get out there and drive!
How often do you need to charge your EV?
It all depends on what EV you’re driving, what charger you’re using and your driving habits. But for most EV drivers, 2–3 times a week is enough. If you’re driving your EV on a daily basis and own a smart charger, you can also schedule your car to be charged at night. This way you’ll always wake up to a fully-charged EV, while also saving on energy costs.