As we mentioned previously, charging speed is measured in kilowatts (kW). The higher the number, the faster your car will charge (up to your car’s maximum charge rate). Let’s recap with some context.
1-2kW / 3-5 miles per hour
5-20kw / 12-60 miles per hour
50-350kw / 200-1000+ miles per hour!
So what does this mean for a full electric car with an average-sized 75kWh battery pack (like a Tesla Model Y)?
Level 1: 1+ days (40+ hours)
Level 2: 6-10 hours
DC FAST: 20-45 minutes
Now that we have a general sense of charge times, it’s important to understand which factors can have an impact on how fast your car is able to charge.
Your EV is likely to have an active battery temperature management system on board. That means the car is working to keep your battery warm or cool depending on the ambient temperature around you. Your car may even be doing this while parked and turned “off”.
The ideal temperature for charging is 23 degrees C or 75F. If temperatures are above or below this - especially if below this, charging speed may drop off significantly.
Some EVs are intelligent, and will warm the battery in anticipation of charging. For example, if your next charging stop is included in your GPS directions so that the car “knows” you’re stopping there, it may begin to "condition" the battery by warming or cooling to the ideal temperature before you arrive at the charging station.
If you’ve been driving for a while, odds are your battery is pretty warm and ready for charging. Where you’ll run into the most problems is when the car is very cold and you try to charge right away. Your charge rates will drop, and your charge time will increase significantly.
Another big factor that affects your charge speed is “state of charge”. State of charge refers to how much juice your battery currently has. Charging from 0% to 80% is much faster than charging from 80% to 100%.
This is important to remember and consider for two reasons:
When you’re driving long distances, it often makes more sense to make more frequent stops, charging to 80% each time (instead of waiting for 100%). Even though you’ll make more charging stops, you’ll spend less time at the plug overall. Of course, this assumes there are enough charging stations along your route to conveniently space it out this way.
Since your car will charge fastest between 0% and 80%, you may want to buy a car that has all of the range you need within 80% of your battery capacity. So if you know you need 150 miles of range, buy a car that has 190 miles of range. That way, you'll regain all 150 miles that you need at the faster charge rate.
This also means that BIGGER batteries will actually gain more mileage back faster, because they offer more mileage out of that initial 80%.
As we’ve mentioned previously, both the charging station and the car each have a maximum rate that they’re able to charge.
If your car can charge to a max of 250 kW, but the charger has a max speed of 50 kW, you’ll charge at no more than 50 kW.
If your car has a max speed of 50 kW, but the charger is capable of 250 kW, you’ll charge at no more than 50 kW.
It’s hard to predict what the max charging speed of any particular charging station may be, but you can give yourself the best chance of fast charging by choosing a car with a high max charge rate. This is especially important if you’re someone who will lean on public charging often, either due to long trips or due to not being able to reliably charge at home.
If you see two plugs at a shopping center side-by-side, it’s possible that those plugs share the same power source. If that’s true, your plug may share its available power with the plug next to it. If you’re the only car charging, the max charging speed of that plug should be available to you. If there is someone else using the plug next to you, the power may be shared by both cars, leading to reduced charging rates for both.
Sometimes these charging stations will prioritize the car that arrived first, other times the charge rate will split evenly. It’s hard to predict which may happen at which location, but you can give yourself the best chance of charging quickly by parking farther away from other cars.
For example, if there are 4 plugs available and a car is charging on plug #2, you’re best to select plug #4 instead of a space right next to the other car.
Some charging stations may indicate if they share a circuit. For example, some units on Tesla’s Supercharger network will be labeled in pairs of “A” and “B” to indicate that those two chargers share their power distribution. If there is a driver plugged into 1A, you are best to avoid 1B and grab either 2A or 2B, and so on.