The most frequent question for electric vehicle owners is “How long does it take to charge?” In a previous post titled “The Reality of Charging an EV on the Road,” I discussed the three categories of charging (L1, L2, and L3).
As a Tesla owner, the next set of questions almost always have to do with Supercharging. While I talked a lot about where to find Superchargers and generally how they work in the previous post, I only touched briefly on the factors affecting charging speed. I said:
L3: “fast charging” is typically 50 kW or greater. Tesla’s superchargers are capable of about 120 kW at peak rates. With L3 charging, a 60 kWh battery can be fully charged in an hour or so. A special note: L3 chargers adjust their power levels based on temperature, battery capacity, battery state of charge, and other factors to protect the battery. L3 chargers provide peak power when the battery is warm and nearly empty. Charging at L3 rates is an intricate dance between the electrical grid, car, and charger.
************UPDATE (July 2019) ****************
Tesla continues rolling out enhancements to supercharging speeds and battery pre-conditioning for all Models but especially for Model 3. Even on Version 2 superchargers, power is being increased to 150 kW in some cases. The story below remains relevant, even as charging times decline for the newest cars. Older Teslas like mine will not see much of an increase in charging rates. The story’s main theme remains true: supercharging is a complex dance between charger and car. Continue reading below to understand that dance.
************UPDATE (March 2019) ****************
Tesla unveiled its V3 supercharger in early March 2019. V3 supercharging provides a maximum power level equivalent to 1,000 miles of added range per hour. Tesla believes supercharging times will be reduced by 1/2 for vehicles that can take full advantage of these capabilities. However, it will take time for these V3 superchargers to become prevalent so the information below remains largely valid. Cleantechnica has a nice overview of what was announced and Transport Evolved has a nice video overview (see immediately below), which is well worth watching.
************* END UPDATE **************
As a general rule of thumb about how long it takes to charge on a Supercharger, think of it like this:
- 20–30 minutes to go from 20% battery remaining to 80% full.
- 60 minutes to go from 20% battery remaining to 95%.
- 90 minutes to go from 20% battery remaining to 100%.
As always, the ideal state is to partner your charging with another activity, so you don’t have to even think about it. Charging stations are becoming so ubiquitous that it often isn’t hard to find locations within a city where you can charge while you shop or eat and come back to your car with 40, 60, or even 100 miles of additional range. I suspect in 10 years, the question of “how fast” will no longer be necessary. Never leave home without Plugshare loaded on your phone.
For the more wonkish minded, let’s look at that these factors a little more closely. The primary factors in determining the speed of charging at a supercharger are:
1) The type of supercharger (old, new, urban)
2) Whether you have to share the available power with another Tesla
3) The state of the battery in your vehicle.
Tesla installs superchargers around the globe to enable long-distance travel with their electric vehicles. They are optimized to get as much electricity into your car possible, while also managing very high loads to support these charging rates. However, to aid those of us who live in high-density housing, Tesla recently announced their “urban” supercharger strategy, which doesn’t seek absolute speed, but consistent charging. The old superchargers were good for about 200 miles of range added per hour, but they are being phased out. New superchargers are good for more than 300 miles per hour. The maximum I’ve personally seen is about 340 miles per hour.
In more technical terms, a supercharger can push 120 kW of power to your car. An urban supercharger will be limited, I believe to 70 or 75 kW. These numbers provide the theoretical maximum rate for replenishing your Tesla battery. My understanding is that Tesla’s navigation tools will soon show you the maximum power available at any given supercharger stop to aid in planning your charging session.
Each charger is labeled with a number like 1A, 1B, 2A, 2B. The A and B mean those chargers are paired and share a circuit. If someone is charging on 1A and you plug into 1B, you will only get a fraction of the theoretical maximum power. Therefore, you always want to find a charger whose partner is open to maximize your charge rate.
Lastly, the state of the battery in your vehicle has an enormous impact on your charging rate at a supercharger. Because the power levels are so high, the car’s battery management software works overtime to ensure it only accepts as much power as the battery can safely absorb. Large batteries can accept power faster than small batteries. Warm batteries can accept power more quickly than cold batteries. Batteries with low states of charge can accept energy more quickly than those with high states of charge.
Your car and your Tesla app show how rapidly your vehicle is charging and the estimated time remaining to complete the charging session.
While all of this may seem daunting and confusing, in reality, you get an intuitive feel for how long it’ll take after just a few supercharging sessions. For those who don’t want to think about it at all, Tesla’s navigation system will route you through supercharging stops to reach your destination as efficiently as possible. It will tell you where to stop, how much energy you’ll arrive with, how long you should expect to charge, and then, while charging, it will pop up a notice conveying that you now have enough energy to continue to your next stop. The video below is an excellent overview of how this route planning works.
