From Car and Driver

Figuring precisely how long it takes to charge an electric vehicle is akin to asking, “how long does it take to cross the country?” It depends whether you’re in a plane or on foot. Recharge time is dependent on a host of variables, many of them nuanced—even the length of the charging cable can influence it—that make providing a precise answer impossible. But we can give you some reliable guidelines.

Ignoring some of the lesser variables, the charging time of a vehicle comes down to two primary factors: power source and the vehicle’s charger capacity. Ambient conditions play a smaller part, with both cold- and hot-weather extremes adding to charge time.

Power Source

Let’s start with the power source. Not all electrical outlets are created equal. The common 120-volt, 15-amp receptacle in a kitchen is to a 240-volt outlet that powers an electric dryer as a squirt gun is to a garden hose. All EVs can, theoretically, charge their large batteries off the standard kitchen outlet, but imagine trying to fill a 55-gallon barrel with a squirt gun. Recharging an EV battery with a 120-volt source—these are categorized as Level 1 according to SAE J1772, a standard that engineers use to design EVs—is measured in days, not hours.

If you own, or plan to own, an EV you’ll be wise to consider having a Level 2—240 volts, minimum—charging solution installed in your home. A typical Level 2 connection is 240 volts and 40 amps. While fewer amps is still considered Level 2, a 40-amp circuit will likely maximize an EV’s onboard chargers (more on those in a minute). Because, if you’re not maximizing the effectiveness of the vehicle’s onboard chargers, a lower-than-optimal power source is essentially a restrictor plate that lengthens the charge time.

For the absolute fastest charging possible, you’ll want to plug in to a DC fast charger. These are the EV equivalent of filling that barrel with a fire hose. A certifiably lethal current of DC power is pumped into the car’s battery, and miles of range are added in short order. Tesla’s V3 superchargers pump out up to 250 kW, and Electrify America’s automotive defibrillators fire out up to 350 kW of heart-stopping power. But, like all charging, the flow is throttled back when the vehicle battery’s state-of-charge (SoC) is low or high. And vehicles’ ability to accept DC charging varies widely. The Porsche Taycan, for example, can charge at up to 270 kW, while a Chevy Bolt EV can manage only 50 kW (and adding that capability costs an extra $750).

When the vehicle battery’s SoC is below 20 percent or above 80 percent, a DC fast charger’s charging rate slows considerably; this optimizes battery life and limits the risk of overcharging. This is why, for example, manufacturers often claim that fast-charging will get you to “80 percent in 30 minutes.”

That last 20 percent may double the time you’re hooked up to the fast charger. The time-consuming affair of completely filling the battery via a DC charger makes them best utilized on those days when you have anxiety about exceeding the range of your car, or when you are traveling and need to fill-up to reach your destination. Charging at home overnight is a better solution for getting the juice you’ll need for daily, local driving.

Charger Capacity

There is a common misconception that the thing you plug into an EV is the “charger,” when in fact there’s actually a battery charger in the car that converts the AC electricity from the wall into DC to charge the battery. Onboard chargers trickle power into the battery pack safely and have their own power ratings, typically in kilowatts. If a car has a 10-kW charger and a 100-kWh battery pack, it would, in theory, take 10 hours to charge a fully depleted battery.

To gauge the optimal charge time of a specific EV, you divide the battery capacity’s kWh number by the onboard charger’s power rating, then add 10 percent to the losses associated with charging. This is, of course assuming the power source can maximize the chargers.

Typical on-board chargers are at least 6.0 kilowatts, but some manufacturers offer nearly twice that. The current Tesla Model 3 Performance, for instance, has an 11.5-kW charger, which can take full advantage of a 240-volt, 50-amp circuit to recharge its 80.5 kWh battery, while the Model 3 Standard Plus is fitted with a 7.6-kW charger. Doing the recharge-time math indicates that it will take about the same time to fill the two cars’ batteries, though the Performance model’s is 50 percent bigger. The beauty of a well paired electricity source and onboard charger is that you can plug your EV in at home with a nearly depleted battery and have a fully charged steed waiting for you in the morning.