When Should I Precondition an EV?

In regards to an electric vehicle, preconditioning can mean two things: warming or cooling the interior before driving or warming or cooling the battery before charging. Let’s take a look at what it means to precondition an EV’s battery before charging. (Though, particularly if you’re charging at home, you may be able to precondition the interior at the end at the same time, which we’ll touch on at the end.)

Related: Your Guide to EV Batteries: Premature Death, Range Loss and Preservation

What Does It Mean to Precondition the Battery?

Done when it’s quite cold or hot outside, preconditioning heats or cools the battery to a more moderate temperature that allows it to charge and deliver electricity more quickly. It can also help to extend the battery’s life.

Most modern EV batteries have built-in heating and cooling elements that are powered by electricity supplied either by a charger or the battery itself. Note that some EVs — usually older or less expensive ones — may not have these heating or cooling elements and therefore can’t be preconditioned.

Why Would a Battery Need Preconditioning?

Keep in mind that a battery itself does not contain electricity; instead, it contains chemicals that create electricity through a chemical reaction. This chemical reaction slows when the battery is very cold or very hot. That adversely affects how fast the battery can accept a charge — whether when plugged into a charger or during regenerative braking while driving — and also how fast it can supply electricity to the motor under acceleration. Thus, there are advantages to keeping the battery at a moderate temperature.

While batteries likely differ somewhat in their ideal temperatures, generally speaking, they feel most comfortable at about the same temperatures you do. However, the battery warms up some while the car is being driven since the chemical reaction inside the battery creates heat as well as electricity. This allows the battery to become warmer than the ambient air after driving a while.

When to Precondition the Battery

There is no set rule about when to precondition a battery, though manufacturers may have suggestions in the car’s owner’s manual. That’s partly because there’s a gradual decline in the battery’s ability to accept a charge outside its ideal temperature window (roughly 60-95 degrees Fahrenheit) and partly because temperature mostly affects a battery’s ability to charge when charging rates are higher, such as when plugged into a DC fast charger. However, a very general rule might be that it’s beneficial to precondition a battery when it’s below 60 degrees. (Remember, though, that a battery that’s been in use driving will be warmer than the outside air, as it might be if the car has been parked in a garage.)

With warmer circumstances, the driver might plug in the vehicle when they get home but delay charging until electricity rates are lower — usually very early in the morning. However, a different strategy might work better when it’s cold out: Plug in as soon as you arrive, program in a desired departure time and cabin temperature, and let the car decide if and when to precondition the battery. This way — if you’ve allowed enough time — you start off in a car that’s already warm inside and fully charged, which minimizes how much power you’ll need to keep the car warm (it takes far more power to get the car up to a temperature than to keep it there) and maximizes not only range, but also acceleration. Note that if you’re plugged into a Level 1 (120-volt) charger, it may not deliver enough power to fully charge the battery and get the cabin to the desired temperature, and in fact, may dip into battery power to try and heat the interior.

A typical scenario where you might start the preconditioning yourself is when you’re headed to a DC fast-charging station in cold weather. That’s because if the battery is cold when you plug in, the car will drop the charging rate way down, making for much longer charging times. If you’ve programmed the charger’s location into your EV’s navigation system, the car should automatically start preconditioning the battery when necessary to have it at the proper temperature upon arrival. Preconditioning in this case uses some of the battery’s own power to do it, but that’s more than made up for with much faster charging rates when you plug in.

How much in advance do you need to start the preconditioning process? That depends a lot on the battery and temperature, but some sources suggest about 20-30 minutes as a general rule. However, some automakers may have more specific recommendations; for example, Chevrolet says that for its Silverado EV, owners should allow 30 minutes above 20 degrees or 60 minutes at or below 20 degrees — though that truck has a very large battery.

The bottom line for battery preconditioning seems to be that as long as you recognize when preconditioning might be beneficial and allow time to do it, the car can figure the rest out.

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Preconditioning the Interior

It’s one of the great joys of owning an EV: being able to preheat or precool the interior before getting in. Nearly all EVs offer this capability, though some only allow it when the vehicle is plugged into a charger. Preconditioning the interior can be activated automatically if you program your estimated time of departure into the car’s infotainment system, and some EVs allow you to do it through an app on your phone. If your EV allows you to precondition the interior without the car being plugged in, you only need to make sure you’ll have enough battery power left afterward to get home or to a charging station.

Some EVs also offer a special feature called a “heat pump,” which is a far more efficient way to heat the interior of your car. Particularly if you live in a cold climate and are going to make use of interior preconditioning when not plugged in, an EV equipped with a heat pump is well worth considering, as it uses far less battery power to do the same job.

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