How to Jump-Start an Electric Car That has a Dead Battery

If you’re new to electric vehicles—or are starting to research options for an upcoming purchase—you may not know that in addition to the high-voltage battery pack that supplies power to the motor, they also use the same 12-volt batteries that gas-powered vehicles do. And, yes, these 12-volt batteries can lose their charge and prevent the car from starting.

But the good news is, they can also be jump started—including with the help of a gas-powered vehicle. In an article for Kelley Blue Book, Chris Hardesty breaks down the whole process. Here’s what to know.

Safety concerns when jump-starting a battery in an electric vehicle

Before getting into how to do the jump-start, we wanted to point out a few of the safety concerns Hardesty brings up in the article:

• While it’s possible to jump the 12-volt battery in an electric vehicle, never attempt to jump-start their high-voltage lithium-ion batteries.
• Do not use an electric vehicle (EV) to jump-start another 12-volt battery. “The EV’s charging points are for jump-starting the car itself and not for assisting another vehicle with a jump-start,” Hardesty writes.
• The vehicle giving the electric vehicle a jump-start must have a 12-volt battery with a negative ground system—which, Hardesty says, is typical with gas-powered cars.
• The instructions below provide a general overview of how to jump-start electric vehicle batteries, but be sure to check the owner’s manual first, in case that particular make/model needs any special treatment.
• You can also use a portable jump-start device on an electric vehicle’s 12-volt battery.

How to jump-start a 12-volt battery in an electric vehicle

In his article, Hardesty provides the following instructions for jump-starting a discharged 12-volt battery in an electric vehicle:

1. Position the cars. Place the two vehicles, the EV and the vehicle with a good battery, near each other so they do not touch.
2. Turn on the brake. Shift into park and put on the parking brake.
3. Switch off everything. Check and make sure you turn off the lights and accessories in both vehicles.
4. Connect positive clamps. Now you’re ready to connect one end of the red positive (+) cable to the discharged battery’s positive (+) terminal. When done, attach the other end of the positive (+) jumper cable to the positive (+) terminal of the booster vehicle battery.
5. Attach negative clamps. Next, place one end of the black negative (–) cable to the good battery’s negative (–) terminal. Now, connect the negative (-) jumper cable to the negative (-) grounding point for the discharged battery.
6. Check. Ensure that the booster cables are away from any moving parts and that the clamps have good metal-to-metal contact with the battery terminals and charging points.
7. Start the car of the donation vehicle. Take the vehicle with the good battery and start the car.
8. Get the EV started. Finally, try to start the EV with the dead battery.

Read Hardesty’s full article for additional tips, including how to remove the jumper cables.