Charging an EV? Don’t Use an Extension Cord

By Chantel Wakefield 09/28/2023 3:08pm

Extension cords

Quick Facts About EV Charging and Extension Cords

  • Charging an electric vehicle (EV) requires more electricity than the amount common home appliances need. 
  • EV charging draws a large amount of power; an extension cord may overheat if connected to the charging cable.
  • Another safety risk is electric shock.

Many electric vehicle manufacturers provide a Level 1 charging cord when you buy an EV or a plug-in hybrid (PHEV). These “trickle chargers” don’t require special equipment to use and connect to a standard 120-volt electrical outlet at home or elsewhere. The cable length can range from six to 20 feet or more depending on vehicle make and model.

If that charging cable isn’t long enough to plug into a nearby outlet, you may be tempted to use an extension cord. Here’s why you shouldn’t.

Why You Shouldn’t Charge an EV With an Extension Cord

Is it safe to charge using an extension cord? Carmakers say no, and we don’t recommend using one. Charging an electric car requires more electricity than the amount common home appliances need. Therefore, electric car chargers contain thicker wires that can handle more power than smaller gauge wires in typical extension cords.

“While some electric car owners have reported using a typical extension cord, we don’t recommend it,” says Kelley Blue Book Executive Editor Brian Moody. “In fact, Kia and other automakers specifically say not to use an extension cord in the owner’s manual. An electric car pulls more power than a typical home appliance, and using a typical extension cord when charging can harm your home and car.”

Owner manuals are explicit with warnings, such as this one from Chevy to Bolt owners: “Do not use extension cords, multi-outlet power strips, splitters, grounding adaptors, surge protectors, or similar devices.”

A Level 1 cable offers a slower “trickle” charge and supplies a few miles of range per hour, which is suitable for many PHEV owners. Pairing an extension cord with the charger restricts the voltage transfer. This setup will take even longer to boost your battery, in addition to creating safety concerns.

Dangers of Using an Extension Cord to Charge

So what happens if you charge with an extension cord? Since charging an electric vehicle draws a large amount of power, an extension cord may overheat if you connect it to the charging cable. The chance of fire increases because the extension cord attempts to transmit more energy than it was made to carry. Overheating cords can melt plugs and receptacles, and the fire danger is greater when left unattended overnight or while you’re not home.

Another safety risk is electric shock. An EV charging cable is more volatile when connected to an extension cord. Rerouting the power supply from your electrical outlet through an extension compromises the stability of this power transfer. Inserting and removing the plug then becomes a riskier task.

Types of EV charging station and how fast it will charge an electric car.

How to Properly Connect a Level 1 Charger

Consult a licensed electrician if you’ll be connecting an EV or PHEV to a Level 1 charging cable for long-term, at-home charging. An electric vehicle supply equipment (EVSE) professional can ensure you have a dedicated circuit to support the power load.

  • Turn off your EV before every charging session.
  • Insert the charging cable into a 120-volt AC receptacle.
  • Open the EV’s charging port door and connect the charger.
  • Charging should begin when the cord is connected.
  • Disconnect the charger from the vehicle when the charging session is finished.
  • Coil the Level 1 charging cable neatly to protect it from damage.
  • Store the cord in your vehicle for potential use away from home.