Charging an EV? Do not use an extension cord

Many electric vehicle manufacturers provide a Level 1 charging cord when you purchase an electric vehicle or plug-in hybrid (PHEV). These “trickle chargers” do not require any special equipment to be used and connected to a standard 120 volt electrical outlet at home or elsewhere. Cable length can vary from 6 feet 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 might be tempted to use an extension cord. Here’s why you shouldn’t.

Why you shouldn’t charge an electric vehicle with an extension cord

Charging an electric vehicle requires more electricity than is needed for common household appliances. Therefore, EV chargers contain thicker wires that can handle more power than the smaller gauge wires in typical extension cords.

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

Owner’s manuals are explicit with their warnings, like this one from Chevy owners at Bolt: “Do not use extension cords, power strips, splitters, grounding adapters, surge protectors or appliances similar.”

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

Dangers of using an extension cord to charge

Since charging an electric vehicle consumes a large amount of energy, an extension cord can overheat if you connect it to the charging cable. The risk of fire increases because the extension cord attempts to transmit more energy than it was designed to carry. Overheating cords can melt plugs and outlets, and the danger of fire is greatest when left unattended overnight or when you’re away from home.

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

How to Properly Connect a Level 1 Charger

Consult a licensed electrician if you plan to connect an EV or PHEV to a Level 1 charging cable for long-term home charging. An electric vehicle power equipment (EVSE) professional can ensure that you have a dedicated circuit to support the electrical load.

  • Switch off your EV before each charging session.
  • Insert the charging cable into a 120 volt AC outlet.
  • Open the electric vehicle charging port door and connect the charger.
  • Charging should begin when the cord is connected.
  • Unplug the charger from the vehicle when the charging session is complete.
  • Carefully coil the Level 1 charging cable to protect it from damage.
  • Store the cord in your vehicle for potential use away from home.

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