Can you charge an electric car with an extension cord？

It is well known that electric vehicles are very popular and widely used in the market. However, in some cases where there is no charging pile or it is inconvenient, we need to use an extension cord. But is it safe to use an extension cord?

1. The Potential Dangers of Using An Extension Cord to Charge Your EV

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.

2. Extension Cord Safety

Can you use an extension cord for your EV charger?

If charging an EV on a domestic outlet is dangerous, it goes without saying that adding an extension cord—or several—into the mix makes things even riskier.

Charging your EV with an extension cord is dangerous

EV charging requires far more power than your other standard household appliances, and most domestic extension cords are simply not designed to transfer that much power. Not only are they more likely to give you an electric shock, but they can also increase the risk of electrical fires.

Therefore, we never recommend using extension cords to charge your EV.

2.1 How To Choose Extension Cord

Extension cords come in different capacities depending on the gauge and the length.

A lower gauge means bigger wires and can handle higher watts and amps, and a longer length means handling lower watts and amps.

Deciding if your extension cord is up to running your EV charging depends on if your extension cord can handle the amps without overheating and causing a fire.

Your extension cord must handle a minimum of 13 amps to be suitable for your EV; when in doubt, go for a heavier-duty cord.

At 13 Amps, the charging is slow, so depending on your electric car, you may opt for 16 Amps or more. Your extension cord has a label specifying its capabilities.

Up to 50 feet, you need 14 AWG (Medium), 12 AWG (heavy duty), or 10 AWG (extra heavy duty) cords. Up to 100 feet, you can use 12AWG or 10AWG, but at 150 feet, only the extra heavy-duty (10AWG) extension cord is suitable.

If you need an extension cord to charge your EV, check the manufacturer’s recommendations and invest in the one most appropriate to the role rather than reaching for the nearest one at home.

2.2 Using extension cords 

The attraction of an electric car is that you can choose where to charge it to take advantage of cheap power overnight.

When you drive a petrol or diesel vehicle, keep an eye on the fuel gauge to ensure that you can fill up before getting stranded.

An electric car isn’t that different; you keep an eye on the power levels to ensure you have enough juice to complete your journey or fit in a charging stop.

However, an electric car gives you the ability to turn any outlet into a charging station. Using a specialist setup for fast, efficient charging is better, but you have more options.

If you carry a spare tire, a warning triangle, and other emergency supplies to keep you motoring, then a specialist extension cord is a helpful emergency kit.

It is better to have it and never use it than to find yourself in difficulties with limited options.

2.3 Caring for extension cords 

Most electric car manufacturers do not recommend extension cords because they can’t guarantee the quality of another company’s product.

The significant concern is starting a fire if the extension cord suffers from overload with the prolonged demand of overnight charging.

If you use an appropriately rated extension cord:

Fully Uncoil the Cord

It is handy to have the extension cord neatly stored in a reel; maybe you don’t need the entire length.

A coiled cord doesn’t let heat escape and increases the fire risk.

Check for Damage Before Use

When you uncoil the cord (before you connect to power), check the cable for signs of melting, breaks, and other wear or tear.

Replace a damaged extension cord, and don’t (unless you are a qualified electrician) attempt a repair.

Don’t Set Up for Permanent Use

You may think to leave your extension cord plugged in and ready for use. You may consider running it under the carpet or pinning it to the wall to avoid a trip hazard is an excellent idea.

An extension cord is not a substitute for a hard-wired solution, and the extension cord is an emergency backup for your usual charging facilities.

Putting the extension cord under the carpet means the heat can’t escape.

Pinning it to the wall risks damage to the cable and the potential for a shock when touched.

Don’t Daisy Chain

Buy an appropriate length of the extension cord.

When you link extension cords together to create the length, you reduce the effectiveness of the cable and increase the safety risks.

The entire setup depends on the weakest link.

Stay Cool

Check your extension cord every hour to ensure that it isn’t overheating.

If you can’t touch the back of your hand to the plug, it is too hot, and you need to switch the power off.

Don’t Use Overnight

Using the extension cord to charge your EV is an emergency last resort, and you need to monitor it for excess heat.

You can’t watch your extension cord if you and your family are asleep.

The continuous current passing through your extension cord may overload it, so restrict usage to about an hour to put some miles in your battery.

Use an Appropriate Outlet

Although you can use a domestic outlet, the charging speed is low.

The best results come from pairing a 16-amp extension cord with a 16-amp outlet installed by a qualified electrician.

If you get an electrician to install an outlet, it makes sense to ditch the extension cable and have the outlet installed in a convenient location for the EV.

3. Conclusion  

You can use an extension cord to charge your electric car, but a dedicated charging station is better.

The extension cord is for emergency use; ideally, you plan to recharge without using it.

You can think of the extension cord as the equivalent of the fuel can. You use it to get sufficient battery power to drive your car to a service station, but most drivers plan their journeys to avoid using it.