Charge EV with an Extension Cord? (6 Must-Know Facts!)
Electric cars are mainstream vehicles, and the batteries take you further. But a significant barrier in many people’s minds to moving to an EV is the need for a home charging station.
Do you need a purpose-built charging station, or can you hook your electric car to a conventional outlet with an extension cord?
1. Not All Extension Cords Are Equal to the Job
An extension cord, extension lead, or granny cable is a length of wire encased in rubber or plastic with a plug at one end and one or more sockets (outlets) at the other.
These useful power cords allow you to plug in devices where you can’t plug directly into an outlet or need more outlets than available with your home’s current wiring.
Extension cords are helpful, most homes have a couple, but there are risks with their use. Most fire departments recommend that extension cords be a short-term rather than a long-term solution.
If your charging cable doesn’t reach the outlet, you may want to wheel out an extension cord to bridge that gap. You use an extension cord to move the power to your chosen device rather than trying to get your device to the outlet.
An EV is no different; you want to hook the charging cable to the outlet, and the cord on your charger is too short.
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. Can You Use a Domestic Multi-Socket Extension Cord?
The short answer is no; these cords aren’t suitable for carrying the power load for the time necessary to charge your EV.
These are a fire risk as the components are at risk of overheating.
In an emergency where you are at a friend’s house without access to your standard power cables, you may want to risk it to get enough power into your vehicle to get it to a recognized charging station.
It is not a safe option, and if for whatever reason you feel it is necessary, then take precautions:
- Aim to charge the vehicle for the minimum time – an hour gives you approximately 8 miles, but the exact range depends on your car.
- Keep checking the plugs and sockets; switch off the power and disconnect if they get too hot.
- Use a circuit breaker as part of the setup if possible.
Ideally, travel with a suitable heavy-duty extension cord suitable for the job along with the charging cable, and you’ll never find yourself in the position of risking an unsafe option for charging.
If you find yourself stuck and reaching for the domestic extension cable, you may want to consider the option of breakdown recovery to take you to the nearest charging station.
3. What About Outdoor Use?
When you invest in a heavy-duty extension cord suitable for charging your EV, consider how you will use it.
Even if you usually charge your electric car in a dry, clean garage, there will be occasions when you need to charge your car outside.
It makes sense to get a robust extension cord suitable for outdoor use, and you can use an outdoor cable inside, but the opposite does not apply.
The heavy-duty outdoor extension cord may serve double duty for running garden equipment and power tools. But you may want a dedicated cable for specific car use.
If you use your extension cord for other purposes, remember to store it in the trunk so you don’t reach for the extension cord hanging in the shed or garage.
4. Other Safety Tips?
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.
5. What Is the Best Length Extension Cord for an EV?
Ideally, you don’t use an extension cord but plug the charging cable directly into the specialist outlet.
For emergency use, you need to assess the most helpful length for your needs and then match the gauge to give you the appropriate capability.
Longer cables need a lower gauge.
When will you use an extension cable?
How far away will your EV be from the nearest outlet?
If you regularly use a cabin in the woods and need a 150-foot cable to reach your vehicle, that is the best length for your needs.
A smaller extension cord is your best emergency option if you never park more than fifty feet from an outlet.
6. Do You Need an Extension Cord for Your EV?
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.
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.
