How Many amps Does a Home EV Charger Use?
The power demands of EV charging stations are often misunderstood, leaving consumers unsure how many amps they actually need for home charging.
This article provides a comprehensive look at EV charger amperage to help consumers make informed decisions when installing home charging stations.
EV Charging Basics
There are three main levels of EV charging:
- Level 1 uses a standard 120V household outlet and provides about 2-5 miles of range per hour of charging. This is the slowest charging option but requires no additional hardware other than the cordset that comes with the EV.
- Level 2 uses a 240V circuit and provides 10-20 miles of range per hour of charging. This requires installing a dedicated 240V circuit and charging station.
- DC Fast Charging uses 480V or higher power and can provide 60-200 miles of range in 15-30 minutes. This requires specialized commercial charging stations and is not available for home installation.
For home charging, Level 2 is the “sweet spot” that offers faster charging times while remaining practical for most residential electrical systems. But to install a Level 2 charger, it’s important to understand how many amps your EV and home electrical system can handle.
EV Charging Power Ratings
EV chargers are rated by the maximum power they can deliver, measured in kilowatts (kW) or amps. For example:
- A charger rated for 7.2 kW delivers up to 30 amps (7.2 kW ÷ 240 volts = 30 amps).
- A charger rated for 9.6 kW delivers up to 40 amps.
So when you see amperage or kilowatts listed for an EV charger, it refers to the maximum power it can provide. This determines how quickly it can charge your vehicle.
How Fast Can My EV Charge?
The speed of an EV charger is limited by two factors:
- The onboard charger in the vehicle
- The amperage of the electrical circuit
Onboard Charger: All EVs have an onboard charger that converts AC electricity from the charging station to DC to charge the battery. This charger has a maximum amperage it can handle, usually ranging from 10-20 amps for most models.
Electrical Circuit: The circuit breaker and wiring that supplies power to the charger must be rated high enough to deliver the needed amps without overheating. For a Level 2 charger, a 40 amp or 50 amp circuit is typical.
The lower of these two ratings limits the maximum charging speed. For example, if your EV’s onboard charger is rated at 16 amps but your home circuit can only deliver 40 amps, the maximum charge rate will be 16 amps. Upgrading to a 50 amp circuit won’t make charging any faster in this case.
How Many Amps Does My EV Charger Need?
With those basics in mind, follow these steps to determine the optimal amp rating for your home EV charger:
- Check your EV’s specs: The owner’s manual or manufacturer website will list the maximum amps the onboard charger can accept. This is the critical starting point.
- Understand your daily driving needs: If you drive less than 40 miles per day, a lower amperage may suffice since you have all night to recharge. If you drive more, you may want a faster charger.
- Consult an electrician: Have an electrician evaluate your electrical service panel and determine if it can support the installation of a high amperage circuit for an EV charger. A load calculation is recommended.
- Compare charger costs: Higher amperage chargers and circuits will cost more. Make sure to get quotes for both equipment and installation costs.
- Consider future needs: If you plan to purchase additional EVs, install the highest amp circuit you can now for two chargers later.
Here are some guidelines based on onboard charger ratings:
- 10-16 amps: Level 2 charger should be rated for 16-20 amps minimum.
- 20 amps: 32 amp Level 2 charger is ideal.
- 30+ amps: Install a 40 amp or greater circuit with appropriate charger.
Always follow manufacturer recommendations and check with an electrician regarding your home’s electrical capacity. Installing a lower amperage circuit and charger now provides flexibility to upgrade later as needed.
Charging Speed Comparisons
To help visualize the impact of charger amp ratings, here are some examples of Level 2 charging speeds for different EVs:
| EV Model | Onboard Charger (amps) | Miles of Range Per Hour |
|---|---|---|
| Nissan Leaf (early model) | 16 | ~10 miles |
| Tesla Model 3 | 32 | ~25 miles |
| Ford Mustang Mach E | 48 | ~35 miles |
As you can see, a higher amperage correlates with more range recovered per hour of charging. However, for many consumers, 10-20 miles per hour overnight is sufficient to meet daily driving needs. Installing the maximum amperage may be overkill if you don’t require the fastest charging times.
Key Considerations for Home EV Chargers
- For most EVs, a 32 amp Level 2 charger provides a good balance of charging speed and installation cost. But always double check your vehicle specs first.
- If your home electrical service must be upgraded to install an EV charger, a higher amperage may be worthwhile for future expansion.
- Outdoor chargers may need to be hardwired instead of plug-in to meet electrical codes. This can increase installation costs.
- Consider a smart charger that can adjust charging speed based on your electric rate plan, if offered by your utility. This provides cost savings when rates are lower overnight.
Conclusion
Determining the optimal amp rating for a home EV charger involves checking your EV’s charging capacity, home electrical system limitations, and daily driving needs. While faster charging is appealing, in many cases a lower amperage Level 2 charger in the 16-32 amp range is sufficient and more affordable. Consult with both automaker specs and an electrician to make the right choice for your unique situation. Careful planning and smart charging habits ensure your EV is charged and ready to roll whenever needed.