Amps are the number most home charger specifications lead with, but the question that matters is how many amps your household actually needs. The answer depends on how much energy you add each day and how long the car stays parked. A charger with more amps is not always better, because the circuit, the vehicle, and your schedule all set practical limits.
Amps, kilowatts, and the circuit
Charging power is voltage times current. On a 240-volt home circuit, each amp delivers about 240 watts, so a 40-amp charger delivers 9.6 kilowatts. The circuit feeding the charger must be larger than the charger's rating. Because a continuous load may use at most 80% of the breaker rating, the breaker has to be sized up.
| Charger output | Power at 240 volts | Typical breaker |
|---|---|---|
| 16 amps | about 3.8 kW | 20 amps |
| 32 amps | about 7.7 kW | 40 amps |
| 40 amps | 9.6 kW | 50 amps |
| 48 amps | 11.5 kW | 60 amps, hardwired |
Estimate your daily energy need
A simple way to size the charger is to start with energy. Multiply your average daily driving distance by the energy your vehicle uses per mile, then compare that with the hours the car is parked at home. Many EV owners use roughly 0.3 kWh per mile as a starting estimate, but check your vehicle's own figure.
For example, if you drive 40 miles a day, you need about 12 kWh each day. A 16-amp charger at about 3.8 kW adds that energy in around 3 to 4 hours. A 40-amp charger at 9.6 kW does it in about 1.25 hours. If the car is parked for 10 hours overnight, the smaller unit already covers the need, and the larger one only finishes sooner.
Limits that cap the useful amps
Your vehicle has an onboard charger that converts AC power for the battery, and it sets a maximum AC charging rate. A charger rated higher than that limit will not speed up charging for that car. Your panel's capacity and existing breakers also limit what you can install without upgrades.
When more amps make sense
Higher amps are worth considering if you have a large battery, plan to charge more than one vehicle, need a full charge in a short window, or want room for a future car with a higher onboard charger. In those cases, sizing the circuit for the higher rating now can save a later upgrade.
How this applies to EVIQO chargers
EVIQO offers chargers rated at 40 amps (9.6 kW) and 48 amps (11.5 kW), all running on 240 volts. A 40A (9.6 kW) plug-in NEMA 14-50 model is available, and a 48A (11.5 kW) hardwired model is available as well. One listed model can be installed as either a 40A plug-in or a 48A hardwired unit. Each charger comes with a 25 ft cable and a 3-year warranty.