Estimate only. Most EVs slow down charging as the battery gets close to full, and cold batteries charge more slowly.
How the time is calculated
- Energy into the battery: usable battery size × (the level you want − the level now).
- Energy from the outlet: that energy ÷ the charging efficiency, since some energy is lost as heat. Charging efficiency is often 84% to 93% (fueleconomy.gov).
- Charging time: energy from the outlet ÷ charging power.
- Range added: energy from the outlet ÷ your EV's kWh per 100 miles from its EPA label.
Level 1 vs Level 2
| Level 1 | Level 2 | |
|---|---|---|
| Outlet | 120 V | 240 V at home (208 V in many commercial buildings) |
| Typical power | about 1.9 kW | up to 7.2 kW for most home chargers (30 A) |
| Range per hour | about 5 miles | about 25 miles |
Values from the Department of Energy's Alternative Fuels Data Center (AFDC). Level 1 uses the cord that comes with most EVs; Level 2 needs a charger on a dedicated 240 V circuit. To size that circuit, use the EV charger amperage calculator.
Your car's onboard charger also limits Level 2 speed: if it accepts 7.2 kW, a faster wall charger will not charge it faster.