Level 1 · Level 2 · DC fast charging
EV charging calculator
How long will it take, and what will it cost? Work out one charge from any level to any level, or switch to the road trip tab to count the charging stops for a drive.
How the estimate works
The battery takes in its usable size times the change in charge. Some energy turns to heat on the way in, so you pay for a little more than it stores; the losses figure is an estimate you can change. Time is the energy drawn divided by the charging power: the charger's power or your car's maximum, whichever is lower.
Fast charging slows as the battery fills, often markedly from about 80%. Here DC power falls in a straight line from the level you choose to a share of full power at 100%, a rough estimate to adjust for your car. AC charging is treated as steady.
The presets follow the US Department of Energy: Level 1 (120 V) at about 1.9 kW, Level 2 at up to 7.2 kW for most home units, and DC fast charging at up to 500 kW. Trip mode drives down to your reserve, charges to your chosen level and repeats; the last stop adds only what you need.
Sources
- US Department of Energy, Alternative Fuels Data Center: Electric Vehicle Charging Stations (Level 1 at 120 V, about 1.9 kW; Level 2 from 2.9 to 19.2 kW, most home units 7.2 kW; DC fast charging up to 500 kW; power varies by vehicle and battery state of charge).
- US Department of Energy, Vehicle Technologies Office, Fact #919 (4 April 2016), Plug-in Electric Vehicle Charging Options and Times Vary Considerably: charging slows considerably once a battery reaches about 80% (archived copy).
- Charging losses and the shape of the slow-down are estimates, not published constants; adjust them for your car.
- Mile: exactly 1.609344 km, from NIST Special Publication 811, Appendix B.8.
Questions
Why stop at 80% on a road trip?
The last part of a fast charge is the slowest. Driving on at about 80% and charging again later often gets you there sooner than waiting for 100%, though it can mean an extra stop.
What are charging losses?
Energy lost as heat between the plug and the battery, so you pay for more than the battery stores. It varies with the car, the charger and the weather; 10% is a starting estimate, not a measurement.
Why does my car charge slower than the charger's rating?
Your car may accept less than the charger offers, and a cold or nearly full battery charges more slowly. Enter your car's maximum charging power if you know it.