HomeExplainedLevel 2 charging time for common battery sizes
Level 2 charging time for common battery sizes
At the 11.5 kW AC limit, taking a 75 kWh battery from 20 to 80 % takes about 4 h 21 min at 90 % charging efficiency: 45 kWh into the battery, 50 kWh from the grid. On a 32 A (7.68 kW) charger the same job takes 6 h 31 min.
The arithmetic
Charging time on AC comes down to three numbers: how much energy has to go into the battery, how much is lost on the way, and how much power reaches the car. The energy into the battery is the usable capacity times the share being added: 75 kWh from 20 to 80 % is 45 kWh. Dividing by the charging efficiency gives the energy drawn from the grid; at 90 % that is 50 kWh. Dividing again by the power gives the time.
The power is the lower of two ratings: the charger's rated output and the car's own AC charging limit. With an 11.52 kW charger and a car limited to 11.5 kW, the power is 11.5 kW, and the job takes 4 h 21 min.
Times at five ratings and five battery sizes
The first table runs the same 20 to 80 % job for five battery sizes at the five common ratings, with a car limit of 11.5 kW and 90 % efficiency. The columns for 48, 50 and 80 A are identical, because each of those chargers is rated above the car's limit.
| Battery | 32 A | 40 A | 48 A | 50 A | 80 A |
|---|---|---|---|---|---|
| 40 kWh | 3 h 28 min | 2 h 47 min | 2 h 19 min | 2 h 19 min | 2 h 19 min |
| 60 kWh | 5 h 13 min | 4 h 10 min | 3 h 29 min | 3 h 29 min | 3 h 29 min |
| 75 kWh | 6 h 31 min | 5 h 13 min | 4 h 21 min | 4 h 21 min | 4 h 21 min |
| 100 kWh | 8 h 41 min | 6 h 57 min | 5 h 48 min | 5 h 48 min | 5 h 48 min |
| 130 kWh | 11 h 17 min | 9 h 2 min | 7 h 32 min | 7 h 32 min | 7 h 32 min |
20 → 80 %, 90 % efficiency, car AC limit 11.5 kW, linear charging. Arithmetic, not measured times.
With a car that accepts the full 19.2 kW on AC, the higher ratings separate, as the second table shows.
| Battery | 32 A | 40 A | 48 A | 50 A | 80 A |
|---|---|---|---|---|---|
| 40 kWh | 3 h 28 min | 2 h 47 min | 2 h 19 min | 2 h 13 min | 1 h 23 min |
| 60 kWh | 5 h 13 min | 4 h 10 min | 3 h 28 min | 3 h 20 min | 2 h 5 min |
| 75 kWh | 6 h 31 min | 5 h 13 min | 4 h 20 min | 4 h 10 min | 2 h 36 min |
| 100 kWh | 8 h 41 min | 6 h 57 min | 5 h 47 min | 5 h 33 min | 3 h 28 min |
| 130 kWh | 11 h 17 min | 9 h 2 min | 7 h 31 min | 7 h 13 min | 4 h 31 min |
Same job with a car AC limit of 19.2 kW.
Energy into the battery and from the grid
Time is only half of the result. The energy drawn from the grid is larger than the energy stored in the battery, by the losses set by the efficiency figure. For a 20 to 80 % charge, the table below gives both for each battery size at three efficiency levels.
| Battery | Into the battery | From the grid at 85 % | From the grid at 90 % | From the grid at 95 % |
|---|---|---|---|---|
| 40 kWh | 24 kWh | 28.2 kWh | 26.7 kWh | 25.3 kWh |
| 60 kWh | 36 kWh | 42.4 kWh | 40 kWh | 37.9 kWh |
| 75 kWh | 45 kWh | 52.9 kWh | 50 kWh | 47.4 kWh |
| 100 kWh | 60 kWh | 70.6 kWh | 66.7 kWh | 63.2 kWh |
| 130 kWh | 78 kWh | 91.8 kWh | 86.7 kWh | 82.1 kWh |
20 → 80 %. Energy from the grid = energy into the battery ÷ efficiency.
The gap grows with the battery. At 90 % efficiency, a 40 kWh battery takes 26.7 kWh from the grid to store 24 kWh, and a 130 kWh battery takes 86.7 kWh to store 78 kWh. The ENERGY STAR file does not give a charging efficiency for cars, so the tool and these tables leave it as an assumption that can be changed.
Battery size moves the time in direct proportion. At the same 11.5 kW, the 40 kWh battery needs 2 h 19 min and the 130 kWh battery 7 h 32 min. A narrower charge window shortens it in the same way: 40 to 80 % of a 75 kWh battery takes 2 h 54 min.
Miles per hour of charging
Range added per hour is the power into the battery times the car's efficiency in miles per kWh. At 3.5 miles per kWh and 90 % charging efficiency, the five ratings give the figures below with an 11.5 kW car limit. Change either assumption in the tool and the figures move in proportion.
All the ratings in these tables assume 240 V, which is how 423 of the 424 Level 2 listings are rated; the remaining 1 is listed at 240.6 V. The tool takes each listing's kW figure as published, so picking a listed charger fills in exactly the rating on its ENERGY STAR record.
How much the assumptions matter
Efficiency moves the result less than the power limit does. For the same 75 kWh job at 11.5 kW, 85 % efficiency gives 4 h 36 min and 95 % gives 4 h 7 min. A car limited to 7.2 kW on AC turns the same job into 6 h 57 min, whatever the charger is rated.
Real charging is not perfectly linear: it slows near full, so a charge to 100 % takes longer than the straight-line figure. The tables use 20 to 80 % for that reason. The ENERGY STAR data does not include charging curves or measured times; it supplies only each charger's rating.
Level 1 and dual-input listings are rated much lower, mostly 1.44 to 1.92 kW at 120 V. At 1.92 kW the same 75 kWh job takes 26 h 3 min. Level 1, Level 2 and dual-input chargers compares the three groups.
Working out your own case
The charging-time tool runs this arithmetic for any battery, charge window, charger rating and car limit, and lets you change the efficiency and miles-per-kWh assumptions. It can fill in the rated output of any of the 461 listed chargers, and the address bar keeps the inputs so a result can be shared. The guide to amp ratings covers what the ratings themselves mean.
Sources
- U.S. EPA, ENERGY STAR Certified Electric Vehicle Supply Equipment (AC-Output), data.energystar.gov, as of October 27, 2026.
- Computed figures are defined on how to read the data.