Electric Vehicles
AC Charging Time Calculator
Estimate AC charging duration between two displayed charge levels. The vehicle may reduce power near full charge or because of battery temperature.
Enter one vehicle measurement set
Keep units and reference points consistent before comparing the output with a specification or earlier measurement.
Scope of the calculation
Estimate AC charging duration between two displayed charge levels — temperature, control limits, and conversion losses can separate a calculated value from a dashboard estimate.
The vehicle may reduce power near full charge or because of battery temperature — that condition defines when estimated charging time is comparable with another result.
Control software, temperature, wiring loss, battery condition, and equipment limits can alter the measured electrical result — for starting state of charge, the page specifically expects battery percentage at connection.
Collecting compatible values
Usable battery capacity is defined here as usable battery energy at 100 percent displayed charge — keeping that definition intact requires you to keep the percentage basis explicit and do not mix a decimal fraction with a percent value.
For Starting state of charge, use the quantity described as battery percentage at connection — in the vehicle record, keep the percentage basis explicit and do not mix a decimal fraction with a percent value.
Document Target state of charge as desired battery percentage — this means you should keep the percentage basis explicit and do not mix a decimal fraction with a percent value.
AC charging power. Power delivered by the charger before losses — for this measurement, identify whether the reading is taken at the source, charger, battery, or accessory.
Document Charging efficiency as share of wall energy stored in the battery — this means you should keep the percentage basis explicit and do not mix a decimal fraction with a percent value.
Build another useful comparison to estimate available single-phase charging power from circuit voltage and continuous current with the Home EV Circuit Power.
Formula used on this page
In “time = battery energy added ÷ (charger power × efficiency),” the relationship answers the question stated above without adding an unstated correction factor.
No term beyond usable battery capacity, starting state of charge, target state of charge, ac charging power, and charging efficiency is introduced in “time = battery energy added ÷ (charger power × efficiency).”
Example using the displayed inputs
The sample vehicle case enters Usable battery capacity = 74 kWh, Starting state of charge = 20%, Target state of charge = 80%, AC charging power = 7.2 kW, and Charging efficiency = 90%.
That specific combination leads to Estimated charging time = 6.85 hr and Battery energy added = 44.40 kWh.
When the vehicle decision also requires you to estimate how a continuous HVAC load changes EV range at an average speed, calculate it independently with the EV Climate-Control Range Impact.
Interpreting the headline value
Estimated charging time answers “Estimate AC charging duration between two displayed charge levels.” The additional display, Battery energy added, is a different view of the same entered measurements.
Use the lower of vehicle and charger AC limits — when that condition changes, compare separate calculator runs instead of blending the inputs.
Because the vehicle may reduce power near full charge or because of battery temperature, a disagreement between estimated charging time and an outside reference should trigger a review of usable battery capacity and charging efficiency.
A related vehicle record may need to estimate battery and wall energy for a charging session, a relationship covered by the Charging Session Energy.
Collecting the data in practice
Identify the measurement point and allow the electrical system to reach the intended operating state before recording values — this workflow must also account for the fact that the vehicle may reduce power near full charge or because of battery temperature.
- Record Usable battery capacity as usable battery energy at 100 percent displayed charge — keep the percentage basis explicit and do not mix a decimal fraction with a percent value.
- Record Starting state of charge as battery percentage at connection — keep the percentage basis explicit and do not mix a decimal fraction with a percent value.
- Record Target state of charge as desired battery percentage — keep the percentage basis explicit and do not mix a decimal fraction with a percent value.
- Record AC charging power as power delivered by the charger before losses — identify whether the reading is taken at the source, charger, battery, or accessory.
- Record Charging efficiency as share of wall energy stored in the battery — keep the percentage basis explicit and do not mix a decimal fraction with a percent value.
If the next task is to compare time-based public charging with an energy-based rate, continue with the Per-Minute vs Per-kWh Charging.
Questions about the formula and inputs
What measurement source fits Usable battery capacity when it represents usable battery energy at 100 percent displayed charge?
Because usable battery capacity represents usable battery energy at 100 percent displayed charge, use a source tied to the exact vehicle, component, and operating period described by the other fields.
How does the warning “The vehicle may reduce power near full charge or because of battery temperature” affect Estimated charging time?
The condition “The vehicle may reduce power near full charge or because of battery temperature” is not corrected automatically by the numeric inputs, so create a separate ac charging time case when it changes.
What assumption is expressed by “time = battery energy added ÷ (charger power × efficiency)”?
In “time = battery energy added ÷ (charger power × efficiency),” usable battery capacity and starting state of charge are treated as parts of one vehicle case.
How narrowly is Starting state of charge defined by “Battery percentage at connection”?
The definition “Battery percentage at connection” excludes a similarly named rating or a measurement taken at another reference point.
Why does AC Charging Time note that use the lower of vehicle and charger AC limits?
Because use the lower of vehicle and charger AC limits, keep that condition consistent or calculate another case rather than expecting the formula to compensate for it.
When should Charging efficiency be collected again if it represents share of wall energy stored in the battery?
Collect charging efficiency again when a changed vehicle configuration, component, load, temperature, or operating procedure affects share of wall energy stored in the battery.