*Calculation assumes 90% efficiency for Level 2 and adjusts for charging curves.
Understanding Electric Vehicle Charging Times
Switching to an electric vehicle (EV) involves a shift in how you "refuel." Unlike a gas station visit that takes five minutes, EV charging depends on your battery size, current state of charge, and the power delivery of the charging station. This calculator helps you estimate exactly how long you'll be plugged in to reach your desired range.
How the EV Charging Time is Calculated
The fundamental formula for charging time is relatively straightforward, though real-world variables like temperature and charging curves can influence the final result. The core math is:
Time (hours) = (Energy Needed in kWh) / (Charger Power in kW)
To get the Energy Needed, we take your battery's total capacity (e.g., 75 kWh) and multiply it by the difference between your target percentage and current percentage. If you are at 20% and want to reach 80%, you need to add 60% of your battery's capacity.
Key Factors Affecting Your Charging Speed
Onboard Charger Limit: Your car has an internal limit. If your car's onboard charger is capped at 7.2 kW, plugging into a 22 kW AC station will still only charge at 7.2 kW.
Charging Curve: DC Fast Chargers slow down significantly once the battery reaches 80% to protect battery health. This is why we often calculate the "80% charge" time.
Ambient Temperature: Extremely cold or hot weather can slow down the chemical processes in the battery, leading to longer charging sessions.
Efficiency Loss: Approximately 10-15% of energy is lost as heat during the conversion from AC (wall power) to DC (battery storage).
Common EV Battery Sizes Reference
Vehicle Model
Typical Battery Size
Common Charger Type
Tesla Model 3 (Long Range)
75 – 82 kWh
Level 2 or Supercharger
Nissan Leaf
40 – 62 kWh
Level 2 or CHAdeMO
Hyundai IONIQ 5
58 – 77.4 kWh
Ultra-Fast DC
Plug-in Hybrids (PHEV)
10 – 18 kWh
Level 1 or Level 2
Example Calculation
Imagine you own a 60 kWh battery EV. You arrive home with 20% charge and want to charge it to 100% overnight using an 11 kW home wallbox.
Energy required: 80% of 60 kWh = 48 kWh.
Adding 10% for efficiency losses: 48 * 1.1 = 52.8 kWh required from the grid.
Time: 52.8 kWh / 11 kW = 4.8 Hours.
function calculateEVTime() {
var batterySize = parseFloat(document.getElementById('evBatterySize').value);
var currentCharge = parseFloat(document.getElementById('evCurrentCharge').value);
var targetCharge = parseFloat(document.getElementById('evTargetCharge').value);
var chargePower = parseFloat(document.getElementById('evChargerPower').value);
var resultDiv = document.getElementById('ev-result-display');
var resultText = document.getElementById('evFinalResult');
if (isNaN(batterySize) || isNaN(currentCharge) || isNaN(targetCharge) || isNaN(chargePower) || chargePower = targetCharge) {
alert("Target charge must be higher than current charge.");
return;
}
if (currentCharge 100) {
alert("Percentage values must be between 0 and 100.");
return;
}
// Calculation Logic
// Energy needed in kWh
var percentageToFill = (targetCharge – currentCharge) / 100;
var energyNeededKWh = batterySize * percentageToFill;
// Account for efficiency (AC charging is usually ~90% efficient, DC is higher but has curves)
// We'll use a standard 90% factor for a realistic estimate
var efficiency = 0.9;
var actualEnergyRequired = energyNeededKWh / efficiency;
// Time in hours
var timeInHours = actualEnergyRequired / chargePower;
// Convert to hours and minutes
var hours = Math.floor(timeInHours);
var minutes = Math.round((timeInHours – hours) * 60);
// Format output
var outputString = "";
if (hours > 0) {
outputString += hours + " hr ";
}
outputString += minutes + " min";
resultText.innerHTML = outputString;
resultDiv.style.display = "block";
}