EV Charging Cost & Time Calculator
Estimate the cost and time required to charge your electric vehicle based on its battery capacity, current charge, desired charge, charger power, and local electricity rates.
Understanding EV Charging
Electric Vehicle (EV) charging involves replenishing the energy stored in your car's battery. Unlike gasoline cars, EVs are "fueled" by electricity, and the process can vary significantly in terms of time and cost depending on several factors. This calculator helps you estimate these key metrics for your specific situation.
Key Factors Affecting Charging:
- EV Battery Capacity (kWh): This is the total energy your car's battery can hold. A larger battery (e.g., 100 kWh) will take longer to charge and cost more than a smaller one (e.g., 40 kWh) to fill from the same percentage.
- Current vs. Desired State of Charge (SoC): You rarely charge from 0% to 100%. The calculator considers the specific range you need to charge (e.g., from 20% to 80%).
- Charger Power (kW): This is the rate at which energy is delivered to your car.
- Level 1 (120V AC): Typically 1.4 – 2.4 kW. Very slow, often used for overnight trickle charging.
- Level 2 (240V AC): Typically 3.3 – 19.2 kW. Common for home installations and public chargers. A 7.2 kW charger is a popular home setup.
- DC Fast Charging (DCFC): Typically 50 kW to 350+ kW. The fastest option, found at public charging stations, but often more expensive per kWh.
- Electricity Cost ($/kWh): This is your local utility rate for electricity. It can vary significantly by region, time of day (time-of-use rates), and utility provider.
- Charging Efficiency (%): Not all electricity drawn from the grid makes it into your car's battery. Some energy is lost as heat during the conversion process (AC to DC) and within the battery itself. Typical efficiencies range from 85% to 95%.
How the Calculator Works:
The calculator uses the following steps to provide your estimates:
- Calculate Usable Energy Needed: It first determines how many kilowatt-hours (kWh) are needed to go from your current SoC to your desired SoC, based on your battery's total capacity.
- Account for Charging Efficiency: It then adjusts this needed energy to account for the energy lost during the charging process, giving you the total energy that will be drawn from the grid.
- Estimate Charging Cost: This total grid energy is multiplied by your electricity cost per kWh to give you the total charging cost.
- Estimate Charging Time: The total grid energy is divided by the charger's power (kW) to determine the approximate time required for charging.
Example Scenario:
Let's say you have an EV with a 60 kWh battery. You're currently at 20% charge and want to reach 80%. You're using a 7.2 kW Level 2 home charger, and your electricity costs $0.15 per kWh. Assuming a 90% charging efficiency:
- Energy Needed (usable): 60 kWh * (80% – 20%) = 36 kWh
- Energy Drawn from Grid: 36 kWh / 0.90 (efficiency) = 40 kWh
- Total Charging Cost: 40 kWh * $0.15/kWh = $6.00
- Total Charging Time: 40 kWh / 7.2 kW = approximately 5.56 hours
This calculator provides a useful estimate for planning your EV charging habits and understanding the associated costs and time commitments.
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function calculateEVCharge() {
var batteryCapacity = parseFloat(document.getElementById('batteryCapacity').value);
var currentSoC = parseFloat(document.getElementById('currentSoC').value);
var desiredSoC = parseFloat(document.getElementById('desiredSoC').value);
var chargerPower = parseFloat(document.getElementById('chargerPower').value);
var electricityCost = parseFloat(document.getElementById('electricityCost').value);
var chargingEfficiency = parseFloat(document.getElementById('chargingEfficiency').value);
var resultDiv = document.getElementById('result');
resultDiv.innerHTML = "; // Clear previous results
// Input validation
if (isNaN(batteryCapacity) || batteryCapacity <= 0) {
resultDiv.innerHTML = 'Please enter a valid EV Battery Capacity (kWh).';
return;
}
if (isNaN(currentSoC) || currentSoC 100) {
resultDiv.innerHTML = 'Please enter a valid Current Battery State of Charge (0-100%).';
return;
}
if (isNaN(desiredSoC) || desiredSoC 100) {
resultDiv.innerHTML = 'Please enter a valid Desired Battery State of Charge (0-100%).';
return;
}
if (desiredSoC <= currentSoC) {
resultDiv.innerHTML = 'Desired State of Charge must be greater than Current State of Charge.';
return;
}
if (isNaN(chargerPower) || chargerPower <= 0) {
resultDiv.innerHTML = 'Please enter a valid Charger Power (kW).';
return;
}
if (isNaN(electricityCost) || electricityCost < 0) {
resultDiv.innerHTML = 'Please enter a valid Electricity Cost ($/kWh).';
return;
}
if (isNaN(chargingEfficiency) || chargingEfficiency 100) {
resultDiv.innerHTML = 'Please enter a valid Charging Efficiency (1-100%).';
return;
}
// Calculations
var chargePercentageNeeded = (desiredSoC – currentSoC) / 100;
var usableEnergyNeededKWh = batteryCapacity * chargePercentageNeeded;
var actualEnergyDrawnKWh = usableEnergyNeededKWh / (chargingEfficiency / 100);
var totalChargingCost = actualEnergyDrawnKWh * electricityCost;
var chargingTimeHours = actualEnergyDrawnKWh / chargerPower;
// Display results
resultDiv.innerHTML =
'
Charging Estimate:
' +
'
Energy Needed (Usable): ' + usableEnergyNeededKWh.toFixed(2) + ' kWh' +
'
Energy Drawn from Grid: ' + actualEnergyDrawnKWh.toFixed(2) + ' kWh' +
'
Estimated Total Cost: $' + totalChargingCost.toFixed(2) + " +
'
Estimated Charging Time: ' + chargingTimeHours.toFixed(2) + ' hours';
}