Last updated: 2026-06-22

EV Charging Time

Electric vehicle charging time depends on three factors: how much energy the battery needs to absorb, how fast the charger can deliver it, and how efficiently the system converts grid power into stored charge.

The Formula

Where $C$ is battery capacity (kWh), $\text{SoC}_1 - \text{SoC}_0$ is the state-of-charge range to cover, $P$ is charger power (kW), and $\eta$ is charging efficiency.

Worked Example

A vehicle with a 75 kWh battery is at 15% and needs to reach 80% before a trip. The driver uses a 11 kW home charger with 91% charging efficiency.

• Energy to add: $75 \times (0.80 - 0.15) = 75 \times 0.65 = 48.75\ \text{kWh}$
• Effective charging rate: $11 \times 0.91 = 10.01\ \text{kW}$
• Charging time: $48.75 \div 10.01 \approx 4.87\ \text{h}$ (about 4 hours 52 minutes)

Charger Levels

The effective power is the lower of the charger output and the vehicle's on-board charger acceptance rate. A 22 kW public AC charger connected to a vehicle limited to 7.4 kW AC will only deliver 7.4 kW.

Charging Efficiency

Energy is lost as heat in the charger electronics and the battery itself during acceptance. AC Level 2 charging typically runs at 88–92% efficiency. DC fast charging efficiency varies more widely with battery temperature and the vehicle's thermal management system.

SoC Recommendations

Lithium-ion cells degrade more quickly when held near full charge. Most manufacturers recommend routine charging to 80% and using 100% only before trips where range is needed. The 20–80% range also covers the region where charging rates are highest; above 80% most vehicles taper power to protect the battery.

Related Calculators

• EV Charging Cost Calculator — find the electricity cost for the same charging session
• Electricity Cost Calculator — estimate running cost for any electrical device
• Fuel Cost Calculator — compare EV charging with fuel costs for conventional vehicles