CalKit

EV Charging Time Calculator

Calculate EV charging time from battery capacity, SOC and charger power.

kWh
%
%
%
예상 충전 시간
31분

20% → 80% (60%p) · 100kW 충전기 · 효율 90% 기준

상세 결과

배터리에 들어가는 전력량46.4 kWh
전력망에서 사용하는 전력량51.6 kWh
실효 충전 출력90.0 kW
예상 충전 시간31분

충전기 출력별 소요 시간 비교

완속 7kW7시간 22분
급속 50kW1시간 2분
급속 100kW31분
초급속 200kW15분

결과 공유

실제 충전 시간이 더 걸릴 수 있는 이유

  • 급속 충전은 배터리 보호를 위해 약 80% 이상 구간에서 출력이 크게 제한됩니다(충전 커브 테이퍼링). 그래서 통상 급속은 80%까지만 충전하는 것이 권장됩니다.
  • 완속(AC) 충전은 차량 탑재 충전기(OBC, 보통 7~11kW) 한계까지만 받아들이므로 충전기 출력이 더 높아도 속도가 빨라지지 않습니다.
  • 겨울철 저온에서는 배터리 컨디셔닝 때문에 충전 속도와 효율이 모두 떨어집니다.

Overview

The EV Charging Time Calculator estimates how long it takes to charge an electric vehicle from battery capacity (kWh), current and target state of charge (SOC), and charger power (kW). It includes presets for 7/11kW AC, 50/100kW DC fast, and 200kW ultra-fast chargers, plus an adjustable charging efficiency (default 90%) to account for conversion losses.

Formula

Charging time (h) = Battery capacity (kWh) × (Target SOC% − Current SOC%) ÷ 100 ÷ (Charger power kW × Efficiency).

Example: a 77.4kWh battery from 20% to 80% on a 100kW charger at 90% efficiency needs 77.4 × 0.6 = 46.44kWh; effective power is 90kW, so time = 46.44 ÷ 90 ≈ 0.52h ≈ 31 minutes.

How to Use

  1. 1Enter your vehicle's battery capacity in kWh (from the spec sheet).
  2. 2Enter current and target SOC percentages — DC fast charging is typically recommended up to 80%.
  3. 3Pick a charger preset (7/11/50/100/200kW) or enter a custom power.
  4. 4Adjust charging efficiency if needed (85–95% is typical).
  5. 5Read the estimated time, energy delivered to the battery, grid energy used, and the comparison across charger powers.

Examples

Ioniq 5 Long Range, 100kW DC (20%→80%)

Charging a 77.4kWh battery from 20% to 80% at a 100kW highway fast charger.

Battery capacity77.4kWh
Current SOC20%
Target SOC80%
Charger power100kW
Efficiency90%
ResultEnergy needed 46.4kWh (77.4 × 60%), effective power 90kW → about 31 minutes; roughly 51.6kWh drawn from the grid including losses.

Overnight 7kW AC charging (30%→100%)

Filling a 64kWh battery from 30% to 100% on a 7kW home/apartment AC charger.

Battery capacity64kWh
Current SOC30%
Target SOC100%
Charger power7kW (AC)
Efficiency90%
ResultEnergy needed 44.8kWh (64 × 70%), effective power 6.3kW → about 7 hours 7 minutes; plug in at 11 pm and it finishes around 6 am.

Background

Charging time follows a simple physics formula — energy to add divided by effective power — but real-world sessions deviate because the battery management system tapers charging current above roughly 80% SOC to protect the cells, which is why manufacturers quote DC fast-charging times on a 10–80% basis. AC charging is capped by the vehicle's onboard charger (typically 7–11kW for passenger EVs), and DC charging is capped by whichever is lower: the charger's output or the vehicle's maximum acceptance rate. The default 90% efficiency reflects typical conversion and thermal losses.

Tips

  • Fast-charge to 80% only — the 80–100% segment can take as long as 0–80%.
  • A higher-power charger doesn't help if your vehicle's maximum charging rate is lower.
  • In winter, precondition the battery (set the charger as a navigation destination) before DC fast charging.
  • For AC charging, calculate with your car's OBC rating (usually 7kW), not the wallbox rating.
  • Billing is based on grid energy including losses, so you pay for 5–15% more than what lands in the battery.

FAQ

Q. Why does real charging take longer than the calculated time?

DC fast charging tapers sharply above ~80% SOC, cold batteries charge slower, and shared chargers can split output between vehicles. This calculator assumes constant power, so treat it as a best-case estimate.

Q. What does 90% charging efficiency mean?

Not all energy from the charger reaches the battery — 5–15% is lost to conversion and heat. At 90% efficiency, drawing 10kWh from the grid stores about 9kWh in the battery, and you are billed for the grid-side amount.

Q. Why is AC charging calculated at 7kW?

AC charging speed is limited by the vehicle's onboard charger (OBC), which converts AC to DC. Most passenger EVs have a 7kW (sometimes 11kW) OBC, so a larger wallbox won't charge faster.

Q. Does frequent fast charging degrade the battery?

High-power charging generates more heat and can accelerate long-term degradation. Manufacturers commonly recommend AC charging for daily use, DC fast charging for road trips, and keeping charge below 80% for battery longevity.

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