# EV charging cost and time calculator

> EV charging cost and time between two battery levels at any charger power, with range added and cost per 100 km or miles against petrol.

Phiên bản tương tác: https://www.calcopenly.com/vi/construction/ev-charging-calculator
Chủ đề: Máy tính xây dựng và nhà ở

Energy added is the battery's usable capacity times the change in charge level, and dividing by the charging efficiency gives the energy drawn from the grid. Charging time is that grid energy divided by the charger's power, and the cost is grid energy times the price per kWh. The car's energy use turns the same figures into range added and a running cost per 100 km or 100 miles, set against a petrol car.

The defaults take a 75 kWh battery from 20% to 80%: 45 kWh into the battery, 50 kWh from the grid at 90% efficiency, just under 7 hours on a 7.2 kW charger (the output of most home Level 2 units, per the US Department of Energy) and 8.00 at 0.16 per kWh. That adds about 281 km at 16 kWh/100 km.

The time assumes constant power. DC fast chargers slow as the battery fills, and on AC the car's onboard charger can cap the rate below the charger's rating.

## Dữ liệu đầu vào

- **Battery capacity (usable)**
- **Charge from**
- **Charge to**
- **Charger power**
- **Charging efficiency**: Share of the grid energy that reaches the battery, often 84–93% (fueleconomy.gov). Use 100% with an EPA rating, which already includes charging losses.
- **Electricity price per kWh**
- **Car's energy use given as** (lựa chọn: kWh/100 km, kWh/100 mi, mi/kWh, km/kWh)
- **Car's energy use (from the battery)**: The trip computer's figure; a mid-size EV uses about 15–20 kWh/100 km (3–4 mi/kWh).
- **Petrol car to compare**
- **Petrol price per** (lựa chọn: Litre, gallon Mỹ, UK gallon)
- **Petrol price**

## Kết quả

- Charging cost — kết quả chính
- Charging time
- Energy into the battery (kWh)
- Energy from the grid (kWh)
- Range added (km)
- Range added (mi)
- EV cost per 100 km
- Petrol cost per 100 km
- EV cost per 100 mi
- Petrol cost per 100 mi

## Công thức

$$
E = C \times (b - a),\quad E_{\text{grid}} = \frac{E}{\eta},\quad t = \frac{E_{\text{grid}}}{P},\quad \text{cost} = E_{\text{grid}} \times p
$$

## Ví dụ có lời giải

### 75 kWh battery, 20 → 80% on a 7.2 kW charger

- Battery capacity (usable): 75 kWh
- Charge from: 20%
- Charge to: 80%
- Charger power: 7.2 kW
- Charging efficiency: 90%
- Electricity price per kWh: 0.16
- Car's energy use given as: kWh/100 km
- Car's energy use (from the battery): 16
- Petrol car to compare: 7 L/100 km
- Petrol price per: Litre
- Petrol price: 1.75
- **Energy into the battery: 45 kWh**
- **Energy from the grid: 50 kWh**
- **Charging time: 6 h 56 min 40 s**
- **Charging cost: 8.00**
- **Range added: 281.2 km**
- **EV cost per 100 km: 2.84**
- **Petrol cost per 100 km: 12.25**
- Nguồn đối chiếu: Hand calculation: 75 × 0.6 = 45 kWh ÷ 0.9 = 50 kWh ÷ 7.2 kW = 6.944 h × 0.16 = 8.00; 16 ÷ 0.9 × 0.16 = 2.844 per 100 km; 7 × 1.75 = 12.25

### 60 kWh, 10 → 90% at 11 kW, lossless, 0.30 per kWh

- Battery capacity (usable): 60 kWh
- Charge from: 10%
- Charge to: 90%
- Charger power: 11 kW
- Charging efficiency: 100%
- Electricity price per kWh: 0.3
- Car's energy use given as: kWh/100 km
- Car's energy use (from the battery): 16
- Petrol car to compare: 7 L/100 km
- Petrol price per: Litre
- Petrol price: 1.75
- **Energy into the battery: 48 kWh**
- **Charging time: 4 h 21 min 49 s**
- **Charging cost: 14.40**
- **Range added: 300.0 km**
- Nguồn đối chiếu: Hand calculation: 60 × 0.8 = 48 kWh ÷ 11 kW = 4.3636 h = 15,709 s; 48 × 0.30 = 14.40; 48 ÷ 0.16 kWh/km = 300 km

### Edge: empty to full, 82 kWh, 3.5 mi/kWh against a 30 mpg car

- Battery capacity (usable): 82 kWh
- Charge from: 0%
- Charge to: 100%
- Charger power: 11.5 kW
- Charging efficiency: 90%
- Electricity price per kWh: 0.16
- Car's energy use given as: mi/kWh
- Car's energy use (from the battery): 3.5
- Petrol car to compare: 30 mpg (US)
- Petrol price per: gallon Mỹ
- Petrol price: 3.5
- **Charging cost: 14.58**
- **Charging time: 7 h 55 min 21 s**
- **Range added: 287.0 mi**
- **EV cost per 100 mi: 5.08**
- **Petrol cost per 100 mi: 11.67**
- Nguồn đối chiếu: Python decimal: 82 ÷ 0.9 = 91.11 kWh × 0.16 = 14.58; ÷ 11.5 kW = 7.92 h; 82 × 3.5 = 287 mi; 100/3.5 ÷ 0.9 × 0.16 = 5.08; 100/30 × 3.50 = 11.67

## Câu hỏi

### How long does it take to charge an electric car?

Divide the energy needed by the charger's power. Taking a 75 kWh battery from 20% to 80% draws 50 kWh from the grid, which is 6.9 hours at 7.2 kW. The US Department of Energy's Alternative Fuels Data Center puts Level 1 (120 V) at about 5 miles of range per hour, Level 2 at about 25 miles per hour, and DC fast charging at 100 to 200+ miles per 30 minutes.

### How much does it cost to charge an electric car?

Multiply the energy drawn from the grid, including charging losses, by your price per kWh. The default session puts 45 kWh into the battery, draws 50 kWh at 90% efficiency and costs 8.00 at 0.16 per kWh. At 16 kWh/100 km that is 2.84 per 100 km, against 12.25 for a petrol car using 7 L/100 km at 1.75 a litre.

### How much energy is lost when charging an EV?

Typically 7% to 16%. fueleconomy.gov, citing Idaho National Laboratory data, says battery charging efficiency is often 84% to 93%, so a 45 kWh top-up draws roughly 48 to 54 kWh from the meter. The 90% default sits in that range. The EPA names the charging cable and the car's onboard charger as the places where the energy is lost.

### Should I enter the EPA rating or my car's own energy figure?

Either, but set the efficiency to match. The EPA measures energy at the wall outlet, including losses in the charging cable and onboard charger, so an EPA kWh/100 mi figure already counts charging losses: set efficiency to 100%. Keep the 90% default for a figure that measures energy taken from the battery.

### Does cold weather reduce EV range?

Yes, mostly through cabin heating. fueleconomy.gov, citing AAA's 2019 tests, reports that at 20 °F (−7 °C), compared with 75 °F (24 °C), EV range fell about 41% with the cabin heater in use and about 12% without it. Raise the energy-use figure in winter to see the effect on range and cost.

### “EV charging cost and time calculator” chính xác đến mức nào?

Độ chính xác phụ thuộc vào dữ liệu nhập và giả định của phương pháp. Phép tính thập phân dùng 50 chữ số có nghĩa, nhưng ước lượng, phương pháp số và dữ liệu nguồn có thể kém chính xác hơn; làm tròn khi hiển thị không loại bỏ các giới hạn đó. Ví dụ có lời giải đã đối chiếu với nguồn độc lập: 3. Ví dụ, “75 kWh battery, 20 → 80% on a 7.2 kW charger” được kiểm tra bằng Hand calculation: 75 × 0.6 = 45 kWh ÷ 0.9 = 50 kWh ÷ 7.2 kW = 6.944 h × 0.16 = 8.00; 16 ÷ 0.9 × 0.16 = 2.844 per 100 km; 7 × 1.75 = 12.25.

### Phương pháp này lấy từ đâu?

US DOE Alternative Fuels Data Center — charging electric vehicles at home (levels and power); fueleconomy.gov — electric vehicle energy use and cost comparison; US DOE Alternative Fuels Data Center — charging levels and range added per hour; US EPA — fuel economy and EV range testing (MPGe measured at the wall outlet).

## Nguồn

- [US DOE Alternative Fuels Data Center — charging electric vehicles at home (levels and power)](https://afdc.energy.gov/fuels/electricity-charging-home)
- [fueleconomy.gov — electric vehicle energy use and cost comparison](https://www.fueleconomy.gov/feg/evtech.shtml)
- [US DOE Alternative Fuels Data Center — charging levels and range added per hour](https://afdc.energy.gov/fuels/electricity-stations)
- [US EPA — fuel economy and EV range testing (MPGe measured at the wall outlet)](https://www.epa.gov/greenvehicles/fuel-economy-and-ev-range-testing)