November 10, 2023

How long does it take to charge an EV?

EV Chargers Charging time

The answer is more involved than you might think. The time to charge an electric vehicle (EV) can vary drastically depending on the vehicle's hardware and the charging station's power. You might be used to seeing this number quoted in hours from "empty" to "full," but that is not the most practical way to estimate the charge time. Since most EV drivers never drive their cars to zero, it is easier to look at the miles of range added for every hour plugged in.

Getting the fastest charge 

You will learn about the formula to calculate your EV's estimated charge time here, or you can also find an EV Charger that is ideally suited to your vehicle's make, model, and installation preference. When we match you to a charger, we will also share a summary of your vehicle's various power stats that affect the charge time, like the battery acceptance rate and size.

What are all the factors that determine charge time? 

To find your EV's charge time manually, start by finding a few figures: 

1. Battery size: Electric vehicles can be equipped with various battery pack sizes that determine the energy stored in the vehicle (also known as an EV's range). The vehicle specs should report this number in kWh.  

2. Charging station output power: The amperage (A) and voltage (V) determine the maximum power that can be supplied to an EV at any given time.  

3. Battery acceptance rate: The maximum power an EV can accept from a charging station.

What is the battery acceptance rate? 

The battery acceptance rate is the limiting factor determining the maximum power your EV can accept when charging. No matter how powerful a charging station is, the speed at which you can charge will always be limited and managed by the vehicle.

For example, a 2020 Chevy Bolt has an acceptance rate of 7.2 kW. A 32 Amp HCS-40 will add about 24 miles of range per hour of charging. A 40 Amp HCS-50 will not charge it any quicker because it is limited by the acceptance rate. Our recommended station is an HCS-40 for the fastest possible charge.  

If you plan to add an EV with a higher acceptance rate to your family in the future, consider sizing up to a more powerful charger now. It will not affect how quickly the Chevy Bolt charges, nor will it harm the vehicle.

Calculating charge times 

First, find the output power of the charging station by multiplying the amperage and voltage, then divide by 1000 to convert the number to kilowatts to make it more manageable.  

For example, you are looking at an HCS-60 EV Charger. The voltage is 240 and the amperage is 48.  

240 V x 48 A = 11,520 W 

11,520 W / 1000 = 11.52 kW = charging station output power 

Second, find hours to a full charge by dividing your EV's battery pack size by the lower limiting factor: the vehicle's acceptance rate or the charging station's output power. 

Continuing the previous example, you plan to use the HCS-60 to charge a Tesla Model 3 Long Range. The battery pack has 75 kWh, a total range of 310 miles, and an acceptance rate of 11.5 kW. Because the Tesla Model 3's acceptance rate is slightly lower than the HCS-60's output power, we will use that as our limiting factor.  

75 kWh / 11.5 kW = 6.52 hours for a full charge 

Finally, find the miles of range per hour plugged in by taking the total range of the EV, in this case, 310 miles, and divide by the 6.52 hours to a full charge.  

310 total miles / 6.52 total hours = 47.5 miles of range per hour plugged in 

Remember, if you need help finding those stats to complete those equations, we can help you find your EV Charger. All you need is your vehicle make, model and whether you would like to hardwire or plug in your station. We will provide a single recommendation to meet your needs. 

Questions? Contact us. We’ll help you build your system, today.
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