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How To Calculate Your Electric Vehicle's Charging Time

Woman charging EV holding charger and mobile phone.

When contemplating the switch to an EV from a gas powered car, charging time is one of the first considerations everyone looks into. The process of fueling up an EV can feel like an unknown when a driver has spent years filling up an ICE (internal combustion engine) vehicle. While pumping gas takes a few minutes, how long does it take to charge an EV?

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How Long Does It Take To Charge An Electric Vehicle?

An EV’s charging time depends on two major factors: how much charge (kWh) is needed, and how much power (kW) the EV charging station provides. Divide the charge needed by the power provided to get the estimated hours of charge time required. There are other variables that play into this calculation but these two factors are the most significant variables when estimating your electric vehicle’s charging time.

Calculation for EV Charging Time:

To calculate your charging time, divide the amount of charge needed by the power provided by the charger. Use the formula and example below to help estimate your charge time.

Formula:
Charge needed (kWh) / Charger power (kW) = Hours of charging time

Example:
A Tesla Model 3 with an 80 kWh battery size parks at a 7.68kW Level 2 charging station with 20% battery left. They would like to charge their EV to 80%.

Find charge needed:
80% – 20% = 60% needed
80kWh x 0.6 = 48kWh needed

Calculate charging time:
48 (kWh needed) / 7.68 (kW charging speed) = ~6.25 hours of charging time

How Much Charge Does My EV Need?

To estimate how much charge your EV needs, subtract the EV’s max battery capacity (kWh) from the amount of charge it has left. Most, if not all, EVs will display the remaining battery percentage or number of kWh left within the battery. Just as most people do not wait until their gas cars are completely empty, EV drivers will always have some charge left in the batteries when they stop to refuel.

According to an EV Consumer Behavior report, about 70%-80% of EV drivers charge at home or at work every day/night or every other day/night. The average American drives around 250 miles per week or roughly 36 miles per day. This equates to around 10-13 kWh of charge per day or 20-26 kWh every other day. The average EV battery size is around 40-50 kWh, providing around 150 miles of range or 2-4 miles per kWh. Knowing your EV’s battery size and efficiency will help shape your charging routine when estimating your EV’s range. Tips on how to improve your EV’s range.

How Fast Is The EV Charger?

Charging speed is determined by the amount of kilowatts (kW) a charging station can provide per hour (kWh). There are 3 types of EV charging stations, all with varying levels of charging speeds: Level 1, Level 2, and Level 3 (DC fast charger). As the names suggest, the higher the level, the faster the charging speed. Most chargers will display their charging speed either on the charger itself or within a connected charging app.

Level 1: 12A/120V

  • Kilowatts per hour: 1.44 kWh
  • Range per hour: ~4mi

Level 2: 32A/240V

  • Kilowatts per hour: 7.68 kWh
  • Range per hour: ~24mi

Level 3 DC Fast Charger: 100A/480V+

  • Kilowatts per hour: 50kWh+
  • Range per hour: 150mi+

The majority of EV charging happens on Level 2 and Level 3 charging stations as Level 1 chargers are generally too slow for most drivers. While Level 3 is faster, Level 2 chargers tend to be more practical for installation and supporting most drivers’ daily needs. Check out the difference and which charger or configuration of chargers is best for your property.

Other Factors To Consider When Charging an EV

Other factors such as load sharing, temperature / weather conditions, EV battery protection settings, and EV charge acceptance rate can play a role in an EV’s charging time. While these factors are unique to the car model and charging location, they are important for EV drivers to know and take into consideration when starting a charge or planning their route for the day.

EV Charger Load Sharing:

EV charger load sharing is when two or more EV charging stations are connected to the same circuit and power / load is distributed between all the stations connected. In most cases, the power is only split if multiple EVs are charging at the same time on the same circuit. So if four chargers were installed on one circuit, you would receive 100% of the power if charging by yourself, and 25% of the power if every charger was being used. While this can potentially increase a driver’s charge time, load sharing is a great strategy for properties looking to manage their electrical load and/or add a larger number of chargers to their property.

Weather and Temperature Effects On Charging:

Weather and temperature conditions can play a role in the efficiency of your charge. Charging stations and EVs will often charge slower in extreme temperatures to preserve the health of the batteries. Many EV drivers will also stay inside their cars while charging at public charging locations. Running the climate control while charging can increase charging times, especially on very hot or cold days. Allocate some extra charging time or find charging stations in more protected environments when charging in these conditions. Extreme temperatures can have an even larger effect on an EV’s range.

EV Battery Protection Settings:

Many EV manufacturers will have default or recommended battery restrictions, driving modes, and other settings to protect the short term and long term life of the battery. For instance, some manufacturers recommend charging their batteries to 80% max and avoid going under 5%. While following these kinds of guidelines may decrease the range of one charge, they are meant to preserve the lifespan of the batteries with an added benefit of saving some charging time by not having to go all the way to 100%. Of course most of these are just recommended settings and can be changed at the owner’s discretion.

EV Charge Acceptance Rate:

The EV charge acceptance rate is the maximum kW an EV is able to consume or accept from a charging station. Many EV manufacturers will throttle or cap the rate of power their EVs can consume . The acceptance rate for an EV can decrease as it gets closer to 100% charged. For example an EV could be charging at a 100 kWh Level 3 fast charger and receive 100 kWh from 10-80% but slow down to 65kWh from 80-100%. This information will be noted in the manufacturer’s specifications of the vehicle.

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We provide EV drivers fast, reliable charging through our network of Level 2 and Level 3 charging stations. Our 98%+ network availability ensures drivers come back to a fully charged car and our 24/7/365 support allows us to help at every turn along the way.

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Add value, not work, with our turnkey solution for commercial and multifamily properties. Our in-house teams provide properties with end-to-end project management, installation, and ongoing operations and support. We’ll even do all the rebate paperwork and applications for you. Reach out to our team of EV infrastructure experts for a free installation evaluation.