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Basic technical knowledge for charging EVs

How to calculate charging power, charging time and range

Charging power

(single- or triple-phase)

For working out the charging power, you will need the number of phases, the voltage and amperage of your power connection for the charging station. For a triple-phase connection, the way in which the charging station is connected to the network is also important. It will depend on whether the voltage is 230 V or 400 V, arranged in a star or delta connection. If you have this information to hand, you can easily work out the values using the following formula:

Charging power (single-phase alternating current):

Charging Power (3.7 kW) = Phases (1) x Voltage (230 V) x Amperage (16 A)

Charging power (triple-phase alternating current), star connection:

Charging Power (22 kW) = Phases (3) x Voltage (230 V) x Amperage (32 A)

Alternatively: charging power (triple-phase alternating current), delta connection:

Charging Power (22 kW) = Root (3) x Voltage (400 V) x Amperage (32 A)

An example:

If you want to reach a charging power of 22 kW, your electric installation must be set up for triple-phase charging with an amperage of 32 A.

Renault Zoe - Charging time - The Mobility House Renault Zoe - Charging time - The Mobility House

Charging time

You can work out the charging time simply by dividing the battery capacity by the charging power of your electric car. For Tesla, it is 85 kWh divided by 22 kW, which equals 3.9 h. However, during the charging process, the charging power is not constant; rather, it can be limited, depending on the situation of the battery. For this reason, we add at least half an hour to our calculations.

Charging Time = Battery Capacity  / Charging Power

For example: 3,9 h = 85 kWh / 22 kW



For calculating the range, you simply divide the battery capacity by the energy usage and multiply the total by 100. Please bear in mind that this only concerns calculated values. The actual range depends on the mode of operation and the usage of electrical loads, such as heating, amongst other things. Moreover, the entire capacity is often unavailable, for the purposes of protecting the battery.

Range = Battery Capacity / Energy Load  x 100

For example: 469 km = 85 kWh / (18,1 kWh / 100 km) * 100

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