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How to Choose a Suitable Charger

Choosing a suitable charger may seem complicated at first sight, but if you correctly answer a few key questions right at the beginning, you are almost done. This article concentrates on how to choose a charging station for private and semi-public charging (e.g. apartment or office building garages). Public charging stations, where the choice of suitable technology depends on their providers, will be discussed another time.

So, what do you have to take into account when choosing a charger?

What is the purpose of the charger?

This requirement determinates the functions your charger should be fitted with.

Charging a private electric vehicle at home or at work without the need to monitor the consumed power requires only a basic charger without any additional functions. You simply connect your electric vehicle to the charger with a charging cable and you are done.

If you use two electricity tariffs, choose a basic charger fitted with a DSM (demand-side management) function. This function enables you to choose whether you want to charge your electric vehicle only in low tariffs or at any time.

In case you need to monitor the amount of consumed energy, pick a smart charger. A smart charger enables you to monitor the amount of consumed energy when charging a company car in your private garage or charging in an apartment house garage, and to match the consumed power with particular users.

Where is the charger to be installed?

No further arrangements are required if a charger is located in a private space preventing unauthorized access of vehicles. You can use a basic charger and install it in a suitable place where its charging cable easily reaches the socket on your electric vehicle and you can comfortably go past both the charger and the vehicle.

In other cases, a charger location is determined by its specific use and the need to control the access to it depending on the authorisation to use the charger.

What electric vehicles are to be charged?

The essential criteria for choosing a suitable charger are the size of the electric vehicle battery and the type and power consumption of the electric vehicle on-board charger. You must keep in mind that the maximum possible charging power is always determined by the weakest segment in the on-board charger-charging station chain. Which means that, for example, an electric vehicle fitted with 2.4kW single-phase on-board charger is always charged at a maximum of 2.4kW, completely independently on the available power consumption or the installed garage charger capabilities. For calculating the charging time and the required power consumption, you can use our EV Charging Time Calculator.

Electric vehicle on-board chargers vary in the maximum power consumption (max 22kW three-phase and 7.4kW single-phase) and also in the number of phases. This information is always specified in electric vehicle specifications.

A particular electric vehicle requires a corresponding charging cable, or rather a corresponding connector, which is to be connected to the electric vehicle. Older electric vehicles of non-European origin use various types of charging sockets. Electric vehicles purchased in Europe from authorized distributors make it easier as they are now fitted with the same “Type 2” charging sockets.

What is the available power consumption?

The charging speed along with the choice of a suitable charger is determined by the power consumption available on site. A maximum power consumption used with AC charging is 22kW. This value can be reached in case the available connection is 3x32A. In practice the supply points are most often dimensioned to 3x16A (housing units), 3×25 or 3x32A (detached houses). The contracted power consumption is charged with regular fees, so it is advisable to set it well and make optimal use of it to keep charging costs reasonably low.

That is why the best solution in this case is a charger fitted with a DLM (Dynamic Load Management) function. The charger monitors, in real time, the current consumption of the entire building and if the total consumption reaches the limits of the contracted power consumption (i.e. main circuit breaker capacity), the DLM function temporarily decreases the maximum allowed consumption for charging electric vehicles, so that it does not blow the circuit breakers. Therefore there is no need to oversize the circuit breaker and you regularly save on charging costs every month.

Example: You live in a detached house with the contracted power consumption of 3x32A and have two electric vehicles to charge. Both electric vehicles are fitted with 11kW three-phase on-board chargers, so together they use the power consumption of 22kW for peak charging, i.e. full 3x32A. However, this will use the maximum contracted power consumption for the entire household and if you switch on another electrical appliance with significant consumption, you exceed the contracted power consumption, blow the main circuit breaker and disconnect the entire house from power supply. Using a charger fitted with a DLM function enables you to decrease the speed of electric vehicle charging temporarily and prevent blackouts. In case of charging two or more electric vehicles at the same time, the DLM function allocates the remaining power consumption equally to the electric vehicles.

How many people will use the charger?

If a charger is located in a semi-public space and there is the need to control the access to it, the users have to be issued with corresponding chip cards and the cards have to be uploaded to the charger system. Then you can easily see who and how long they have been connected to the charger and divide the costs among particular users.

Conclusion

When choosing a suitable charger, you have to ensure that the charger is not the weakest segment of the charging chain and that its functions cover both the current and the expected future requirements for its use.

The charger power consumption is to be chosen especially with respect to the contracted power consumption available in the house or the considered increase in power consumption. The role of electric vehicle on-board chargers is less significant. You never know when you will buy a new electric vehicle and it is very impractical to change your charger every time.

If enabled by the infrastructure in the place of planned charging, a universal solution is to purchase a three-phase charger, ideally 22kW (i.e. 3x32A) and set a limit to lower power consumption, if temporarily needed. A minimum recommended compromise solution is 11kW (i.e. 3x16A). Single-phase chargers are only recommended to be installed in places where the infrastructure does not enabled and in the future it is not planned to enable using a three-phase connection.

Except for the places with excess power consumption (e.g. some industrial companies), we recommend to purchase a charger allowing DLM. Other charger functions are then chosen according to a particular purpose and a place of use. These are DMS in the place with two-tariff connections, chip card authorisation in semi-public spaces, consumed power metering when charging company cars in private spaces etc. If you hesitate about the final charger configurations, you can consult everything with our experts on info@voltdrive.com.