Installing several charging points creates a new question for a building: how much power can the cars use while everything else keeps running? The sum of the chargers’ nameplate ratings does not describe the available spare capacity. Heating, lifts, kitchens and other equipment also draw electricity. Managed charging coordinates vehicle demand with the limits of the installation and the needs of its users.

A dynamic system can monitor the building’s demand and adjust charging power as other loads change. When more capacity becomes available, charging can increase within the permitted limits. This is different from simply starting every charger at the same hour. It is also different from vehicle-to-grid operation: controlling how a car charges does not mean the car can supply electricity back to the building.

The engineering problem has two separate constraints: instantaneous power and energy delivered before departure. Suppose an illustrative site allows 60 kW of total electrical demand and its other equipment is currently using 38 kW. Only 22 kW remains for charging before applying any design margin. Four nominal 11 kW charging points would request 44 kW if all ran at their maximum. A shared controller therefore has to reduce or sequence charging. Those numbers describe an example power budget, not a recommendation for a particular connection. Current limits on individual phases can constrain the arrangement even when total power appears acceptable.

Time can be as important as charger rating. If four vehicles each need 20 kWh delivered to their batteries, the combined requirement is 80 kWh. Assuming an illustrative charging efficiency of 90%, the site must supply about 88.9 kWh. Spread evenly over an 8-hour stay, that corresponds to an average of approximately 11.1 kW. With only 2 hours available, it becomes about 44.4 kW. The same vehicles therefore create very different infrastructure requirements depending on dwell time. Actual efficiency varies with the vehicle, temperature and operating conditions; it should be measured or obtained from suitable product data.

A fair allocation strategy needs an explicit definition of priority. Departure deadlines, minimum requested energy and the treatment of visitors should be agreed before commissioning. Giving every vehicle an equal instantaneous share may leave an early departure undercharged while a later departure receives energy it could have taken afterwards. Conversely, allowing unrestricted priority claims can make the service unpredictable. Record requested and delivered energy, departure targets and charging interruptions. These records help distinguish an insufficient connection from a communication fault, an unrealistic request or a vehicle that accepts less power than the charger can offer.

The response to missing measurements is a design decision rather than a minor software setting. If the building meter becomes unavailable, continuing with the last generous allowance may no longer respect the site limit. The designer should specify a suitable fallback, protective coordination and a recovery sequence. Test simultaneous restart after an outage, changes in building load and any single-phase constraints. Charging management can improve use of an existing connection, but it does not replace electrical protection or create additional energy during a short parking window. Acceptance should be based on both electrical limits and delivery of an agreed charging service.

Consider an illustrative office car park where some vehicles leave at lunchtime and others remain until evening. A useful policy would consider departure times and requested energy, rather than divide power without regard to the journeys ahead. The interface should explain any reduction in charging speed. If demand exceeds what the connection can provide over the available time, software cannot remove that physical constraint; some requests will need to change.

Before installation, assess the electrical supply, phase loading, protective devices and communication requirements with the responsible designer. Agree how chargers behave if their meter or network connection fails, and test that behaviour during handover. Keep an operational record of delivered energy and missed charging targets. With these basics in place, managed charging becomes a practical part of building automation, helping the site use its available capacity more deliberately while giving drivers a clearer service.

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