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EV Charging Priority Algorithms: Fairness and Departure Time

Once capacity is scarce someone charges slower. The allocation rules available, what each optimises, and why the choice is a business decision rather than a technical one.

Technically reviewed by Anees P K, Director of Technology. Last reviewed 2026-09-01.

Load management decides how much energy a site may deliver. Priority decides who gets it. The second question only appears once capacity is genuinely scarce, and by then the system is usually already installed with whatever default it shipped with.

Every rule below is defensible. None is neutral, and the choice belongs to the operator rather than the software.

Equal division

The available budget is split equally among active sessions. Simple, obviously fair, and it ignores that a vehicle leaving in twenty minutes and one leaving in eight hours have different needs.

It is a reasonable default for public sites where nothing is known about the drivers, and a poor one for fleets where a great deal is known.

First come first served

Earlier sessions receive their full rate and later ones receive what remains. This rewards arriving early and can leave a late arrival with almost nothing, which at a workplace becomes a complaint about people who start work later.

It is the least defensible rule in a setting where all users have an equal claim.

Departure-time aware

Allocate to meet each vehicle's required charge by its stated departure. This is the most useful rule where departures are known, because it optimises for what people actually need rather than for equality of rate.

It requires drivers or a fleet system to supply departure times, and it degrades to equal division when they do not.

Need-based

Prioritise vehicles with the lowest state of charge. This serves the driver who most needs energy and can penalise someone topping up who nevertheless has a long journey ahead.

It requires state-of-charge information, which is not always available to the charger and may come from a fleet system instead.

Tiered by entitlement

Fleet vehicles before staff, tenants before visitors, paying sessions before free ones. This encodes a commercial or organisational hierarchy directly, which is honest where such a hierarchy genuinely exists.

It generates the strongest reactions when applied where users consider themselves peers, which is why it suits fleet and mixed-use sites better than workplaces.

What the system should do

Implement the operator's rule rather than impose one. Systems with a fixed fairness model tend to be overridden or worked around, which produces worse outcomes than the rule they replaced.

It should also make the allocation visible. A driver charging slowly with no explanation assumes a fault; one who can see the site is at capacity does not.