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Dynamic load management (DLM) shares a circuit’s available power across the chargers connected to it, recalculating every time a vehicle starts or stops charging, so the fuse is never exceeded.

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Overview

A charger left to itself delivers whatever the vehicle asks for, first come first served. Put four of them on one circuit and the first two vehicles can take everything the fuse allows, leaving nothing for the next arrival — or tripping the fuse and taking the site down. The usual fix is a bigger grid connection, which is slow and expensive. DLM is the alternative. It treats the fuse capacity as a budget and divides it among the connectors that are actually drawing power, so you can put more chargers on the connection you already have. A circuit is the platform’s representation of the physical electrical circuit your chargers are wired to in the cabinet on site. It holds a fuse capacity, set in amps, and larger installations can break it into sub-circuits. A circuit normally covers one geographical site, but it isn’t tied to a single location: several floors of a car park, or two operators sharing a DC hub, can sit on one circuit.

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How it works

DLM works from three inputs: the circuit’s fuse capacity, the maximum current each connector is rated for, and which connectors are drawing power at this moment. Every connector that is actively charging is first guaranteed a floor of 6 A. Whatever capacity remains is then split in proportion to how much headroom each connector has above that floor, so a connector rated for more current receives a larger share than a smaller one beside it. Connectors that are idle, unavailable or faulted are left out of the calculation entirely, and their share goes to the vehicles that can use it. The whole circuit is recalculated from scratch whenever something changes:

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A worked example

A depot circuit is fused at 200 A and feeds three identical connectors. With all three charging, each is allocated roughly 66 A. When two of the vehicles finish, the remaining one is free to take its full rated current, up to the fuse limit. Scarcity is where the 6 A floor starts to bite. On a 40 A circuit with seven vehicles plugged in, there isn’t enough capacity to give all seven their minimum: six charge at the floor and the seventh is held at 0 A until capacity frees up. The vehicles that get the minimum are the ones whose sessions started first. The small amount left over — 4 A in this case — is spread across the six, taking each to about 6.6 A. That behaviour is deliberate. A connector below 6 A can’t deliver usefully, so the platform would rather charge six vehicles slowly than seven not at all.

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Options and configuration

The capacity itself is a fixed number, which suits a site where the chargers are the only significant load. Where they aren’t — a building drawing from the same connection, on-site solar, a battery — the limit needs to move during the day. That’s programmatic charger control, which lets external software raise and lower the circuit limit while DLM keeps distributing whatever is available. The industry calls the combination advanced dynamic load management (aDLM).

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When to use it

  • A depot adding vehicles faster than grid capacity. DLM lets you put the next four chargers on the existing connection instead of waiting on an upgrade. Overnight there is usually slack in every session, so a smaller share per vehicle costs you nothing.
  • A car park with chargers on several floors. One circuit spanning the floors keeps the whole installation inside the building’s supply.
  • A public site with mixed hardware. Proportional distribution means a 150 kW unit isn’t held to the same allocation as an 11 kW one beside it.

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Set up

DLM is configured in Connect, on the circuit.
1

Check your charger models

DLM runs only on charger models Spirii has validated for it. Validation is assessed per model and per firmware version, so confirm with Spirii before you plan around a specific unit.
2

Create the circuit and set its fuse capacity

Enter the capacity in amps, matching the fuse that protects the installation.
3

Add the charge boxes

Attach every charge box wired to that supply.
4

Enable DLM on the circuit

From that point the circuit rebalances automatically.

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Dependencies and limitations

  • Validated charger models only. Feature validation is per model and per firmware version — a model validated two years ago can fall out of compliance after a firmware update. This is what keeps the fuse protected, so it isn’t waived.
  • Some chargers run their own load management in hardware. Those setups don’t integrate with Spirii’s DLM; the two would work against each other. Pick one.
  • A connector that can’t be given 6 A is given nothing until capacity frees up, with the oldest session served first.
  • An unresponsive charger is treated as though it is still drawing its last known limit, and is taken out of the balancing pool until it answers again. The circuit stays protected, but the capacity it is assumed to be using isn’t offered to anyone else.
  • DLM is the outer boundary, not a competitor to the other capabilities. Grid balancing, programmatic charger control, prioritised charging and scheduled charging all work inside the limit DLM sets.

Programmatic charger control

Let external software move the circuit limit as conditions on site change.

Prioritised charging

Give chosen vehicles the maximum available power while a limit is active.

Energy management

How the four local capabilities resolve when more than one applies.

Charge boxes

The units whose output DLM adjusts, and where firmware is managed.