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General info

Several parameters are needed to estimate time spent at charging stations and minimize overall Estimated Travel Time (ETT).

Charging curve

A function that maps State of Energy (SoE) to maximum charging power at that SoE that is used to calculate charging time. Charging time calculation assumes that the battery is already preconditioned to an optimal temperature for charging.

The charging curve can be specified as either a piecewise-constant or a piecewise-linear function.

Piecewise-constant curve

For a specified power at a given SoE, that power applies from that SoE value to the next specified SoE in ascending order. The curve is defined by 1–20 pairs of SoE and corresponding power values. Below the first specified SoE value, the power from the first specified SoE is used.

If the charging curve is unknown from measurements, use this typical curve:

  • 0–10% SoC: 50% of peak power
  • 10–50% SoC: 100% of peak power
  • 50–80% SoC: 75% of peak power
  • 80–90% SoC: 35% of peak power
  • 90–100% SoC: 20% of peak power
Example of a piecewise-constant charging curve

Example of a piecewise-constant charging curve

Charging curves vary significantly. For instance, some LFP battery packs start limiting the charging power at SoEs as low as 20%. Relying on this default may result in charge time predictions that are off by 50% in edge cases.

Piecewise-linear curve

For a specified power at a given SoE, linear interpolation is used between that SoE and the next specified SoE in ascending order. The curve is defined by 2–20 pairs of SoE and corresponding power values, with an entry for 0% SoE being mandatory.

Charging connectors

Charging connectors define the physical and electrical specifications for vehicle-to-station connections. The connector list can model different physical connectors and other constraints such as voltage ranges and charging power limitations.

Product-specific information

For detailed information on how to configure charging parameters for specific products, refer to the following pages: