Step-by-Step: Compute a Charging Cost from Charging Station and Tariffs data#

This tutorial walks you through how to turn the data you already retrieved from the Charging Station and the Tariffs services into a charging cost estimation.

The Charging Cost service does not look anything up by itself: it prices a charging session from the values you provide. Those values are exactly the ones returned by the two previous calls, so the whole job is to copy the right fields into the right place.

The Big Picture#

• 1. Charging Station search, /chargingstation/search/1.0 → 2. Charging Station Tariffs, /chargingstation/tariffs/1.0/search: poolId, chargingPointId, connector operatorId
• 1. Charging Station search, /chargingstation/search/1.0 → 3. Charging Cost, /chargingcost/1.0: connector type id, power, currentType, timeZone
• 2. Charging Station Tariffs, /chargingstation/tariffs/1.0/search → 3. Charging Cost, /chargingcost/1.0: currency, tariffItems, minPrice, maxPrice
• Vehicle, /vehicle/1.0/findvehicles → 3. Charging Cost, /chargingcost/1.0: vehicle key
• 3. Charging Cost, /chargingcost/1.0 → Estimation, chargingTime, energyUsed, chargingCost: withoutVat / includeVat

Each box of the diagram is one call, and each arrow is data you carry from one call to the next:

1. Charging Station search locates the stations around a coordinate. Pick the connector the driver is going to plug into: the answer holds both the identifiers naming that connector at the operator, and its technical characteristics.
2. Charging Station Tariffs returns the prices of that exact connector. It is asked with the three identifiers of step 1, so it answers for one connector and not for the whole station.
3. Vehicle provides the vehicle key. It is a one-off call: get the key once and reuse it for every estimation.
4. Charging Cost puts everything together. From the vehicle and the connector it works out how long the charge takes and how much energy it needs, then prices that energy with the tariff of step 2.

The result is an estimation: the charging time, the energy delivered, and the cost before and after taxes.

Nothing is looked up twice. Steps 1 and 2 are the ones that talk to the charging network; step 4 only computes, from the values you hand over.

All the requests below are sent with the HTTP method POST and the header Content-Type: application/json. See the authentication page for the login and password process.

Step 1: Collect the connector data (Charging Station service)#

Start from a regular charging station search. See Build Your First Charging Station Request if you are not familiar with it.

Request sent to /bgis/service/chargingstation/search/1.0:

POST https://bemap.benomad.com/bgis/service/chargingstation/search/1.0
{
  "geoserver": "osm",
  "providers": ["ecoMovement"],
  "mode": "LOCAL_OR_REMOTE",
  "options": ["PATH_POINT"],
  "radius": 100,
  "coordinate": {
    "lon": 2.3058,
    "lat": 48.8542
  }
}

Response (only the fields used by this tutorial are shown, and one of the pool's six charging points):

{
  "pools": [
    {
      "providerName": "ecoMovement",
      "id": "009c54c4-a364-11f0-abfd-42010aa40043",
      "nameOfPool": "Electra Paris 7 - Indigo Parking Joffre Ecole Militaire",
      "timeZone": "Europe/Paris",
      "chargingStations": [
        {
          "chargingPoints": [
            {
              "id": "FR*ELC*EXNJF",
              "currentType": "DC",
              "power": 200,
              "voltage": 800,
              "connectorTypes": [
                {
                  "id": 38,
                  "key": "TYPE_2-CABLE_COMBO_CCS",
                  "operatorId": "combo-ccs-eu_2",
                  "name": "Type 2 Combo",
                  "norm": "Combo Type 2 based, DC",
                  "maxPower": 350,
                  "power": 200,
                  "dc": true,
                  "cable": true
                }
              ]
            }
          ]
        }
      ]
    }
  ]
}

Keep these values, they feed both of the next steps:

⚠️ Do not mix up the two connector identifiers:

• connectorTypes[].operatorId is the identifier of the physical connector at the operator, used to ask for its tariffs;
• connectorTypes[].id is the BeMap connector type identifier (see the connector glossary), used to price the charge.

The timeZone is what makes a time based tariff (night rate, week-end rate…) resolve to the right local time. Always carry it over.

Step 2: Get the tariffs (Charging Station Tariffs service)#

Build the links array with the three identifiers collected in step 1. Optionally add the chargePassHashIds of the charge passes your user owns; the AD_HOC (direct payment) tariffs are always returned anyway.

The hash IDs come from the Charge Pass service. The example sends none: for this connector, ecoMovement returns the same items with any of its charge passes.

Request sent to /bgis/service/chargingstation/tariffs/1.0/search:

POST https://bemap.benomad.com/bgis/service/chargingstation/tariffs/1.0/search
{
  "providerName": "ecoMovement",
  "links": [
    {
      "poolId": "009c54c4-a364-11f0-abfd-42010aa40043",
      "chargingPointId": "FR*ELC*EXNJF",
      "connectorId": "combo-ccs-eu_2"
    }
  ]
}

Response (one of the nine items returned, see step 3):

{
  "items": [
    {
      "poolId": "009c54c4-a364-11f0-abfd-42010aa40043",
      "chargingPointId": "FR*ELC*EXNJF",
      "connectorId": "combo-ccs-eu_2",
      "tariffContent": {
        "id": "6ab9e0d7300bd65f024c03f8",
        "providerName": "ecoMovement",
        "updateDate": 1790566612731,
        "providerUpdated": "2026-09-27T08:50:30Z",
        "providerTariffId": "82e897a6d083861efd1deeb3f1436e498fb504dfb94b533effd91e8b576b4551",
        "type": "AD_HOC",
        "chargePass": {
          "hashId": "be14e3a120421ea56f9e01acf7f22898",
          "networkName": "TE61",
          "title": "Adhoc price",
          "description": "Adhoc price",
          "currency": "EUR",
          "subscriptionType": "n/a",
          "subscriptionFeeExclVat": 0
        },
        "currency": "EUR",
        "tariffItems": [
          {
            "restriction": {
              "minDuration": 3600,
              "maxDuration": 19500
            },
            "prices": [
              {
                "type": "TIME",
                "unit": "PER_HOUR",
                "price": 20,
                "vat": 20,
                "minAmount": 60
              },
              {
                "type": "PARKING_TIME",
                "unit": "PER_HOUR",
                "price": 20,
                "vat": 20,
                "minAmount": 60
              }
            ]
          },
          {
            "prices": [
              {
                "type": "ENERGY",
                "unit": "PER_KWH",
                "price": 0.5333,
                "vat": 20,
                "minAmount": 1000
              }
            ]
          }
        ]
      }
    }
  ]
}

This tariff carries no minPrice or maxPrice: they are sent only when the tariff sets them, although the specification marks them as always present.

Step 3: Pick the tariff to apply#

One connector can be sold under several tariffs, so items may contain several entries for the same link. Several entries are not always several tariffs, though: for the link above the service answers nine items, three stored copies of one AD_HOC tariff, each repeated three times. The copies share their providerTariffId and differ in id and updateDate (here also in chargePass and in the order of tariffItems). Keep one entry per providerTariffId, the one with the latest updateDate.

Then pick one tariff, and only one, before computing a cost:

Filter on type, or on tariffContent.chargePass.hashId when you want the tariff of a specific charge pass.

⚠️ A recurring subscription fee (chargePass.subscriptionFeeExclVat) is not part of a session cost and is never included in the estimation. Display it separately if your UI needs it.

Step 4: Pick the vehicle#

The charging time, and therefore the energy actually billed, depends on the vehicle charge curve. Get the vehicle key once from /bgis/service/vehicle/1.1/findvehicles and reuse it:

"vehicle": "d729502b-12ba-4adb-89bd-cff6a2d00919"

See the Vehicle service for the full list.

Step 5: Map the collected fields into the Charging Cost request#

This is the heart of the tutorial. Every field below is copied, not recomputed:

And these ones describe the session you want to price, they come from your application:

Copy tariffItems in its original order. The order is meaningful: for each dimension, the service applies the price of the first item that carries this dimension and whose restrictions hold. Reordering or filtering the array changes the price.

The charges array accepts several charges at once, one per connector you want to compare. Estimations are returned in the same order.

Step 6: The complete request#

Request sent to /bgis/service/chargingcost/1.0:

{
  "geoserver": "osm",
  "vehicle": "d729502b-12ba-4adb-89bd-cff6a2d00919",
  "time": 1781526600000,
  "temperature": 20,
  "cur": "EUR",
  "charges": [
    {
      "curBatLvl": 23,
      "toBatLvl": 80,
      "currentType": "DC",
      "power": 200,
      "cnnTypeId": 38,
      "timeZone": "Europe/Paris",
      "currency": "EUR",
      "tariffs": [
        {
          "restriction": {
            "minDuration": 3600,
            "maxDuration": 19500
          },
          "prices": [
            {
              "type": "TIME",
              "unit": "PER_HOUR",
              "price": 20,
              "vat": 20,
              "minAmount": 60
            },
            {
              "type": "PARKING_TIME",
              "unit": "PER_HOUR",
              "price": 20,
              "vat": 20,
              "minAmount": 60
            }
          ]
        },
        {
          "prices": [
            {
              "type": "ENERGY",
              "unit": "PER_KWH",
              "price": 0.5333,
              "vat": 20,
              "minAmount": 1000
            }
          ]
        }
      ]
    }
  ]
}

Note how tariffs is a verbatim copy of tariffContent.tariffItems from step 2, and currency a copy of tariffContent.currency. The timestamp 1781526600000 stands for 2026-06-15 14:30, local time of Europe/Paris.

Response Analysis#

{
  "estimations": [
    {
      "chargingTime": 1765,
      "energyUsed": 34.2,
      "batChargeLvl": 80.0,
      "chargingCost": {
        "currency": "EUR",
        "withoutVat": 18.665499,
        "includeVat": 22.398598
      }
    }
  ]
}

Checking the numbers. The session lasts 1765 s, which is below the minDuration of 3600 s, so the first tariff item never applies. The second item prices the whole energy, rounded up to its step of 1000 Wh (minAmount, see below):

34.2 kWh, billed as 35 kWh
35 kWh × 0.5333 €/kWh      = 18.6655 € excluding VAT
18.6655 € × (1 + 20 / 100) = 22.3986 € including VAT

The service returns these two amounts to floating-point precision: 18.665499 and 22.398598.

⚠️ chargingTime and energyUsed depend on the vehicle charge curve, on the temperature and on the power actually delivered, so your own figures will differ. The cost, however, is always the plain arithmetic above applied to the returned energyUsed.

How the cost is computed#

The calculation follows the OCPI pricing rules. Understanding them explains most of the results that look surprising at first sight.

The four price dimensions#

⚠️ The Charging Cost service prices a session that ends when the charge ends, so the idle period is zero and a PARKING_TIME price contributes 0 to the result. This is why the PARKING_TIME line of the example above never adds to the total, even for a session longer than its minDuration, where the TIME line beside it is billed. Use TIME if you want to bill the charging period itself.

Selection of the applicable price#

For each dimension, the service walks the tariffs array in order and keeps the price of the first item that:

1. carries a price for this dimension, and
2. has no restriction, or a restriction that holds for the session.

If no item matches, the dimension is simply not billed.

Restrictions#

Time and date restrictions can only be resolved when time is provided. Without it, they are ignored rather than treated as unmatched, so that a purely time based tariff does not silently return a cost of zero.

minAmount, minPrice and maxPrice#

• minAmount is the OCPI step size: the billed quantity is rounded up to the next multiple. It is expressed in Wh for ENERGY and in seconds for TIME and PARKING_TIME. In the example, "minAmount": 1000 on the energy means a 1 kWh step: the 34.2 kWh delivered are billed as 35 kWh. The specification describes minAmount as the "minimum amount to be billed"; the service applies it as this step size.
• minPrice and maxPrice are session floors and ceilings. They are set on charges[], not inside a tariff item, and are applied at the very end of the calculation.

VAT and currency#

Prices are given excluding taxes; vat is the percentage applied to produce includeVat. A vat of 0, or an omitted vat, means no tax is added.

When cur differs from charges[].currency, both amounts are converted with the current exchange rate of the Currency service. If the rate cannot be found, the amounts are returned in the original currency, so always read chargingCost.currency rather than assuming it equals cur.

Troubleshooting#

Checklist#

Before sending the Charging Cost request, make sure that:

• cnnTypeId is the connector type id, and power and currentType come from the same charging point;
• timeZone is the timeZone of the pool;
• currency is the currency of the tariff, while cur is the currency you want to display;
• tariffs is the tariffItems array of the selected tariff, copied in the same order;
• time is set whenever the tariff carries time or date restrictions;
• curBatLvl is lower than toBatLvl, both in the 0-100 range.

Going further#

• Charging Cost service: full API reference
• Charging Station Tariffs service: full API reference
• Charging Station service: full API reference
• Charging Time service: charging duration only, without pricing
• Connector glossary: the list of connector type ids
• Charging Cost example: run a request live