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OCPP WS Simulator
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EV Charger Simulator & Emulator: Charging Sessions Online

Simulate EV charging sessions in your browser: plug in, authorize, charge with live meter values and state of charge, inject faults and stop — all over real OCPP.

What an EV charger simulator does

An EV charger simulator (or EV charger emulator) stands in for a physical charging station. It reproduces what a real charger reports to its backend — connector status, authorization, energy delivered, faults — so you can build and test charging software without a car, a charger or a lab.

This one speaks OCPP, the open protocol most chargers use, so the backend you test against it is the same one that will run your real fleet.

A full charging session, step by step

  1. Plug in — the connector goes from Available to Preparing.
  2. Authorize — the simulator sends the ID tag (RFID) to the CSMS and shows whether it was accepted.
  3. Start the transaction — status becomes Charging and the transaction ID appears.
  4. Charge — meter values arrive at the configured sample interval: energy, power, voltage, current, state of charge and more.
  5. Stop and unplug — with the stop reason you choose (Local, Remote, EVDisconnected and others), then back to Available.

Or press Auto charge and the simulator runs the whole session for you until the battery reaches its target.

Battery and state of charge

Pick a vehicle preset — PHEV (18 kWh), city EV (30 kWh), sedan (60 kWh), SUV (77 kWh) or truck (100 kWh) — or enter any capacity. State of charge is the energy delivered this session divided by that capacity, sent in MeterValues with one decimal place.

Choose where auto charge stops: 80% (daily charging), 90% or 100%. The energy register carries over between sessions, like a real meter, while each new session starts from an empty battery.

Meter values you can send

  • Energy and power

    Energy.Active.Import.Register in Wh and Power.Active.Import in W.

  • Voltage and current

    Per phase, with single- or three-phase wiring.

  • State of charge

    SoC in percent, measured at the EV.

  • Temperature and frequency

    Optional measurands for thermal and grid testing.

Faults and other edge cases

  • Fault injection — trip any OCPP error code on a connector; active transactions stop as they would on real hardware.
  • Offline mode — drop the network, queue messages and replay them when the charger comes back.
  • Response latency — delay every reply by up to 30 seconds to test CSMS timeouts.
  • Reservations, charging profiles and local auth lists — all handled when the CSMS sends them.

Simulate your first charging session

Open the simulator, point it at your CSMS URL and connect. Everything runs in your browser.

Open the simulator

Frequently asked questions

Can I simulate an EV charging session without hardware?

Yes. The simulator emulates the charger side of the session over OCPP: plug in, authorize, start the transaction, report meter values and state of charge, then stop and unplug — all from the browser.

How is state of charge (SoC) calculated?

SoC is the energy delivered in the current session divided by the configured battery capacity, sent with one decimal place. Every session starts from an empty battery; the energy meter itself keeps counting across sessions, as a real meter does.

Can I stop charging at 80%?

Yes. Set the auto-charge target to 80%, 90% or 100% of the battery capacity. Auto charge stops the transaction when the session reaches that state of charge.

Can I simulate charger faults?

Yes. Trip any OCPP error code (for example GroundFailure or OverVoltage) on a connector, force the charger offline, or delay every response to test CSMS timeouts.