What Is an OCPP Backend and How Does It Work?

The short answer

OCPP (Open Charge Point Protocol) is the common language EV chargers use to talk to software. The OCPP backend is the server on the other end of that conversation.

The charger tells it when a car plugs in, how much energy flows and when something breaks. The backend tells the charger whether to start, when to stop and which settings to use.

You will also see the backend called a CSMS (Charging Station Management System), a CPMS or simply a CMS. In practice these names describe the same thing. Our guide to EV charging software terms explains each one.

What the backend does

Every networked charger depends on its backend for the jobs below.

• Decides who may charge: it checks a card, an app user or a payment before a session starts.
• Starts and stops sessions remotely, so a driver can begin from a phone or a QR code.
• Records meter readings during each session, which become the bill.
• Tracks the status of every plug: free, charging, finished or faulty.
• Changes charger settings and installs firmware updates without a site visit.
• Limits the power a charger draws, which is how load management shares a building's supply.

How a charger connects

With OCPP 1.6J and 2.0.1 the charger opens a WebSocket connection to an address set in its configuration, identifying itself by its charge point ID. It announces itself with a boot message, then keeps the line open with regular heartbeats. From then on, messages flow both ways in JSON.

1. The installer enters the backend's address and the charger's ID in the charger's settings.
2. The charger connects and sends a boot notification with its make, model and firmware.
3. The backend accepts it, and the charger starts reporting the status of each plug.
4. When a session starts, the charger sends meter values until the session ends.

Because the address is just a setting, moving a charger to a different backend usually needs no new hardware. You change the address, and the charger reports to the new server.

OCPP 1.6J vs 2.0.1

OCPP 1.6J is the version most chargers in the field run today. OCPP 2.0.1 is newer and is being adopted by newer hardware. The main differences are below.

• Transactions: 2.0.1 replaces separate start, stop and meter-value messages with one transaction event message, which makes sessions easier to follow.
• Security: 2.0.1 defines security profiles, from password authentication to TLS with client certificates.
• Device model: 2.0.1 describes every component of a charger in a standard way, so settings and diagnostics work the same across brands.
• Smart charging: both versions let the backend set power limits; 2.0.1 adds more detail and supports the ISO 15118 standard behind Plug & Charge.

For most charger owners the practical question is simpler: does the backend support the version your chargers run? Savekar's charging management software works with OCPP 1.6J and 2.0.1 chargers from many brands.

What a backend needs beyond OCPP

OCPP only covers the conversation with the charger. A charging business also needs the parts around it, and this is where backends differ most.

• Payments: how drivers pay, and whether the money reaches your own account.
• Pricing: different prices by time of day, plug or customer.
• Roaming: OCPI, a separate standard, lists your chargers in other charging networks' apps.
• Access: logins for partners or site owners who should see only their own chargers.
• Faults: alerts and repair jobs when a charger stops working.
• Integrations: an API so charging data reaches your accounting or fleet software.

Questions to ask before you choose

1. Which OCPP versions do you support, and have you connected my charger model before?
2. Can I move my chargers to another backend later without changing hardware?
3. Where does drivers' money land, and is there a per-session cut?
4. Do you support OCPI roaming, and with which networks?
5. Can I give partners or site owners their own login?
6. How are faults reported, and who fixes them?

Where Savekar fits

Savekar is an OCPP charging management system with appless charging built in: drivers scan a QR code, charge in WhatsApp and pay by UPI.

See the charging management system, compare the plans, or, if you need a backend built around your own requirements, see custom CSMS development.