Every network has a failed-session rate. Few operators know theirs, because failure is not a single event — it hides in sessions that never started, sessions that started and delivered nothing, and sessions that delivered energy but never got paid for. Each of those has a different cause and a different owner.
The eight classes
1. Authorisation refused
The driver presented a tag or started from the app and was refused. Legitimate reasons — expired tag, insufficient balance, station not permitted for that group — should be distinguished from platform faults. The authorisation log should carry the reason, not just the rejection.
2. Payment failed before start
Usually the driver’s bank, sometimes the gateway. This is the largest category on public networks and mostly not your fault — but the abandonment rate after a failed payment attempt is entirely a function of how quickly you let them retry with a different method.
3. Cable or connector not seated
The session reaches Preparing and stops. The charger is fine, the driver did not push the gun home or the vehicle refused the lock. High rates on a specific unit usually mean a worn latch.
4. Vehicle refused the handshake
Common with certain vehicle and charger combinations, particularly on older CCS implementations. The signature is a session that starts, delivers zero energy, and ends within a minute — repeatedly, with the same vehicle model, across different chargers.
5. Charger fault mid-session
The genuine hardware failure. Energy was delivered and then the session terminated abnormally. These need refunds handled automatically and a fault attached.
6. Connectivity loss mid-session
The charger kept charging but the platform lost sight of it. If the charger buffers and replays the transaction on reconnect, this is a reporting delay rather than a failure. If it does not, you have a session with no stop record and a billing problem.
7. Meter values missing
Energy was delivered but not reported, so the session closes at zero or at an implausible figure. The most expensive class, because you either refund a genuine session or bill a driver for a number you cannot defend.
8. Payment capture failed after the session
Energy was delivered, the driver left, and the capture failed on a pre-authorisation that had expired or been released. Recoverable only through follow-up, so the real fix is authorisation sizing and capture timing.
Telling them apart in the data
| Signature | Likely class |
|---|---|
| No StartTransaction, Authorize rejected | Authorisation refused |
| No StartTransaction, no Authorize | Payment failed before start |
| Preparing → Available, no transaction | Cable not seated |
| Transaction < 60s, energy = 0 | Vehicle handshake |
| Energy > 0, StatusNotification Faulted | Charger fault |
| StartTransaction present, StopTransaction late or absent | Connectivity loss |
| Transaction long, energy = 0 or implausible | Meter values missing |
| Session complete, payment status failed | Capture failed |
Which ones are yours
Classes 1, 5, 6, 7 and 8 are the operator’s to fix. Class 3 is partly yours — hardware wear. Classes 2 and 4 belong to the driver’s bank and the vehicle respectively, but they still shape your reputation, so they belong in the report even if not in the remediation plan.
A network that measures this typically finds a failed-session rate between 4% and 12% and can move the operator-owned half of it substantially within a quarter. A network that does not measure it usually believes the rate is around 1%, because that is how many drivers bother to complain.