Session Management

Payter return a sessionId to Charger Controllers when an EMV Card is successfully Authorized. As covered in Setting the Authorization Amount, Controllers can select the amount to be Authorized. This amount is then reserved in the cardholder’s account, reducing the available balance to spend.

There are two ways an amount is finalised:

1. The charge session stops.
   This is done by the driver or Charger Controller, sometimes with input from the Payter terminal.

2. The charge session is cancelled or otherwise never starts.
   Usually an error with the Charge Station, this scenario can also occur when an inexperienced driver is using the Charge Station, or changes their plans.

Typically, scenario 1 is covered with the normal ‘happy’ flows described elsewhere on this site. It is a fundamental requirement that the final amount is confirmed to Payter by the Charger Controller, and this is a key success criteria for the Charger Controller as well. Scenario 2 however is less obvious, especially where the Charger Controller is not familiar with card payments or the industry generally.

If a sessionId is not cancelled, it can take weeks and sometimes months for the reserved amount to expire from the cardholders “Pending Transactions”.

The time taken for this expiry varies greatly across the many hundreds of Visa, Mastercard and American Express Card Issuers. It is therefore vitally important that the Charger Controller is aware of any and all ‘open’ sessionId’s and uses Commit and Cancel commands in a timely fashion to ensure only active charging sessions are open.