What happens
You plug in the car (or tap the card) and the connector goes to Preparing, but charging never starts. In OCPP, Preparing means the connector is taken but there is no transaction yet: the charger is waiting for something.
Check it in two minutes
Connect the charger to the test server and repeat what you do on site: plug in and tap the card. The log shows every connector status change and what the server answers to the card, so you see which step it gets stuck on. Open the OCPP test server →
The causes, most likely first
1. Authorisation is missing
With the cable plugged in, the charger waits for a card, a start from the platform or a QR payment. If nobody authorises it, it stays in Preparing until unplugged.
How to fix it: Tap the card or start from the platform. If you want it to charge without authorisation, that is free mode, and it is switched on on purpose.
2. The card is rejected silently
The charger asks (Authorize) and the platform answers Invalid or Blocked: an unregistered or expired card, or a prepaid wallet with no balance. Many chargers don't show it on screen: they just don't start.
How to fix it: Check on the platform that the card exists and is active, and that the customer has balance if they prepay.
3. The platform doesn't recognise the charger
If the charger is not registered on the platform, or is registered but nobody has accepted it, the platform answers Invalid to every card and there is no way to start.
How to fix it: Register it with the same identifier it connects with, or accept it if it shows as pending.
4. Authorised, but waiting for the cable
The other way round: if you tapped the card first, the charger waits for the plug for ConnectionTimeOut seconds. If the cable isn't fully in or the car doesn't respond, it goes back to Available when that time runs out.
How to fix it: Check the plug goes all the way in and the car doesn't have a charge scheduled for later.
What askacharge.com does
A charger that connects without being registered doesn't stay silent: it shows up under Chargers, pending, with a notice to accept it. In Real-time you see each connector's status live.
Frequently asked questions
What does Preparing mean in OCPP?
That the connector is no longer free (a cable is plugged in or a card was presented) but no transaction has started yet. It is a waiting state: authorisation or the cable is missing.
How long can it stay in Preparing?
The ConnectionTimeOut configuration key sets it: the time the charger waits, from entering Preparing, for whatever is missing. When it runs out, it goes back to Available.