How does an access control system in a charging station work?
When presenting a charging card to a charging station, the control system performs two operations: authentication of the tag (the Hidden ID) and determination if it has sufficient credentials to open a specific lock (a.k.a. the white list lock in a charging station).
The key (NFC tag) and lock mechanism (White List) for a charging station work just like any other. For example, you may have a card with an NFC tag to enter the gates at your gym and nowadays you have a bus or train card which also work the same way.
When talking about charging cards in the EV sector we have a Visible ID and Hidden ID. The Visible ID is letter and digit combination that is visible on the charging card and a Hidden ID is a NFC tag that is not visible to the eye but can be acquired.
Charging cards have NFC tags which have an unchangeable serial number (also known as a UID or tag code – or to us, a Hidden ID) baked into the chip at the factory. For most tag technologies, each manufacturer is assigned a block of tag codes to use for their tags, which the manufacturers generally then assign in a globally unique fashion. In order to use this serial for authentication, the charging stations can be programmed with a white list of tag codes that they should accept. If the locks are provided with individualised white lists, the tag code also functions as the access credentials. Alternatively, a system-global ‘white list’ that contains all the tags in the access control system may be used, in which case the tag contains its credential information in its read/write memory. In the Netherlands, this access control system is known as the CIR (Central Interoperability Register). The CIR is a data server consisting of all Tag Ids provided by Service providers in the Netherlands.
Where to charge, where can you charge and with which card?
Everyone’s wallet is growing daily with the amount of cards and in the EV sector, we also found this was a simple solution. However, things may get complicated when you receive a card from a charge point operator, your lease company or from another business.
Which one do you use?
To explain this, we need to understand three types of charging stations:
- Standalone: A charging station that does not have a connection with a back office or an access control system known as the CIR.
- Charging station and back office combination: A charging station connected to a back office
- Charging station, back office and CIR combination: A charging station connected to a back office and the CIR (reminder here, only applicable in the Netherlands, every country has its own solution for this)
On charging station #1 Standalone you can only start a charging session with charging cards that are listed in the White list. These charging stations are usually private at-home charging stations.
On charging station #2 Charging station and back office connection you can start a charging session with a charging card that is listed in the White list, but not with a charging card from a Service provider because this charging station has no connection with the CIR.
On charging station #3 Charging station, back office and CIR connection (a.k.a. public charging station) you can start a charging session with a charging card you received from your Service provider and if your charging card (very unusual when talking about public charging stations) is listed in the White list, you are also able to start a charging session.