NFC at EV Charging Stations: How Tap-to-Charge Works Offline

Tap-to-charge uses NFC to identify your account at an EV charger, so you can start a session by touching your phone to the unit instead of opening an app. Some chargers can approve that tap with no network at all, using a list of known user IDs stored on the charger itself.

What it is

The clearest recent example is SWTCH Tap. SWTCH Energy announced it on April 7, 2026 as a feature of its Cortex platform. The problem it targets will be familiar: underground garages and remote sites often have poor cellular coverage, so the app that starts your charge can't load. As Electric Autonomy reported, SWTCH's Thomas Martin said more than 80 percent of its users authenticate through the app, which is exactly the method that fails in a basement.

NFC fits because it needs no signal. It's a short-range radio link between your phone and the charger, nothing more.

How a tap starts a session

Per SWTCH, there are three situations:

1. Everything online. The tap gives you a one-click Start page, with no QR code or station ID to type.
2. Your phone has no signal. The charger recognizes your SWTCH account over NFC and authenticates the session locally.
3. The whole site is offline. Authorization relies on local intelligence, either SWTCH's Nexus edge layer or user IDs cached on the charger.

In the Electric Autonomy account, the charger reads your phone's credentials, identifies the account, and authorizes the session. SWTCH chargers already include NFC hardware, so no new equipment is needed.

Under the hood this is the same radio layer as an RFID charging card. NFC is based on ISO/IEC 14443, works at 13.56 MHz, and has a range of roughly 4 to 10 cm. If you wonder how NFC and Bluetooth differ, this is the short-range, no-pairing side of that split.

Why it works offline

An offline charger can't ask the cloud whether a driver is allowed. So it answers from memory. SWTCH says it uses a standard OCPP framework to cache authorized users locally, then bills later in a "store and forward" model: the session starts immediately, and the transaction data syncs once connectivity returns.

OCPP, the protocol chargers use to talk to their network, describes two mechanisms. Easee's configuration reference lists the keys:

• Authorization Cache: a record the charger fills itself from identifiers it has already seen authorized.
• Local Authorization List: a list the backend pushes to the charger.
• LocalAuthorizeOffline: whether the charger may start a transaction for locally authorized IDs while offline.
• AllowOfflineTxForUnknownId: whether it may also accept IDs it has never seen.

That last one is a policy choice, so offline behavior differs by operator and charger.

Some questions remain open. SWTCH hasn't published how long a charger can stay offline, how many IDs it stores, or how a cached ID is revoked. Its claim that the tap works regardless of network status is the company's own, with no independent test data behind it.

Where you'll see it

Most public chargers already accept an ISO 14443 RFID card. ISO 15118 Plug & Charge is a different method: it uses digital certificates over the charging cable and is not directly related to NFC. A car with a registered certificate can skip the tap entirely, while others fall back to a card or phone.

The pattern resembles tapping a bank card on the subway: a quick local read, with the heavy accounting done afterward.

Tips, gotchas, and a quick check with NFCore

SWTCH hasn't said which phones are supported, so confirm with your network before relying on it. A thick phone case can also weaken an NFC read.

If you carry a charging card you own, you can see what kind of tag it is. Scan it in NFCore on iPhone or on Android to read its type and UID. Only inspect cards you own, and keep in mind that iOS exposes less of the NFC stack than Android does. Operator-issued cards are usually locked to the network's own system anyway.

Conclusion

A tap works offline because the charger already knows who is allowed, and settles the bill later. Check your network's offline policy before you depend on it.

Frequently Asked Questions

Does tap-to-charge need cell signal?

Not for SWTCH Tap, according to SWTCH. The charger recognizes your account over NFC and authorizes locally. Other networks may behave differently.

Is NFC charging the same as Plug & Charge?

No. Plug & Charge (ISO 15118) uses certificates over the cable. NFC taps use ISO 14443 at 13.56 MHz.

Can an offline charger approve anyone?

Only if the operator allows it. OCPP has a setting for unknown IDs, and cached IDs are the normal path.

Can I use any NFC phone?

SWTCH hasn't published supported phone models, so check with your charging network.