When you pull up to a public EV charger, plug in, and charging just starts — no card, no app — there are two technologies that might be making it happen. ISO 15118 Plug & Charge (coming soon) (PnC) is the standards-based approach. Autocharge is the simpler pragmatic alternative that emerged in parallel.
Both work; they work differently; they have different trade-offs. This article explains each, compares them, and discusses why both exist and what’s likely to happen long term.
What Autocharge does
Autocharge identifies the vehicle to the charger by reading the vehicle’s MAC address on the charging-pin powerline communication.
The flow:
- User plugs in.
- Vehicle and charger establish basic communication on the pilot pin.
- The charger reads the vehicle’s MAC address from this communication.
- The charger sends the MAC address to its CSMS as an identifier (typically via OCPP Authorize).
- The CSMS looks up: is this MAC associated with a known user?
- If yes, authorize. Start session.
No certificate exchange. No ISO 15118 application-layer messaging. Just MAC-based identification.
For Autocharge to work, the user must have pre-registered their vehicle’s MAC address with the charging network. Setup is one-time per network.
What Plug & Charge does
Plug & Charge uses ISO 15118 certificates for cryptographic authentication. For the full message-by-message walkthrough, see Plug & Charge end to end (coming soon).
The flow (simplified):
- User plugs in.
- Vehicle and charger establish ISO 15118 communication.
- Vehicle presents a contract certificate.
- Charger validates the certificate’s signature and chain.
- Charger sends the EMAID (from the certificate) to CSMS for authorization.
- CSMS confirms the user is authorized.
- Session starts.
For PnC, the vehicle must have a contract certificate from an eMSP that the charger trusts. Setup involves the eMSP relationship plus certificate provisioning to the vehicle.
The key differences
At a high level, the charger decides which seamless method to attempt based on what the vehicle supports.
flowchart TD
A[Driver plugs in] --> B{ISO 15118<br/>supported?}
B -->|Yes| C[Present contract cert]
C --> D{Cert valid?}
D -->|Yes| E[Plug and Charge]
D -->|No| F{MAC registered?}
B -->|No| F
F -->|Yes| G[Autocharge]
F -->|No| H[RFID or app fallback]
style E fill:#dcfce7,stroke:#16a34a
style G fill:#dbeafe,stroke:#2563eb
style H fill:#fef9c3,stroke:#ca8a04A side-by-side comparison.
| Aspect | Autocharge | Plug & Charge |
|---|---|---|
| Standard | Pragmatic, network-specific | ISO 15118 |
| Identifier | Vehicle MAC address | Contract certificate (EMAID) |
| Security | Medium (MAC can be spoofed in theory) | High (cryptographic signatures) |
| Vehicle requirement | Any vehicle with HomePlug GreenPHY | Vehicle with ISO 15118 support |
| Charger requirement | Standard CCS charger | ISO 15118-capable charger |
| Back-end requirement | CSMS supports Autocharge | Full PKI + ISO 15118 stack |
| Cross-network | Limited (per-network registration) | Possible with broader cert trust |
| Setup friction | Register MAC with network | Sign up with eMSP, get certificate provisioned |
| User experience when it works | Equally smooth | Equally smooth |
The user experience is similar when each works. The differences are in security, scalability, and infrastructure requirements.
Why Autocharge emerged
The history is illuminating.
In 2018-2020, ISO 15118 Plug & Charge was the “official” standards-based answer to seamless authentication. But it required:
- Vehicle hardware and firmware support.
- Charger hardware and firmware support.
- Complex PKI infrastructure.
- Vehicle certificate provisioning.
- eMSP back-end integration.
Most of the stack wasn’t ready. Vehicles were starting to ship with PnC capability but the infrastructure took years.
Some operators (Fastned was prominent here) noticed they could implement most of the user-facing benefit without the full ISO 15118 stack. The HomePlug GreenPHY layer that ISO 15118 rides on exposes the vehicle’s MAC address. That’s enough to identify a vehicle, if the user has pre-registered.
Autocharge was born — a pragmatic, network-specific, MAC-based authentication scheme that delivered Plug-and-Charge-like UX years before PnC was deployable at scale.
The trade-offs
Autocharge’s pragmatism comes with limits.
Security. MAC addresses can be spoofed by a determined attacker. In practice, the risk is low (a charger session being initiated using a spoofed MAC would only deliver energy at the spoofer’s expense, not steal money), but the cryptographic robustness of PnC is genuinely stronger.
Cross-network compatibility. Autocharge MAC registration is per-network. Your MAC registered with Network A doesn’t work at Network B. PnC’s certificate-based approach can work across networks that trust the same PKI root.
Per-vehicle setup. Each user-vehicle pair must be registered at each network. Manual setup; not automatic.
Replacement vehicle problem. Buy a new car, you need to re-register the new MAC. Old car’s MAC may still be associated with your account.
Privacy. Your vehicle’s MAC is being broadcast every time you plug in anywhere. PnC’s certificate-based exchange leaks less.
PnC’s standardization solves most of these in theory. In practice, PnC’s infrastructure complexity has slowed its rollout.
Where each is deployed
In 2026:
Autocharge is deployed at:
- Fastned (Europe), which pioneered the approach.
- A number of North American operators that adopted MAC-based auto-detection to smooth the experience for pre-PnC vehicles.
- Several smaller networks on both continents.
- Some installations as a fallback when PnC fails.
Coverage is limited but real. Users with registered MACs at participating networks have a smooth experience.
Plug & Charge is deployed at:
- Tesla Supercharger (for Tesla vehicles natively, expanding for non-Tesla).
- Electrify America (North America).
- EVgo and ChargePoint (newer DC sites, North America).
- IONITY (Europe).
- Most major networks in 2026, with growing coverage.
The PnC coverage is now broader than Autocharge, having caught up in 2022-2025.
Why both exist long term
Even as PnC adoption grows, Autocharge has some practical advantages that may keep it around.
Older vehicles. EVs from 2015-2019 don’t support ISO 15118 PnC. Autocharge works with these.
Fallback when PnC fails. Certificate expired, trust root mismatch, PKI issue — Autocharge can still work where PnC doesn’t.
Operator-controlled deployment. Autocharge doesn’t require participating in any external PKI. Operator-side decision.
Lower infrastructure cost. No need for the full ISO 15118 + PKI stack.
For these reasons, Autocharge is likely to persist as a secondary option even as PnC dominates.
The long-term picture
A reasonable projection through 2030.
PnC will dominate as the primary seamless-auth mechanism. Most new EVs and chargers support it. Most major networks support it. Cross-network coverage improves as PKI trust expands.
Autocharge will persist in specific contexts. Fastned and a few others continue. Older vehicles use it. Some networks use it as a fallback.
RFID and app will remain as universal backups. Even with PnC and Autocharge widespread, both will exist for vehicles or situations where automatic methods don’t work. For how these methods stack up, see RFID vs Plug & Charge vs app authentication (coming soon).
The end state: multiple methods coexist, automatic ones (PnC, Autocharge) dominate when available, manual ones (RFID, app) backstop the rest.
User experience considerations
For users, the practical implications.
If you’re buying a new EV in 2026: PnC capability is the future. Verify your vehicle supports it. Sign up with an eMSP that supports PnC at networks you’ll use.
If you have an older EV: Autocharge may be available at networks you use. Register your MAC.
Carry an RFID card. Even with PnC and Autocharge, the universal fallback matters.
Test new networks. Different networks have different auth support. Test before depending on a method.
Be patient with the rollout. Both PnC and Autocharge are still expanding. Coverage improves over time.
For network operators
If you’re a CPO or eMSP deciding what to support.
Support PnC. It’s the standards-based future. Investing here pays off long-term.
Consider Autocharge if it makes sense for your fleet. Some networks add Autocharge for older-vehicle coverage. The implementation effort is modest.
Keep RFID and app working. Don’t deprecate these in pursuit of seamless auth. They’re the safety net.
Track which auth methods are working in your operations. Per-network, per-vehicle-model data informs roadmap.
The honest summary
Autocharge and Plug & Charge are two paths to the same destination: frictionless EV charging without cards or apps. Autocharge is the pragmatic near-term solution; PnC is the standards-based long-term answer. Both are real and deployed; PnC is now dominant and growing; Autocharge persists as a fallback. The user experience when either works is excellent. The underlying technology choices reflect the different priorities of operators and vehicle makers in the 2018-2024 period — pragmatic vs principled. The market is converging on PnC as the standard with Autocharge as a useful complement.