What Your Charger Screen Is Actually Telling You
Every charger looks different. The messages mean the same things.
Updated March 2026
Short answer
Charger screens show status messages, error codes, and instructions. The wording changes between brands, but the underlying states are the same: available, preparing, charging, finishing, faulted. If you see something you do not understand, the EVcourse app can scan any charger screen and explain it in plain English.
You pull up to a public charger and the screen says something you have never seen before. Maybe it is an error code. Maybe it is in another language. Maybe it just says "Preparing" and nothing is happening.
Every charger manufacturer uses different wording, different colors, and different layouts. But underneath, they all follow the same protocol, usually OCPP (Open Charge Point Protocol). Once you understand the basic states, you can read any charger screen. For hardware-specific guides, see our detailed explainers for Alpitronic Hypercharger screens and Kempower charging screens.
Here is what the most common messages mean, organized by what the charger is doing.
Normal States (Everything Is Fine)
Available / Ready / Idle
The charger is free and working. Plug in your car to start. Some chargers require you to authenticate first (tap RFID card or scan QR code), others let you plug in first. If you are not sure, plug in and see what happens next on the screen.
Preparing / Connecting / Initializing
Your car and the charger are talking to each other. They are negotiating voltage, current limits, and running safety checks. This takes 5-30 seconds for AC chargers and up to a minute for DC fast chargers. If it stays here for more than two minutes, unplug and reconnect. A cold battery can make this phase longer.
Charging / Session Active / Delivering Power
Power is flowing to your battery. The screen typically shows current power (kW), energy delivered (kWh), time elapsed, and sometimes estimated time remaining. The kW number may start lower than the charger's rated speed and ramp up as the battery warms up. It will also taper down as you approach 80% state of charge.
Finishing / Session Complete / Fully Charged
Charging has stopped, either because your battery is full, you reached your charge limit, or the session timed out. Unplug your car. Many chargers charge idle fees if you leave your car plugged in after charging finishes, so move promptly.
Authorization Messages (It Wants You to Pay)
Authorization Required / Please Authenticate
The charger needs you to identify yourself before it will start. Tap your RFID card on the reader, scan the QR code with the charging network's app, or use contactless payment (card or phone) if the charger has a payment terminal. Some chargers need you to do this before plugging in.
Authorization Failed / Card Declined / Payment Error
Your payment method was not accepted. Common causes: the network does not accept your card or app, your RFID card is not registered with this network, your prepaid balance is too low, or there is a temporary payment system issue. Try a different payment method. If you have a roaming card (like Plugsurfing or Chargemap), try that.
Scan QR Code / Use App to Start
This charger does not have an RFID reader or contactless terminal. You need to download the charging network's app, create an account, and start the session through the app. The QR code usually opens the app or a web page where you can authorize. This is common on newer chargers, especially in urban areas.
Warning Messages (Something Needs Attention)
Reduced Power / Power Limited
The charger is working but delivering less power than its rated maximum. This can happen when multiple cars are sharing the same power cabinet, when the charger is overheating, or when grid capacity is limited. Your car will still charge, just more slowly. There is nothing you need to do.
Vehicle Not Compatible / Protocol Mismatch
The charger and your car cannot agree on a charging protocol. This sometimes happens with older cars at newer chargers, or if you are trying to use the wrong connector type. Check that you are using the correct plug (CCS for DC fast charging in Europe, Type 2 for AC). If the connector fits but you get this message, try a different stall or charger.
Charge Rate Limited by Vehicle
Your car is deliberately limiting how fast it charges. This is normal behavior, not a charger fault. Common reasons: the battery is cold (especially in winter), the battery is above 80% state of charge, the battery is too hot from a previous fast charge, or the car's battery management system is protecting battery health. Preconditioning the battery before arriving at a fast charger helps in cold weather.
Session Timeout / Maximum Time Reached
Some chargers have a maximum session length, typically 45-60 minutes for DC fast chargers. The session ended because you hit that limit, not because of an error. Unplug and start a new session if you need more charge. This is more common at busy locations to keep chargers available for other drivers.
Error Messages (Something Is Wrong)
Ground Fault Detected / Isolation Fault
The charger detected electrical current leaking where it should not. This is a safety mechanism. It can be triggered by moisture in the connector, a damaged cable, or an internal charger fault. Unplug, check the connector for water or debris, dry it if needed, and try again. If it persists, use a different charger. Do not try to override this.
Communication Error / PLC Failure
The charger and your car lost their communication link. This is one of the most common errors at DC fast chargers. Unplug, wait 10 seconds, and plug in again. If it keeps happening, try a different stall. The issue is usually on the charger side, not your car. Temperature extremes can make communication errors more frequent.
Emergency Stop / E-Stop Activated
Someone pressed the emergency stop button, or the charger triggered an automatic safety shutdown. Check if a red physical button on the charger has been pressed. If so, twist or pull it to release it (the mechanism varies by manufacturer). If the charger shut down on its own, do not try to reset it yourself. Report it to the network operator and use a different charger.
Over Temperature / Thermal Protection
The charger or the cable is too hot and has reduced power or stopped to protect itself. This happens more often on hot days or when a charger has been running continuous sessions. Wait 10-15 minutes for it to cool down, or use a different stall. Liquid-cooled cables (common on 150 kW+ chargers) are less prone to this.
Connector Lock Failure
The charger cannot lock or unlock the connector in your car's charge port. For locking failures, push the connector in firmly and try again. For unlocking failures (cable stuck), check your car's manual for the manual release location, usually a lever or pull strap in the trunk or under the hood near the charge port.
Out of Service / Faulted / Unavailable
The charger is broken and cannot start a session. Nothing you can do except use a different charger. Report it through the network's app so the operator knows. If the charger shows a specific error code, note it down or scan it with the EVcourse app to see what it means.
What the Numbers on Screen Mean
During an active session, most chargers show several numbers. Here is what each one means:
| Number | What it means |
|---|---|
| kW (e.g. 47 kW) | Current charging power. Higher is faster. This number changes throughout the session. |
| kWh (e.g. 32.4 kWh) | Total energy delivered so far. This is what you are paying for if the charger bills per kWh. |
| V (e.g. 400V) | Battery voltage. 400V and 800V are the two common EV architectures. Not something you need to act on. |
| A (e.g. 125A) | Current flowing to the battery. Power (kW) = Voltage (V) x Current (A) / 1000. |
| SoC (e.g. 62%) | State of charge. Your battery level. Some chargers show this, others do not. |
| Time (e.g. 00:14:32) | How long the session has been running. |
| Cost (e.g. 8.40 EUR) | Running cost of the session. Not all chargers show this on screen. |
Charger Screen in Another Language?
Many chargers default to the local language. Some let you switch to English by tapping a flag icon or language menu. If there is no language option, look for universal icons: a plug icon for "plug in," a card icon for "tap to pay," and a green circle or checkmark for "ready."
The EVcourse scan feature works with any language. Point your phone at the screen and the app reads the text, translates it, and explains what to do next. This is especially useful when charging in a country where you do not speak the language.
Don't recognize the screen? Scan it.
Point your phone at any charger screen and get an instant explanation. Any brand, any language.
Frequently asked questions
Why does my EV charger say 'Preparing' for so long?
The 'Preparing' phase is a handshake between your car and the charger. They are negotiating voltage, current, and safety checks. This typically takes 5-30 seconds but can take up to a minute on DC fast chargers. If it stays on 'Preparing' for more than two minutes, unplug and try again. A cold battery can also extend this phase.
What does 'Authorization Required' mean on a charger?
The charger needs you to identify yourself before it will start. Tap your RFID card, scan the QR code with the network app, or use contactless payment if available. Some chargers require you to authorize before plugging in, others after. If your payment method is not accepted, try a different card or app.
What does 'Ground Fault Detected' mean?
The charger detected a small electrical current leaking to ground, which is a safety concern. This could be caused by moisture in the connector, a damaged cable, or a fault inside the charger. Do not ignore this message. Unplug, check the connector for moisture or debris, and try again. If it persists, use a different charger and report the issue to the network operator.
Can I use the EVcourse app to read charger screens?
Yes. The EVcourse scan feature lets you point your phone at any charger screen and get an instant explanation in English. It works with any charger brand or language. Text recognition runs on your device, and your photos never leave your phone.
Don't understand the screen? Scan it.
Point your phone at any charger or car screen for instant help. Any brand, any language. Free to try on iOS.
Free to try on iOS. Android coming soon. Join the Android waitlist.