DC fast charging troubleshooting

A connector can fit and lock, yet charging still fails. In many cases, the issue is not the connector shape. It happens during the charging session: safety checks, communication setup, authorization, or power negotiation.   Here, compatibility means the full path from plug-in to stable energy delivery. The connector standard can match, and the session can still fail to start, stop early, or run at unexpectedly low power.       Checks to do before you change anything 1. Re-seat the connectorUnplug, then plug in again firmly until it is fully seated and latched. Keep the cable straight and avoid side pull.   2. Remove strain on the handleIf the cable weight twists the handle, support the cable or reposition slightly so the connector sits straight.   3. Inspect the connector tipLook for water, dirt, or visible damage. If it is wet or dirty, stop and try a different stall or connector.   4. Try a different stallIf another stall works, the issue is likely tied to the first stall or its connector.   5. Read the station messageNote the exact wording or code. It usually points to payment, communication, safety checks, or temperature protection.   If the session starts and stops more than once on the same stall, switch stalls or switch sites instead of repeating the same attempt.     Symptom to cause map What you see on site Most likely category What to do next “Authorization failed”, “Payment required”, app/RFID step not accepted Authorization and backend approval Confirm the app/RFID/payment step completed, retry once, then switch stall or site “Communication error”, “Handshake failed”, repeated start attempts without charging Communication setup and protocol behavior Re-seat, switch stall, then switch site and report the stall ID + error Plug locks, then stops within 1–3 minutes Contact instability or a protection trigger Remove strain, keep the tip dry, switch stall, avoid repeated retries Charging starts but power is far lower than expected Station limit, battery conditions, negotiated cap, thermal derating Try another stall, compare behavior, check battery state/temperature Works at one site but fails at another Operator rules, firmware differences, backend differences Use a different operator/site, capture error code + time + stall ID Connector locks but won’t release Lock routine or latch friction End the session, unlock the vehicle, then follow the station/vehicle release steps. Do not force the handle     Where failures happen in the charging sequence Charging sequenceConnect and latch→ Safety checks (grounding, insulation, temperature sensors)→ Communication setup (vehicle and station align on protocol and limits)→ Authorization (account/payment, session approval)→ Power negotiation (voltage/current limits, ramp)→ Energy delivery (monitoring and protection)→ Controlled stop and release         Common causes and what typically triggers them 1. Contact instability under cable loadA connector can be inserted but still sit under side load. Small contact resistance can rise under current, which may trigger protective stops or early derating.   Common on-site triggers ·Cable weight pulls the handle down or sideways ·The latch did not fully engage ·There is dirt, moisture, or wear at the contact surfaces   2. Communication setup problemsBefore power flows, the vehicle and station need a stable communication sequence and an agreed set of limits. Differences in implementation can cause a failed start or repeated handshake attempts.   Common on-site triggers ·The station shows a communication or handshake error ·Charging works on one stall but not another at the same site ·It works at one operator but fails at another with the same vehicle   3. Authorization and session approvalA session can be refused even when the hardware connection is solid. The cause can be account state, payment flow, roaming rules, or operator policy.   Common on-site triggers ·The station asks for a step that the app did not complete ·RFID is read, but the session is rejected ·Another site starts normally shortly after   4. Electrical envelope overlapCharging requires overlap between what the station can output and what the vehicle requests. When the overlap is limited, the session can fail during negotiation or run at reduced power.   Common on-site triggers ·The station stays in a negotiating state and then stops ·One hardware generation gives low power while another is normal ·The result changes with battery temperature and state of charge   5. Thermal protection and deratingStations and vehicles reduce current or stop to protect hardware when temperature rises too quickly. This can show up as slow charging, repeated stops, or sensitivity to weather.   Common on-site triggers ·Ambient temperature is high ·The connector is under strain or not fully seated ·Repeated retries are done on the same warm connector     What you can do, and what belongs to the site operator Some actions are in the driver’s control. Others require the site operator or installer.   For drivers Re-seat fully and remove side load Switch stalls early instead of repeating the same attempt Keep the connector dry and off the ground If power drops, try another stall and compare behavior Record the exact message/code, stall ID, time, and conditions   For site operators Inspect and clean contacts; check latch engagement and cable condition Validate grounding and insulation checks Review logs for handshake failures, authorization failures, and thermal events Update station firmware where applicable Improve on-screen guidance so users can separate payment issues from communication or safety stops   For manufacturers and integrators Validate contact stability under real cable load and repeated mating cycles Confirm thermal margins at sustained duty Test interoperability across common vehicle stacks and operator backends Provide actionable error codes and consistent fallback behavior   When to stop and switch approach Stop and switch stalls or switch sites if any of the following happens: The session starts and stops twice on the same stall The connector becomes hot to the touch You notice a burnt smell or visible discoloration The station repeatedly cycles through start attempts without charging   What to record when you report the issue Site name/location and time Stall ID and connector type Vehicle model/year and battery state Exact station message or code (a photo is best) Weather (heat, cold, rain) and whether the cable was under strain Whether another stall worked     FAQ Why does it work at one site but fail at another?Operators can differ in station firmware, backend authorization rules, and protection thresholds. Battery conditions can also change the negotiated result.   The plug fits and locks. Doesn’t that mean it should charge?Fit and lock confirm the mechanical interface. A charging session still depends on safety checks, communication, and authorization.   Is this an adapter problem?If the connector standard matches, swapping adapters usually does not help. Focus on seating, strain, station behavior, and the stage where it fails.   What should I send to the operator or installer?Share the stall ID, time, connector type, the exact error message/code, and whether another stall worked. Add weather and battery state if you can.     Workersbee note For fleets and CPO projects, stable interfaces reduce avoidable session failures. Workersbee supplies EV charging connectors and cable assemblies designed for repeatable mating, secure locking, and consistent contact performance across cycles. We also support connector selection and validation around your target use case, duty cycle, and environment.