Charging Slowed — Some AC Phases Not Powered

Common Symptoms

• Alert on the touchscreen: "Charging slowed - Some AC phases not powered — Check power source and charging equipment"
• AC charging runs slower than the equipment's rated speed
• Most relevant on three-phase charging installations (common outside North America)
• DC fast charging / Supercharging still works normally

Probable Causes (Ranked by Likelihood)

• One or more of the onboard charger's power converters isn't receiving the necessary AC input voltage — e.g. a missing phase during three-phase charging, caused by the external equipment or its power source Likely
• A condition affecting the vehicle's onboard charging hardware (per Tesla, this alert usually points to the external equipment or power source) Unlikely

Step-by-Step Diagnostic Procedure

1. On a three-phase installation, this alert usually means one phase is missing from the supply — a tripped single-phase breaker, a wiring fault, or a supply-side issue. The vehicle keeps charging on the remaining phase(s), just slower.

2. Per Tesla's official guidance: try charging with multiple, different types of charging equipment to isolate whether the equipment or its supply is at fault.

3. If one installation consistently triggers this, have an electrician check its phases, breakers, and wiring.

4. Supercharging is unaffected — a Supercharger or Destination Charger is a good fallback. If the alert follows the vehicle across known-good equipment, schedule Tesla service.

Frequently Asked Questions