Charge Rate Reduced — Unexpected Voltage Drop While Charging

Common Symptoms

• Alert on the touchscreen: "Charge rate reduced - Unexpected voltage drop — Remove extension cords / Have wiring inspected"
• Charging continues but noticeably slower than the equipment's rated speed
• Often appears when charging from a wall outlet or with an extension cord
• Driving is unaffected

Probable Causes (Ranked by Likelihood)

• Problems with the building wiring and/or the wall outlet sagging under charging load Likely
• An extension cord or other wiring that cannot support the requested charge current Likely
• Other high-draw devices on the same branch circuit running while the vehicle charges Possible
• An incompatible charging adapter used with the station (e.g. the wrong adapter type appearing to fit but preventing proper power transfer) Possible

Step-by-Step Diagnostic Procedure

1. The vehicle reduces charge current on purpose when it sees a large voltage drop — sagging voltage under load is the signature of undersized or degraded wiring, which overheats. Take the alert seriously at a home charging location.

2. Remove any extension cord and plug the Mobile Connector directly into the outlet; don't run other high-draw appliances on the same circuit while charging.

3. If using an adapter, confirm it's the correct type: J1772 adapter for J1772 AC stations, CCS Combo 1 adapter for CCS DC stations.

4. If the alert has appeared multiple times at your normal charging location, Tesla's official guidance is to have an electrician inspect the installation: the charging equipment and its connection, the building wiring and outlet, and the utility connection to the building — then decide whether to lower the vehicle's charge current or upgrade the installation.

Frequently Asked Questions