OpenEVSE Overheating Connections or Undersized Wiring

EVSE or cable becomes unusually hot to the touch during charging, though charging continues.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Loose terminal screws on line or neutral, Undersized branch circuit conductors, Worn or oxidized contacts in J1772 handle, Overrated current setting for connector rating

How to Fix / Troubleshooting

Safety first: Overheating can lead to fire. If components are too hot to touch comfortably, stop charging and turn off power.

  • Step 1 – Reduce current: Temporarily lower the maximum current setting in the OpenEVSE configuration and see if temperatures drop.
  • Step 2 – Tighten connections: With power OFF, open the enclosure and tighten all terminal screws on the input and output side, including the contactor lugs.
  • Step 3 – Inspect for discoloration: Look for browned insulation, melted plastic, or darkened copper. Replace any damaged wires or components.
  • Step 4 – Check cable rating: Confirm that the J1772 cable and handle are rated for the configured current (e.g., 32 A, 40 A). If not, replace with a properly rated assembly.
  • Step 5 – Verify branch circuit: Ensure the breaker and wire gauge are appropriate for the EVSE's maximum current. Consult an electrician if unsure.
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Repair Difficulty

Medium 3/5

Required Part

J1772 Charge Cable Assembly
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