INPUT VOLTAGE LOW
OpenEVSE
Undervoltage Detection
Display shows 'INPUT VOLTAGE LOW' or 'LOW VAC', charging may not start or runs at reduced current.
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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
Undersized supply wiring causing voltage drop, Loose line or neutral connection, Utility brownout or low service voltage, Faulty AC voltage sensing circuit on main board
How to Fix / Troubleshooting
Safety first: Low voltage can overheat motors and electronics. Do not force charging at full current when voltage is low.
- Step 1 – Measure supply voltage: With a multimeter, measure voltage at the EVSE input while charging (if possible). Compare to nominal (e.g., 240 V). If significantly low, reduce current or pause charging.
- Step 2 – Inspect connections: With power OFF, tighten all line and neutral terminals in the EVSE and at the breaker panel. Look for signs of overheating.
- Step 3 – Check wire size: Verify that the branch circuit wire gauge is appropriate for the breaker size and run length. Long runs may require larger wire to limit voltage drop.
- Step 4 – Utility check: If house voltage is low on multiple circuits, contact your utility provider.
- Step 5 – Board sensing: If measured voltage is normal but the EVSE reports low, the AC sensing circuit on the main board may be faulty. Replace the main control board.
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Repair Difficulty
Medium
3/5
Required Part
OpenEVSE Main Control Board
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