Schumacher Metering / Current Sensing Inaccuracy

Charger display shows incorrect amperage or energy readings compared to the vehicle or an external meter.

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.

Possible Causes

Drifted current transformer calibration, Firmware bug in metering, Loose CT harness, Faulty metering IC on control board

How to Fix / Troubleshooting

Safety first: Ensure the charger is installed per the manual before relying on its metering for billing or load management.

Compare readings: Use a clamp meter (qualified person) on the output conductors to compare actual current to the display.
Firmware update: Install the latest firmware, which may correct metering issues.
Reseat CT harness (qualified only): With power OFF, open the unit and ensure the CT sensor harness is firmly connected.
If inaccuracy remains significant: The CT sensor or control board metering circuit may need replacement.

Repair Difficulty

Hard 4/5

Required Part

Output Current Transformer (CT) Sensor

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