AL15
SDMO
Generator Undervoltage
Controller displays AL15 indicating generator undervoltage; output voltage is below nominal.
Advertisements
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.
Advertisements
Possible Causes
Weak excitation due to failing AVR, Loose alternator stator or rotor connections, Excessive load causing voltage sag, Shorted alternator windings
How to Fix / Troubleshooting
Safety first: Disconnect all loads from the generator before testing. Undervoltage under load can damage motors and electronics.
- Measure no-load voltage: Start the SDMO generator and measure line voltage with no load. If still low, suspect AVR or alternator issues.
- Inspect alternator terminals: Tighten all power and sensing connections in the alternator terminal box. Look for burnt or discolored insulation.
- Check AVR: Verify that the AVR receives correct sensing voltage and DC excitation output. If excitation is low or unstable, replace the AVR.
- Test under moderate load: Apply a balanced load (25–50% rated) and monitor voltage. If it collapses, the alternator windings may be damaged and require professional testing.
- Reset AL15: After repairs, clear the alarm and perform a full functional test.
Advertisements
Repair Difficulty
Hard
4/5
Required Part
Automatic Voltage Regulator (AVR)
Check Price on Amazon
We may earn a commission from links on this page.
Advertisements