DC Under Voltage

What does F48 mean?

This Automatic Fault indicates a DC under-voltage shutdown that occurs if the DC voltage stays below the Low Battery Cut Out (LBCO) for a specified delay. The inverter restarts when the voltage reaches LBCO + LBCO Hysteresis, suggesting similar troubleshooting steps as F47.

• Degraded battery bank capacity or high internal resistance causing significant voltage drop under load.
• DC bus cabling excessive length or insufficient gauge (e.g., AWG 00) leading to voltage drop under current.
• External DC power supply failure or insufficient output current capability to maintain voltage.
• Low Battery Cut Out (LBCO) parameter (e.g., P3-10) set too high relative to battery bank minimum operating voltage.
• Faulty DC voltage sensing circuit on the inverter control board.

Click steps to track your progress.

1. 1

   1. Measure actual DC bus voltage at the inverter's DC input terminals (e.g., DC+ and DC-) using a calibrated multimeter.

2. 2

   2. Verify the battery bank's state of charge and measure individual battery cell voltages under load to identify weak cells (e.g., cells below 2.0V).

3. 3

   3. Inspect DC bus cabling for loose connections at terminals, corrosion, or signs of overheating. Torque terminals to manufacturer specifications (e.g., 20 Nm).

4. 4

   4. Review inverter parameter (e.g., P3-10 or 'Low Battery Cut Out') and adjust if necessary, ensuring it aligns with battery manufacturer's discharge recommendations.

5. 5

   5. Check for excessive load on the DC bus that might be drawing current beyond the battery or supply capability.