Generator will not crank; controller shows AL07 – Battery Voltage Low

Safety first: Ensure the generator cannot start automatically. Turn selector to OFF and isolate external start signals.

• Measure battery voltage: Use a multimeter across the 12 V or 24 V battery bank. If below about 12.2 V (for 12 V) or 24.4 V (for 24 V), the batteries are undercharged.
• Inspect terminals: Check for white/green corrosion on battery posts and cable lugs. Clean with a wire brush and apply dielectric grease. Tighten all connections securely.
• Check battery charger: Locate the FG Wilson or third-party charger in the control panel. Confirm it has AC supply and that its DC output matches the battery voltage. Indicator LEDs should show charging status.
• Charge or replace batteries: If batteries are old or will not hold charge, replace with the correct CCA-rated starting batteries. Dispose of old batteries properly.
• Retest: After charging or replacement, clear the alarm and attempt a MANUAL start. Verify that the controller no longer reports low DC voltage.