IMPORTANT: Read the manual thoroughly and understand all of the instructions, cautions, and warnings before using this equipment. If any section of the manual is not understood, contact an Independent Authorized Service Dealer (IASD), contact Generac Customer Service at 1-888-436-3722 (1-888-GENERAC), or visit www.generac.com with any questions or concerns.

Charger Missing AC code 2780

Home standby generators may display Charger Missing AC code 2780 when the controller does not detect the expected voltage on the T1 battery charging circuit.

WARNING: Generac does not recommend end users attempt to modify or service internal generator wiring or attempt to service the transfer switch. For assistance, see How Can I Find a Generac Service Dealer in My Area?

Independent Authorized Service Dealers (IASDs) are trained to diagnose and resolve these issues. Use the dealer locator to find a service dealer.

Environment

This warning can occur on Generac home standby generators. On Guardian Series generators, the warning displays on the controller or in Mobile Link. On Next Generation Air-Cooled Standby generators with a Power Zone 200 controller, the warning displays in Mobile Link.

A limited number of Next Generation Air-Cooled Standby generators may display Charger Missing AC code 2780 even when the generator is operating normally and the battery charger is maintaining the battery. Click here for instructions on how to verify proper battery charging and voltage.

Overview

Error code: 2780

LED indicator: Yellow

Message type: Warning

Message: CHARGER MISSING AC

Issue: Code 2780 normally indicates that the controller is not detecting the expected 120 VAC on the T1 battery charging circuit. This may be caused by an issue with the T1 wire or T1 fuse. On a limited number of Next Generation Air-Cooled Standby generators, the warning may remain displayed even though the battery charging system is operating normally.

Scenarios

During an active outage when the generator is running

During an outage, the T1 charging circuit must receive power from the generator. Charger Missing AC may occur if the automatic transfer switch did not transfer to generator power or the generator main line circuit breaker (MLCB) is not set to ON. Check that the MLCB is set to ON. If the generator is running but power did not transfer to the home, see Troubleshooting Automatic transfer switch issues.

When utility power is available

• A qualified technician can use a multimeter to confirm the voltage received on the T1 wire. The T1 charging circuit should receive 120 VAC when utility power is available.
• A qualified technician can inspect the T1 fuse inside the transfer switch to determine whether it has blown. If the fuse is blown, it must be replaced by qualified personnel. For assistance, see How Can I Find a Generac Service Dealer in My Area?

What if my battery is charging normally but the warning will not clear?

A limited number of Next Generation Air-Cooled Standby generators may display Charger Missing AC code 2780 even though the generator and battery charger are functioning normally. This may be a nuisance warning when a qualified technician confirms all of the following:

• The battery voltage is greater than 12.1 VDC
• The battery charger is maintaining the battery properly
• The T1 wiring is correctly connected
• The T1 fuse has been inspected and is not blown

If the battery voltage is less than 12.1 VDC, contact an IASD for further diagnosis and battery evaluation.

Note: If a qualified technician confirms the conditions above, the Charger Missing AC warning may remain displayed even though the generator is functioning normally. The generator should continue to exercise and operate during an outage, and this warning does not by itself prevent the generator from running.

If the battery voltage is greater than 12.1 VDC, the battery is charging properly, the T1 wiring and fuse have been verified, and the warning persists, contact an IASD using the dealer locator. The dealer can work with Generac Technical Support to determine whether this known warning condition applies to the generator. Generac is actively investigating this behavior.

For a standard Charger Missing AC condition caused by missing T1 voltage, code 2780 should clear automatically after the underlying issue is corrected. If the warning does not clear, further diagnosis may be required. On qualifying Next Generation generators described above, the warning may remain displayed even though the charging system is operating normally.

See also

• What is the T1 fuse in my transfer switch?
• Understanding the home standby generator's battery charging system
• My Generator was just installed and is giving a "Charger Warning" or "Charger Missing AC Warning"
• For a complete list of home standby generator error codes, see Where can I find a list of error codes for my generator?