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 your nearest authorized dealer, or contact Generac Customer Service at 1-888-436-3722 (1-888-GENERAC), or www.generac.com with any questions or concerns.

Home standby generator battery alarms and what they indicate

Generator battery alarms are essential tools for identifying potential issues with your generator’s battery or charging system. Promptly recognizing and understanding these alarms is crucial for maintaining the reliability and longevity of your generator. Below is a guide to common battery alarms, including steps to address them and the significance of maintenance reminders.

This article provides an overview of common generator battery alarms and basic troubleshooting steps.

Note: This article is intended for informational purposes only. Electrical systems can be complex and hazardous. If you're unsure or the problem persists, seek assistance from an Independent Authorized Generac Service Dealer (IASD). Prioritize safety and adhere to your generator's Owner's Manual guidelines to avoid risks and potential equipment damage.

• How Can I Find a Generac Service Dealer in My Area?
• Where can I find a user manual or other documentation for my home standby generator?
• For a complete list of air-cool home standby generator error codes, see: Where can I find a list of error codes for my generator?

Environment

This article applies to:

• Generac Next Generation Series 10–28 kW air-cooled standby generators
• Generac Guardian Series 10–26 kW air-cooled standby generators (2017 to present)

Battery access

To gain access to the battery compartment see How Do I Remove the Generator Side Panel? for more information.

Battery charging - quick facts

• The battery charging system is automatic and is not adjustable.
• The battery charger begins a charge cycle when the battery voltage drops below 12.6 VDC.
• Batteries charge on an 18 or 24-hour charge cycle
• If during the charge cycle, the engine cranks for any reason, then the charge cycle is reset
• For more information: How Is My Home Standby Generator Battery Charged and What Voltage Should It Read?

Battery and circuit charging alarms

LED alarm color indication:

• Yellow: Will not necessarily prevent the operation of the unit.
• Red: Will prevent the operation of the unit.

"Low Battery" WARNING

• Triggered when the battery voltage falls below 12.1 VDC. The battery needs to go on a 24-hour charge cycle.
• If the alarm persists after a 24-hour charge cycle, there may be an issue with the battery or charging circuit.
• This could be due to an aging battery, a defective battery, or charging system issues.
• If the battery voltage is low enough, it can prevent the unit from starting.

Troubleshooting next steps

1. Check and confirm the health of the battery; view the battery status on the controller (Evolution control panels only) or in Mobile Link.
   • If the battery condition is “Good” — the battery needs to be charged. Allow 24 hours for the battery to complete a charge cycle before inspecting again.
   • If the battery condition is “Inspect Battery,” proceed to step 2.
2. Check connections. Ensure all battery connections are secure and corrosion-free—particularly the battery terminals. See: How Do I Inspect the Battery On My Home Standby Generator?
3. Use a multimeter to check the battery voltage: How to perform a battery voltage test on a home standby generator with a multimeter.
4. Replace the battery: How do I replace the battery on my home standby generator?

"Very Low Battery" ALARM

This is activated when the battery voltage has dropped below 9 VDC for at least 60 seconds.

Troubleshooting next steps

1. Check and confirm the health of the battery; view the battery status on the controller (Evolution control panels only) or in Mobile Link.
   • If the battery condition is “Good” — the battery needs to be charged. Allow 24 hours for the battery to complete a charge cycle before inspecting again.
   • If the battery condition is “Inspect Battery,” proceed to step 2.
2. Check connections. Ensure all battery connections are secure and corrosion-free—particularly the battery terminals. See: How Do I Inspect the Battery On My Home Standby Generator?
3. Use a multimeter to check the battery voltage: How to perform a battery voltage test on a home standby generator with a multimeter.
4. Replace the battery: How do I replace the battery on my home standby generator?

"Battery Problem" WARNING

This is activated when the battery voltage exceeds 16 volts or the charger current is over 600 milliamperes at the end of an 18-hour charge cycle, suggesting a malfunctioning battery or an overcharging issue.

Troubleshooting next steps

If the unit is part of a new home installation:

Contact a Generac Authorized Service Dealer to professionally diagnose the issue. An IASD may perform the following troubleshooting steps:

1. Examine the charging system: Check the voltage on the charging circuit (120 VAC).
2. Check for loose connections or mixed-up connections with the N1/N2 wires at the generator and transfer switch.
3. Ensure your home standby generator is not missing the Neutral/00 customer connection wire. See: My Generator was just installed and is giving a "Charger Warning" or "Charger Missing AC Warning"

If the unit is part of an existing installation:

Contact a Generac Authorized Service Dealer to professionally diagnose the issue. An IASD may perform the following troubleshooting steps:

1. Visual inspection of battery: Look for signs of damage or overheating.
2. Examine the charging system: Check the voltage on the charging circuit (120 VAC).
3. Consider replacement: Damaged or consistently overcharged batteries may need replacement.

"Charger Warning" WARNING

What it indicates: This alarm signals when the battery voltage is below 12.5 volts at the end of an 18-hour charge cycle, indicating the battery isn’t charging properly.

Troubleshooting next steps

Contact a Generac Authorized Service Dealer to professionally diagnose the issue. An IASD may perform the following troubleshooting steps:

1. Check charger connections: Ensure the charging circuit is correctly connected and has proper voltage.
2. Assess battery health: Test the battery’s charge retention. If the battery is healthy, the issue might be with the charging system.

"Inspect Battery" WARNING

What it indicates: This is a maintenance reminder that appears yearly, signaling it is time for a routine battery inspection. It does not necessarily mean there’s an issue with the battery but serves as a prompt for scheduled maintenance.

*This alarm will not prevent the unit from operating in the event of a utility outage.

Troubleshooting next steps

1. Perform routine maintenance – How Do I Inspect the Battery On My Home Standby Generator?
2. Consult maintenance schedule – ensure all maintenance tasks are up to date according to the maintenance schedule – see Where Can I Find the Maintenance Schedule for My Generac Home Standby Generator?
3. Document/record maintenance.

"Charger Missing AC" WARNING

What it indicates: Common during utility outages, indicating the charger’s AC power source is interrupted. During installation or when unexpected, it could point to wiring issues or a blown T1 fuse, affecting the charging circuit.

Troubleshooting next steps — define the environmental situation

During Installation

Contact a Generac Authorized Service Dealer to professionally diagnose the issue. An IASD may perform the following troubleshooting steps:

1. Verify electrical connections and ensure the charger is correctly installed. See My Generator was just installed and is giving a "Charger Warning" or "Charger Missing AC Warning" for more information.
2. Inspect the T1 fuse; replace it if necessary. The T1 fuse is always under 120 V of current, even when the generator is powered off. Inspecting and replacing this fuse is potentially dangerous and should only be performed by a trained professional.

During Utility Outage

• During an outage, the battery will be charged through the T1 connection while the generator is running. If you see this error in this scenario, either your T1 fuse has blown or there is a more serious issue. Contact your authorized service dealer.

Unexpectedly with Utility Present

• Contact a Generac Authorized Service Dealer to inspect the T1 fuse, replacing it if necessary. The T1 fuse is always under 120 V of current, even when the generator is powered off. Inspecting and replacing this fuse is potentially dangerous and should only be performed by a trained professional.