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.

Diagnosing starting issues: Battery or charger

Starting issues in home standby generators can arise from various sources, such as battery and charger problems or other mechanical issues. This guide provides a systematic approach to differentiate between these problems, with an emphasis on the importance of situational awareness and seeking professional help when necessary. See “How Can I Find a Generac Service Dealer in My Area?” for more information.

Checking the battery is a fundamental first step in troubleshooting generator starting issues. However, differentiating between battery, charger, and other mechanical issues requires careful consideration of the symptoms and external factors. For persistent or unclear issues, especially with new installations, consulting a professional is crucial for a safe and accurate resolution.

Environment

This article applies to air-cooled Home Standby Generators 10 kW – 28 kW.

Troubleshooting flow

For safety reasons, the manufacturer requires that this equipment be initially installed by an IASD or other competent, qualified electrician or installation technician who is familiar with applicable codes, standards, and regulations. The operator also must comply with all such codes, standards, and regulations. Repair generally requires simple replacement of the assembly with a new unit, which can usually be performed by the generator owner.

The guide aims to assist in diagnosing common generator starting issues and is for informational purposes only. Electrical systems can be complex and dangerous. If in doubt or if issues continue, it’s essential to seek professional assistance. Prioritize safety and adhere to the owner’s manual guidelines to prevent potential equipment damage.

1. Initial assessment

• Check for errors or alarms
  • Check Mobile Link for notifications.
  • Check the LED indicator on the side of the generator.
  • If your controller has a display, check the display for errors or alarms.
• If the generator cranks but doesn’t start, the issue is likely not with the battery.
• If it does not crank in Automatic mode, try starting in Manual mode.

2. Manual mode testing

• Cranking in Manual mode but not starting usually indicates a non-battery issue.
• Failure to crank in Manual mode suggests a potential battery or connection issue.

3. Battery health check

• Check the battery’s health status.
  • This is displayed in the generator information page in Mobile Link.
  • For Evolution controllers, the battery status can be checked on the display.
• Measure the battery voltage with a multimeter. A fully charged 12V battery should show around 12.6V.
  • Mobile Link will display the voltage for Power Zone 200 (PZ200) controllers.
  • If you are comfortable with the process, you can perform a voltage test with a multimeter.
• Review status history for alarms indicating charging issues.
  • How to view generator status history in Mobile Link
  • For Evolution controllers: How do I check the alarm log on my generator’s control panel?

4. Investigate battery and charging system

Warning: Generac does NOT recommend end users attempt to modify or service internal generator wiring or attempt to service the transfer switch. How Can I Find a Generac Service Dealer in My Area?

• For a completely dead battery, inspect the T1 customer connection at the generator and automatic transfer switch (120VAC). Check for the charging circuit neutral if applicable.

Note: For more information on the battery charging circuit’s neutral connection, see this article.

• Check the T1 fuse for damage, as a blown fuse can interrupt the charging circuit.

Note: The CHARGER MISSING AC error indicates that 120VAC is not present on the T1 circuit. If utility power is present to the home, then the T1 fuse in the transfer switch is likely blown and preventing the battery from charging.

Additional troubleshooting

RPM Sensor Loss alarm

This alarm might suggest a battery issue if the unit fails to crank. If the unit cranks, look beyond the battery for issues.

Situational factors

Old battery: When is the last time the battery was inspected or replaced? Battery inspection is part of routine yearly maintenance, and batteries typically last between 3 and 5 years.

Low ambient temperature: Cold weather can affect battery performance; see the article on cold weather kits and battery warmer pads, if applicable.

Fault alarms: “Charger Missing AC” warnings are expected during outages and are not indicative of charger faults.

Considerations for new installs

Wiring checks: Ensure all connections are secure and correctly configured according to the installation manual. See “My Generator was just installed and is giving a ‘Charger Warning’ or ‘Charger Missing AC Warning’” for more information.

Initial charge cycle: New batteries might require an initial 18-hour charge cycle to fully charge, even if the battery is new.

Battery charge: Some new batteries may require a charge before the first use to ensure optimal performance.

Blank display – dead battery (Evolution controllers)

A dead battery may be the result of a defective battery, problems with the charging circuit, or a blown fuse.

If the 7.5 AMP controller fuse is blown, the controller’s charging mechanism is unable to function, thus preventing the battery from going on a charge cycle. Over time this can result in a low, very low, or dead battery.

If the battery is dead, you will need to remove and replace the battery or use an appropriate battery charger (see battery manufacturer guidelines).