Generator Exerciser Settings and Tuning

Why this matters

The weekly exercise is the single most-important maintenance event for a standby generator. It verifies the generator starts, runs, and produces power; it circulates oil through the engine; it warms the engine to evaporate condensation; it charges the battery. The default exercise schedule on most modern generators (Sunday 12:00, 12 minutes, no-load) is a starting point, not the optimum for every install. Customers complain about noise from Sunday-morning exercises in residential neighborhoods. Some installations need longer exercise to reach full battery charge. Some installations should be exercising under load monthly to verify capability. Tuning the exerciser to the specific situation is the discipline that maintains the system without disturbing the customer.

What exercise does

The weekly exercise:

1. Cranks the engine (verifies battery and starter)
2. Runs the engine for the configured duration (typically 10 to 20 minutes)
3. Engages the generator output (no-load or under-load depending on settings)
4. Runs the engine through full operating temperature
5. Shuts down

Benefits of weekly exercise:

• Battery stays charged (the engine alternator replenishes any losses)
• Oil circulates through the engine (prevents seal drying)
• Combustion chamber stays clean of moisture (prevents rust)
• Cooling system circulates (prevents stagnation)
• Mechanical components stay free (no seizing from disuse)
• Customer sees the generator works (psychological reassurance)

Skipping the exercise:

• Battery slowly discharges (charger may not be sufficient alone)
• Seals dry out
• Condensation accumulates in combustion chambers (especially diesel)
• Mechanical components may seize after extended idle

Exercise types

Default factory settings

Most modern generators ship with:

• Day: Sunday
• Time: 12:00 PM (noon) or 1:00 PM
• Duration: 12 to 22 minutes
• Mode: no-load

These defaults work for most installs but are not optimal for many.

Tuning for customer comfort

Day and time

The default Sunday noon is intentional: Sunday is typically lowest noise sensitivity (people not commuting, not working), and noon is mid-day (not early or late). But:

• Customer who works from home Sundays may find noon disturbing
• Customer who entertains Sunday afternoons may want morning exercise
• Customer in a noise-sensitive HOA may need specific quiet hours

Move the exercise to a time that fits the customer's schedule. Common alternatives:

• Wednesday mid-morning (residential area, low ambient noise hours)
• Saturday morning before noon
• Late afternoon weekday

Avoid:

• Early morning (under 8 AM) - neighbor complaints
• Late evening (after 7 PM) - quiet hours
• Weekend evening - entertaining hours
• Holiday timing - skip if scheduled on holidays in some controllers

Duration

Default 12 to 22 minutes is sufficient for engine warmup and oil circulation. Longer is not necessarily better:

• 12 to 22 minutes: standard, sufficient for normal operation
• 30 to 60 minutes: extended exercise for diesel engines or extended-storage diesel fuel; useful for verifying fuel system
• Very short (under 10 minutes): not recommended; engine may not reach full operating temperature

The longer the exercise, the more fuel consumed and the more wear accumulated. Match to the actual need.

Exercise with load

A no-load exercise verifies the engine starts and runs. It does NOT verify:

• Generator can produce stable voltage and frequency under load
• ATS transfers correctly
• Generator can carry actual loads
• Wiring from generator to ATS to panel works

A with-load exercise (where the ATS transfers actual home loads to the generator briefly) verifies all of the above. The trade-off:

For NFPA 110 commercial installations, monthly with-load testing is required. For residential, with-load is optional but recommended at quarterly or monthly intervals.

Modern Generac, Kohler, Cummins residential generators all support exercise mode selection. Most default to no-load; with-load is a configuration setting.

Configuration procedure (Generac example)

For a Generac Guardian residential standby:

1. At the generator controller, press "Exercise" (or navigate to Settings > Exercise)
2. Select Day (Sunday through Saturday)
3. Select Time (24-hour format)
4. Select Duration (typical 12 or 22 minutes)
5. Select Load (No-Load or With-Load)
6. Save

Verify the next scheduled exercise time on the display.

Configuration via mobile app

For monitored generators (Mobile Link, OnCue, PowerCommand):

• The app typically shows the configured exercise schedule
• The app may allow modification of the schedule
• The app may notify when exercise completes successfully (or fails)

For brand-monitored installations, the app is the easiest interface for the contractor to use.

Exercise verification

After configuring, verify the first scheduled exercise:

1. Note the next scheduled time
2. Visit the generator (or monitor via app) at that time
3. Verify the generator starts
4. Verify the generator runs the full duration
5. Verify the generator stops at the scheduled end
6. Check the controller display for any faults during the exercise

A failed exercise should produce a fault code and (for monitored systems) an alert.

When exercises fail

A failed exercise indicates underlying issues:

References

• NFPA 110 (Standard for Emergency and Standby Power Systems), Section 8.4 (Exercise requirements).
• NFPA 70 (NEC) 2023, Article 700/701/702 (Standby Systems).
• IEEE 446 (Recommended Practice for Emergency and Standby Power Systems).
• Manufacturer literature: Generac, Kohler, Cummins, Briggs and Stratton exercise programming guides.
• Manuall internal: Generator Exercise Cycle, Generator Annual Generator Maintenance, Generator Cold Weather Operation.