How often should a standby generator run?
Updated July 2026
A standby generator should self-exercise weekly, typically a 10–20 minute run the controller starts on its own (some newer units are set to biweekly). The catch is that the exercise only helps if you confirm it happened: stand near it once, watch it crank and run smooth, and check the controller for alarm or maintenance lights. A unit that has not run in months is where the trouble hides. The 12V battery goes flat and the fuel gums, so it cranks and dies the night the grid drops.
What changes the interval
| Your situation | Interval | Why |
|---|---|---|
| Factory default (weekly self-test) | Every 7 days | Keeps the battery charged, oil circulated, and contacts clean |
| Newer quiet/eco models | Biweekly | Some makers set a lighter no-load exercise to save fuel |
| Just installed or freshly serviced | Watch the first cycle | Confirm it starts, runs steady, and clears any alarm |
| 12V battery over 3 years old | Load-test or replace | A dead battery is the number-one no-start cause |
| Cold climate, below freezing | Confirm the cold-weather kit | Thick oil and a weak battery both fight a winter start |
| After a long outage or repair | Manual test that week | A hard run reveals a weak battery before the next storm |
| Town has a noise ordinance | Set a daytime exercise slot | Many towns limit early-morning generator runs |
The cost of skipping it
What skipping it costs: a generator that sits for months is the one that fails when you need it. A flat 12V battery runs $100–250 to replace, and gummed fuel means a carburetor or fuel-system clean. Meanwhile the outage it was bought for spoils a fridge and freezer ($300–800 of food) and kills a sump pump, and a flooded basement runs $3,000–10,000+. Annual pro service, oil, filter, plug, and battery check, is $150–400. Watching the weekly exercise is free. See standby generator service intervals for the full maintenance side.
How to do it (10–20 min to observe · pro service $150–400/yr)
- Find the day and time the controller runs its self-exercise, then be near it once to hear the cycle.
- Confirm it cranks, starts within a few seconds, and runs steady for the full run.
- Read the controller screen for warning or maintenance lights and log any alarm.
- Look under the enclosure for oil or coolant drips and listen for surging or knocking.
- Once a month, run a real load test: cut utility power at the transfer switch and confirm it carries the house.
- Keep the battery, oil, and air filter on the annual service schedule.
Knowing the interval is the easy half. OnOtto reminds you at the right interval, and it won't let you snooze it into next year. Tasks persist until they're done, and completing generator exercise checks schedules the next one automatically.
Put this on autopilot, free for 30 daysFrequently asked questions
Should the weekly exercise run with a load or without?
Most home standby units run a no-load self-test weekly, which circulates oil, charges the battery, and keeps the engine limber. That is fine for routine health, but a no-load run never proves the unit can carry your actual house. So add a real load test roughly once a month: cut utility power at the transfer switch, let the generator pick up the load, and watch it hold voltage while the AC, well pump, and fridge all cycle. That is the test that matters before storm season.
What if I have never actually heard mine run?
Then treat it as untested, not as working. A dark controller, a tripped exercise setting, or a dead battery all leave it silent and useless. Go out during its scheduled slot and confirm it cranks and runs, or start a manual exercise from the controller. If it will not start, the usual culprits are a flat 12V battery (2–3 year life) or stale fuel gumming the system. Fix that before the next outage, not during one.
Does the fuel type change the maintenance?
It changes the failure mode. Natural-gas and propane units never have stale-fuel problems, so their weak point is the battery and the starter, which the weekly exercise guards. Diesel and gasoline standby units add fuel that degrades: diesel grows algae and water, gasoline gums in months. Those need stabilizer, fresh fuel, and closer attention to the fuel filter. Whatever the fuel, the 12V starting battery is the part most likely to leave you dark.
How much does professional standby generator service cost?
A yearly service visit runs about $150–400 depending on engine size and whether it needs oil, an air filter, a spark plug, and a battery. Larger liquid-cooled units cost more. Many owners split the work: watch the weekly exercise and do visual checks themselves, then have a technician handle the annual oil change, filter, and load-bank test. A whole-house unit installed runs $5,000–15,000, so the service is cheap insurance on it.