Standby Generator Weekly Exercise: How Long It Runs and How to Set It (Generac and Kohler)

A home standby generator spends nearly its whole life waiting. To make sure it will start when the power fails, it runs itself on a schedule while the lights are on. That scheduled run is called the exercise cycle, and it behaves differently depending on the brand. Generac’s owner’s manual describes a short run of about five minutes. Kohler describes a weekly run of about 20 minutes, with several modes if you pair the generator with a particular transfer switch. This guide explains what each maker says, why the exercise exists, what it does to your house while it runs, and what can quietly stop it from happening.

Why does a standby generator exercise itself?

A generator that sits for months can fail the one time it matters. Batteries lose charge, fuel and oil sit still, and a fault can go unnoticed until the outage. The exercise is a regular, low-stakes start that proves the engine cranks, the controller works and the unit can shut down normally. If a problem shows up, it appears as a warning on the controller on an ordinary Tuesday rather than during a storm.

Generac’s manual ties the exercise to the controller’s AUTO position. Its description of the AUTO button says it activates fully automatic system operation and allows the unit to automatically start and exercise the generator according to the exercise timer. The manual also says the exercise feature will operate only when the generator is in AUTO, and that it will not work unless the timer has been set. That is the first practical lesson: a generator left in OFF or MANUAL after service will not exercise, so check the controller mode after service.

How does the Generac exercise cycle work?

The details here come from Generac’s owner’s manual for 60 Hz air-cooled generators, which covers its 10 to 24 kW air-cooled home standby line. The manual is from 2018, so use it as a guide to how the system behaves and check the manual for your own unit’s age and controller.

The manual says the generator has a configurable exercise timer that you can set at the control panel or through the Mobile Link app. There are two settings. The first is the day and time: the unit starts and exercises for a period defined by the manual on the day of the week and time you choose. During that period, the unit runs for approximately five minutes and then shuts down. The second is the frequency, which can be weekly, biweekly or monthly. If you choose monthly you pick a day from 1 to 28, and the generator exercises on that day each month.

Generac’s support center says the same thing from the other direction: Guardian-series air-cooled home standby generators have a non-adjustable five-minute exercise period, though the schedule can run weekly, biweekly or monthly. You cannot lengthen the run, only move it.

What is Quiet-Test?

Generac’s manual describes a low-speed exercise profile called Quiet-Test. The unit runs at operating speed for about five seconds, then drops speed to prepare for the test, reaches the predetermined Quiet-Test speed after about 40 seconds, and keeps running until the test is complete, a total of five minutes. If Quiet-Test is disabled, the manual says the generator exercises at its rated rpm instead.

The reason owners care is noise. A generator at full speed is louder than one at reduced speed, and a weekly run at the same hour can bother neighbors. A lower-speed profile is the maker’s answer to that. The manual does not claim it tests the generator as hard as full speed does, so treat Quiet-Test as a convenience feature and not a replacement for seeing the generator carry a real load.

Does the house lose power while it exercises?

For Generac’s air-cooled units, no. The manual says transfer of loads to the generator output does not occur during the exercise cycle unless utility power is lost. Its controller logic table is more specific: the unit will not exercise if it is already running in AUTO or MANUAL, and during an exercise the controller only transfers if the utility drops for five seconds, a delay the manual says the dealer can program, at which point it switches to AUTO and handles the outage. In other words, the exercise is designed to hand off to the real job if the grid fails mid-test.

That matters if you are the type who worries about a start-up spike in your electronics. On the Generac air-cooled system as described, the house stays on utility power throughout, and the generator is running unloaded.

How does the Kohler exercise cycle work?

Kohler’s exercise FAQ says the weekly exercise runs approximately 20 minutes. It also explains that two Kohler transfer switches can be used with the generator. With an RDT switch, the weekly exercise can be duplicated, and Kohler’s advice is to set the exercise only at the generator or only at the transfer switch, not both.

If the generator is paired with an RXT automatic transfer switch, Kohler says you can choose among three modes. An unloaded cycle runs the engine 10 minutes at exercise speed, then a one-minute transition, three minutes at full speed, another one-minute transition and a five-minute cool-down. An unloaded full-speed exercise runs the engine about 20 minutes at full speed without transferring the load. A loaded full-speed exercise transfers the electrical load to the generator and runs 20 minutes.

Kohler says a loaded full-speed exercise is recommended if possible because it exactly simulates emergency power conditions. The trade-off is easy to see: a loaded exercise proves the transfer switch and the generator can carry the house, but your home runs on generator power for 20 minutes, with the brief transfer that implies. For an owner who works from home, that is a decision worth making deliberately rather than by default.

Which approach is better?

The two makers are designed differently, so the comparison is about what each approach proves. Generac’s five-minute unloaded run confirms that the engine starts, runs and stops, and the controller reports faults. Kohler’s 20-minute cycle gives the engine more time to warm up, and the loaded option checks the transfer. Neither maker claims its approach makes a unit last longer than another maker’s, and we do not either.

What you should take from the comparison is that a longer run is not automatically better: the right exercise is the one your maker designed for your controller and transfer switch. Our Generac vs Kohler comparison covers the broader differences between the two brands.

What can stop an exercise from running?

The sources point to a handful of practical causes. Generac says the exercise runs only in AUTO, so a unit left in OFF or MANUAL will skip it. The manual also says that without Wi-Fi, the current date and time need to be reset every time the 12 volt battery is disconnected and reconnected, or when the fuse is removed. If the clock resets to a default, the exercise happens at the wrong time or not at all. With Wi-Fi enabled the timer adjusts automatically for daylight saving time.

The manual’s list of protection alarms includes “Exercise Set Error,” along with low battery and battery problem warnings, which means the controller flags a bad exercise schedule or a weak battery on its display. The battery itself is a field-supplied part: the manual lists a 12 volt Group 26R battery with a 540 CCA minimum or a Group 35 AGM with a 650 CCA minimum. A weak battery is one of the simplest ways to turn a routine exercise into a failure to start, which is why battery checks appear in the maintenance section of the manual.

What should I check on my own generator?

Treat the exercise as a status report. Confirm the controller is in AUTO and that the date and time are right. Note the exercise day so you can listen for it, and look at the display after the run for any warning. If you replaced or disconnected the battery for any reason, check the clock again. If you use Wi-Fi monitoring, confirm it still reports in.

Then connect the exercise to the rest of your maintenance. Our standby generator maintenance guide covers oil, filters and the service schedule, and our guide to standby generator fuel consumption helps you plan what an outage run costs. For the bigger picture on what a system costs to put in, see standby generator installation cost.

Common questions

How long does a Generac standby generator exercise? Generac’s manual for its 10 to 24 kW air-cooled generators says about five minutes, and Generac’s support text says the Guardian-series period is non-adjustable.

How often can I schedule it? Weekly, biweekly or monthly, per Generac’s manual. Monthly uses a day from 1 to 28.

Does the house lose power during an exercise? Not on the Generac system as described. Loads transfer only if utility power is lost. On Kohler with an RXT switch, the loaded full-speed mode does transfer the load for 20 minutes by design.

What is the Kohler exercise length? About 20 minutes for the weekly exercise, with an unloaded cycle that includes 10 minutes at exercise speed plus transitions, full-speed operation and cool-down, totaling 20 minutes.

Why did my generator not exercise this week? The sources suggest checking that it is in AUTO, that the date and time were not reset by a battery disconnection, and that no alarm such as a low battery or exercise error is showing.

Bottom line

The exercise is a weekly check that your generator will start when needed. Generac describes about five minutes and Kohler about 20, and each depends on the controller being in the right mode with the right clock. Check your own manual, keep the battery healthy, and check today’s price if you are comparing models in our best standby generators of 2026 guide.