Why you need to exercise your generator regularly

Why you need to exercise your generator regularly? In this blog, we discuss the importance of load testing and maintenance tips to keep your generator ready.

July 7, 2023
BY BISON

To ensure your power system is truly ready for an emergency, simply starting it occasionally isn’t enough. Regular “exercise”—specifically running your generator under load—is the most critical step in maintaining long-term reliability.

As a generator manufacturer, we emphasize that there are two distinct types of operation: no-load and on-load. While running a generator without a load may seem sufficient, it is the on-load operation that truly prepares the engine and critical components for real-world outages. Running your generator under load for extended periods generates the necessary heat to burn off condensation and prevent moisture buildup, which is essential to safeguarding your equipment against internal corrosion and performance degradation.

Why you need to exercise your generator regularly? In this blog, we discuss the importance of load testing and maintenance tips to keep your generator ready. Generators should be run at no load once a week to once a month. Load testing should be done monthly or quarterly. If your unit runs on diesel, plan on exercising it more frequently than a natural gas or propane model, since fuel degradation occurs faster in storage and stale fuel can cause hard starts or clogged injectors.

The run cycle of your inverter generator can be automated by a timer, ensuring regular testing of the generator. Gensets that generate electricity regularly for long periods do not require the same exercise cycle. In this case, unreliable grid power replaces the exercise cycle. If you rely heavily on your generator, routine maintenance is crucial!

Getting your generator ready for wildfire season

In Northern California, we are approaching the red zone as we face the threat of hot weather, high winds, and wildfires. At the same time, we should deal with intentional blackouts to protect an overloaded grid.

Whether a small portable generator or a large gensets, a generator is the go-to support for your backup power reliability strategy. That is why, regardless of generator type, a consistent weekly exercise routine is the foundation of reliable backup power.

Weekly generator exercise

During a power outage, reliable operation is critical, but generators are often overlooked between emergencies. It would help to run your generator weekly or at least every other week, and at a minimum once every 30 days for about 20-30 minutes, ideally under some load.

If a generator is not operated for an extended period, its power generation capacity will decrease. Fuel can begin to break down, the battery can lose its charge over time, and oil that isn’t recirculating can leave moving parts dry and stiff, so run the unit and check for fuel levels, leaks, loose connections, frayed wires, and anything interfering with smooth operation.

Even if it’s running, make sure it delivers the rated power. Exercising your generator under load helps flush the fuel lines, keeps the battery charged, and recirculates oil so parts don’t stiffen or wear prematurely — all part of a complete maintenance program to ensure your generator works when you need it.

Exercise your backup generators to maintain operational readiness

Backup generators need an exercise program unless your local utility has frequent outages (more than a few seconds). It is standard practice to set the ATS or switchgear controls to automatically start the engine and run it idling (without ATS transfer) for approximately 30 minutes; this is done weekly, but not less frequently than monthly. Exercises can also be started manually. If activated automatically, the operator should be on-site to observe average performance.

However, running the generator at a heavy load regularly is essential to prevent wet stacking, where unburned diesel accumulates in the exhaust system. A minimum of 40% load should be applied at least quarterly and at most once a month. Suppose a sufficient building load and the risk of equipment failure under test is acceptable. In that case, generator testing under load can be done by performing an ATS transfer after starting the generator. For the open transfer ATS, two brief power surges during the transfer and re-transfer tests caused the lights to flash, the UPS and batteries were also affected, and critical loads not protected by the UPS were affected.

For closed transfer ATS or switchgear, the risk of failure may be higher during brief synchronization and paralleling, but no power fluctuations during transfers or re-transfers. Load banks can be used when there is not enough building load or if there is concern about the risk of live diversion and unnecessarily running the facility on the generator. A permanent load bank rated at least 40% of the engine capacity can be installed, purchased, and built into the generator enclosure. This equipment applies a controlled electrical load to the unit, which reveals how it actually performs under real demand rather than simply confirming that it starts.

7500-watt big power generator for home-2

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While the system is running, either during testing or during a utility power failure, the following observations should be made:

normal engine sounds and vibrations
stable voltage and frequency
no excessive exhaust
normal engine temperature
Proper fuel transfer, especially between main and day tanks (if applicable)
normal oil pressure
No engine oil leaks, fuel leaks, or coolant leaks
no alerts or reminders
Record actual loads and conditions (time of day, day of week, critical building loads on or off) – tracking substantial building loads is vital to overall load management.
Critical load acceptance of generator power (UPS, HVAC, drives, etc.)

Routine maintenance and load bank testing serve two distinct purposes and are best treated as separate checklists rather than one blended task. Maintenance addresses the generator’s physical condition — fluid levels, filters, batteries, and connections — while load bank testing separately evaluates whether that condition actually translates into stable, adequate performance once real electrical demand is applied.

To keep your generator reliable, routinely check fuel, oil, and coolant levels, keep a maintenance log tracking run hours and issues, and schedule periodic professional inspections to catch problems before they cause a failure. A solid maintenance routine should include: following the manufacturer’s oil and filter change interval, adding fuel stabilizer to fuel that will sit unused for extended periods, keeping batteries clean and properly charged, and periodically checking that the transfer switch engages correctly.

Watch for warning signs like unusual noises, rough or uneven running, difficulty starting, excessive vibration, or smoke and odd smells from the exhaust—these signal fuel, battery, or mechanical issues requiring prompt attention.

While routine self-tests confirm that a generator’s engine cranks and controls respond, they cannot validate whether the unit will actually deliver stable voltage and frequency when powering real equipment during an outage. A comprehensive maintenance program should include periodic load testing to ensure the generator performs reliably under genuine electrical demand, not merely that it starts.

Load bank testing becomes particularly valuable for homeowners whose generators seldom experience genuine operational stress, as this specialized procedure simulates full-capacity loads to prevent wet stacking—a condition where unburned fuel accumulates in the engine—and validates the system’s readiness during actual emergencies. To properly test capability, ensure lubrication throughout the engine, and evaporate accumulated moisture, connect the generator to a load of at least 50% of its maximum rated capacity and let it run for a minimum of two hours. Larger residential standby systems or those in areas with infrequent power disruptions are especially strong candidates for periodic load bank testing to ensure they can reliably deliver their rated output when called upon.

Conclusion

Caring for your generator is essential to its longevity and reliable performance. By following manufacturer guidelines, considering your specific needs, and incorporating expert tips, you can determine how often to exercise your generator and keep it running smoothly. Prioritize regular maintenance and testing of your generator.

As a leading generator manufacturer with years of expertise in industrial reliability, BISON understand that true peace of mind comes from equipment that is always ready when you need it. By choosing BISON generators, you are investing in engineered performance that excels even in the most demanding conditions, ensuring your business stays powered up and productive. Partner with BISON for reliable, high-performance power solutions that your customers can trust.

How often should you use your generator?

A general rule of thumb is to run the generator with no electrical load once a week or a month. The recommended time to use the generator is approximately 30 minutes.

What is a generator exercise?

The generator can keep running as long as it has fuel. However, certain fuels may be more difficult to obtain during natural disasters or other emergencies. You can keep your generator running as long as you get the fuel it needs.