After watching a 22-kilowatt standby generator bounce between 235 and 245 volts, a homeowner went to Reddit hoping to avoid paying for another repair visit.
Here's what to know
Writing in a Reddit thread on a generator-focused forum, the homeowner explained that their system included a three-year-old, 22kW air-cooled generator. While testing the unit, however, it repeatedly fluctuated between 235 and 245 volts in 20- to 30-second cycles.
The same issue persisted during a 45-minute run without utility service.
"It never settles," the original poster said, adding that "House lights (LED mind you) visibly pulse."
The OP explained that a service technician had already been out to take a look, but what the technician said seemed to conflict with the manufacturer's own guidance.
"Based on what I'm reading, Generac's own tolerance is +/-1% which is only 2.4V up/down; not 5, let alone 10," as the technician had indicated.
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During their visit, the technician had lubricated the mixer assembly, saying stiffness there might be causing the OP's issue.
People replying to the post doubted that fuel or throttle behavior was a likely cause.
"Unlikely it's a throttle or fuel issue because your frequency is stable," advised one commenter. "Look at brushes and VR system."
Going deeper
According to the OP, the generator's voltage was wandering even though frequency stayed at 59/60 hertz and engine speed held roughly between 3,585 and 3,620 rpm. They also said the pattern stayed the same whether the generator was under load.
Some commenters questioned how the OP measured the generator's voltage, suspecting their methods could be the issue.
"Are you using a meter to confirm this, or trusting GenMon/other plugged in devices?" asked one.
"Getting all the numbers from GenMon," the OP replied. "Watched the fluctuations on the Evolution panel yesterday. And then the obvious light dimming, etc with my eyes. But no, have not used a meter anywhere as of yet."
Whatever steps the OP decided to take next, they had to do so quickly.
"My warranty expires in 5 weeks!" they exclaimed.
Where can I learn more?
Other generator owners have dealt with similar problems, from unstable output and repair headaches to visible issues around the house. These articles cover flickering lights, hard-to-pin-down shutdowns, warranty disputes, and generator safety concerns.
• After a conduit was cut, a 26-kW generator caused flickering lights and raised OLED damage fears.
• For one generator owner, a loose ribbon connector spared a $1,300 control-panel replacement.
• A generator owner questioning noise, airflow, and warranty risk sparked debate over so-called zombie boxes.
• After Hurricane Beryl, experts warned that backup generators can turn deadly when carbon monoxide builds indoors.
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