# Low Voltage on Portable Generator



## dalesimp21 (Aug 25, 2017)

Hi all, new to the forum. I have a Champion 40026 portable generator (3500 peak / 3000 running watts) that I've had for several years. I've followed all recommended maintenance and it has always run like a top, starting first pull even after storage. I use the generator for tailgating at for football games, and I recently changed the oil, plug, cleaned filter and spark arrester and filled with non-E fuel (which I always do). It still seems to be running well, but I've noticed that on the digital gauge which reads running hours, voltage, and hertz, that the voltage readout was showing in the 20's. This obviously alarmed me, so I used a tester, and it was reading around 50 volts at the outlet (of which there are two). this was with no load on the outlets. The gauge shows that it's running at or around the recommended 60Hz. Any ideas on what might cause this? Researching, I came up with it potentially being a problem with the AVR. 

Any advice that you could provide would be very much appreciated. Thanks!


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## thehandyman1957 (Feb 11, 2017)

If it's showing 60hz and the rpms are right then it is most likely the AVR.

Here is a copy of the wiring schematic.


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## dalesimp21 (Aug 25, 2017)

Thanks so much for the info! I actually had a new AVR shipped to my house, but, alas, still getting the same readings on the multimeter - right around 46v. I assume that running a couple of fans and a TV on low voltage would be a pretty bad idea at this point, so I will likely be using an inverter to my car battery and keep the engine running.


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## thehandyman1957 (Feb 11, 2017)

You might give this a read, Onan 10HDKAG 61731x Generator Has Low Voltage - Electrical - FMCA Motorhome Forums

They talk about this very thing on another generator.


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## dalesimp21 (Aug 25, 2017)

Wow, and it's even another Dale asking the question. I will give it a read, thanks again!


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## ngyuen (Feb 13, 2019)

The capacitor, they are used for voltage regulation on simple generators, the more complex type ( not yours) use an avr, automatic voltage regulator.

You should be able to take the capacitor to a motor rewind specialist and they will be able to test it for you.

Otherwise, if you fail to fix it or gonna pick new generator, there is a good review about them https://generatoron.org/best-tailgating-generator/


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## chadjones999 (7 mo ago)

dalesimp21 said:


> Thanks so much for the info! I actually had a new AVR shipped to my house, but, alas, still getting the same readings on the multimeter - right around 46v. I assume that running a couple of fans and a TV on low voltage would be a pretty bad idea at this point, so I will likely be using an inverter to my car battery and keep the engine running.


did you get it fixed ? what was the fix ?


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## tabora (Sep 6, 2018)

chadjones999 said:


> did you get it fixed ? what was the fix ?


He hasn't been active for 5 years...


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## chadjones999 (7 mo ago)

tabora said:


> He hasn't been active for 5 years...


yeo but still comes up when you google this issue.... Just says


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## chadjones999 (7 mo ago)

chadjones999 said:


> yeo but still comes up when you google this issue.... Just says


And you never posted a follow up date 5 years ago, or we would know the answer LOL


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## GenKnot (Dec 20, 2021)

chadjones999 said:


> did you get it fixed ? what was the fix ?


Since he replaced the AVR and it didn't solve his problem, it was likely bad windings in the rotor or stator and he threw in the towel.


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## chadjones999 (7 mo ago)

GenKnot said:


> Since he replaced the AVR and it didn't solve his problem, it was likely bad windings in the rotor or stator and he threw in the towel.


I have similar issues, generic diesel XD5000E, putting out like 156 volts on 220 plugs and around 76 on 120 plugs... Capacitor ( no AVR ) is a 25 MFD + - 5 % and it tests at 24.7 MFD so I'm confused but the generator was not being used like the last 3 years and only has 28 hours on it total


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## OrlyP (Oct 19, 2021)

chadjones999 said:


> I have similar issues, generic diesel XD5000E, putting out like 156 volts on 220 plugs and around 76 on 120 plugs... Capacitor ( no AVR ) is a 25 MFD + - 5 % and it tests at 24.7 MFD so I'm confused but the generator was not being used like the last 3 years and only has 28 hours on it total


I can't find a schematic diagram for it. It seems unusual for a generator this size and tier to have no AVR or some sort of controller. But if you're certain it's brushless capacitor type, I'll take your word for it. In that respect, I'll try replacing it anyway.


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## tabora (Sep 6, 2018)

OrlyP said:


> I can't find a schematic diagram for it.


It's a Generac, not "generic". See this thread: Please Help: My Generator Has Low Voltage!


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## chadjones999 (7 mo ago)

tabora said:


> It's a Generac, not "generic". See this thread: Please Help: My Generator Has Low Voltage!


LOL well it is kind of generic ....... my bad


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## chadjones999 (7 mo ago)

chadjones999 said:


> LOL well it is kind of generic ....... my bad


question , for testing purpose, If my 25 MFD cap is bad and I have a 35 MFD to replace it already here on had, what would that do if installed?


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## tabora (Sep 6, 2018)

chadjones999 said:


> question , for testing purpose, If my 25 MFD cap is bad and I have a 35 MFD to replace it already here on had, what would that do if installed?


The voltage should be different if the original capacitor was bad or failing. Anecdotally, one poster said _"I raised the voltage on my capacitor controlled alternator by going from 31.5mf to 35mf. Raised it from ~114v to ~126v no load."_ 

I would not plug anything into it other than a multimeter until you determine what the new output voltage is. The capacitor has two functions; it induces voltage into the rotor as well as regulates voltage. A bad capacity will result in a low voltage reading from the generator.


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## chadjones999 (7 mo ago)

Ok so another update and further into the rabbit hole. So I had a 35 MFD cap ( spare for my AC ) so I figured let's try it. well, it boosted the voltage to near perfect 222 volts to 228 and L1 & L2 to N or G I got like 110 to 111 . but when I plugged the RV in every time the inverter blocked power and showed red LED on the power button ( like a fault but no fault code ) .... I could not figure out what the heck was going on. So I tested the generator outlet and found it to be 53 HZ ( not 60 ish ) So that's why my inverter blocked it I guess. So I thought to myself it's not the cap cause that should not affect HZ..... maybe RPMS! so I moved the governor bracket (it had only like a 1/4 movement in the slotted bolt hole ) and the engine did speed up a hair and sounded smoother, I put the old CAP in cause probably not the issue. voltage did pick up a few volts and HZ went up to 54 to 55 now. but I'm lost cause I can't








speed up the engine anymore to correct the low HZ I know if I could get the HZ up another 5 the voltage ( with old cap at 190 ) would probably pick up. see attached pics
here is the spare capacitor I tried


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## tabora (Sep 6, 2018)

Frequency (Hz) is determined by pulses per unit of time. You should be at EXACTLY 3600 RPM for 60 Hz on that generator. Most diesel generators are 1800RPM with 4-pole stators, but you have a 2-pole stator.


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## chadjones999 (7 mo ago)

tabora said:


> Frequency (Hz) is determined by pulses per unit of time. You should be at EXACTLY 3600 RPM for 60 Hz on that generator. Most diesel generators are 1800RPM with 4-pole stators, but you have a 2-pole stator.


I agree, I'm just stumped ... I upped the speed to max, and it still not at 60 HZ , what else could affect this ?? very weird it differently sounds like its at 3600 RPM or higher , I don't have a tach but I have had these type before and know what they sound like ... and its factory meaning I was on the job when it was bought and I know it wasn't used for years. They didn't want to ship it at the end of the job so I got 2 of them ( we had 4 ) So its not like someone has had it for years and has unknown work done to it. also to repeat it has 28 hours on the clock...I even double-checked the name plate to make sure we didn't some how get a 50 Hz model by mistake ( even though that should not be possible )


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## chadjones999 (7 mo ago)

once again tabora thanks for your help, I know its difficult trouble shooting something that is not in front of you


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## OrlyP (Oct 19, 2021)

Totally missed that one. Yes, a brushless (capacitor-excited) generator requires the engine to run at 3600 RPM to generate both the correct frequency (60Hz) and rated output voltage. If it spins slower than that, expect both the frequency and output voltage to sag.

It's quite possible that someone inadvertently adjusted the throttle and/or governor settings (spring tension, spring position, calibration, etc.) or the engine probably just needs a tune-up because it is down on horsepower.

If you push or pull on the governor arm to open the throttle, does it reach 3600 RPM (60Hz) or higher?


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## chadjones999 (7 mo ago)

OrlyP said:


> Totally missed that one. Yes, a brushless (capacitor-excited) generator requires the engine to run at 3600 RPM to generate both the correct frequency (60Hz) and rated output voltage. If it spins slower than that, expect both the frequency and output voltage to sag.
> 
> It's quite possible that someone inadvertently adjusted the throttle and/or governor settings (spring tension, spring position, calibration, etc.) or the engine probably just needs a tune-up because it is down on horsepower.
> 
> If you push or pull on the governor arm to open the throttle, does it reach 3600 RPM (60Hz) or higher?


well without a tach Im guessing but I can say it sure sounds like it is at 3600, now that could be off a few RPMs without a tach. , I am at 8k feet above sea level also... but this is like a 750 CC diesel engine, rated only at 5kw, it should not sag unless heavily loaded , all these readings are no load. also its not blowing smoke ( like a none turbo diesel truck does at 8k elevation lol )
It was on a job site someone could have screwed with it, but I have moved the governer all the way to the opposite side and it did speed up. but still not reaching required HZ ,
its at the point if I pull on the spring it only slows it down now. .
oh one more thing I took my meter and tested a gas generator I have to verify meter is reading correct. and my gas gen is reading dead nuts 60 HZ , 62 unloaded and 122 volts at same 8k above sea level ( not even jetted for this elevation )


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## OrlyP (Oct 19, 2021)

No need for a tach if you can measure the frequency with a multimeter. Once you hit 62Hz unloaded, the engine RPM will be around 3,720 RPM.

Formula:
RPM = Frequency (Hz) x 60

So anyway, your problem is the engine. It's not reaching the correct RPM so along with the frequency, the voltage is also low.


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## tabora (Sep 6, 2018)

chadjones999 said:


> this is like a 750 CC diesel engine


Actually, it should be a Yanmar LW Series 435cc air-cooled direct injection, industrial-grade diesel engine... 








Powering your home, your business, your world.


website




www.generac.com


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## chadjones999 (7 mo ago)

tabora said:


> Actually, it should be a Yanmar LW Series 435cc air-cooled direct injection, industrial-grade diesel engine...
> 
> 
> 
> ...


You are correct, either way enough to spin this up to speed unloaded. it runs GREAT . I have had them for about 2 to 3 years and I have never even charged the battery and pushed the button to start them twice ( until this latest issue ) , both times I started it, it fired right up like it was bought yesterday! ( as for the engine )


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## chadjones999 (7 mo ago)

SO I guess next to buy a tach...
part 1 part one Generac 5kw diesel has low voltage and low frq (HZ 53 )

part 2 part 2 generac low voltage & HZ

part 3 part 3 generac low voltage & HZ


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