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generator low voltage output

We are seeing bouts of our 8kw generator output voltage going below 100 volts. 

We do have Progressive Industries EMS protecting us by cutting off the low voltage.

We will order a new voltage regulator to see if that fixes us.  A couple of years ago we were seeing 170 volts for a few moments, which was fully cured with a new voltage regulator, which was a plug-in change.

Re: generator low voltage output

Reply #1 –
This is very timely.  While running the generator for about 8 hours today I noticed the voltage down to 112.  The other leg was at 119.  I'd expect to see this a bit higher.

Re: generator low voltage output

Reply #2 –
Mark's generator may be wired for 240 volts with separate legs, and loading one leg more than the other (ie: only 1 roof air) 112v & 119v sounds reasonable.
Our generator is wired for 120 volts with both legs tied together sharing loads.

Re: generator low voltage output

Reply #3 –
(Moderators: Quote button is not working)

Mark:
"This is very timely.  While running the generator for about 8 hours today I noticed the voltage down to 112.  The other leg was at 119.  I'd expect to see this a bit higher."

Barry:
"Mark's generator may be wired for 240 volts with separate legs, and loading one leg more than the other (ie: only 1 roof air) 112v & 119v sounds reasonable. "

Yes, I agree. Mark - do you remember what loads you had on at the time?
Peter and Tammy Fleming
1991 U300 GV 40 - Sold, owned for 4 years
Downsized to Roadtrek Popular 210 class B

Re: generator low voltage output

Reply #4 –
Be very careful with the new voltage regulator.  Verify it is e correct one before installing. 
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: generator low voltage output

Reply #5 –
Quote from: John S –
Be very careful with the new voltage regulator.  Verify it is e correct one before installing. 

And read the manual.  I remember someone posting that the insert that came with it mentioned that the wires had to be switched around.  They failed to read it and it smoked the whole generator end.

Re: generator low voltage output

Reply #6 –
Quote from: prfleming –
(Moderators: Quote button is not working)

Mark:
"This is very timely.  While running the generator for about 8 hours today I noticed the voltage down to 112.  The other leg was at 119.  I'd expect to see this a bit higher."

Barry:
"Mark's generator may be wired for 240 volts with separate legs, and loading one leg more than the other (ie: only 1 roof air) 112v & 119v sounds reasonable. "

Yes, I agree. Mark - do you remember what loads you had on at the time?

I may have to do some more testing before I decide anything.  The panel I was reading (the one that comes with the coach) has always read the one leg higher than the other regardless of the power supply.  This happens even when I hook it up to a 30 amp 120v power when both legs should obviously be the same.  At the time I only had the front a/c on and the tv and a computer.  Those are all on the one leg.  What concerned me is that before the low leg read 116 volts and the high leg read 122 or so, so it does seem to be falling down over time.

Re: generator low voltage output

Reply #7 –
The posting on a new voltage regulator needing wiring change BEFORE being plugged in, was from us (Barry & Cindy).  A friend ordered a new voltage regulator and it came with instructions to swap wires before installing.  Friend did not RTP (read the paper), plugged in new voltage regulator and smoked his windings on startup, requiring a new pumpkin (generator) weighing and costing thousands.
Good reminder. . .

Re: generator low voltage output

Reply #8 –
The NEMA standard for voltage tolerance is +10%, -15% of nominal voltage, so your acceptable voltage range is 102-132 volts on a 120v system.
Current coach 1996 U320 40'
Previous coach, 1990 36' U280

Re: generator low voltage output

Reply #9 –
I baught a solid state voltage regulator last summer for my 12k and had to adjust the pots on it, there are 3 total voltage, and cant remember the other 2 but it didnt work right and took me a few times of fiddling to get it right or I should say it seems to be ok, I checked it again a few months ago and it puts out correct voltage and doesnt draw down much, There is a lot of info on computer and I spent a lot of time reading up, I dont claim to be a electrician,
Adam Byler
1999 U320 M4200 DGFE Build #5389
2014 Sundowner 26 ft Enclosed
2015 Ford F150 King Ranch crew cab

Re: generator low voltage output

Reply #10 –
I moved the rv with the generator running and the voltage jumped up to 120v so I assume I have something getting loose in the box.

Re: generator low voltage output

Reply #11 –
Quote from: Kemahjohn –
The NEMA standard for voltage tolerance is +10%, -15% of nominal voltage, so your acceptable voltage range is 102-132 volts on a 120v system.

This may be true but I can tell you our air conditioners HATE being operated at anything under 110v or so.  They start vibrating, carrying on and generally not performing very well.  But yes, everything has so far survived those lower voltage conditions.

Re: generator low voltage output

Reply #12 –
Quote from: Mark D –
  our air conditioners HATE being operated at anything under 110v or so. 

We are on the gen-set right now, showing 118 volts with the stern ac on low, both battery banks are taking a "trickle charge".  Under 110v is not a good thing for any electrical do-dad!
1993 U-240 "La Villa Grande"..CAT 3116 w/ Pacbrake PRXB...Allison 3060 6-speed..
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                                      Build # 4297
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                        Full-Timers 'Sailing the asphalt sea'

Re: generator low voltage output

Reply #13 –
Hope this is consistent with this thread.  When operating the ACs with our gen set the needle wags.  It doesn't drop to low area but constantly moves back and forth in the green.  Problem?  I have same setup as Barry.
George and Steph
1997 U270 36 Build 5081 "Honu"
1180w Solar 400A lithium all Victron house system
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73 VW Camper, 79 VW Camper, 2363 Sunline, and an Arctic Fox 25P
 

Re: generator low voltage output

Reply #14 –
George & Steph,

Our analog volt meter also bounces around sometimes. 

I think it is a function the meter being very sensitive and the generator not being as good a source of perfect sine wave as utility electric power.  I do not think it indicates a problem.

The analog meter also reads different and often lower than our digital volt meters.  I consider all of our volt meters to be approximate, partly because Alternating Current electric voltage is a moving target and meter calibration and designs are not perfect.  Read about RMS (Root Mean Square) volt meters.