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Old 05-04-2020, 07:07 AM   #1
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1977 25' Tradewind
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Low Voltage when running a/c

Hey guys, I've searched and read threads for hours, but I just don't see how some people are getting away with running there airstreams on smaller generators.

I have a '77 25' Tradewind with what i believe is the Armstrong 15k ac unit. Hooked directly to a 30amp Camper receptacle the ac starts and runs fine, pulls the voltage down from 124vac to 121vac no issues. However if I plug into my generator. Pulsar 4500 starting watts/3500 running watts, I show 124vac with the ac off, and 104 with the ac running. The generator does not sound labored, and it doesn't lug out when the ac starts, but the voltage seems very very low, and I don't want to let it continue to run this way. I see a lot of posts with people saying they run no problem on one Honda 3000, or 2 2000s in parallel.

Do i have an issue with my generator you think?

Thank you!
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Old 05-04-2020, 08:07 AM   #2
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Either a poor connection or regulator on the generator. Where are you measuring voltage? Measure it at the generator. If low there, the problem is in the generator. If OK, the problem is in the power cord or trailer. If you don’t hear a change in the generator, its regularor may be defective. It should load up when the AC starts.

Edit: The Pulsar 4500G generator I looked up is a 120/240 volt generator with only 8 amps on each 120V leg. That is not enough for your AC if that is what you have..

Al
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Old 05-04-2020, 08:15 AM   #3
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Hi,
Since the Gen is the only power source when experiencing low voltage, would think issue points to the Gen.

Is the Pulsar an inverter or frame style ?

Another easy test is to try a different like draw load (hairdryer on high, big toaster etc.) and measure the voltage.

If still low, opt for an inverter style which has much better electronics for stabilizing output voltages. Many like the dual fuel, quality, price of 3500 watt Champions or the red or blue if preferred.
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Old 05-04-2020, 08:19 AM   #4
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I have a PG4500 Pulsar, says 4500 starting watts/3500 running. Ill check voltage at the generator. I have been looking at voltage with my Fluke meter inside at a outlet by the sink. I also checked voltage at the breaker panel and it shows a little more than the outlet shows. I don't see any voltage drop when on shore power from my 30amp outlet, so i assume the power cord on the trailer is good.
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Old 05-04-2020, 08:20 AM   #5
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This is an open frame generator, not inverter style.
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Old 05-04-2020, 08:21 AM   #6
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Just a note...i tried an older Champion 3500 starting/3000 running generator for comparison, but it bogged really bad when the ac started and shows voltage as low as 85, so i quickly turned it off. Just wanted to try another out.
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Old 05-04-2020, 08:53 AM   #7
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Bad generator probably.

I run a 13500 ac on an older Honda 2000 just fine. It will put out slightly more than its rated output all day. I keep a voltmeter plugged in and the voltage does not drop with the AC on. I do have a cutoff switch for the converter. If you have low batteries the converter the converter can draw a large amount of current.

Not sure how a non inverter generator works but maybe the rpm is dropping enough to drop the voltage. I doubt if there is feedback to self adjust the voltage? My guess is that despite the rating it is just not a good generator for the job. Neither of the generators you choose to try seem like good bets to me.
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Old 05-04-2020, 08:54 AM   #8
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Quote:
Originally Posted by JCurry2885 View Post
This is an open frame generator, not inverter style.
Open frames output can be more brute force and less stable and saturate on high loads.

Great opportunity for a much quieter, stable and perhaps smaller Gen ! You and neighbors will enjoy camping more as well
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Old 05-04-2020, 09:12 AM   #9
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weird thing was I tried adjusting the idle, and the lower and lower I went, the higher and higher my voltage read inside... I had adjusted the idle of the gen prior to using it on the camper by getting it as close the 60hz as possible. I would like to buy an inverter style generator, but just not sure of the size to use. I hear alot of good about the Predator inverters, but they are 3500 starting/3000 running.
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Old 05-04-2020, 09:21 AM   #10
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Look at what they are rated at. Like a Honda 2000 is actually rated at 1600. Then determine if you think the generator will make what it is rated at. Looks like it ought to be enough but I have never seen one in use. Maybe someone that actually uses one will answer.
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Old 05-04-2020, 09:45 AM   #11
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My Yamaha 2300 pumps out 120 volts continuously while my air conditioner runs.

It ran my old Armstrong well, and it runs my Coleman well also.
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Old 05-04-2020, 11:13 AM   #12
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I'm going to try to find someone with a known good generator in the 3000 watt range and see what it does. Sounds like mine just isn't cutting it anymore.
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Old 05-04-2020, 11:44 AM   #13
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Most non-inverter generators do not provide a feedback loop in order to adjust the excitation to the field and thus increase output voltage. RPM's correlate to the frequency, not the output voltage.

I have a diesel 6k portable that I backfeed my house with in times of power outages. No load output is about 124v then depending on load can drop to about 114v. Any lower and I cut off demand.
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Old 05-04-2020, 01:34 PM   #14
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Quote:
Originally Posted by JCurry2885 View Post
I have a PG4500 Pulsar, says 4500 starting watts/3500 running. Ill check voltage at the generator. I have been looking at voltage with my Fluke meter inside at a outlet by the sink. I also checked voltage at the breaker panel and it shows a little more than the outlet shows. I don't see any voltage drop when on shore power from my 30amp outlet, so i assume the power cord on the trailer is good.
That generator is rated 14.5amps@240volts continuously. With most generators that means each leg is only rated 14.5amps@120volts. It works like you have 2 separate generators and you only get to use 1 for your trailer or you can only use 1/2 the output.
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Old 05-04-2020, 06:58 PM   #15
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Look at its rating on Amazon. 3.4 stars... 22% 1 star... 38% 5 stars. Ratings are not always reliable, but these numbers would make me buy a different generator.
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Old 05-04-2020, 07:36 PM   #16
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As I suspected in my post, above, the PG4500 is a 120/240V generator with only half the wattage available on each 120V leg. For your purposes it is a 1750 watt generator. The total wattage number is deceptive. It is only available if you run 240V loads, or multiple 120V loads on different phases.

Further, I didn't see anything in their diagram that would indicate there is feedback to the engine controls to regulate the voltage. It is apparently intended for a job site generator running power tools.

Al
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Old 05-05-2020, 04:34 AM   #17
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Champion Dual Fuel is the way to go.
Great customer/technical service.
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Old 05-05-2020, 06:53 AM   #18
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That's interesting, this generator was given to me for fixing 2 others for an older gentleman. Never ran anything on 240v before. Very deceptive indeed. Well I'm going shopping for a new generator, but i do have a little hope to be ok with a smaller inverter type, since this "1750" watt gen did run the camper, just didn't quite have enough.

Thanks for the help everyone!
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Old 05-10-2020, 09:45 AM   #19
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Recognize that your AC unit only needs about 15 amps when running. However, based on reports I've read, it needs around 45 amps to start. Because of the way electricity works, shore power 30 amp breakers can absorb that demand without issue. However, many, especially smaller, generators cannot. You can determine what your AC unit needs by checking the info plate on the unit. It should have a number for LRA - locked rotor amps. The reason Microair's EasyStart units are popular is that it limits the ACs power demand during startup keeping power down in the 20-30 amp range, which these generators can tolerate.
FWIW, I would be looking at the plugs on your generator to make sure they are clean with no corrosion. A spray with CRC Electronic Cleaner or the like may help.
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Old 05-27-2020, 08:51 AM   #20
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Just wanted to update everyone that I purchased a Predator 3500 inverter generator from Harbor Freight, and it has ran the trailer perfectly. With the AC up and running, inverter running, and the fridge on electric it shows about 2200 watts. Keeps the voltage at 121vac. I have about 55 hours on the Predator so far without any issues, I have just changed the oil at 4, 8 and 25 hours now.

Thanks everyone!
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