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pchuckie · 06-30-2016, 05:55 AM

Have you checked the generator ouput voltage and frequency? A drop in voltage could definetly create a higher amp draw. A wrong frequency would make the motor not turn the right speed, not sure what improper frequency would do to the amp draw.

jharrell · 06-30-2016, 06:23 AM

Quote:

Originally Posted by relaxn

No need to yell.

Each AC unit is on its own 20amp breaker so I will assume they are rated up to 20amps. None of those tripped so I will assume that none of the individual AC's ever exceeded 20amps.

And...based on my description in my initial post, the breaker on the generator did properly trip when the three AC's running together exceeded the generator's max load.

This is what lead to my question of - Could the excessive heat cause each AC unit to increase its load enough(but still be within it's acceptable operating range) that when all running together, they exceed the generator's capacity?

I see two possibilities, all three AC's are wired to the same leg of your electrical system causing the 45 amp breaker to trip with all 3 exceeding 15 amps each but no single one exceeding 20 amps. This could be fixed by moving one of the AC's to the other leg of the system. Remember 45 amps is only 5400 watts at 120v, so yours must have two legs with a double pole 45 amp breaker.

The other possibility is the startup surge caused the trip. The startup surge on my 15k BTU AC gets up above 60amps for a very short time. My 30 amp breaker doesn't trip because they are designed with a time delay so they can handle surges like that. However on yours two AC where already drawing 30-40 amps then a 3rd startup surge could have had it hit 100 amps which might have tripped it faster. Start surge can be reduced some with hard start capacitors(cheap) or more so with soft starters like a Micro-Air easy start (not cheap).

jacwjames · 06-30-2016, 06:44 AM

Do you have an EMS system which shows what the total amp draw is?? If so run each AC unit seperately and look and the amperage draw, if possible do this for longer periods of time to make sure the AC unit is at operating temp etc. If you have a meter check the what the start amps bump to on each AC unit. As the compressor kicks on and off see if the amps go up/down over a period of time. What amps do the fans pull by themselves. Do all AC units sound about the same.

You generator should run all the AC's at one time plus some.
10000 watt / 120 volt = 83 amps. The only way it would is if the wiring has all 3 AC's on one leg of the generator power. In most cases the generators are sized so the RV can operate all required systems.

On my coach I have an Intellitec EMS system. When the generator is running it sends a 12 volt signal to the EMS circuit board at which point the system is disabled and will not shed load. I have a 7.5KW Onan, meaning it is rated to put out 7500 watt / 120 volt = 62.5 amps. Part of the Onan maintenance is to run it at max amps for 45 minutes to clean the spark arrestor screen. Last year I did this, I ran both AC's, a toaster oven, and a small portable heater to get the load up to max, at times I was bumping 64 amps and the generator continued to put out and no breakers tripped.

I did have a problem with my front AC unit, the fan would sometime not want to start, and it would sometimes kick the breaker. I noticed really high start amps and it was running higher amps just with the fan then the rear AC. After a trip I got on the roof and took the shroud off, I tried to turn the fan motor, it was really hard to turn. I took the motor out and found that the bearings were almost seized, this is what was causing my problem. Got a new motor and installed. It now pulls less amps then the rear AC and is considerably quieter.

relaxn · 06-30-2016, 10:11 AM

Quote:

Originally Posted by jacwjames

Do you have an EMS system which shows what the total amp draw is??

You generator should run all the AC's at one time plus some.
10000 watt / 120 volt = 83 amps. The only way it would is if the wiring has all 3 AC's on one leg of the generator power. In most cases the generators are sized so the RV can operate all required systems.

On my coach I have an Intellitec EMS system. When the generator is running it sends a 12 volt signal to the EMS circuit board at which point the system is disabled and will not shed load.

In order...
I do have an EMS. However, when hooked up to 50amp shore power, it does not show my total draw. It only shows it when hooked up to less than 50amp. The owner manual confirms this is correct.

The gen has/does run everything no problem. I have made 8 hour drives with all three AC's and the fridge running off of it. My wife has even heated up coffee in the microwave at the same time. I ran it two hours yesterday just to test everything. No issues while sitting in 102 degree heat. The only time I have had the problem was in the extreme 118 degree heat.

I have the same system so when the generator is running, it doesn't show the load. Again, the owner's manual confirms this is correct. Which honestly seems silly, as that is when I would want to know the most!