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95jersey's avatar
95jersey
Explorer
Dec 31, 2018

Generator sizing issues?

I have a 2017 Jayco 273 Toy Hauler (30 amp) with a single 13,500 BTU AC (according to their website). It has gas/electric water heater and fridge, micro, 2 (TV's), digital antenna, stereo and LED lights.

I occasionally dry camp and use my Harbor Freight Generator (4000/3200) to run the AC and assorted electronics (water pump, TV, stereo). I try to run the water heater and fridge on gas during these trips. Please no inverter recommendations, not interested in spending the money at this point.

I have run the generator right from the RV power cord as well as tried extension cords (10 guage) to run the generator further from the camper, with mixed success.

With the extension cord, the generator will overload occasionally and "pop the breaker" with the AC on. I have to go outside and reset the fuse. Sometimes this rarely happens and sometimes it happens frequently. I don't get why its so haphazard.

If I don't run an extension cord, it is more reliable, but will still occasionally "pop the breaker". I try to only run the minimal while running the AC such as (lights, water pump, maybe stereo/tv).

The manual says 13,500 BTU AC, but there was an optional 15,000 BTU available from the factory. I bought mine used so not sure which one it has. Also, it never "pops" at start up, it is usually when it has been running for a bit. So it seems the generator has enough power to get the AC going without issue. It is just a random breaker pop for no reason. It never pop's the camper fuse, just the generator.

So few questions...

1)why is the fuse popping more often with an extension cord? how long can you run an extension cord and what size to prevent this?

2)do I need to up size my generator to prevent further overloads? or do I have another issue with the RV?

Harbor Freight has a 4250/3500 and 6500/5500 in my budget. I would rather get the 4250/3500 as it is cheaper/smaller and more quiet, but I don't want to buy it and just have the same issue. They have a 6500/5500 for another $90, but it is another 40lbs heavier and 4db louder.

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  • MrWizard's avatar
    MrWizard
    Moderator
    Dec 31, 2018
    Water pump lights etc...use battery power, your generator is powering the converter, let it charge the batteries before you turn on the A/C

    Using the extension cord will increase voltage drop and breaker trips

    Having other items using power

    Letting the A/C cycle the compressor will increase the chances of breaker trips
    As the A/C compressor warms up, and ambient temp warms up, the start surge for the compressor takes more amps
    This is the most likely problem, having the A/C on a setting where it cycles the compressor

    In a mild day it might cycle without overload
    On a day that gets hot, you reach a critical point where the restart cycle load is too much for the generator
  • time2roll's avatar
    time2roll
    Nomad
    Dec 31, 2018
    If the battery is low on charge the converter can draw around 1000 watts. Microwave will pull 1500. Fridge 350. Water heater 1400. Coffee 800 to 1750. Electric cooking will also draw 400 to 1000 watts each appliance. Some of these run on a thermostat so it could seem random when the overload hits.

    So you may need to give your converter an hour to charge the battery before you crank on the A/C. Otherwise watch what else is plugged in.

    Also if you are at 4000+ feet altitude your generator will be derated some due to the thin air.

    I doubt the #10 extension is causing any meaningful issues.
  • George3037's avatar
    George3037
    Explorer
    Dec 31, 2018
    Just remember your TT only has a 30A circuit. Usually the factory 30A cord is 25-30' long. If you are running the A/C, Microwave, Coffee pot, Toaster, and your distribution center is probably charging the house battery at the same time. The combination of using more than one of these devices at the same time can easily trip a 30A breaker either in the TT or on the generator. Adding an extension cord only adds to the load and makes it worse.

    Your generator is more than capable of running your TT. The problem is you are maxing out the 30A circuit from time to time. Going to a larger generator will not help as you are still limited by the 30A circuit in the TT.

    You need to buy or borrow a DC amp meter to measure the amp draw of your TT. My guess is you are maxing out at 30 amps or more causing the breakers to trip.

    Also, if you take off the cover when you clean your A/C filter there should be a label inside that will say whether you have a 13.5 or 15K A/C unit.
  • Boomerweps's avatar
    Boomerweps
    Explorer
    Dec 31, 2018
    Www.calculator.net voltage drop calculator
    Voltage will drop over a wire's length and gage (AWG). The amount of drop depends on the amperage load.
    I used a Kil-a-Watt meter (~$25 at Harbor Freight) that you plug into your outlets or inlets. It's made for a standard house 15 amp Edison plug. So I run an extension cable from my source to the meter, then into the TT using a 15 amp to 30 amp adapter. Then I turned on various items one at a time to measure the wattage/amps used and how much voltage loss I had. I also metered using multiple items turned on at the same time. So I now have a good idea of what I can run together, given the length of extension cords I used, all 12ga.
    I've not run any 30 amp or 10 AWG extension cables while measuring.
    The amount of voltage drop can be significant based on AWG & cable length. I actually ran 195 feet of 12AWG from my circuit breaker box to my TT at one spot on my property. My voltage read 112VAC at the TT inlet with just the 12VDC converter powered. Add fridge, 109.7VAC. Cut fridge, turn on Air Conditioner, 100.7VAC. I no longer consider parking the TT there ;)
    On the concrete pad out my back door, very little drop with 45-50' of wire.
    At my current storage site, about 85-90 cable feet from the CB box, 107.7VAC with the AC on but within operating specs. I did add a Progressive Industries EMS install unit so I don't need the Kil-a-Watt to measure amperage use and voltage on the whole TT. But it would shut down all power coming in if I was to use that 190' spot due to low voltage.
    Starting amp draw on motors increases by 50% or more when starting.
  • 95jersey's avatar
    95jersey
    Explorer
    Dec 31, 2018
    I never run micro with AC on. Maybe the AC/TV/Water pump/refrig/Lights and some iPhones charging. It may run for 3 hours fine and with no load changes, and then it just pops the breaker. I agree the generator is cheap. Also, yes the power cord was not a 30 amp, so I need to get the appropriate cord. But that does not account for why a 3500 watt generator is popping the breaker randomly.

    I have no issue upping the size, but will the 4370/3500 be enough? That is only 300 more watts running than the one I have. The 6500/5500 is only $89 more, but it weights another 50lbs and is probably a little louder.

    Is there anyway to test the generator? Do dealer have a watt meter to measure my actual usage?
  • nineoaks2004's avatar
    nineoaks2004
    Explorer
    Dec 31, 2018
    You stated a 10 GA cord, but you failed to state how long the cord is, you will have a voltage drop according to length. I can run anything in my TT with no problem but I do not use an extension cord. Are you using a microwave at the same time the breaker trips? This can /will cause a problem. Also could be a weak breaker at the Gen.
  • RoyF's avatar
    RoyF
    Explorer
    Dec 31, 2018
    The extension cord I would use is of the same gauge as your Rv's 30-amp cord. That's not the "ordinary" extension cord which is good for only 15 or 20 amps and is not rated for 30 amps.
  • 2oldman's avatar
    2oldman
    Explorer II
    Dec 31, 2018
    cheap generators (a good assumption since it's HF) are likely not to live up to their ratings, or surge capabilities.

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