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Discussion Starter · #1 ·
Do most of you out there find that a class B rv with only 2800 Kw generator seems to be just "OK" since the times when you need much more wattage are usually in campgrounds where you can have shore power? Or,do you wish you had more Kw for those times when you don't have the advantage of unlimited Kw power.

Hope this isn't too confusing, but we're building a class B unit and the 2800 Kw Onan has a good small footprint but obviously won't handle running the air, a toaster, a microwave, coffee pot, etc. for breakfast. Obviously for all that stuff we need to be hooked to shore power, and sometimes we just don't have that advantage.

Could use your alls thoughts.

First timer, so hope I've done this all correctly
 

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The wattage rating for your Onan is probably 2800 watts, not 2800Kw (or 2,800,000 watts).

Now that the rating is more clear, this 2800 watts would be the maximum peak surge rating like when things first power up, then the demand drops soon after. You want to know the RUNNING WATT rate which is probably closer to 2200-2400 watts. Hopefully your generator manual will tell you. You could probably run the A/C with that generator because most RV compatible A/Cs run off a 20 amp circuit or 2200 to 2400 watts. and consider that the A/C needs this wattage ONLY when it starts up and after the fan compressor gets going they will use less. You should be able to check its specs, too.

Another way to look at things is to look at amps. Amps = Watts/volts, so for a 2800 watt generator divided by 110 to 120 volts, this means the generator can handle about 23 to 25 amps peak or about 20 amps running rate.

You are right, you won't be able to run every electrical device at the same time and probably not two big wattage users at the same time, but check the ratings of your toaster, MW, coffee maker to know for sure. You could turn off the other things, and run one device at a time (don't forget to consider your fridge), or run what you can off 12v/propane, like the water heater and fridge. Also remember that the 12v converter being used by these devices uses generator power too.

It's estimated that the converter runs about 4 to 6 amps for the 12v stuff which only leaves about 15 amps left for everything else. This would be the same as being connected to a single standard house circuit and trying to run everything. Since you know you can't do that at home, you can guess what precautions to take.

A better rating for the generator for your Class B is 3500 to 4000 watts (peak), to give you the typical 30 amps for most trailers and Class Bs. Otherwise know your usage and your ratings and stay within them.

I have a Fifth wheel which is capable of 50 amp and therefore I would need about a 6000w to 5500 watt generator to power the rig. I currently use two Honda portable generators tied together with a parallel cable that allows for 4,000W peak and satisfies the 30 amp requirement but I can't use 50 amps of stuff in my trailer in this case (I can't run the second A/C if I had one, so I'm okay). But I've calculated I am only able to run the A/C and one other high wattage thing or I will blow a circuit breaker somewhere.
 

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Discussion Starter · #4 ·
Thanks guys,

Some of this I was aware of, but I wanted the info straight from the people who have truly experienced it........not just the way it draws out on paper.

Thank you,
Rick (Swissrick)
 
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