Tuesday, June 13, 2017

The Generator and Power Draws

Onan QG2500LP Generator - Onan-Cummans photo
One thing you have to remember when using the generator on the Winnebago Fuse is that is not capable of powering everything in the coach at the same time.   The Onan QG2500 that is supplied with the Fuse is capable of supplying a constant 2500 Watts which is 20.8 amps and has a 25amp breaker for self protection.

If you try and use more than 25amps, you will trip the circuit breaker that is physically located on the generator.  Actually it is under the access panel on the QG2500. Resetting it on the 23A  means crawling around underneath the Fuse to get to it.

So what can I run while on the generator?  The simple answer and rule of thumb is one large appliance and several small things.   The large appliances are the: air conditioner, microwave or water heater (on electric).  

Small appliances do NOT include your space heater or your blow dryer.

The generator can handle and run anything that is in the Fuse, but not in certain combinations.   Let's look at the power requirements of the big appliances to see why.

The Coleman Mach 10 air conditioner uses 1350 watts.  Depending on high or low cool it uses between 13.2 - 13.6 amps.   That is when the compressor is running.  When just the fan is running it uses 2.5 amps.   That leaves 7 amps for everything else.

Air Conditioner

The water heater uses 1400 watts when set to use electric, 11.9 amps.  That would leave 9 amps for everything else.   But why would you use the hot water heater when on generator, just let it use LP gas to heat water for you when using the generator.

Atwood Hot Water Heater

The microwave uses 1500 watts or 12.5 amps.  This leaves 8 amps for other things.


The refrigerator can also run on generator power.  Not a good thing to do unless you are out of LP, since it can use LP also.   It will only use 2.5 amps when on AC power.  Not a large draw, but some power never the less.


From this you can see that any combination of the above other than the refrigerator will cause you to go over 20.8 amps.   This will cause the generator to stall or it will trip the breaker.

There is one other load you need to be aware of and you can't turn it off.  The battery charger/converter, a Progressive Dynamics 9245c, uses 725w or 6 amps.  It can use less, but if your batteries are low it will use all 725 watts and you can not turn this off.

What else is there that would use power from the generator?  Whatever else you plug into a socket.   The good thing for us is that the Fuse powers most everything else that is built in from the battery bank.  These systems are all 12v.  Using these on while on generator might cause the converter to work harder, but they will never use more than the converter can supply.

A good reference is published by Cummins/Onan.  It is called the RV Generator Handbook.   Take a look.  There is some good information and a list of common power requirements.

Not really related but while I was making sure I did not miss anything I captured what was on the AC portion of the electric panel:

Looking at the 120v breaker panel:
Main30 Amps
Converter15 Amps
Air Conditioner20 Amps
Refrigerator15 Amps
Microwave20 Amps**Water heater is on this circuit
Receptical 215 Amps**Entertainment/TV areas
Receptical 115 Amps**Everything else

Winnebago Fuse Electric Panel
***** Update *****
I took another look at the electrical drawings.  The Microwave and the Water Heater are on the same circuit as stated above.   They are on a relay that causes the electric portion of the water heater to turn off when the microwave is running.  This way the draw stays under 20 amps.


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  2. First of all, let me say that I am so happy I stumbled upon your blog! Your entries are so informative and I just love the way your personality comes through! I just bought my Fuse a few days ago and although it is the 23T there is much in your blog that applies to my model and I am learning a great deal from you.

    I've only had mine for 2 days and I think I am going to have to call Winnebago and get some help. I keep tripping my breaker on the generator anytime I turn on the air-conditioning. I have no lights turned on, no microwave in use, and I don't understand what's going on. I am in Texas and it's mighty hot and even trying to explore my new toy in my driveway is miserable without the AC.

    I have spent the last several hours reading every one of your blog posts. I've bought fans, an ottoman, an induction cooktop, dogbones, an army surplus quilt, and more... all in the last couple of hours and all because you wrote about them.

    You and your wife sound like amazing adventurers and I hope to cross paths with you someday. This is my very first RV and I am a lone female traveler who is little nervous but excited at the next chapter of my life.

    I just wish I were a little more mechanically and technologically savvy.

    ---Tami Jo

  3. If you keep tripping the breaker I would first look to make sure the water heater is off. Ok the electric side of the hot water is off. You can heat water using either gas or electric or both. The hot water heater is a big draw.

    If that is not the problem then getting the dealer/Winnebago to look is the right approach

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