Generator usage

My RV has a generator and I want to make sure it is run as often as necessary to keep it from gumming up. When I bought this (used) unit the generator had been run for about 1 hour every year so it was in pretty bad shape. I had the carburetor rebuilt and now it seems to run better (although it still has problems at heights of 5000 ft and above), but I am not sure how often to run it when it is in storage.

I have gotten different advice from different service departments and the minimum usage suggestions range from 30 - 120 minutes per month "under load". Well, I understand 30 minutes and I understand 120 minutes but I don't much understand "under load". Usually this is given with the suggestion of running the AC and that is certainly "under load". But I still have some questions.

1) What is the suggested minimum run time when in storage? 30 minutes? 60 minutes? 90 minutes? Something else?

2) If the unit is run for 2-3 hours when camping with various loads from toasters to microwaves, but not the AC, is that enough load to constitute "under load"?

3) Is 3 hours with minimum load sufficient to allow me to not run it for a month when I get back? Or do I need to run it again "under load"?

4) Why is it insufficient to just run the generator rather than running the AC (or other appliances)?

I have more questions but perhaps that is enough to get started. Thanks.

The reason for running it with a load is to get the operating temperature up to normal.  This is to ensure that any moisture in the rotor coils and elsewhere is driven out.  The usual recommendation is an hour, but if it's stored in normally dry conditions, 30 minutes is probably enough.  Once a month is sufficient.

From my experience, here are my suggestions

1. 60 minutes under load once a month if it is not used in the previous 30 days
2. 2-3 hours should be enough, especially if it is a couple of times while on a trip
3. Yes- 3 hours should bring it up to operating temp and dry it out
4. Answered by Ned.  The key is to warm up the entire piece of equipment and dry it out

When you have more questions, someone will have more answers

Bill

Thanks, but I am still wondering what "under load" really means. Is it enough to run the generator while using the microwave? Is 900 watts "under load" enough? Or the toaster (which I assume is more than 900 watts)?

In the winter time turning on the AC probably is meaningless since the compressor will not run. it is not warm enough to trigger the thermostat, so what is enough wattage to be considered "under load"? And if the purpose of running the generator is to get it up to temperature, why is it no sufficient to just run it for 30-60 minutes with no load? Surely the generator will warm up to normal operating temperatures without having the AC on if it is run long enough?

I am not trying to be difficult; just to understand.

Thanks again.

The best way to load a generator I know of is to turn the air conditioning on. 

Not always feasible in the dead of winter.  If you have an AC/gas refer switch it over to AC.  That will present a pretty good load, as would a microwave oven or hair dryer.

In cold weather, an air cooled engine may not ever reach normal operating temperature unless it's working fairly hard.  If you aren't drawing power from the generator it's just running at a fast idle and not producing much heat.

Likewise, the generator windings are just spinning in air unless there's current flowing through them to create some heat.  Running the air conditioner with it actively cooling the RV will do this.  If it's too cold to keep the a/c compressor engaged, plug in one or two portable heaters to do the same thing.

MikeFromMesa said:

Thanks, but I am still wondering what "under load" really means. Is it enough to run the generator while using the microwave? Is 900 watts "under load" enough? Or the toaster (which I assume is more than 900 watts)?

In the winter time turning on the AC probably is meaningless since the compressor will not run. it is not warm enough to trigger the thermostat, so what is enough wattage to be considered "under load"? And if the purpose of running the generator is to get it up to temperature, why is it no sufficient to just run it for 30-60 minutes with no load? Surely the generator will warm up to normal operating temperatures without having the AC on if it is run long enough?

I am not trying to be difficult; just to understand.

Thanks again.

Click to expand...

As Lou said... plug in a couple electric heaters in the winter. Running the MW or toaster isn't really helpful because one normally only runs those items for a few minutes. You can leave 2, 1500W portable heaters for hours. Just don't use extension cords with them.

The stand by generator at work has a auto excoriates clock that runs the unit once every 2 weeks.  It all way scares the smokers when ever it starts..    I wander if you can install a exicorise clock on your rv generator

Under load is generally considered to be 1/2 the generator's rating.

So for a Onan 5500 that would be 5500/2 watts (2750 watts) or two air conditioners or 2 1500 watt space heaters.

Smaller generators might only need one, and you can toss in a water heater to replace one, provided teh water needs heating.

Onan recommends 2 hours monthly at 50% load, per the owners manual.

I'm new to this MH thing....& I've been wondering these same questions....
Skimming my manual, I saw mention of the need to exercise the genny, but no definition of what that meant.
As a mechanical engineer with many years in maintenance engineering with industrial rotating equipment.....Personally my gut checks says this.....
a) you're over thinking it a bit....
and 2) I don't think that this is solely about driving out moisture from the machine hardware, windings.....

The reason I say this is, well I'll paint a scenario...
rv parked in the weather.... say a grass field in florida where it rains hard and often.
OK, so you get the genny up to operating temp and drive out the moisture.  That afternoon, it's now cooled and it rains.  The next am, there's condensation on the metal...... this cycles day after day until the next month when you exercise the genny again....
So what did we accomplish?
it was dry for what?.... 3 hours out of a month?.... 3hours/744hours = 0.4% of the time.....

Now as with any machine, there's benefit to be had from driving moisture out of the crankcase oil, this is actuallly a bigger concern i think, as the oil will collect moisture with every temperature cycle of warm to cold through each day.... but there's also a need to keep things like the seals moving around, keep oil circulated over the internal surfaces, etc.... and to replace the gasoline that sits in there so taht it's not varnishing up the little orifices....
so sure, running regularly is better for any machine.....
so running an hour a month seems like a good idea to me..... I actually think running a couple different times at half an hour might even be better....
And then the question... how long does it take to warm it up?  Wouldn't an air cooled engine get to operating temp in a few minutes....... boy, i would think 5-10 minutes would do it.....
.... and what's a load...... i would think any electrical load would work.  Just turn something on.....  Charging the battery for half an hour to top it off along with some lights on gets the electrons flowing so the electrical contact bits get a workout......
Just a guess, but that's what I'm thinking.....

There are more things in this world than you have dreamed of Horatio.

Or to be more specific to the generator.

Running it 1/2 to one hour a month under load not only dries out the outside, but.

An engine sitting can suffer from acid build up in the oil.  Getting it good and warm for a while can burn off this acid, not doing that can result in a oil pan that looks like it was visited by metal eating termintes.(It gets religion and drips all your oil out through the Holy, er, holey part).

It polishes up the slip rings

Condenses of the electrolytic type like to be used from time to time, else they dry out and change value rsulting in som nasty waveforms.

It keeps fresh gasoline in the carb (Gas models)

It keeps the INSIDE of the engine properly lubricated.

And so on.. in short it is an all around maintenance run... The outside is actually NOT a consideration though your thoughts do apply there too.

John From Detroit said:

Condenses of the electrolytic type like to be used from time to time, else they dry out and change value rsulting in som nasty waveforms.

Click to expand...

Now this is what I know nothing about...... I get the engine and mechanical stuff, and really don't think they would require so much thought in terms of load and time..... run it "a little while".... long enough to really warm up..... and run it regularly.  Should be good.
It's these electrical considerations I don't understand....

I have always wondered what makes generator engines so fussy.

When I lived in Philadelphia over 30 years ago, my snowblower went for many months without being run, but it would start when required. The lawnmower never was started and run in the winter. The root-tiller ran only a few times a year. My Yamaha 115 can go for months without being run and then kick right over.

What is it with gen-sets?

aggiedad said:

I have always wondered what makes generator engines so fussy.

When I lived in Philadelphia over 30 years ago, my snowblower went for many months without being run, but it would start when required. The lawnmower never was started and run in the winter. The root-tiller ran only a few times a year. My Yamaha 115 can go for months without being run and then kick right over.

What is it with gen-sets?

Click to expand...

great question!

aggiedad said:

What is it with gen-sets?

Click to expand...

Electronics that your yard tools don't have.

It's a good idea to put fuel preservative in your yard tool engines. "Sea Foam" is a good one. Put a little in the oil too. It keeps the gasoline from turning to varnish and gumming up the carburetor and fuel lines. I put a quart of Sea Foam in my MH fuel tank with my last fill up, before it sits for awhile (generally about 25 miles before getting home). I run the generator for an hour then also.

Wavery said:

Electronics that your yard tools don't have.

It's a good idea to put fuel preservative in your yard tool engines. "Sea Foam" is a good one. Put a little in the oil too. It keeps the gasoline from turning to varnish and gumming up the carburetor and fuel lines. I put a quart of Sea Foam in my MH fuel tank with my last fill up, before it sits for awhile (generally about 25 miles before getting home). I run the generator for an hour then also.

Click to expand...

I never used Sea Foam, but I'll be looking for it....  Better than Sta Bil, eh?
and I never thought of putting anything in the oil.... but it sure makes sense.
I have been putting say bil in my fuel since I've had the motorhome.... mostly for the genny, since our usage is weekends only and not every weeknd so things are sitting a bit.... well not so much now, since the new hasn't worn off yet ;D

blw2 said:

I never used Sea Foam, but I'll be looking for it....  Better than Sta Bil, eh?
and I never thought of putting anything in the oil.... but it sure makes sense.
I have been putting say bil in my fuel since I've had the motorhome.... mostly for the genny, since our usage is weekends only and not every weeknd so things are sitting a bit.... well not so much now, since the new hasn't worn off yet ;D

Click to expand...

I'm not sure if it's any better or worse than StaBil..... Personally...... I dislike all of these chemical additive companies. I just don't like it when I have to pull the carburetor off of engines or deal with a gunky fuel tank because fuel has sat in them too long.

I've been using Sea Foam in all of my engines (gas and diesel)  for the last 45 years and I never have fuel or engine problems.

If I'm not using my RV I take it out once a month.  Usually to a restaurant about 10 miles away. I run the gen for about 90 min with a/c or plug in heater, leaving it going while we eat. The drive  is 20 miles and I try to use my dash a/c for a while too. I put $20 of gas in it if it will take it. Don't bother with the fridge or water heater or furnace. 8 years now and no additives or problems at all.

Wavery - The electronics should not have anything to do with the engine - they are effective after the generator engine has started.

Sta-Bil, Sea-Foam, and any number of others are fine. The purpose is to stop the fuel from degrading over time and absorb the water that tends to separate out of ethanol-based gasoline (the ethanol attracts moisture).