Exercising the generator

[rbrand]

This is the first RV we have had with a generator. My question is how often should I run it just to keep it running well?

[Sam_Spade]

Matt_Colie wrote:
thermal cycles are what kill engines faster than anything else.

Well except:
Running with insufficient lubrication.
Running with insufficient cooling.
Overloading.
Lugging.
Running in extremely dirty conditions.
On and on.
😉

[pnichols]

I run our Onan about an hour each month with either a 1500 watt heater loading it (winter) or the A/C loading it (summer) for what is - to me - a much more important reason than the Onan manual saying to. I do it to make sure that it still works to allow for repair lead time so there are no surprises when attempting to use it first time while on a trip.

I check out - or should ckeck out if I remember - other RV items periodically to make sure they're working for future RV trips too, such as:

1. Run the furnace.
2. Run the water pump.
3. Keep the batteries on float.
4. Idle the main engine for awhile and check to make sure that full alternator voltage is getting applied to the coach batteries because switching solenoid contacts can corrode.
5. Run the roof vent fan.
6. Run the cooktop exhaust fan.
7. Run the bathroom vent fan.
8. If some of the above checks are OK, then I also know that the converter is still functioning ... mine failed once but I discovered it well before heading out on a trip.
9. Keep an eye on tire pressures to make sure no slow leaks have developed in between trips.

[Matt_Colie]

Of course Onan suggests you start it all the time and add useless hours to the running time, they sell parts and thermal cycles are what kill engines faster than anything else.

Ex Ship's engineer and OE engine development engineer.

Matt

[joebedford]

I exercise mine at 1/2 load for ~one hour each month. Normally I'm snowbirding so I don't have to worry about really cold Canadian starts, but this year we didn't snowbird (went to New Zealand - it was GREAT). I waited for a relatively warmish day (near freezing) to do the exercise.

[midnightsadie]

I have a onan lp gen set I run it every two months with a electric heater on, for about half hoir its a 2007 not one problem.

[MEXICOWANDERER]

ONAN? FOG? Boy have they ever got that right...

Onan is to generators what Lucas is to electrical.

Sell at manufacturer's cost to the military then screwum on maintenance and repair parts. Been inside everything from a 1,000 watt to a 10 Megawatt Onan and they are insanity incarnate. They spend endless time and money to design units that will not function with anything other than Onan parts.

Company in Vallejo CA. wanted to sell me an Onan generator so bad they cut the price in half. I didn't let the door hit me in the --- on the way out. They supplied my KATO generator. Then went out of business. They supplied Mare Island Naval Shipyard for decades.

Me and Oh-MAN (!) don't get along too good. I like stuff that lasts. With lowest upkeep.

[DownTheAvenue]

Matt_Colie wrote:
Rbrand,

Without knowing anything about the generator, my first response would be don't.

Some say you need to run it at load to heat and dry the windings. That has not been true since the end of WWII.

Is it fueled with:
Gasoline ?
Diesel ?
Propane (LPG)?

That is in order of PITA....
If it is gasoline fueled, figure out how to shut the fuel off and run the carburetor dry, that or some way to drain the float bowl. This will stop the "bad/old gas in the carburetor" problem. The little bit that remains will cause no issue.

LPG fuel has no issue this way. Nor does diesel, but diesel can get old in a few years and it will be smoky at start-up.

If you know you are going to be leaving it idle for an extended period, learn how to "fog" the engine. This amounts to putting an oil fog into the engine to protect the internal parts from corrosion. It is simple and on an engine as small as a generator, you can do it actually without starting the engine. You can do an adequate job one the starter motor. The engine does not have to be hot.

So, fog it, drain the fuel (if gas) and leave it alone until you need it again.

I have been doing this for my own and client's engines for many years. They are invited to call me if they have trouble restarting, and the only trouble ever is that they didn't get the fuel supply restarted.

Matt

Interesting. Onan specifically recommends otherwise. My money is on the people who designed and built the generator!

[ksg5000]

Onan recommends you exercise under load for 2 hours each month.

[ctilsie242]

I would check the generator manual out, as that is the truly official word. Last time I read it, it said to run it every few weeks with a load on it for 2-3 hours.

Of course, Onan's manual also has the option of fogging the generator as well.

[Sam_Spade]

Trackrig wrote:
Use some judgment in starting the generator in the winter since you live in Canada,

Good point.
Probably best just left alone when it is REAL cold.

But if the temps fluctuate a lot spring and fall, then condensation can be a problem......in the engine, pipes and fuel supply.

[MEXICOWANDERER]

Exercising the motor means heating the engine oil to 180 degrees F long enough to boil off moisture and hydrocarbon light ends. Putting a load on the generator heats the motor faster.

With EPA rules and scumbag manufacturer ethics these days I am not at all convinced today's winding varnish is the same as it was 20 years go.

I purchased my Mil-Spec KATO in 1987 and OEM stridently insists the windings be periodically dried out.

I would lean toward OEM recommendations with winding maintenance. But unless the engine is dedicated LPG the rule about cooking the engine oil remains the same.

[Sam_Spade]

Matt_Colie wrote:

Without knowing anything about the generator, my first response would be don't.

Some say you need to run it at load to heat and dry the windings. That has not been true since the end of WWII.

Sorry but I think that is unnecessarily complicated and overall bad advice.

Running it once a month for half an hour certainly will NOT HURT anything. 30 minutes is plenty in the summer time to heat up the oil and drive out moisture and get some fresh fuel into it......no matter what the fuel.

It probably is more important to stabilize a stagnant fuel supply and exchange it, or use it up, at least once a year.

[Trackrig]

Use some judgment in starting the generator in the winter since you live in Canada, though you do live in a warmer area. You could do more harm to the generator trying to start it when it's cold out than it's worth. When my MH was in Fairbanks, AK for the winter, there was no way it was worth trying to start in the middle of winter to exercise it.

When using the MH if you don't have need for the generator occasionally, then as stated above, when traveling start it up and power the A/C and water heater for a while.

Bill

[DutchmenSport]

Here's more input from a discussion on April 27: Click here.