Onan Generator

haste maker wrote:
I have seen where Cummins has said that the Onan generator needs to run 2 hours each month under load ……

An interesting side note, the design hasn’t changed in many decades, but about 30 years ago the instruction manuals started to warn the owners of all the horrendous things that would happen if the generator wasn’t ‘exercised’ faithfully *every* month.

BTW, 30 years ago is just after Cummins bought Onan……..l guess they have better lawyers.

My 30-year-old Onan manual specifies two hours monthly. I run it an hour once or twice a month.

Running the gen will scrub crud off the slip rings and brushes.

I do not agree with Onan. I never have, but I have only been taking care of other people's (usually very expensive) engines since 1960.
If you take care to drain (or at least run the) carburetor dry, that is most of the issue. I have never seen significant internal corrosion on engines that were merely "bottled" up when shut down. This was all on tidal water (salt). If you are worried, learn to "fog" the engine. (This means introduce a cloud of oil as you shut it down.) If you think you need to warm the windings, the varnish that needed that was replaced before the second world war.
Keep in mind that the people that want you to run the engine regularly are also the ones that will want to sell you parts that got thermal cycled to death.
Matt_C

wa8yxm wrote:
I had always heard a shorter period of run but won't argue.

I used electric heaters in the winter.. Usually while changing campgrounds.
And the Roof A/C's in the summer. Never had a generator issue other than a sticking choke and I never noticed that (Mechanic spotted and fixed it as part of an oil change)

Check that I did have a couple problems with the Generator stopping suddenly.... When it ran out of gas... (Easily fixed at the pump.. well. expensively fixed but still easy)

I had always heard a shorter period of run but won't argue.

I used electric heaters in the winter.. Usually while changing campgrounds.
And the Roof A/C's in the summer. Never had a generator issue other than a sticking choke and I never noticed that (Mechanic spotted and fixed it as part of an oil change)

I'm sure the documentation for my Onan 5500 says 30 minutes a month. I guess Onan has upped the hours in the 12 years since mine was installed.

From Onan:

I usually turn on the Aquahot electric heating element and run the heat pumps. That'll put 40 - 50 amps worth of load on the generator. The theory is, I suppose, that "free-revving" an engine is never a good idea (hence the need to apply a load, since generators run at speed) and sitting engines have plenty of issues with drying, rusting, etc. (the frequency and duration).

I'd use 2 1500 watt heaters. If 50 amps--one on each leg.

My 7.5 Onan got
120 hours in 22 years.. still works