Generator Usage?

[angnjake]

We are shopping for our first RV.  All of the listings include the number of hours on the generator.  What is the significance of this?  How often do generators need to be serviced?  What is too many hours on a generator?  What should we be looking for in a generator when purchasing a used RV?

Thanks!

 

[AndyinLexington]

The following is my opinion only.  Opinions will vary.

1.  Hours on the generator are an indication of the amount of wear on the generator.  A generator with 5000 hours should be expected to have much more wear than one with 500 hours.

2.  Generators typically should have the oil and filter changed about every 100 hours.  Consult the manual for the specific make/model for precise requirements/recommendations.  My Onan manual recommends oil/filter every 150 hours, but I still do it at 100-Hour intervals, unless the time period is very short.  If it's been a couple of months and I get to 100-hours, I change the oil and filter.  If it's been two weeks, and I've just been using it a lot, I will wait a while.  It's a judgement call.  Air filters can be replaced on condition.  They are easy to inspect.  Same with spark plugs, wires, etc.  I change my fuel filter once a year, unless I'm having symtoms that could indicate a fuel issue.  I also change it every time I replace the fuel pump (only done this once).

3.  I think a generator that has more than 2000 hours on it can generally be considered to be on "borrowed time", especially if you don't know or can't verify the maintenance history.  With good maintenance, and being run regularly, a good quality generator can last 3500 hours or more (gasoline). A diesel can last much longer.  I don't have experience with propane generators but have heard that they use a LOT of propane which can get expensive.  It can also be difficult to find "on the road", so I would steer clear of a propane generator unless you don't plan on using it much.

4.  I would look for a good quality generator (Onan is what I'd prefer, but you will get a lot of variation on opinions here), that has been run regularly, with documented maintenance, and not too many hours.  You should also look for one that is well matched to the load.  In my mind this means 4KW - 5KW if the RV has one air conditioner and 5KW-6KW if it has two air conditioners.  This is just a guideline, but I think it's a pretty good rule of thumb.

 

[Lou Schneider]

A generator has an internal combustion engine, just like your car.  Think of hours of operation in automotive terms.

A car traveling an average of 50 MPH will go 7500 miles in 150 hours.  Time for an oil change, right?

A car running for 2000 hours @ 50 MPH will travel 100,000 miles.  3500 hours is 175,000 miles.  When do you rebuild the engine?

 

[Jim Dick]

Onan has a maintenance requirement to run the generator each month. Mine requires 30 hrs/mo min/mo for proper maintenance. If you find a coach where the generator has low hours compared to the year of manufacture, you most likely will have some work to do on the engine.

If the unit is new, under warranty, and you have a problem, most likely they will check the hour meter. If it has not been run enough to cover the maintenance requirement, the warranty may not cover the cost since it was not maintained properly.

 

[Jammer]

We are shopping for our first RV.  All of the listings include the number of hours on the generator.  What is the significance of this? 

They report it because it is an objective fact that is easy to report.  In most cases it doesn't mean much, by itself, because the condition of the generator isn't, in the greater scheme of things, that big of a deal in the overall purchase of an RV.

If the generator has much higher hours than expected, considering age and miles, on a fairly new RV it might lead you to ask questions about how the RV was used.  Kind of like seeing worn-out brake pedals and floor mats on a car that is only has 20,000 miles on it.

How often do generators need to be serviced?

Typically every 100 hours or so depending on the unit.  See the maintenance schedule on page 23 of this document:

http://www.cumminsonan.com/www/pdf/rv/f-1123.pdf

Other manufacturers are similar.

What is too many hours on a generator?

Most fail due to age or lack of maintenance before failing due to wear.  Wear is affected by load, too.

I would expect to get at least 2000 hours out of a generator in most cases.  Usually this is about what we get from higher quality small engines on lawn mowers and so on.  New generators are typically around $4,000 installed depending on the generator and the difficulty of the installation.  It is also possible to have the engine overhauled which may make economic sense on larger units.  Usually the electrical side outlasts the engine side.

What should we be looking for in a generator when purchasing a used RV?

On a newer unit, 1-3 years old, you should expect maintenance records, and expect hours to be proportional to age and miles.  For example, if you're looking at a one-year old RV with 1500 miles on it, and the generator has 2000 hours on it, you should assume that someone was living in it at an archeological dig the whole time, and adjust your offer accordingly.

On an older RV it's just going to be one more reason to dust off the toolbox no matter how many hours are on it so it doesn't really matter much.

 

[angnjake]

Thank you all for your responses.  You've given me good background knowledge on generator usage in used RVs. 

 

[Gary RV_Wizard]

My 2004 diesel generator has 1780 hours on it. That's considered fairly high (lots of generator usage) for its age, but by no means excessive or on its death bed. I fully expect to see 4000+ hours from it without major repair. Might get 5000 or more. An electronic part or drive belt is more likely to fail than the diesel engine itself.

I change the oil & filters annually and the radiator coolant every 3-4 years. It gets exercised any month when it is not run for the usual purposes.

 

[Wendy]

I thought exceptionally low hours on a generator was also a problem. Don't they need to be used?

Wendy

 

[Gary RV_Wizard]

Sure do, Wendy. Less than 12 hours per year is a warning sign that it did not receive regular exercise. I'd even be concerned under 20/yr, because there is likely a day or two of regular use in there and it may have sat idle the rest of the year.

 

[RLSharp]

Onan has a maintenance requirement to run the generator each month. Mine requires 30hrs/mo for proper maintenance.

Hi Jim,

I am intrigued by your statement that your Onan requires 30 hrs/mo for proper maintenance. That is one hour per day--can that be right? Seems high to me but I do not have any experience with a diesel genset.

Glad to hear that Pat is better with no heart involvement. Linda and I hope to see you some time next year.

R

 

[Jim Dick]

Richard,

You caught me! Not having the manual handy right now I think it's 30 MINUTES a month! ;D Mind just wasn't working properly, perhaps because of Pats situation. Sorry for the confusion!

 

[RLSharp]

Sorry for the confusion!

No problem Jim. Thirty minutes per month sounds more reasonable.  ;D

R

 

[Howard R]

I thought exceptionally low hours on a generator was also a problem. Don't they need to be used?

Wendy

We are on our second class a with a generator.  Both had low hours when we got them .... 01 Mirada had 41.5 hours after 5 years and I didn't know any better then .... 2nd owner had to have carb replaced/repaired before we took delivery, refused to start the second time we looked at the unit. 

At about 480 hours generator would not run when start switch was released .... diagnosed as shorted stator by Cummings ... I replaced the stator (about a $600 part) and it works well to this day with pretty much regular exercise during "off season".

Brother also has a 4 KW Onan ... he wasn't able to keep up regular exercise and had to replace the carburetor. 

Current 5.5 KW in our 01 Southwind I think had about 96 hours when we got it almost 2 years ago (about 500 hours now).  This time I was more knowledgeable and knew going in that the low hours could be a potential problem ... so far so good.

4 KW Onan manual says to exercise the genset at least 1 hour each month if use is infrequent.  Run the genset at approximately 1/2 rated power.

AC's work good in the summer for a load, a couple of electric heaters will do the trick in cooler weather .... one 1500 W and maybe a second at 750 W for the 4KW.

They also say a single exercise period is better than several shorter periods. 

Exercising a genset drives off moisture,  re-lubricates the engine, replaces stale fuel in fuel lines and carburetor and removes oxides  from electrical contacts and generator slip rings.  So says Onan.

Along with regular maintenance I try to faithfully exercise the generator monthly during the off season .... during the summer it gets plenty of use ... use it often going down the road in hot weather to run the roof AC's as needed.

As they say, your mileage may vary, but so far that is our experience ... use it or lose it as they say.  ;D

Howard