Use of Generators

[Jon Wehrenberg]

It seems we go through periods where there are a number of posts relating to generators. We have just had one in which overheating was the topic, but I think we have seen almost every problem discussed.

From time to time I swing by Russell Coach just to see what is happening and to try to learn. On a recent visit Rob Russell and I were talking about generators. To put this in perspective a generator problem on an entertainer coach is as serious as a heart attack. Literally, because on an entertainer coach those five or six roof airs are not going to work unless the generator is working. Rob stated that it is not unusual when a coach starts out on a tour that the generator is started immediately and except for shut downs to service the generator such as an oil change, the generator doesn't get turned off until the bus returns from the tour.

So what does that mean relative to us? Simple, his generators are working and working almost all the time. It is not unusual for his generators to rack up the hours, and the hours on his generators range from 20,000 to over 35,000 hours. The lesson for me is clear. We need to run our generators often and hard. If we need to run our roof airs or cruise airs we shouldn't try to rely on inverters or battery power, but we should turn on the generator and run all the units at once. We are doing the best thing we can for our generators by exercising them and loading them.

Long ago we got in the habit when we were not connected to shore power to crank up the generator and load it up. But we have been cautioned about running a generator with a light load. I'm not sure any of us, or the entertainer coaches ever really put a heavy load on our generators. The roof airs on a typical entertainer number 5, so the maximum load might be 5 times the current draw from the AC units plus maybe some lights or a microwave used for a few minutes to make popcorn. That might add up to 75 amps on a 20KW generator which is about 167 amps. So basically even when everything is running generators are not even working at 50%. When the interior temps on a coach get where they need to be the AC units start cycling so the load drops a whole lot more. Same with us. So apparently running a generator, even lightly loaded is not going to adversely affect it.

So every chance I get to run the generator, and load it up I do so. It is in my opinion never going to wear out as we use it, and it is just nice not having to worry about energy management such as when connected to shore power, or running down the highway.

[truk4u]

Yep, that's what Kohler told me, 35,000 hrs before even thinking about overhaul.

[merle&louise]

When we are tailgating my generator runs from Friday at noon to Sunday about 1 PM - 48 continuous hours. The outside temps down here in Louisiana are about 90 degrees so we are drawing about 60 amps more or less for most of the day. So the generator gets a good work out. Presently I have about 3200 hours on the generator and it really runs great.

You know it's funny, when you look at MH for sale ads you see a '97 coach with 500 hours on the generator! This is supposed to be a plus! I would much prefer a higher hour generator than one with low hours.

[dogear]

Hi all, don't entertainer coaches have two generators?

[johnklopp]

I totally agree with Jon. Maximum load is far easier on the engine and reduces fuel consumption per Kw produced.

I recently completed a system design upgrade for General Dynamics. GD is the prime contractor for the Marine Corps combat operating bases. Each base has ten 25Kw generators and an equal number of 10 ton air conditioners.

The issue was simply light load operation causing problems for the generators as well as increased fuel consumption. The solution was a controller that would monitor all of the generators and turn off as many as possible to maintain operation at a minimum of 75% of full power.

The difficulty was to add the 3 phase generator back on the power grid and automatically parallel them.

Ten generators are used instead of one 250 Kw generator in order to keep the weight of the generator, trailer and 100 gallons of fuel less than the maximum weight towable by an up armored Humvee or lifted by a small helicopter.

The fuel savings from full load operation alone paid for the modifications in less than 6 months.

In our case, I tend to run on inverter power as much as possible then manually start the generator that then runs at full load to recharge the batteries.

A 97 with 500 hours doesn’t sound low to me. I purchased my coach last year with only 219 hours on the generator. After 10 months the run time is only up to 340 hours.

[Jon Wehrenberg]

Hi all, don't entertainer coaches have two generators?

Not always. It depends on the converter. On an entertainer coach bay space is a huge benefit so adding a seond generator may be robbing space that is more important for the group or person leasing or owning the coach. If Rob Russell is lurking he is the one to answer that question.

[Jon Wehrenberg]

Generator hours sometimes are a clue to how a coach is used and how much use it has had, or you cannot read anything into what the hours show.

If I saw a coach with low miles, but high generator hours if could mean the owner ran his generator a lot, maybe even while driving, and that he may not have spent much time in a campground hooked to shore power. Or high hours on a low mileage coach might mean the coach was used for a lot of dry camping.

Conversely low generator hours could mean the coach was hooked to shore power most of the time it was used. Without other signs like very worn upholstery or almost brand new upholstery knowing generator hours alone is only part of the information necessary to figure how a coach was used.

But bottom line for me is low generator hours is not necessarily a plus and Tuga's 3000 plus hours is more likely to mean the generator is healthier.

[jack14r]

Having had a controller failure last year on my Kohler generator I carry a spare,I have a 6120 watt air cooled Yanmar Diesel generator from Central Maine Diesel that is my back up.I needed it in Louisville 10 days ago when the Kohler would not start because the starter or the solenoid was overheated,it burns about .3-.4 of a gallon an hour but it has a very small tank,I am building a 4 gallon tank next week so that it will run all night.The problem that I see with most generator installations is that the heat from the radiator is radiating under the bus on those 90+ degree days,I do like the idea of putting the radiator on the roof.With cruise airs discharging the hot air from the condensers and the generator radiator discharging hot air under the coach it can get very hard to cool the bus on some days.I really like the small generator at night because I have it 75 feet from the bus and there is no hot air under the bus from a radiator,when I get up in the morning the floor in the salon is cool rather than hot.

[Jon Wehrenberg]

Uh, Jack.........you are aware that you are only the second POG member to use or advocate a second generator mounted OUTSIDE the coach. The other one is our own runaway Jeff Bayley.

[jack14r]

Yea Jon I am aware,but my reason is different from his,I really must have a spare since I have had a total generator failure we have a comfort level knowing that the spare will get us through almost anything.I will state again that the heat created by the generator under the coach is a problem and the spare solves this issue.

[Jon Wehrenberg]

Jack,

Are all the baffles in place? We have run the generator for long periods in excessive heat and so far, so good. But when I got my coach the generator baffle had been squashed kind of flat, and the cross baffle for the middle two Cruise Airs was handng on with one bolt. I repaired each problem and do get a chance to get under and check things out often. I think the baffling is critical.

[JIM CHALOUPKA]

Jack,

Are all the baffles in place? We have run the generator for long periods in excessive heat and so far, so good. But when I got my coach the generator baffle had been squashed kind of flat, and the cross baffle for the middle two Cruise Airs was handng on with one bolt. I repaired each problem and do get a chance to get under and check things out often. I think the baffling is critical.

Jon, could you post pictures of those three baffles, I only have one for the OTR air.

JIM:)

[jack14r]

Yes,they are all in place.

[Jon Wehrenberg]

Jim,

I'm jammed up and cannot get pictures yet, but you should have a baffle under your generator that allows exhaust air from the generator radiator to blow to the rear of the coach. That is a steel baffle. That stops the air from returing to the radiator. The fan which takes heat and air from the generator box has a small steel baffle on the exhaust so the air from that box does not re-enter.

In the approximate center of the second bay beneath the coach there is a rubber (like a mud flap) baffle that extends crosswise. That baffle separates the air exhausting from the two Cruise Airs in the middle of the second bay from returning to the air intake of those Cruise airs. The way our coaches are set up (yours, mine, Fred's, Tony's, and all others from the same vintage) all the air intakes will not have heated air returned to them as long as the baffles are in place.

The front Cruise Airs have intake air from behind the bumper and it is exhausted out the bottom.

[JIM CHALOUPKA]

OK, I can wait.
I do have the long crosswise flap and the OTR baffle.

JIM