Generator PTO Generator

[RonMar]

I believe if you will reread my thread you will notice that one of the differences I noted was that the generator will go down to an idle and when you are not pulling any apreciable current. As the current demand goes up then it will speed up the motor on the generator. The tractor does not have that capability so it will be running at full rpms any time you are using the generator. The governor will make some difference but basically it will not be sitting at an idle until you need it. I have not checked to see how long my tractor will run with 7 gallons of fuel but the generator will do somewhere between 10 and 12 hours maybe longer depending on how much electricity I use. I also believe there is a difference in price of almost 1.00 per gallon locally. since gas here is running about 1.90 a gallon on the average that is going to make a huge difference in computing the cost.

The generator you describe, DC/inverter type is only now becoming commonplace, probably due to their price(but they sure are nice though). The honda's I have looked at do offer a very nice inverter output. With some added circuitry, they can also be combined/paralleled to increase your system capacity. This comes back to the horsepower used. An idleing generator is moving less air thru it's blower and consuming less HP. They are also firing less times per minute at that reduced load RPM. That however is about the only thing that gets the gassers competive with the diesels. Diesel also has quite a few more BTU than gas does, so more potential work is available in each gallon of diesel.

 

[gemini5362]

The generator you describe, DC/inverter type is only now becoming commonplace, probably due to their price(but they sure are nice though). The honda's I have looked at do offer a very nice inverter output. With some added circuitry, they can also be combined/paralleled to increase your system capacity. This comes back to the horsepower used. An idleing generator is moving less air thru it's blower and consuming less HP. They are also firing less times per minute at that reduced load RPM. That however is about the only thing that gets the gassers competive with the diesels. Diesel also has quite a few more BTU than gas does, so more potential work is available in each gallon of diesel.

I dont believe i have a dc inverter type of generator. I do however I am sure have a monitor that if I am not useing any current or just a small amount (I have not checked to see) it sets the rpms at idle. If the load goes up then the motor changes to full rpms. Since I have not done any tests to see what happens and how long it will actually run I dont have empirical facts to back my estimates up. If we assume the price of gasoline at 2.00 a gallon and the price of diesel fuel at 3.00 a gallon then we can make the assumption that if my generator runs 12 hours on a tank of gas which is 7 gallons then we could assume the same amount of money spent for 7 gallons of diesel would buy us aproximately 10.5 gallons of gas. now if we can run for 12 hours on 7 gallons of gas then we should run approximately 18 hours on 10.5 gallons of gas. Because of the price of diesel we are only going to have 7 gallons of gas for the 49 horse montana. Now I am not an expert on how much difference work makes versus just idleing but If you dont use any diesel when you are not doing work then my tractor should be able to run at 2400 rpm's ( 540 pto speed) for ever without my having to fill the tank. That obviously does not happen. Actually i kind of thought that if the tractor was running 2400 rpm's it takes a certain amount of fuel to fill the cylinder to get 2400 rpms so it is going to use some fuel. I would be totally amazed if I could set my tractor out there with no load ( even though the generator would be a load not sure how much of one it would be for a 49 horse tractor) and run for 18 hours at 2400 rpm on 7 gallons of diesel. It might and i have never tried it but it would amaze me.

 

[Soundguy]

4] ~6.5 : 1 gearboxes [3600/540] are pretty inefficient. Much nicer to have an 1800 rpm gen -- or else one designed for 1000PTO.
larry

Good point.. the more poles the better ( and more $$ ).

soundguy

 

[Soundguy]

Sure. You're adding a trailer with a bunch of wind resistance and a handful of tires. Pretty much what I said above.

Think of an over-the-road semi with a dry van trailer. It can double its weight when loaded, and still stay within 10% of its unloaded milage. Or Boneville Salt Flat racers. Those cars are heavy as heck, but very slippery.

Nobody has proven Newton wrong yet.

I agree.. I drove 2260 miles round trip to texas at easter.. used a ford f250 diesel.. pulled an empty 16' trailer up.. got 14.1 mpg total.. pulled that rig back with a 3000# tractor on it.. got 14 mpg back...

soundguy

 

[Soundguy]

I believe if you will reread my thread you will notice that one of the differences I noted was that the generator will go down to an idle and when you are not pulling any apreciable current. As the current demand goes up then it will speed up the motor on the generator. The tractor does not have that capability so it will be running at full rpms any time you are using the generator. The governor will make some difference but basically it will not be sitting at an idle until you need it. I have not checked to see how long my tractor will run with 7 gallons of fuel but the generator will do somewhere between 10 and 12 hours maybe longer depending on how much electricity I use. I also believe there is a difference in price of almost 1.00 per gallon locally. since gas here is running about 1.90 a gallon on the average that is going to make a huge difference in computing the cost.

I think you are missing the point.. generated alectricity is frequency dependent.. and that is rpm dependent.. to get that machine to idle down.. I'm betting it has to have -0- load.. otherwise it wouldn't be making the correct frequency power... I don't let my gennies set and run if there is no load for extended times.. thus the idle down argument is less attracive.. since my tractor engine uses NO FUEL when i turn it off ( when i don't need electric ).. vs your idled gas engine using some fuel when you aren't making power.. well.. I'm sticking to my original argument..

soundguy

 

[Soundguy]

If it is not an inverter type.. then it's all or non on the current / idle issue.. since at idle the frequency of the generated power would be way wrong.. thus if it s flowing ANY current.. it's not idling.

If it was an inverter type.. then it would be expensive to get one with much cpacity.. let along anything near what a 13hp engine could kick.. ie easilly in the .5kw range.. an inverter that big would be expensive.. plus need a decent battery to suck on. Inverter's throw additional ineficency into the mix...

Like I said.. I'll stick tot he diesel engine vs the lawnmower engine.. vs the inverter ...

soundguy

I dont believe i have a dc inverter type of generator. I do however I am sure have a monitor that if I am not useing any current or just a small amount (I have not checked to see) it sets the rpms at idle. If the load goes up then the motor changes to full rpms. Since I have not done any tests to see what happens and how long it will actually run I dont have empirical facts to back my estimates up. If we assume the price of gasoline at 2.00 a gallon and the price of diesel fuel at 3.00 a gallon then we can make the assumption that if my generator runs 12 hours on a tank of gas which is 7 gallons then we could assume the same amount of money spent for 7 gallons of diesel would buy us aproximately 10.5 gallons of gas. now if we can run for 12 hours on 7 gallons of gas then we should run approximately 18 hours on 10.5 gallons of gas. Because of the price of diesel we are only going to have 7 gallons of gas for the 49 horse montana. Now I am not an expert on how much difference work makes versus just idleing but If you dont use any diesel when you are not doing work then my tractor should be able to run at 2400 rpm's ( 540 pto speed) for ever without my having to fill the tank. That obviously does not happen. Actually i kind of thought that if the tractor was running 2400 rpm's it takes a certain amount of fuel to fill the cylinder to get 2400 rpms so it is going to use some fuel. I would be totally amazed if I could set my tractor out there with no load ( even though the generator would be a load not sure how much of one it would be for a 49 horse tractor) and run for 18 hours at 2400 rpm on 7 gallons of diesel. It might and i have never tried it but it would amaze me.

 

[Egon]

Originally Posted by Smokin Diesel
Sure. You're adding a trailer with a bunch of wind resistance and a handful of tires. Pretty much what I said above.

Yea, but I unhook that trailer and take the camper off the truck so shouldn't the Fuel Mileage just go to astronomical levels if it's about HP required.

By the way fellows, all those degrees aside, have any of you ever heard of topography relief!

 

[Smokin Diesel]

By the way fellows, all those degrees aside, have any of you ever heard of topography relief!

Yep. For every uphill there's a downhill. For the extra fuel burn on the way up, you'll get that much free energy on the way down. I'll get my best towing mpg when I'm in the mountains, which was a surprise the first time I experienced it. But it does make sense, considering that I'm 10-20 mph slower in the mountains than I am across the plains, and that my net elevation change is zero.

Wanna start another thread about towing mpg in the proper forum and give this guy his thread about generators back?

 

[Egon]

[QUOTEWanna start another thread about towing mpg in the proper forum and give this guy his thread about generators back?QUOTE]

Never deviated. Thought fuel economy was brought into play as part of the issue or did you miss that?

You fellows always in the habit of ignoring facts if they don't suit your opinions

 

[gemini5362]

I think you are missing the point.. generated alectricity is frequency dependent.. and that is rpm dependent.. to get that machine to idle down.. I'm betting it has to have -0- load.. otherwise it wouldn't be making the correct frequency power... I don't let my gennies set and run if there is no load for extended times.. thus the idle down argument is less attracive.. since my tractor engine uses NO FUEL when i turn it off ( when i don't need electric ).. vs your idled gas engine using some fuel when you aren't making power.. well.. I'm sticking to my original argument..

soundguy

you are probably right about the 0 current. I have not tried it so I dont know. but your arguement on that point makes sense. I guess your arguement goes back to what you are going to use the power for. If you are going to have a generator running so that you can have power for lights or tv or whatever then you can start the generator and have it run when you need it and turn it off when you are done. I believe I could do the same thing with my genrator. However if you are going to have power available so that you can turn on a light or power a fan for a heater. Then you are going to need to leave the generator running and my idle down feature on the generator would be a lot better. Luckily for both of us they make and sell both kind of generators so that we can both be satisfied with our choice whichever one is better.