Stand-by generator

[Tom_Veatch]

I just thought of a couple of other factors with propane. When it is cold outside, there will be a lower vapor pressure and if there is not enough surface area of the tank to evaporate the propane, then the pressure will drop and the engine will be starved of fuel. I don't know the conditions where this occurs, but it should be checked. You may find it runs OK for a while, but as the propane evaporates it will get colder inside the tank and pressure will drop. There will not be enough surface are on the outside of the tank to let enough heat in to keep the propane warm enough to maintain adequate pressure.

Here is a chart showing maximum draw at various temperatures. You'll have to do some unit conversions but it may help determine whether there is a problem or not.

 

[BobRip]

Yep,Thats what I was thinkin.Wrap the bottle with 1/2" copper or 5/8" heater hose & it would also help cool the motor.I have the heater lines routed through the vaporizer now so would'nt be a big job to heat the bottle.
Mike

This is a good head source.
If you get it too hot, the pressure in the bottle could go too high. Does somebody know the limit.

You can also parallel bottles to give more flow. You will probably need more that a 20 pound bottle to run it anyway.

 

[Olmike]

I have a 100# bottle for standby,the 20's are easyer to tote.

 

[86turbodsl]

I seriously doubt you'll have a problem with cold weather and the propane. The vapor / liquid temp point for propane is about -44C. If it's that cold, he's got other problems too...

 

[BobRip]

I seriously doubt you'll have a problem with cold weather and the propane. The vapor / liquid temp point for propane is about -44C. If it's that cold, he's got other problems too...

You may be right, but the outside temperature does not have to be -44F to have it not run a generator. As the gas expands its temperature will drop. The smaller the internal surface area and the smaller the volume in the tank, the quicker it will drop. At -44F it has zero pressure. No gas would flow out of the tank. I don't know the pressure requirements for a generator, but obviously greater than 0 PSI. I am out of my area here so I will let others comment.

 

[Highbeam]

I have no problem freezing my BBQ sized propane tank to the ground when using the weed burner to start a slash fire in 40-50 degree weather. When this happens the output rate of gas to the burner is greatly diminished.

But, there is still enough gas flow to use the weedburner to heat the propane tank and then get more gas to boil off.

 

[Tom_Veatch]

...
But, there is still enough gas flow to use the weedburner to heat the propane tank and then get more gas to boil off.

Ouch! The picture I have of applying that torch flame to the propane bottle really increases the old pucker factor for me

 

[BayouMan]

I'm with you Tom!!!

 

[Olmike]

A follow-up on the gen project.I haven't tried to power the house yet,but since nobody offered any advice on wheather I could weld with ,it I did what any self respectin DIYer would do.I hooked A welder lead to the dc output & grounded to the frame of the gen & it run a very nice bead on 1/2" at about 2200rpm.Now I need install plugs for welder leads & figure out how to adjust the governer for welding & generatin.

 

[sandman2234]

Since you have already tried it, I think I will go with the "it will work theory"
David from jax

 

[Nuru]

I've been puttin this together for about A month. The motor is A 2.5 chevy 4 cyl. out of an 85 cj5 jeep. My son gave me the motor cause he upgraded to A 4.3. The generator was originally powered by an onan water cooled 2 cyl And came out of a houseboat. It was given to me by my BIL. I got the propane stuff from a freind who had it in his basement,also for free.It puts out 6.5 KW.Total cash investment is less than $200.We ain't gonna count the time invested.It also has a DC output of 36 volts,I want to try to make a welder out of that part.If any of you guys know how that would I'd like to hear from you.

How do you plan to pipe the exhaust out of the garage? I am interested in finding out the best materials to do this so I can work on the tractor on bad weather days.

 

[PILOON]

If I'm not in error, I believe you would need to control the field voltage in the generator to vary the output amperage.

I think you have a 'one rod' sized welder.
Try different type rods and rod sizes.
Each type and size has different amperage specs, however forget about thin stuff.
With rod selection you probably can weld down to 1/8" safely.

I know because I once made a homemade welder without any control and with practice welded from 1/8 (with 1/6 or 3/32 rod) all the way up to 1/2" stuck with 5/32 rod.
Naturally I'd often have more penetration than I wanted but the welds sure stuck.
Was even able to use cutting rod that wanted about 200 amps.

But with DC, you sure will do nice welds.
Some rods are specifically made for DC welding, while others do AC and DC.

 

[Olmike]

NURU, I don' plan to run it inside anymore,I was testing it the pic & it was too cold to open the door. If you want A good way to vent exhaust,I use A vent fan motor out of an old high efficency furnace.Vent the outlet to the outside & get some exhaust hose from a good parts house & make an adapter to fit your tractor pipe.

PILOON, I haven't used it alot for welding,but it seems that the more rpm the hotter it welds.

 

[Tom_Veatch]

...I haven't used it alot for welding,but it seems that the more rpm the hotter it welds.

I strongly suspect that you are right. I doubt there is any control electronics to vary voltage and maintain current to a set point like there is on a CC welding source. If that's the case, the amperage (heat) will vary directly with the voltage developed by the generator (all other things, lead length, arc length, etc., being the same).

On my PTO driven generator, the output voltage rises and falls with RPM.