Stand-by generator

[Olmike]

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.

 

[BobRip]

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.

That's cool. You might want to measure the gallons per hour fuel consumption so you can be prepared with enough fuel. I suspect it will use a lot more than a gallon per hour. Still, for what you have in it, it's a good emergency generator.

 

[CurlyDave]

That's cool. You might want to measure the gallons per hour fuel consumption so you can be prepared with enough fuel. I suspect it will use a lot more than a gallon per hour. Still, for what you have in it, it's a good emergency generator.

I was thinking gallons per minute .

Actually it looks really good, especially for the price.

Is it running in the last pic or is that just a shaky camera? I sure wouldn't run it in an enclosed garage, even for a few minutes.

 

[Cottonhawk]

The price is great. Hope that your generator works as well as you expected.

 

[Olmike]

Thanks for the comments. Dave, Yea it was runnin in the shop. I had the door cracked open & the exhaust fan On.The building is bigger than it looks in the pics. I don't what fuel consumtion will be,But for what I got in it I don't care if never have to use it. Even then it'll be better than sittin in the dark!

Mike

 

[Tom_Veatch]

...
I don't what fuel consumtion will be,
...

I don't know what the rated power output of that engine might be, but at 6.5KVA, you're only going to be consuming 12-15HP. My guess is that is a light load on the engine and the fuel consumption will be less than you expect.

You didn't say anything about an engine governor so I'd be more concerned with RPM/Voltage/frequency control. No big deal if all you're doing is burning some light bulbs, but it could get dicey if there are any motors, electronics, etc. in the load.

 

[BTDT]

Does it have it's on propane source, or are you going to tie it in to house/shop tank. I have a small Onan 2cyl. that came out of a motorhome that I mounted on a trailer with tank off of motorhome for fuel supply. Portable power. No fancy diffuser or regulator, just ran a small 1/4" copper tubing to top of carb. Push button to start, then open valve on tank, works ok.

 

[Olmike]

I have a govnerner on the engine.It only runs 1800 rpm,just a good fast idle.Right now it runs on a 20# bottle but don't know for how long.
Mike

 

[George2615]

Great project. That's a lot of motor for a 6.5KW gen. Does your 1800 RPM give you a steady voltage and 60 cycle frequency? At that RPM fuel usage should be minimum. Good standby power supply. If the rating is 6.5KW continuous you can probably run a small house with minimal load. I ran a 5KW as my house backup power for a couple years before getting a larger 10KW gen.

 

[Olmike]

Thanks,George. The generator is rated at 1800 rpm.It pulls down A little at the first hard load but recovers quickly.I'm gonna hook it to the house soon & see what it does.I post it here after I try it.

 

[chim]

If my "figgers" are correct, here's what the values are AT 100% EFFICIENCY. Caps because I have no idea what the efficiency will be. Could be anything.

Anyway, 6.5KW = 8.72 HP = 22,190 BTU/Hr = 4 Hrs 9 minutes of run time per gallon.

If it is 50% efficient, it will still run for 2 hours on a gallon................chim

 

[Ronbo]

how did you mate your generator to your engine? I see the plate, but how about some close up pictures and how about the shaft?

ron

 

[Mickey_Fx]

If my "figgers" are correct, here's what the values are AT 100% EFFICIENCY. Caps because I have no idea what the efficiency will be. Could be anything.

Anyway, 6.5KW = 8.72 HP = 22,190 BTU/Hr = 4 Hrs 9 minutes of run time per gallon.

If it is 50% efficient, it will still run for 2 hours on a gallon................chim

Internal combustion engines are only about 25% thermally efficient. Diesels about 10% higher.

 

[BobRip]

Internal combustion engines are only about 25% thermally efficient. Diesels about 10% higher.

They are at best 25% efficient. This is generally at some moderate load (I believe). Lightly loaded they are less efficient. At idle they are even less efficient. If you run a 100 HP engine with a 1 HP load, it still has to turn the alternator, water pump, and oil pump, push the pistons against the rings and overcome bearing friction, open and close valves etc. So efficiency drops drastically. Run down a 20 pound tank at about 1/2 electrical load and see how long it takes or not.

 

[Bob_Skurka]

Interesting project.

 

[BobRip]

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.

 

[Olmike]

how did you mate your generator to your engine? I see the plate, but how about some close up pictures and how about the shaft?

ron

Ronbo,I made A flat plate to bolt where the pressure plate bolted.I welded a
1" stub shaft in the center & used A lovejoy type coupler to hook em together.The front mount plate of the gen almost centered perfectly in the bellhousing.I machined A shaft for the gen input cause it was mounted directly to the crank & block of the onan engine.

Mike

 

[Olmike]

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.

Bob, I think you're right about the evap rate.I'll have to figure A way to heat the bottle.Hot water maybe?

 

[sandman2234]

How about hot water from the heater core lines coming from the engine? Seems letting it heat itself might be the best way, or build an enclosure for the whole thing?
David from jax

 

[Olmike]

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