Making yer own backup generator?

[etc., etc.]

Prolly not what your looking for but still a pretty cool approach:

. My brother used to work for this guy - hes pretty nutty, but still, it's a cool setup.

If you want quality and quiet in a packaged standby generator you have to bypass the air cooled consumer lines (any brand) and move up to the liquid cooled commercial models. Those models from most any brand are pretty decent.

Yes indeedy, I've seen/heard WhisperWatt diesel generators (used by outside food trucks), very impressive. But, $6K++ for 6 kW, and you need diesel fuel. Also the better units are

1800 rpm, which quiets things down.

So do you think a car muffler would help?

Prolly not what your looking for but still a pretty cool approach:

. My brother used to work for this guy - hes pretty nutty, but still, it's a cool setup. ======================================================

A great idea, and in principle, any car engine would work. A guy I know in fact uses his car with a small inverter, just to keep his boiler going, which uses circulating hot water, so no big blowers or anything. And mebbe a radio and a light bulb or two. Not bad, actually, and a lifesaver in the winter..

But I'm using this to A/C and shop stuff, so I need some oomph.

The smaller packaged liquid cooled standby generators are usually Nat gas/LP. This is not the same as the Multiquip Whisper Watt diesel mobile generators.

I think the commercial standby units are pretty much all 1800 RPM. A car muffler or even a critical grade muffler will do *nothing* to quiet an air cooled engine as most of the noise emanates from the engine block, not the exhaust.

"Pete C." fired this volley in news:4ffefee4$0 $14808$ snipped-for-privacy@newsreader.readnews.com:

Weeelllll... it sure will do _something_ positive. I have a 1962 Dayton

3.5KW with an old-style updraft 8HP Briggs on it. (It'll run a 4.2KW load all day).

I replaced the silly pancake muffler with a small, low back pressure automotive style, and cut the noise level by way more than half.

Yes, the engine makes a lot of noise all by itself, but half as noisy is still a good deal.

LLoyd

A reliable engine is going to cost, no matter what you put on the alternator side. The breakpoint on cost seems to be at the 5-6KW point, twice that power costs way more than twice the price. If you just want some kind of AC out, you can probably cobble something up from a lawn tractor engine and a surplus alternator. If you want AC that's got stable voltage AND stable frequency, then that's going to cost more. You'll have to have some sort of governor that adjusts the engine speed with the load and does so quickly.

I've dealt with the consequences of having crappy auxilary power when the 15 KV feeder line got blown down over the channel at the shipyard and we had to run stuff on borrowed USAF generators for a couple of weeks. They tried running the computer room on one of the semi-sized units, was never clean enough to run the computer for more than 20 minutes without crashing and they damaged four disk drives doing it, several hundred grand's damage from bad power. A minor glitch in the governor design COULD have expensive consequences if you're trying to run freezers and refrigerators from your home-built generator.

You have to watch out with the low-ball guys, engines tend to be chink, ditto alternators, are they going to have parts when you need them? Things like oil filters tend to be a lot more than their automotive counterparts for those engines.

Stan

Stanley Schaefer fired this volley in news:fa45f1c3- snipped-for-privacy@o7g2000yqe.googlegroups.com:

Yeah... I cripple along with my 3.5KW job, doing scheduled runs of the fridges and freezer, but not being able to run much more except a couple of lights. Have gas for cooking, though.

I was given a "worn out" John Deere estate tractor. It had about 15K hours on it. Tranny shot, deck shot, frame shot. But the engine is still good, and currently supported, so a fairly low-cost rebuild should get it really 'right' (although it runs very well as-is).

It's a 36HP, liquid cooled, 3-cylinder Yanmar diesel WITH a hydraulic governor. I have known the guy, and coveted the mower for years, so when he went to junk it, he gave it to me. The thing wouldn't even change notes when it went from pavement to foot-high grass, so the governor seems to work really well.

Should be just the trick for a 22KW job. Now, if I can just find an

1800rpm gen-head at the price I'd like to pay...

LLoyd

Agreed, but half as noisy as the 13KW the OP was looking for is still going to be really loud if it's air cooled. Stationary air-cooled engines have to have large fins, and they tend to amplify the sound a lot. You can get some relief with rubber dampers between the fins, but it's still a pretty big sounding board.

Take a look at the Lister engine (google = lister, listeroid). This guy has an excellent write up on his generator project and includes results. His site seems to be down, but I found it on the wayback machine.

know. It's not nat gas but loads of good info anyway.

Google a gravel bed muffler. They are supposedly able to quiet exhaust so you can't hear it from 100 feet away. Art

Naw, too exotic, and where will you find parts.

[I'm pulling Artemus's leg; the British made them for ~90 years before stopping; but the Indians have taken over. Only a solid piece of sculpture would be simplier that a "Pock-a Pock-a Pock-a.." Lister

I have a used diesel generator (Cummins 25 kW) and like it a lot.

I also do not depend on supply of natural gas.

i

Agreed, but half as noisy as the 13KW the OP was looking for is still going to be really loud if it's air cooled. Stationary air-cooled engines have to have large fins, and they tend to amplify the sound a lot. You can get some relief with rubber dampers between the fins, but it's still a pretty big sounding board. =====================================================

But.... but.... but, it's a HONDA engine!!!! ???

A reliable engine is going to cost, no matter what you put on the alternator side. The breakpoint on cost seems to be at the 5-6KW point, twice that power costs way more than twice the price. If you just want some kind of AC out, you can probably cobble something up from a lawn tractor engine and a surplus alternator. If you want AC that's got stable voltage AND stable frequency, then that's going to cost more. You'll have to have some sort of governor that adjusts the engine speed with the load and does so quickly.

I've dealt with the consequences of having crappy auxilary power when the 15 KV feeder line got blown down over the channel at the shipyard and we had to run stuff on borrowed USAF generators for a couple of weeks. They tried running the computer room on one of the semi-sized units, was never clean enough to run the computer for more than 20 minutes without crashing and they damaged four disk drives doing it, several hundred grand's damage from bad power. A minor glitch in the governor design COULD have expensive consequences if you're trying to run freezers and refrigerators from your home-built generator.

You have to watch out with the low-ball guys, engines tend to be chink, ditto alternators, are they going to have parts when you need them? Things like oil filters tend to be a lot more than their automotive counterparts for those engines. =======================================================

They assure me that their units are stable for electronics. But you have graphically illustrated that this is proly NOT for a diy-er, esp. as a first-time project of this type.

3.5 kW, if continuous, is good for almost 30 A -- that should run more than few fridges and lites, no?

That John Deere price would be nice...

"Existential Angst" fired this volley in news:4fffc4f0$0$1204$ snipped-for-privacy@cv.net:

Sure, but except for AC, the fridges and lights are all that will 'fit'a

3.5KW supply. The central AC draws too much inrush for this genset, even though it would run on 3.5KW. This particular unit quenches the field if you draw too much current. It's output drops to essentially zero, and then stays there as long as there is any non-trivial load still present, even if the inrush demand is removed. Remove the load, and the field recovers (it's a wound, rotating field alternator, not PM).

The last time we were without power for any real time was after the hurricane in (what?) 2004 or 2005? During extended power failures, I won't leave 50 year old unit running continuously, anyway. I have no idea how many actual hours are on it. So we use lanterns for lights, and run the refrigerators, and maybe a couple of table fans on shifts, just to save the victuals and try to stay comfortable.

LLoyd

The last time I hosed out my GE window A/C which draws 430W running I tested it on a 3.5KW (surge) Powermate generator, a simple unit in which the engine governor spring controls the output voltage.

The A/C started OK the first time, but wouldn't restart until the internal pressure had time to drop. That generator will start my Maytag (

"Jim Wilkins" fired this volley in news:jtp577$rd7 $ snipped-for-privacy@dont-email.me:

Hmmm... that's characteristic of most consumer-grade gensets these days.

This old 3.5KW Dayton will start both my 3/4HP irrigation pumps at once, and have run a 2HP well pump on it (for cleanout of a new well, before we had power). It will run a 6KBTU window AC without any problems, and will run a 4.2KW resistance heater at 210V all day long.

I run my Lincoln 155 Mig on it for remote jobs all the time at full current.

The only basic limitations on this unit is that it quenches the field on overload (that's good), and it only has an 8HP engine.

Unlike most modern gensets, though, it has a MASSIVE rotational inertia. The alternator itself weighs about 90lb, and the flywheel on the engine is very large, and cast iron. So it handles surge loads under the quench current very well.

LLoyd

That's why I described its limitations. There isn't much point in reviewing something people can't buy, such as most of my 'vintage' stuff.

jsw