# Thoughts on pairing engine + alternator, 5-8kw, bare bones generator?



## FlyFisher (Jun 30, 2018)

All, 

I've looked at my generator options and I don't have anything between 2600 and 15,000w. One option that would be really handy is a 4-5kw inverter (120v). However, I am thinking a rotary that was in this range would be real nice - possibly with the ability to go all 120v or split 120/240v. 

Looking at generators, engines, and options I don't like the form factor of any of the conventional open frame generators. The 15kw I have is an engine and alternator bolted to a bare steel base with 1x 50 amp connector - thats kinda what I'm after - just a bare bones set up, just smaller. 

As far as engines go I like the Honda engines. If I can get an appropriately sized engine with electric start around, maybe, 10-13hp that might do the trick.

The bigger question is on alternators. 

Is there such an alternator in the 5-8kw range that has a true split alternator with "2x center taps" and not just "center tapped"? I am not sure if I am using the right terminology, but what I am after is being able to phase the 2x halves together to get 120v. You can not do that with a center tapped alternator with 3 leads (2x hots and center tapped neutral) - you need 4 leads and each half physically split because when paralleling one of the neutrals in split phase mode is going to be a hot in paralleled mode, and one of the hots in split phase mode is going to be neutral in paralleled mode.

My goal is to be able to adequately run my small welder on 240v without needing the 15kw. It would be a whole lot easier to move a smaller generator, and would be a good bit more fuel efficient. The power distribution doesn't matter - if I have a 240v plug like an L14-30r for 240 and a 50a 120v like a 5-50r that is all I need at the unit. 

As far as 120v goes - it would make the generator a whole other level more versatile as it would start and run heavier 120v loads that much easier (table saw, air compressor, etc). Redundancy on capabilities in the fleet is a good thing.

If there isn't a suitable off-the-shelf alternator -
How hard would it be to open one up and split it? I know alternators and motors can be rebuilt so I assume it isn't out of the realm of possibilities to get in there and split it then add an extra "center tap"? Being center tapped already that would be a pretty good dead give away where the center of the coil was = where to split. 

Here is an example of something similar - 


5,000 Watt Gasoline Generator



That company (Central Maine Diesel) appears to be defunct, and is actually who put my 15kw together. So I suspect trying to get that unit as a starting point to tweak to my idea I don't think is possible. I wouldn't want to try to go down the road of trying to contact them/order/lose money (already have reached out to them numerous times for info on the 15kw with no response, no biggie - I got all the service info and specs I was after through other channels). As far as a form-factor, though - the only thing different about that one and my idea is the outlets/breakers are on the end cap of the alternator whereas on my idea I want a box like the 15kw. That will be easier to do the wiring and let me put big connectors on it and a large polarity switch.


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## drmerdp (Apr 10, 2018)

Central maine diesels offerings are the only ones I’ve seen that come bare bones like that. The pictures don’t show the alternators tag clearly but you can likely get a model number from them. I remember you were dabbling with the concept of 120-120/240 voltage switches a while back. Maybe the alternators manufacturer can shed some light on its ability to reorient the windings electrically for 120v operation.


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## j.boudreaux88 (Oct 25, 2021)

CMD is not defunct. I reached out and got an email response from the owner ready to place an order for me.


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## FlyFisher (Jun 30, 2018)

j.boudreaux88 said:


> CMD is not defunct. I reached out and got an email response from the owner ready to place an order for me.


Be careful. If you start asking questions after sale you might be met with silence. Buyer beware. 

I'm not sure what you're in the process of ordering, but if it is a honda engine and mecc alte alternator you are in pretty good shape. Excellent components. However, the workmanship of the wiring etc could be questionable. If you go asking for support, that might be an issue through CMD.

The 15kw I got 2nd hand. The original owner never used it. They bought it with plans to install it, but ended up moving and then they sold it. So it sat unused (literally had 0 hours on it) for several years. Im sure its out of warranty now, but given it was a Honda engine alone and never run - I was pretty confident in what I was getting. I did not know it was a Mecc Alte alternator until after having it a while (info/spec sticker was under the bottom of the alternator, I didn't find it until later). Though, for the whole generator I paid less than the engine was worth - GX690. I can't complain and I am pretty mechanically inclined in that I do most of my own work on vehicles/engines so working on this isn't an issue. 

Purchasing a new unit that is possibly in need of warranty work - that is a whole other ballgame. In that case I would spend the coin and get a Northstar or other brand. I would not touch a Generac with a 100ft pole. That might even be too close. If it has a Honda engine or a (new, not old pre-redesign) Briggs & Stratton Vanguard (2 cylinder) engine - that is probably a commercial grade generator. Other engines I would question (smaller, non- new vanguard Briggs & Stratton, Kohler, etc).

Of course, if you are going down the road of a larger prime use 1800 RPM liquid cooled unit - that is a whole other world above the "screamer class" (3600RPM, air cooled engines) generators. The same holds true with the engine work, though - whether it be Isuzu, Kubota, John Deere, Hatz, Cat, or Yanmar - the engine support will likely go through the respective engine manufacturers' support (service centers will usually be certified to work on several manufacturers' engines, aside from bigger names like Cat, John Deere, etc - they don't generally like having their dealers/techs working on competition). Unless you have a local group that services large generators (there are a lot of places that do - for the large building back-ups and peak-shaving units, in fact in several areas peak-shaving is a larger market than stand-by use), you might have to deal with engine-only work from some support groups.


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## j.boudreaux88 (Oct 25, 2021)

*I ordered a GX630 and Mecc alte 12000 watt gen head from a different company, however I emailed CMD for some info on their unit as part of my research to build my own. Apparently the email on their website isn’t monitored anymore but there’s another company email that is. Don’t recall how I found it but I got a response answering my questions, albeit somewhat satisfactorily, and with eagerness to sell me a unit, so they are indeed still in business, that’s all I’m saying. 
The only challenge im running into is finding the outlet box, but I admit I haven’t contacted mecc alte yet to inquire about it directly from them. Winco does sell the outlet box off of their 18000 watt vehicle mounted generator for $245 which includes one 60 amp outlet. Looking on CMD’s website their “deluxe” outlet box with 240 and 120 outlets is around a $400 upgrade, but not sure if it’s offered as a stand alone product. Figure I should be receiving my engine and gen head within the next week and I’ll worry about that after I get to overview the gen head being I’m not in a huge rush. 

I can provide that email if needed *


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## FlyFisher (Jun 30, 2018)

j.boudreaux88 said:


> *I can provide that email if needed *


If you have it send me a private message with it. 

OK on the GX630 and 12kw head. That sounds like it will be a good combo. Truth be told, my 15kw was a bigger unit than I was after but it was just luck I stumbled in to it. The 12-13kw range was what I calculated based off adding up our water heater and well pump at our cabins as essential loads. The water heater is 240v and well pump is 120v. So when you break the power requirement down there is no way to "balance" the 2 loads - you stack the power of the pump on one leg of the alternator with the load of the water heater (if they are running simultaneously). So you have to add the amps up max on 1 leg, then use that higher amperage at 240v to get the wattage gen requirement. Without the actual numbers off the top of my head - 13kw was the size gen the numbers added to. However, in practice, running the whole house here with the 15kw running and AC we do have adequate power so I'm happy with that. 13kw might be a bit low. Though, that kind of power is only needed for AC or if I have a large load I need to run in the field (rare). The water loads at the cabins are rare also. Most of the time I go to my EU2200i for 120v power - its my primary unit. I just don't have anything a bump up from that right now - and that was where the thread was going - looking at a way to do a "middle ground" unit.


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## iowagold (Jan 22, 2020)

FlyFisher said:


> If you have it send me a private message with it.
> 
> OK on the GX630 and 12kw head. That sounds like it will be a good combo. Truth be told, my 15kw was a bigger unit than I was after but it was just luck I stumbled in to it. The 12-13kw range was what I calculated based off adding up our water heater and well pump at our cabins as essential loads. The water heater is 240v and well pump is 120v. So when you break the power requirement down there is no way to "balance" the 2 loads - you stack the power of the pump on one leg of the alternator with the load of the water heater (if they are running simultaneously). So you have to add the amps up max on 1 leg, then use that higher amperage at 240v to get the wattage gen requirement. Without the actual numbers off the top of my head - 13kw was the size gen the numbers added to. However, in practice, running the whole house here with the 15kw running and AC we do have adequate power so I'm happy with that. 13kw might be a bit low. Though, that kind of power is only needed for AC or if I have a large load I need to run in the field (rare). The water loads at the cabins are rare also. Most of the time I go to my EU2200i for 120v power - its my primary unit. I just don't have anything a bump up from that right now - and that was where the thread was going - looking at a way to do a "middle ground" unit.


fly unless you need 240 at the cabin just get a second eu2200i gen and run in parallel when you need just a bit more power.
yea there are times a eu4400i would be nice for sure!
right in the middle range of power.
something like that would work out nice for construction.
big enough to run a saw or breaker (small electric 120 vac jack hammer)
or able to have power for an office trailer with all the tools battery chargers.

i kinda wish they would ditch the eu3000i and go a eu4400i gen!


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## FlyFisher (Jun 30, 2018)

iowagold said:


> i kinda wish they would ditch the eu3000i and go a eu4400i gen!


I 2nd that point. The EU3000i is too small. A friend of mine runs one with his camper and it is adequate - it has head room over the EU2200i, but just a bit. Things that would otherwise just break over the capacity of the EU2200i will run on the EU3000i, but that is about all its good for.

In the case of the thread and pairing an engine with an alternator - I want it for 240v to run the small welder, but adding all 120v would make it a whole world more versatile for me. With a rotary the hit with the voltage sag on arc start shouldn't be too terrible at lower welding powers = could get by on smaller welding tasks. If it didn't have enough power at some point I could go to the big one - its just a huge jump. Not having any options in between I am not sure what would happen at what welding power, but if I can get to the low 100's, maybe 120-130a tops, welding power that would do 98% of all the welding I ever do. With that power available I'd be pretty comfortable doing away with the 15kw when I am out and about - even up north at the cabins. 

Interesting to note on the welding - the technical note for generator specs on the website changed on the welder I have. I thought it was around 7-7.5kw that they recommended. Now they show surge watts at 240v being 8900w and on 120v 4500w. That seems strange. The welder is dual voltage and will drop power that you can dial it to (I want to say it is limited to 150a on 120v and will go to 200a on the dial on 240v, but the lower amperages between 120v and 240v aren't apples to apples - 100a on 120v doesn't weld like 100a on 240v). Yeah 120v is 1/2 240v, but that doesn't drop the wattage consumed in half, per se. Your welding heat has to come from somewhere.


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## drmerdp (Apr 10, 2018)

j.boudreaux88 said:


> *I ordered a GX630 and Mecc alte 12000 watt gen head from a different company, however I emailed CMD for some info on their unit as part of my research to build my own. Apparently the email on their website isn’t monitored anymore but there’s another company email that is. Don’t recall how I found it but I got a response answering my questions, albeit somewhat satisfactorily, and with eagerness to sell me a unit, so they are indeed still in business, that’s all I’m saying.
> The only challenge im running into is finding the outlet box, but I admit I haven’t contacted mecc alte yet to inquire about it directly from them. Winco does sell the outlet box off of their 18000 watt vehicle mounted generator for $245 which includes one 60 amp outlet. Looking on CMD’s website their “deluxe” outlet box with 240 and 120 outlets is around a $400 upgrade, but not sure if it’s offered as a stand alone product. Figure I should be receiving my engine and gen head within the next week and I’ll worry about that after I get to overview the gen head being I’m not in a huge rush.
> 
> I can provide that email if needed *


It would be nice to buy a panel ready to go but making your own would allow lots of flexibility and customization. Wattage meters, multiple 120v and 240v receptacles, slick battery maintainer connection, panel mounted quick connect for NG or Propane.


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## j.boudreaux88 (Oct 25, 2021)

drmerdp said:


> It would be nice to buy a panel ready to go but making your own would allow lots of flexibility and customization. Wattage meters, multiple 120v and 240v receptacles, slick battery maintainer connection, panel mounted quick connect for NG or Propane.


This is why I'm waiting to inspect the unit to make a decision.


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## j.boudreaux88 (Oct 25, 2021)

FlyFisher said:


> If you have it send me a private message with it.
> 
> OK on the GX630 and 12kw head. That sounds like it will be a good combo. Truth be told, my 15kw was a bigger unit than I was after but it was just luck I stumbled in to it. The 12-13kw range was what I calculated based off adding up our water heater and well pump at our cabins as essential loads. The water heater is 240v and well pump is 120v. So when you break the power requirement down there is no way to "balance" the 2 loads - you stack the power of the pump on one leg of the alternator with the load of the water heater (if they are running simultaneously). So you have to add the amps up max on 1 leg, then use that higher amperage at 240v to get the wattage gen requirement. Without the actual numbers off the top of my head - 13kw was the size gen the numbers added to. However, in practice, running the whole house here with the 15kw running and AC we do have adequate power so I'm happy with that. 13kw might be a bit low. Though, that kind of power is only needed for AC or if I have a large load I need to run in the field (rare). The water loads at the cabins are rare also. Most of the time I go to my EU2200i for 120v power - its my primary unit. I just don't have anything a bump up from that right now - and that was where the thread was going - looking at a way to do a "middle ground" unit.



PM Sent


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## iowagold (Jan 22, 2020)

FlyFisher said:


> I 2nd that point. The EU3000i is too small. A friend of mine runs one with his camper and it is adequate - it has head room over the EU2200i, but just a bit. Things that would otherwise just break over the capacity of the EU2200i will run on the EU3000i, but that is about all its good for.
> 
> In the case of the thread and pairing an engine with an alternator - I want it for 240v to run the small welder, but adding all 120v would make it a whole world more versatile for me. With a rotary the hit with the voltage sag on arc start shouldn't be too terrible at lower welding powers = could get by on smaller welding tasks. If it didn't have enough power at some point I could go to the big one - its just a huge jump. Not having any options in between I am not sure what would happen at what welding power, but if I can get to the low 100's, maybe 120-130a tops, welding power that would do 98% of all the welding I ever do. With that power available I'd be pretty comfortable doing away with the 15kw when I am out and about - even up north at the cabins.
> 
> Interesting to note on the welding - the technical note for generator specs on the website changed on the welder I have. I thought it was around 7-7.5kw that they recommended. Now they show surge watts at 240v being 8900w and on 120v 4500w. That seems strange. The welder is dual voltage and will drop power that you can dial it to (I want to say it is limited to 150a on 120v and will go to 200a on the dial on 240v, but the lower amperages between 120v and 240v aren't apples to apples - 100a on 120v doesn't weld like 100a on 240v). Yeah 120v is 1/2 240v, but that doesn't drop the wattage consumed in half, per se. Your welding heat has to come from somewhere.


cool
have you tried the mp series in the Lincoln?

it is like a 210 mp
*K4195-2*
and 
the al spool gun 
*K4360-1*
not sure on the stainless spool gun part number

it will do 120 and 240 vac.
if you watch the heat it will work on 120 vac ok....
but it is better at 240 vac.
at least on mig.
tig i like the 240 cord.
it stays better on power.
i also have a little suitcase inverter unit for tig on the go.
nice for when we have to weld in the meat packing house on stainless.
handy size for sure.


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## Matt88-8 (Dec 27, 2018)

I really like this idea. I've also toyed with it a few times. 
A 3600rpm Kohler diesel hooked to a 5-6k head would do wonders for me. I'm cool with just 240v as I can always make adapter cords. 
I wonder who makes Yamaha alternators? I was always curious if the brushless design is actually as good as they claim?

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## FlyFisher (Jun 30, 2018)

Looks like the smallest engine Honda makes with electric start is the GX270 at 8.5hp. I looked up some generators that use the GX270 and they are in the 4500-5500w range. 

Interestingly, the generator in the link in the first post to the bare bones unit CME supposedly puts together/sells uses the GX270.

The next engine up is the GX340 & GX390 (both are 389cc) at 11hp. Generators with that engine are up around 8kw.

Looking at the wattages - the 270 is on the low side of what I am envisioning, the 340/390 is on the high end - not much middle ground. 

Any thoughts?

If I had access to a generator in the range I am after that has clean enough power (that is the key - under 5% THD) to test the little welder on that would be ideal. Dad has, I believe, a Troy Bilt that is around 5500w running/6500w starting, but I guarantee it isn't low-THD and I'm not inclined to try running the welder on it just for a quick test.


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## iowagold (Jan 22, 2020)

i thought they had a version of the gx200 with electric start at one time


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## FlyFisher (Jun 30, 2018)

iowagold said:


> i thought they had a version of the gx200 with electric start at one time


I did notice there are kits you can get to add electric start to a lot of their engines also. From what I saw ones you can get "off the shelf" with electric start bottom out at the 270, though I didn't look everywhere so they could be out there. 

Either way, though, the 270 seems like the smaller end of the spectrum on wattage ability. 

I'd be curious if I sized up the alternator to, say, one rated to 7-8kw, with the smaller engine if I could limit with a breaker at, say, 25 amps, or approximately 6kw @240v. Or, if I breakered at 20a that would be ~4800w and with the delayed breaking it may take 25a spikes to handle that ~6kw for start ups. 

If there was a way to parallel the alternator halves that could potentially get ~50 amps at 120v. Not sure if the engine would have the torque to maintain RPM with a higher draw.

The ideas with the smaller engine are weight and fuel consumption. If I can get adequate power that would be the idea. I suppose I will have to see what the current draw is on the small welder on the high end of my usual operating range and go from there. I haven't run it more than about 125-150a welding current, and the vast majority is under 100a. As to what draw on the power circuit that pulls - I don't know yet. 

In relation to the small engine vs power output - my small open frame generator supposedly has a 5hp or so engine. I don't see the breaker amperage right off-hand, but if too much power is drawn from either the L14-30 or one of the 5-20's it will stall the engine. I've never seen the breaker pop. I'd like to avoid that - I'd like to have enough engine power to push through the breaker tripping, but not much more. Otherwise, that is wasted fuel to me. I suppose the question really comes down to what the peak wattage/amperage is that I need to hold on to with a breaker - then I can go from there.


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## FlyFisher (Jun 30, 2018)

iowagold said:


> i thought they had a version of the gx200 with electric start at one time


I did a search on the kits and they appear to bottom out at the 160. So I did a search on the 160 with electric start and it appears you can get it equipped off-the-shelf with electric start, but it is a needle in a haystack to find one. It looks like a recoil start with a starter kit to add on might be the quickest way to get any of the smaller engines - but no guarantees there, either. Thats OK - I'm not in a rush at the moment - just looking at ideas and how to do it.


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## FlyFisher (Jun 30, 2018)

Re: Alternators:

Looking just at wattage and THD - the following are in an acceptable range, though not directly able to be paralleled off-the-shelf (they are split phase only, can't parallel poles to get 120v only as they sit):

Mecc Alte S20W-95, 7200w, under 5% THD

The other Mecc Alte's in a similar wattage range show under 6% - too high. The S20F series (what is on my 15kw) is under 4%, but the smallest wattage version is over 10kw - probably too big to spin with a smaller engine, not sure on the shaft size compatibility, either.


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## iowagold (Jan 22, 2020)

phase 60hz sync on a gen set is tricky at best unless it is the latest versions of the solid state inverters.
search sync to grid like they do on the BIG gen sets.
and there are several videos on you tube on this.

for me i just stick to the honda eu series of gen sets,
off the shelf item and yea you can modify them to suit your needs.


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## tabora (Sep 6, 2018)

FlyFisher said:


> Looks like the smallest engine Honda makes with electric start is the GX270 at 8.5hp.


I've got an electric start GXV120 on my HR214 mower and they worked on the smaller GX110, too... Not to mention everything from there up through the GX390 and beyond is e-start capable.


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## FlyFisher (Jun 30, 2018)

iowagold said:


> for me i just stick to the honda eu series of gen sets,
> off the shelf item and yea you can modify them to suit your needs.


How do you switch between 120v and 240v? I'm trying to get 240v for the welder, but having the ability to parallel the alternator poles to get 120v would let me get the rated wattage out at 120v on 1 circuit, not split. That will be a huge benefit and give me more redundancy in my power options.

The other thing is I suspect a rotary is going to keep up with the arc starts better than an inverter - unless it is a real big inverter.


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## iowagold (Jan 22, 2020)

the smaller eu honda gens are 120 vac up to eu3000i
the eu6500 and eu7000is are 120/240 and have a mode switch on the front to lock the gen set in 120 vac mode.
we modify the gens with a 50 amp socket and breaker so we can get out the 46 amps plus of power out of the gen set when in the 120 vac mode.

stock they only have a 30 amp outlet and breaker for the 120 vac mode.


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## Matt88-8 (Dec 27, 2018)

What kind of welder are you using? If it's one of the modern inverter welders, they are remarkably easy to power and have no quarrels being run off gennys with 10% THD.
Great little units that are simply invaluable in the field. 
My 5k rotary welds farm equipment as it's primary role. Never had a problem. The old 4k one was a bit small.
I certainly wouldn't worry about running it off your dad's generator..

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## FlyFisher (Jun 30, 2018)

Matt88-8 said:


> What kind of welder are you using? If it's one of the modern inverter welders, they are remarkably easy to power and have no quarrels being run off gennys with 10% THD.


Everlast PowerArc 210STL. 

I am not going to take any chances. Dirty power has been known to fry a lot of these little machines - not just Everlast, but a lot of lesser-expensive imports be it welders, plasma cutters, and the like. 

Some of the higher end big-name machines may handle dirtier power. 

Everlast says less than 5% THD. They will find any hole in operator/operating conditions to void warranties for service work also. The mere fact of generator power for their warranties, period, is a can of worms should you run in to an issue and have to rely on their warranty. That is a discussion for another day and another forum, not here.


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## Matt88-8 (Dec 27, 2018)

FlyFisher said:


> Everlast PowerArc 210STL.
> 
> I am not going to take any chances. Dirty power has been known to fry a lot of these little machines - not just Everlast, but a lot of lesser-expensive imports be it welders, plasma cutters, and the like.
> 
> ...


Interesting. The lil 140 version claims 10% and can run on a generator. Weird the 210s are different.
I strongly considered one of the everlasts, But my el cheapo one just works so well. Maybe when it dies.

I can't see it hurting anything, but if it's worth the extra $$$ to you hey, have at it!

All the Mecc alternators claim less than 5%. Stick one of them to a Kohler diesel and go?


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## FlyFisher (Jun 30, 2018)

Matt88-8 said:


> All the Mecc alternators claim less than 5%. Stick one of them to a Kohler diesel and go?





FlyFisher said:


> Looking just at wattage and THD - the following are in an acceptable range, though not directly able to be paralleled off-the-shelf (they are split phase only, can't parallel poles to get 120v only as they sit):
> 
> Mecc Alte S20W-95, 7200w, under 5% THD
> 
> *The other Mecc Alte's in a similar wattage range show under 6% - too high.*


Bold and underline added.

As to the Kohler diesel - not sure on the Kohler brand, but that is an idea. I have looked at some of the small diesels before. Back in the day (15-20 years ago) there was a company called Robin, I believe, that made some single cylinder diesels. You don't see them around any. 

There are some small (8-15hp) inboard diesel engines that have been used in sailboats for decades that might work, actually - electric start and liquid cooled. I forget what some of the brands are but there are some that are very serviceable (and the opposite is true - there is at least one brand that, I believe, is French or from some other European country that is extremely hard to get parts for). Though, that size engine - even an 8hp diesel - might be too much engine for the size power output.


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## Matt88-8 (Dec 27, 2018)

FlyFisher said:


> Bold and underline added.
> 
> As to the Kohler diesel - not sure on the Kohler brand, but that is an idea. I have looked at some of the small diesels before. Back in the day (15-20 years ago) there was a company called Robin, I believe, that made some single cylinder diesels. You don't see them around any.
> 
> There are some small (8-15hp) inboard diesel engines that have been used in sailboats for decades that might work, actually - electric start and liquid cooled. I forget what some of the brands are but there are some that are very serviceable (and the opposite is true - there is at least one brand that, I believe, is French or from some other European country that is extremely hard to get parts for). Though, that size engine - even an 8hp diesel - might be too much engine for the size power output.


Oops. Missed that. I must have been looking at something else. I have to read up on them more.

What is the reason you need to split the poles? Can't you just wire it to pull 120V off each leg and wire those in? Or does that unbalance the alternator?

Kohler is good stuff. They have 3600 and 1800 options. Even some with high run time features like oil filled air cleaners and large sumps.
Kubota makes lots of tiny diesels of all flavors.









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## macdenewf (Sep 3, 2021)

FlyFisher said:


> All,
> 
> I've looked at my generator options and I don't have anything between 2600 and 15,000w. One option that would be really handy is a 4-5kw inverter (120v). However, I am thinking a rotary that was in this range would be real nice - possibly with the ability to go all 120v or split 120/240v.
> 
> ...


I bought a NorthStar generator some years back that was touted as all American built, copper windings, bristles ...etc. Not arguing the fact but until recently didn't know that the alternator was built by Mecc AAlte...and from what i've seen..they build good quality gear. this specific generator has a Honda 690...again..good quality.

If your looking to put one together, i don't think you can go wring with Mecc Alta and im certain their technical support can answer your voltage center tap question
As for the engine..love the Honda 690...but if you're doing this from scratch - i don't think these come with a muffler when ordering a stand alone engine...you might want to check on that.
A friend of mine, (picky about quality) built a high power pressure washer a while back and used the Predator 22 HP engine from Harbor Freight. He has been really happy with the result and it does come with a muffler ..so makes a DIY setup a little easier.

Electrical
The Mecc Alte has a small wiring block built into the compartment on the top of the alternator ( at least the larger ones do) where its easy enough to pull the 220 and 110 lines up to a breaker)

Breakers are simple. If you contact Northern Tool..they sell replacement breakers for the generators they sell. I had to replace a 58 amp breaker a while ago ( ya weird size) and it was literally 15 bucks. and of course - simple enough to get outdoor rated electrical box and mount a 50 amp female connection.

sounds like a fun project.
Cheers


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## tabora (Sep 6, 2018)

Matt88-8 said:


> What is the reason you need to split the poles?


On a 240V alternator, the two 120V poles are 180 degrees out of phase. That's how you get 240V across them.


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## Matt88-8 (Dec 27, 2018)

tabora said:


> On a 240V alternator, the two 120V poles are 180 degrees out of phase. That's how you get 240V across them.


Your going to have to dumb it down a bit more. 
Why can't you just wire a 120v plug off one leg of the 240V output?

Sent from my SM-G973W using Tapatalk


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## macdenewf (Sep 3, 2021)

Matt88-8 said:


> Your going to have to dumb it down a bit more.
> Why can't you just wire a 120v plug off one leg of the 240V output?
> 
> Sent from my SM-G973W using Tapatalk


That’s exactly what they do.


Matt88-8 said:


> Your going to have to dumb it down a bit more.
> Why can't you just wire a 120v plug off one leg of the 240V output?
> 
> Sent from my SM-G973W using Tapatalk


If I recall my engineering right. That’s exactly how the generator windings are arranged. They tie the opposite poles together ( the neutral) and the other end of each coil is the hot leg Hot to neutral 120. Hot to hot 240. Regardless. The alternator will have terminals marked for these to connect to. It won’t be something you have to configure.


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## FlyFisher (Jun 30, 2018)

Matt88-8 said:


> What is the reason you need to split the poles? Can't you just wire it to pull 120V off each leg and wire those in? Or does that unbalance the alternator?





tabora said:


> On a 240V alternator, the two 120V poles are 180 degrees out of phase. That's how you get 240V across them.





Matt88-8 said:


> Your going to have to dumb it down a bit more.
> Why can't you just wire a 120v plug off one leg of the 240V output?





macdenewf said:


> If I recall my engineering right. That’s exactly how the generator windings are arranged. They tie the opposite poles together ( the neutral) and the other end of each coil is the hot leg Hot to neutral 120. Hot to hot 240. Regardless. The alternator will have terminals marked for these to connect to. It won’t be something you have to configure.


Sorry for the mumble jumble of quotes. However, see the thread below. I studied this earlier this year - there are scope traces and diagrams in the thread for reference on the explanation. 









Digging today and learning - Voltage selection on some...


Based on the questioning in another thread quoted below for reference: You can reduce your inrush current with a soft start kit for your air conditioner. Most larger generators that can supply both 120V and 240V can be configured to supply a higher 120V only plug which puts the generator...




www.powerequipmentforum.com


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## Matt88-8 (Dec 27, 2018)

FlyFisher said:


> Sorry for the mumble jumble of quotes. However, see the thread below. I studied this earlier this year - there are scope traces and diagrams in the thread for reference on the explanation.
> 
> 
> 
> ...


Wow. Thats pretty far above my pay grade, so correct me if I'm wrong in my over simplified summary. 

If your gen makes 10A @ 240V having it wired like in your schematic allows you to have a 20A @ 120V circuit instead of just pulling power off each leg which gives you a Max of 10A @ 120v.

So it just allows you more amps at a single 120V plug. Correct?

(Ps, all the pic links are dead)

Sent from my SM-G973W using Tapatalk


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## FlyFisher (Jun 30, 2018)

Matt88-8 said:


> Wow. Thats pretty far above my pay grade, so correct me if I'm wrong in my over simplified summary.
> 
> If your gen makes 10A @ 240V having it wired like in your schematic allows you to have a 20A @ 120V circuit instead of just pulling power off each leg which gives you a Max of 10A @ 120v.
> 
> So it just allows you more amps at a single 120V plug. Correct?


Yep. You got it.

Think of wattage. Watts = Amps X Volts. 

If you keep the same wattage, say at 240v (which is what the vast majority of rotary dual voltage generators are rated to) then drop to 120v the available amperage has to double with the halving of the voltage. That is, IF the wattage stays the same. 

The catch, the LARGE catch, to this is that the alternator is only rated to a particular amperage. That is the metric that most people leave out of the equation - in the capacity that the metric is accurate. That is to say - the Amperage is one number through the whole alternator. If an alternator can push, say, 30 amps it can only push 30 amps. It doesn't matter what part of the alternator pushes the 30 amps - pole 1, pole 2, or both poles 1 and 2 in series. Therein lies where people leave out the amperage metric in its correct interpretation.

Generator manufacturers/suppliers may rate their generators to amperage at 120v. Central Maine Diesel does this with theirs. This is not 100% accurate. The reason is that is a combined amperage. You absolutely can not pull that amperage from 1 circuit. It MUST be split in two. Therein, again, lies where people leave out the amperage metric in its correct interpretation.



Matt88-8 said:


> (Ps, all the pic links are dead)


Check your web browser. Clear cookies, stored internet files, history, etc then reload. They all work fine on my end. Maybe try a different web browser also.


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## iowagold (Jan 22, 2020)

so what are the stator connections on the end of the gen set?
are they the same 4 stud and 4 wire?

kinda cool how this works out for the 120/240 to 120 only switchable avr gens.

wacker and a few others in the construction gens have this as well.

it is ok if you are on a job site with cords for each item.
they still do not have a single plug outlet large enough on most of these mid size gens to get a snake to an octa box for total out of the gen that it can produce...
unless they are modified...
most just have 30 amp outlets as the large outlet ..
and have gen ratings for a bit over that...

hey flyfisher
so are your plans for the super large Anderson style?
or will a 50 amp 125 outlet work?
i forgot where your system planned wattage at 120 vac is to be.


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## FlyFisher (Jun 30, 2018)

iowagold said:


> hey flyfisher
> so are your plans for the super large Anderson style?
> or will a 50 amp 125 outlet work?
> i forgot where your system planned wattage at 120 vac is to be.


50 amps at 120v is 6kw. That is plenty. You can use a NMEA 5-50 plug for that.

I'm not too concerned with the upper end of the amp range on 120v. I am not sure what the high end of it would be that I would use. My ruling figure is the wattage at 240v with low THD - in that it is able to provide adequate power to my little welder at the upper end of the range where I operate it (which is not the upper end of the capacity of the machine - 120-130 amps welding current might be the top end, most of what I weld is under 100a) - the machine will provide more welding power, but I don't really have any reasons to run it there and if I did I'd be better off using the old tombstone as it will do 300a. So if I am close to 200a the tombstone won't even break a sweat, whereas the little welder will be at or near max juice.

6kw at 240v is 25 amps. That is still over where I would be. I will have to load test the little welder and see really what it pulls at 240v where I run it. I would be surprised if it pulled more than 20a.

As far as 120v amperage goes - if I can get over 30 amps that would be ideal. But I don't want to pull all that from 1 pole. If I did that would mean I would have to have a 7200w capable generator just to get 30a at 120v. If you go after the same wattage with paralleled poles then the "required wattage" drops in half to 3600w. So if I get back to the 5kw range running wattage, the lower end of the range I am targeting, that would be about 6kw peak/surge/starting which would be 25a @240v and [email protected] That would be plenty.

Also, for reference, here is a spec'd 8500w generator that does have a voltage selection to allow 120v-only (though, notice there is no 3 pin 120v-only twist-lock connection, only 4x 5-20's):








8,500 Watt Gasoline Portable Generator


XP8500E Specifications Gasoline Peak Wattage 8,500 Running Wattage 7,000 Running Amperage at 120V 58.33 Running Amperage at 240V 29.17 Runtime at 25% Load 25 Runtime at 50% Load 12 Engine & Emission Specifications Engine Manufacturer DuroMax Power Equipment Engine Type 4-Stroke Valve Type OHV...




www.duromaxpower.com





That is a couple thousand watts higher than what I'm after, and there is no mention of THD. However, one idea would be to see if I could acquire the head as a "replacement part". I am not sure what the overall quality is of Duromax heads and engines. I know there are a lot of them out there and there are probably several people on the forum here that have them and/or have experience with them. If the THD is low on the head then that might just be an "off the shelf" alternator that would work. I just don't need the engine, frame, wheels, outlet/control panel, etc - just the bare alternator (and what voltage regulation circuitry there is - I assume part of the alternator, but could be wrong). Another wildcard is what engine shaft configuration it requires. If they made some proprietary shaft connection that Honda doesn't make then that would be an issue - to pair the two would require an external jack shaft conversion that would be both a bit of a pain to make and would also rob HP.


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## JRHill (Nov 19, 2020)

I browsed the previous threads and think I have an understanding in general. But what I don't see is any overall system description. You are pondering single and split phase options for a generator, the split phase to power the welder.

You are off grid? You want to power all normal loads while welding? You don't mention what the welder is, I'm guessing MIG but maybe arc too and hopefully not TIG?

If I had one generator, whatever it is, I just wouldn't be risky. When welding disconnect everything else regardless of the type of welding being done. Anyway, that's IMHO. And I wouldn't TIG weld with a HF start that was connected to the rest of the system even if all 3 or 4 lines could be disconnected. HF is HF. Ever keyed a TIG with the ground clamp disconnected and get tickled?


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## FlyFisher (Jun 30, 2018)

JRHill said:


> But what I don't see is any overall system description. You are pondering single and split phase options for a generator, the split phase to power the welder.
> 
> You are off grid? You want to power all normal loads while welding? You don't mention what the welder is, I'm guessing MIG but maybe arc too and hopefully not TIG?


Lots of what you are asking is in the thread discussion here. 

The idea of selectable voltage is to make the generator cover a lot more ground - with high amperage at 120v, done by paralleling the alternator poles, I could have a back up to heavier amperage 120v applications. I am wanting to fill that "gap" with around a 4.5kw inverter generator that does 120v-only. 

What a 120v-only generator does not do, however, is provide 240v

The welder I am trying to run is an Everlast 210STL. I want to run it on 240v. It does run on 120v, but that isn't how I want to run it. All my welding the past couple years has been on 240v and that is where I know my settings. When you switch to 120v - even though the machine will run on it - the welding power does not correlate. That is to say that if I set the machine to run 100 amps (1/8" 6011 rod, lets say) on 240v it might take a setting of 110-115 amps with the welder on 120v to get the "same welding power", regardless of what the dial shows.

The 210STL is a tig machine, also, but does NOT have HF start. 

I have multiple generators. My goal was to have 1 that I could set up as a "throw in the truck" rig that would cover a lot of ground and be pretty easy on fuel. My 15kw will provide all the power I could ask for in either 120v or 240v, but its too big and heavy of a generator to pair with the welder as a portable work solution. I use an EU2200i as my portable generator now and it works fantastic for 120v service.

For the record, I did try running the welder off of the EU2200i trying to see what I COULD weld with the power it puts out and the welder load running stick, even at the lowest wattage, is too much for the EU2200i. So I need a good bump up in power - and that is where the sizing and voltage options discussed in this thread are rooted. 120v-only (higher amperage there, from paralleling poles) significantly increases what the generator can run. Like I said - going to an inverter 4.5kw, if that unit quit I could use the unit discussed in this thread to fill in running 120v-only mode.


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## JRHill (Nov 19, 2020)

JRHill said:


> Ever keyed a TIG with the ground clamp disconnected and get tickled?


Back story: I had a Miller 250 set up for Arc and TIG. I did a lot of TIG welding - I love to TIG weld. But I had to do it late at night. There were three (four) other houses on that pole transformer. If a TV or stereo was on in my house the TV would freak out and if the stereo the power amp would blow its breaker. Other things would malfunction or fail. As for the neighbors I would get immediate nasties as they knew the culprit. The momentary HF start was bad. If aluminum and continuous HF it would wipe out everybody's stuff.

This was on one utility pole out to 3 or 4 drops. Outside of that the system seemed to absorb the HF. It can go a way even from the pole. So on a small system this is critical. I don't care how much grounding you have, welding in general can be a problem.


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## j.boudreaux88 (Oct 25, 2021)

j.boudreaux88 said:


> This is why I'm waiting to inspect the unit to make a decision.


Here's another update on the unit I'm building:

I've been piecing this thing together slowly, however I've tried to expedite purchasing everything I could to hedge against supply chain issues and rising costs. Here are a few pictures of everything on the cart disassembled, and also the NG demand regulator that'll be feeding it. I ended up selling my normal regulator and purchasing the high-flow model. I then put a 3-way L-Port so I can select propane or natural gas with the turn of a valve. Once I get a 3/8" aluminum plate cut out as a mounting plate we will put it together. I think I have a solution for the electrical inlet box that won't involve cutting holes in the black cover on the alternator. Only thing left to purchase are the mounting plate, vibration mounts, electrical box, and exhaust extension.

Should have this thing tested and ready by this year's storm season. Will update again once it's all put together.


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