But wait theirs more, that's just what I could fit in the title line.
Anything worth doing is worth overdoing so here it is.
I decided I would like to get an engine drive.
But since no one can meet my extreme list of specifications for anywhere near the amount I am willing to pay then I will just have to DIY.
Off the top of my head I would like to be able to do CC stick and tig, CV for mig (I do not have a wire feed rig right now so that might be later on) and battery charging 12 maybe up to 48 volts. Plus have the ability for more than one person be able to weld at one time. Have a high enough duty cycle at full power so I will get tired of welding before it over heats. Variable speed to save fuel when full power isn't needed.
The 400 amps will only be the name plate amps on the alternators it might make less it might make more. If it were to make any where near 400 amps I would expect it to only on 12v CV for battery charging and start assist. With the thin air here I expect the engine to only be able to support around 300 amps of SMAW and maybe a little more amps with tig because of the low voltage tig tends to run at. If it can do more than 300 amps for smaw then great, I don't see how or where I would need it.
I believe the best way to do this is just like the title says, start with a 22hp V-twin.
Then to make the 400 amps butcher two SI-10 clones with stators wrapped for 200 amps. SI-10 and SI-12 are my favorite alternator to convert for "other" uses like this.
To convert them I will take the built in 3 phase bridge rectifier and trio diodes out because I don't know what their voltages are rated at and since this is a welding application it could see 70 to 90 OCV and fry them. Then this is where it starts to get weird, convert the alternators stator windings from 3 wire wye to 4 wire wye for maximum current generation and run the wires to external rectifiers. Each alternator having its own set of rectifiers. That way the alternators will produce less heat internally and get more air flow through the windings.
Each alternator will have its own welding plug and receptacles then I will just have to make a special combiner "2 into 1" cable to run both alternators to one stinger or tig torch. Each alternator will kind of be like its own little independent welding machine.
For CC operation I am just going to use a single big rheostat to reduce the voltage from the 22hp motors battery and charging system down and feed it into the alternator rotors.
The only problem I foresee is getting the amps down nice and low if I need to do certain low amp TIG stuff. Taking it down to single alternator mode should do this. Single alternator mode will set me up to do the 2 weldor thing.
Since I will have single alternator mode that will allow me do the 2 weldor thing quite easily. To switch over to 2 weldor mode one alternator will retain use of the big large span rheostat and the second alternator will just have a simple dash bulb dimmer. I do not believe the simple dash bulb dimmer will allow for low amp tig that is why I am hunting for one fairly unique rheostat. In 2 weldor mode each weldor will only have the output of one alternator, so up 150 to 200 amps.
For CV operation I am going to make a circuit reusing the OEM voltage regulators and no trio diodes. In this mode the alternators will not be self exciting like the OEM setup, my guess is that higher voltages (greater than 24v) being fed into the alternator OE style voltage regulator is what will cause it to fail, so CV will also depend on external power from the 22hp engines battery and magneto. All I will need to do is wire in a voltage divider potentiometer to the V-sense tab on the voltage regulator, this will trick the OEM style voltage regulator to making what ever voltage I want. Then to test it crank it up to say 50 or 60 volts and power some stuff. If the voltage regulator fries then go to napa and get 24v voltage regulators and hope they don't fry or find out where it does fry and not go past that point and start looking for some kind of voltage regulator that will let me run whatever voltage I want. But with external excitation power I am very sure this will work how I want it to. And no, I am not expecting to get 400 amps at 55 volts.
To build the inductive choke for CC/CV I was going to gut some Microwave Oven Transformers (MOV) wrap them approximately 50 times with the biggest wire solid wire that I can fit in the MOV core. Parallel them as needed to handle possibly up to 400 amps. Solid wire is inductively much more efficient than stranded.
I find around 50 turns in factory made machines and that 48 turn inductors works very well in my own machines. Welding inductors are very expensive, I can wrap my own so there is no point in spending big $ on this.
To make a true CV system I am going to need a big or several big power supply or welding duty capacitors. 40,000 to 60,000uf should way more than plenty for a 3phase DC with low ripple voltage.
Since all the CC and CV power will will use external excitation this may be too much for the little magneto on the engine. If running any of the settings starts to drain the battery then I will just install a 3rd small alternator that is all stock, nothing special to keep the battery charged and provide all the external welding alternator excitation power I could ever need. I expect the 22hp V-twin magneto to make 10 to 12 amps. With a 150 amp load on each alternator I am thinking each alternator will demand up to 6 to 8 amps, running full tilt may drain the battery and cause the 3rd alternator to be necessary.
Variable speed will save fuel when I do smaller jobs.
The only thing I wont have is AC or auxiliary 120VAC. Well I can fix that lack of 120VAC to some degree with one of my power inverters.
I am not asking how to do this. I already know how, its only a matter of time, money and lots of wiring.
Sounds easy right?
And don't say "buy a cheap engine drive". The only "cheap engine drives" I would buy (Lincoln) appears to be AC only, top out at around 140 amps have a low duty cycle even at 125 amps and cost nearly $2000 and be useless for tig-ing steel. The miller has more amps, DC and a better duty cycle but is around $3,000. Yeah already ruled those out, way out. And they run at fixed 3600RPM so they will be very noisy and their fuel consumption will be no less than catastrophic.