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oil pan 4 07-11-16 06:34 PM

home made inverter generator, welder, battery bank charger
4 Attachment(s)
home made inverter generator, welder, battery bank charger
Next build...
For my next build I am going to build a welding generator with 120v power.
I am using a 25 horse power 1-7/16 inch keyed shaft, air cooled V-twin robin Subaru engine with built in 20 or 30 amp charging coil. The 25hp engine Problem is I cant seem to get an engine with a heavy duty 30 amp charger and heavy duty cyclone air cleaner. I can always generate more 12v power so I will take the HD air cleaner over not having an HD charger. I might just add a third alternator just for battery charging and to help power the 2000w inverter.
As you can guess the 25hp engine, 2,000 watt inverter and low charging amps this rig is mostly a welding machine. The 25hp is a little over powered for what I need but this will help over come the thin air and have plenty of power run at part throttle to save fuel and engine life.
The plan is to use the 25hp engine to drive two specially modified GM type AD244 alternators.
The third alternator, if I used it then it will just be an unmodified 10SI or 12SI alt. The third alternator just produces 12v power for the inverter, fans, starting battery. The power alternators can also do 12 volts.

To save fuel in cold weather I am using one of these:
Thermostatic warm air intake - Fuel Economy, Hypermiling, EcoModding News and Forum -
Its a thermostatic air intake.
Other fuel saving measures:
The engine is going to be built in an enclosure to get the engine up to proper operating temperature and vented with electric fans. This is what I don't want:

Another fuel saving trick will be to unbelt alternators when they are not needed.
Over drive alternators by 1 to 2.5 so they make good power at 2500 engine RPMs and insane power at 3,600.
I can get 120v power with the engine off or at idle. Only the most expensive welding machines provide 120v power at idle, non make 120v power while off.

A little bit about how it works. The 2 power alternators can independently provide constant voltage power for battery charging or starting assist up to 48 volt banks and mig welding or constant current supply up to 150 amps of stick and tig welding.
Constant voltage Each power alternator will provide up to 200 to 250 amps of 12 volt power, at 24 volts around 100 to 200 amps, at 48 volts 50 to 100 charging amps.
Constant current mode provides power for stick and tig welding. The 12 volt charging system will provide exciter field power for the power alternators.
Whats not shown in that schematic: The second alternator, anti CEMF diodes, protection MOVs and stuff that keeps the capacitors from exploding and digital displays from burning out.

As far as where is all this equipment going to go, I think I will put it on a skid.
The 25 gallon fuel tank is out of my old suburban.

oil pan 4 07-20-16 05:57 AM

1 Attachment(s)
I figured out the design for the welding alternators. I am going to by used, non working "for parts only" alternators because they are really cheap.
No point in buying new alternators since I don't need the voltage regulator, the stock bridge rectifier and I am going to replace the stock 145 amp stator with a 250 amp stator from "quick start alternators". But that leaves me with a exciter winding that is only rated to produce 145 amps, absolute max stator output with 14 volts going to the exciter field is something like 170 amps.
Also I have been thinking that the Subaru engines 30 amp magneto isn't enough to support the exciter field of both alternators, recharge the starting battery after starting and provide enough power to run a power inverter to power something like a grinder. To get full power from the welding alternators I need 14 volts only problem is the little Subaru battery charger was never designed to all of this.
So I revised my design adding a 24v alternator, battery, welding alternator excitation system and inverter for powering accessories.

oil pan 4 08-31-16 07:45 PM

3 Attachment(s)
Alright I made a test rig out of a Honda GX200 engine to test the alternator.
It provides about 100 amps of very easy to weld with DC power.

My modified alternator with new slip ring, brush set and 250 amp stator.
This is the final configuration I am going to use with the big engine.

Big rectifier, with bigger heat sink for welding and recharging batteries. It will get a fan in its final configuration but other wise will be used as is.

Fordguy64 09-01-16 07:18 AM

I'm excited to see how this turns out!

oil pan 4 01-14-17 01:47 PM

I haven't forgotten about this project completely yet.
I picked up a second DR44G alternator the other day.
This is used and still actually works, but I am still likely going to replace the stator, brushes and slip rings and modify it for external regulation.

I'm actually thing about putting one of these in my suburban as a dual purpose alternator that can power the electrical system or weld.

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