Need more power. Honda vs predator or Honda vs bigger Honda?

[oil pan 4]

I have a Honda gx200 that powers my home made welding machine that uses an ACdelco DR44 alternator. It works great. Main problem is when I run about 120amps the engine loses speed. Turning it down to around 110amps gives reliable steady welding power.
Other small problems are the welding alternators field current is provided by a 12v battery, that battery goes dead after a while and on hot days the heat sink for the bridge rectifier gets pretty hot after I run it for a bit even at 100 amps. The old battery I'm using takes at least 2 hours to recharge.
For the hot heat sink the easy answer is add a fan or fans, but that will kill the battery even faster. Running a bigger engine will allow me to run 120 to 150 amps so the heat sink will get hotter faster and it will absolutely need fans. So I'm thinking adding a second normal, small 12v alternator.
Upgrade engines I'm thinking about going to are an 8hp predator 301cc or stealing my freshly rebuilt Honda gx390 engine off my pressure washer.
I'm thinking adding a 2nd small 12v alternator even if that alt has an underdrive pulley it will rob at least 1hp. So the 301cc only ends up giving me one to one and a half additional HP to drive the welding alternator, maybe giving me 130amps max.
I'm thinking in this case bigger is better and go with my hot gx390.
Or do I need something even bigger?

 

[c502cid]

I have a Honda gx200 that powers my home made welding machine that uses an ACdelco DR44 alternator. It works great. Main problem is when I run about 120amps the engine loses speed. Turning it down to around 110amps gives reliable steady welding power.
Other small problems are the welding alternators field current is provided by a 12v battery, that battery goes dead after a while and on hot days the heat sink for the bridge rectifier gets pretty hot after I run it for a bit even at 100 amps. The old battery I'm using takes at least 2 hours to recharge.
For the hot heat sink the easy answer is add a fan or fans, but that will kill the battery even faster. Running a bigger engine will allow me to run 120 to 150 amps so the heat sink will get hotter faster and it will absolutely need fans. So I'm thinking adding a second normal, small 12v alternator.
Upgrade engines I'm thinking about going to are an 8hp predator 301cc or stealing my freshly rebuilt Honda gx390 engine off my pressure washer.
I'm thinking adding a 2nd small 12v alternator even if that alt has an underdrive pulley it will rob at least 1hp. So the 301cc only ends up giving me one to one and a half additional HP to drive the welding alternator, maybe giving me 130amps max.
I'm thinking in this case bigger is better and go with my hot gx390.
Or do I need something even bigger?

I don't have an answer but would love to see a picture of your set up!

 

[slacktide_bitog]

The Predator engines are Chinese copies of Honda, built under license by Lifan. The Predator 212 is the same as the GX200. If you buy a Predator, replace the Torch spark plug that comes with it with an NGK iridium

 

[wag123]

I have a Honda gx200 that powers my home made welding machine that uses an ACdelco DR44 alternator. It works great. Main problem is when I run about 120amps the engine loses speed. Turning it down to around 110amps gives reliable steady welding power.
Other small problems are the welding alternators field current is provided by a 12v battery, that battery goes dead after a while and on hot days the heat sink for the bridge rectifier gets pretty hot after I run it for a bit even at 100 amps. The old battery I'm using takes at least 2 hours to recharge.
For the hot heat sink the easy answer is add a fan or fans, but that will kill the battery even faster. Running a bigger engine will allow me to run 120 to 150 amps so the heat sink will get hotter faster and it will absolutely need fans. So I'm thinking adding a second normal, small 12v alternator.
Upgrade engines I'm thinking about going to are an 8hp predator 301cc or stealing my freshly rebuilt Honda gx390 engine off my pressure washer.
I'm thinking adding a 2nd small 12v alternator even if that alt has an underdrive pulley it will rob at least 1hp. So the 301cc only ends up giving me one to one and a half additional HP to drive the welding alternator, maybe giving me 130amps max.
I'm thinking in this case bigger is better and go with my hot gx390.
Or do I need something even bigger?

I don't understand why you are only using the battery for exciting the alternator instead of connecting it directly to the alternator's output and running the welder off of it that way. If the battery is small I would get a bigger battery and run everything off of the current alternator/engine combination. It should work much better than your current setup.

 

[Ride_Red]

I like the idea of building in a 12V supply. That's the way to go IMO.

 

[Cujet]

It does seem that a Honda 390 would be the minimum for doing any significant welding.

I have only used professional grade gas powered welders a few times, but I have run my 200A TIG welder, after the hurricanes, on my 11HP 340cc Subaru genset multiple times, and there is no way the 11HP can run full welding power. Any way you slice it, there are a stack of losses, and it takes a big engine to true 200A welding.

For an example, the Miller 180 amp gas powered welder (bluestar) uses a 14.5HP engine. and the 230 amp gas powered welder (Bobcat) uses a 23.5HP engine.

 

[meep]

What voltage are you welding at?

What rpm are you running the engine at?

 

[oil pan 4]

I don't understand why you are only using the battery for exciting the alternator instead of connecting it directly to the alternator's output and running the welder off of it that way. If the battery is small I would get a bigger battery and run everything off of the current alternator/engine combination. It should work much better than your current setup.

The alternator develops around 80v at no load and then drops to around 25v under arc. The alternator field needs about 8 volt.

 

[oil pan 4]

What voltage are you welding at?

What rpm are you running the engine at?

Open current voltage is around 80v and under arc it's around 25v.
I run the engine at full speed 3800rpm and over drove the alternator nearly 1:2.

 

[oil pan 4]

It does seem that a Honda 390 would be the minimum for doing any significant welding.

I have only used professional grade gas powered welders a few times, but I have run my 200A TIG welder, after the hurricanes, on my 11HP 340cc Subaru genset multiple times, and there is no way the 11HP can run full welding power. Any way you slice it, there are a stack of losses, and it takes a big engine to true 200A welding.

For an example, the Miller 180 amp gas powered welder (bluestar) uses a 14.5HP engine. and the 230 amp gas powered welder (Bobcat) uses a 23.5HP engine.

Then it would seem my setup is most efficient, getting over 100amps with a 6.5hp engine.

 

[oil pan 4]

I like the idea of building in a 12V supply. That's the way to go IMO.

I can't find a 12v power supply that will take 80 to 25vdc and step it down to 12v.

 

[oil pan 4]

I don't have an answer but would love to see a picture of your set up!

Its partially dismantled, I stole the Honda gx200 to use on an air compressor.

 

[oil pan 4]

I don't have an answer but would love to see a picture of your set up!

External rectification and excitation.
The old Briggs flat head is just there for reference.

 

[meep]

This is one of the coolest things I’ve seen in a long time.

I’d absolutely go with the larger Honda engine, and consider going slightly larger on the drive pulley and easing the rpm back.

Can you install an alternator direct to the flywheel like it would be if Honda provided it? Like a riding mower would have? Might need a different flywheel but I’ll bet the engine has provisions for it. Then just add a standard riding mower engine rectifier/regulator which should give you at least 6 amps at 14 volts. ?? That would be more elegant than a separate alternator.

 

[oil pan 4]

This is one of the coolest things I’ve seen in a long time.

I’d absolutely go with the larger Honda engine, and consider going slightly larger on the drive pulley and easing the rpm back.

Can you install an alternator direct to the flywheel like it would be if Honda provided it? Like a riding mower would have? Might need a different flywheel but I’ll bet the engine has provisions for it. Then just add a standard riding mower engine rectifier/regulator which should give you at least 6 amps at 14 volts. ?? That would be more elegant than a separate alternator.

I think the Honda magneto would only make a few amps. I would have to buy an "electric start kit" but I already have a collection of old 12si alternators.

 

[jeepman3071]

Larger Honda engine, but I'm biased. Absolutely nothing wrong with the Predator, but the 212cc will have similar power to the GX200, so if you upgrade, a bigger Predator (420cc) or larger Honda would be my pick. If you go Predator just make sure you swap out the factory failure prone "Torch" Chinese spark plug with an NGK, and do a few short OCIs to get the initial break-in metal out.

 

[oil pan 4]

Larger Honda engine, but I'm biased. Absolutely nothing wrong with the Predator, but the 212cc will have similar power to the GX200, so if you upgrade, a bigger Predator (420cc) or larger Honda would be my pick. If you go Predator just make sure you swap out the factory failure prone "Torch" Chinese spark plug with an NGK, and do a few short OCIs to get the initial break-in metal out.

How do that fail?
When you say fail I'm thinking does the ceramic break?

 

[Astro_Guy]

How do that fail?
When you say fail I'm thinking does the ceramic break?

I had one fail in an Ariens Deluxe snowblower with the 254cc engine. Basically the plug would foul after every use. The only way to start the engine was to clean and gap the plug. I swapped in an Iridium NGK and it has been a new machine ever since. Now it starts on the first or second pull after sitting unused for ten months. I feed it 89 octane Ethanol free fuel and run it sry in the Spring.

There are many threads here about Torch plugs. Try the search function

 

[oil pan 4]

I had one fail in an Ariens Deluxe snowblower with the 254cc engine. Basically the plug would foul after every use. The only way to start the engine was to clean and gap the plug. I swapped in an Iridium NGK and it has been a new machine ever since. Now it starts on the first or second pull after sitting unused for ten months. I feed it 89 octane Ethanol free fuel and run it sry in the Spring.

There are many threads here about Torch plugs. Try the search function

Sounds like heat range means nothing to torch.

 

[jhellwig]

You could get an engine with charging ability. Some of them have fairly high output but many just barley keep the battery charged.

Would be easy enough to add another alternator like you are thinking. Then add fans for the rectifier. The rectifier needs a much larger heat sink unless it is forced air cooled.