Alternator Welding Conversion Info Needed

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Jan 31, 2003
"the whale's vagina", CA
I have searched and didn't find anything specific to the info I am looking for.

I am looking for info on how to setup a 2nd alternator welding conversion on a vortec 350 chevy engine. Cruiser is a 73 with a 99 vortec engine. Right now I have a plate that houses a York air compressor which is running on the belt. It is not being used as I have switched to compressed air. I carry a spare alternator and have been told by others that I could put this alternator in the place of the york and wire it up to become a stick welder. I am looking to do this for emergency needs and repairs on the trail. I don't want to buy an expensive on board mig welder but figure I might as well do this if I have the 2nd alternator already and can fab a bracket up to make the alternator fit on the belt. I am a beggining welder and have not stick welded yet, like I said it is for emergency on trail use.

I think I can fab something up to position the 2nd alternator on the belt and make sure it is spinning with the engine. I have installed a throttle cable in the dash so I can up the throttle when using the welder or the winch. What I really need assistance on is how to wire everything up safely so I can actually weld with a setup like this. What parts I will need, wiring diagrams, tips on safety, install, etc.

If anyone can help or point me in the right direction it is much appreciated!

Your biggest problem is figuring how to drive a second alternator with a serpentine belt. Choose an external regulated alternator, like the Ford large case, or disable the internal regulator, as it is of no use. The wiring is drop dead simple: an on/off switch to energize the field windings (fused for 10A at least) and a stinger attached to the B+ lug and a work clamp attached to ground. A 90 A alternator can easily run 3/32 6011/6010 rod.
So I think I can figure out how to run the alternator on the serpentine belt. I have a spare 2nd alternator and if you look at the pic I plan to pull the york (right hand side in the pic) and replace it with a 2nd stock alternator. I would like to use the stock alternator as it will serve as a spare if I need it. In the situation where the stock alternator craps out I will just swap the two.

Can I use the stock spare alternator I have? You mentioned disabling the internal regulator? Is this completely necessary or can I just use as is? The reason I ask is because as I mentioned above I would like to option of swapping it to be used in the stock alternator position as a spare unit.

So for the wiring I would just attache the "stinger" (which holds the welding rod, correct?) directly to the ouput positive "bolt" on the alternator (the output which would normally go to the battery). So I could probably run a switch to this bolt with some type of quick disconnect for the stinger? The ground strap would be attached to somewhere on the vehicle frame for a good ground? I could probably figure out a quick disconnect for the ground strap as well.

Anyone ever hear of any company selling quick disconnect for a welding ground strap and a welding rod holder? It would be slick to set up a "box" in which one cable goes to the output + on the alternator and one cable goes to the vehicle frame as ground. Then the stinger and ground plug into the box. Mounting a fused switch in line of course.

Thanks for all the help!

Have you considered this MIG?

Just wondering if you have investigated the GoWeld, battery operated, portable MIG welder? I purchased one a few months back; trust is no toy!! With 2 batteries it will weld heavy, heavy material. can use it at home. Also....MIG welding is easier to learn than stick. No clutter under the hood either. I have not seen any GoWelds on the trail yet...probably because of cost. But......what a MIG welder it is!!

Kit comes with the welder, roll of wire, extra tips, cable for connecting batteries, all in a nice carrying case. Very simple.

Before I bought mine, I drove 75 miles to a sales rep for a demonstration. Turns out the sales rep was doing this on the side, and he is a welding instructor at one of the prisons. Before I left......we welded 1/2" aluminum, and 1/2" steel with some mighty fine looking welds.

I just mention it for your consideration.
1973Guppie said:
Can I use the stock spare alternator I have? You mentioned disabling the internal regulator? Is this completely necessary or can I just use as is?

Sure, you can use any alternator that puts out 70 A or more. The junk yard is full of them for about $25. If it has an internal regulator, all you need to do is bypass the internal regulator and run a new connection between the non-grounded side of the field windings to the on/off switch. You can also use the alternator you already have by just running the bypass wire to your existing alternator and disconnecting the B+ wire from your wiring harness when you need to connect the stinger for welding. That way you can use your existing alterntor for welding in an emergency and then switching it back to charging your battery when you switch off the welder.
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thanks pin head, any more info, etc, pictures, writeups out there on bypassing the internal regulator? I like the idea of using the gm alternator and keeping it as a spare. I may as well mount the 2nd GM alternator as I have the space and need to fill it. I don't want to use a ford alternator as I will have to buy another alternator and might have to figure out the serpentine issue.

So the way i understand it is if I am running a 2nd alternator I can just disconnect the internal regulator and run a new wire directly from the winding to an on / off switch? This will allow the alternator to push it's max power. Then if I ever need to use it I can just recconenct the regulator wire? sound right?


1973Guppie said:
So the way i understand it is if I am running a 2nd alternator I can just disconnect the internal regulator and run a new wire directly from the winding to an on / off switch? This will allow the alternator to push it's max power. Then if I ever need to use it I can just recconenct the regulator wire? sound right?



Thass right. When your are welding, it is just balls to the walls and you regulate your welding current by engine RPM. When you turn it off, it is back to normal.

You can even use the single alternator you have without damaging it unless you burn it up. Just carry a spare.
So in theory you hook up a digital amp guage so you can "adjust" you amperage AKa engine rpm.. HMM.. now can you do this to a ready weld MIG pack or???
trollhole, I will do it! I just need more info on how to properly bypass the internal GM alternator regulator. Sounds like I can leave the regulator in place and just run a wire with an on / off switch from the wirewounds to the + output bolt on the bank of the alternator, therefore when switched on all the current rushes around the regulator (least resistance) and is ready for welding.

Problem is I have never pulled an alternator apart, anyone have info on how to operate on an alternator / internal regulator?

Noah has an online manual for a GM CS130.
You have a CS130D, which is similar.

There are two sets of windings in any alternator: The field and stator. You energize the field wingings to control the voltage output from the stator windings. If you want to use an alterator as a welder, you need to fully energize the rotor. Pull the back off and find the brushes. One brush is grounded tothe case, while the other one is connected to the regulator. Run a wire from the non-grounded brush to your switch.

In practice, you are going to need to drive a 100A alternator pretty much full bore (3-4,000 engine RPM) to run 3/32 inch rods. If it is running too hot, back off the RPM. Heat will kill the alternator if it is used continuously. I burn a rod and then let it cool for about 5 min before sparking up another one.
I read that alternator article, interesting but confusing. I am not an engineer. It sounds like there is a way to wire the alternator to put out AC power to run lights, drills, etc. I believe the alternator in its stock config puts out DC power. I would like to set the 2nd alternator up to not only be used as a welder but to have a couple outlets I can run drills, grinder, tv, whatever off of. I am confused however on which of these I can run safely? Do most household appliances run off of AC? checked my grinder and it says AC only. I am also wondering if when I bypass the regulator am I now getting AC or DC power? I believe I would still be getting DC because of the way the alternator is setup to push DC power. If I could find a box to convert DC to AC via a switch I could wire it up to be used when I want to use the power outlets. any comments?
You have the later D model of the CS130, which has a different case style; otherwise they are similar inside.

You get DC out of the B+ terminal of an alternator. There is AC only in the stator windings before the diodes. The AC frequency increases with engine RPM.

It is easy to run resistive load tools (drills, but not variable speed type, grinders, incandescent lights, etc) off of DC, but you can't run inductive loads, like a TV, which requires AC. The DC voltage varies with engine speed in a full field situation and can exceed 200V with no load.

If is too much work to convert an alternator to AC and most things won't run anyway as it will be hard to regulate the frequency at 60 cycles. Just get an inverter for things that have a transformer.
here's an idea. get one of those big rig alts. they put out full rated amprage at 1800 rpm instead of 3600.
Thanks Pinhead, you have been of great help. I am not going to try to convert the output of the alternator to AC.

I had a thought of maybe installed a standard inverter in the engine bay which will be powered by the DC output of the alternator? Does this sound feasable? This way I can have a panel with the welding quick disconnect and as well as a few plugs to run whatever I wish. Plus, they will be powered off the 2nd alternator thus no worries on draining down the system. I would think this would be ok to do as it is the same type of DC power from a cigarrette lighter output or from a car battery, correct? I guess I will need to make sure to only use the inverter when the switch is on off / internal regulator on mode as the inverter probably will only want the regulated 12V DC? I could probably just isolate the inverter with another fused switch. I might even make the inverter somewhat a quick pull style so I can use it in my other vehicle as well. Let me know what you think .

Any welding shop should be able to supply you with quick disconnects for welding cable. 1/2 turn to connect. You don't really need a quick disconnect for the ground, just get two ground clamps. Clamp one onto your frame, and one onto your work.

Doesn't sound to me like you have all that much welding experiance... might want to invest in an evening class - will take a lot of frustration out of welding, and would probably make it easier for you to understand the setup you need.


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