Alternator welder

[bobwills]

I dont think so either. My guess is its about a 50 amp or so. But thats still enough to burn 3/32 6011. Be good just for field quick repairs and suck. So the first step is seeing if it still works though. So i built a stand for it, its hooked to a moter. So which wire powers the field then? And does anyone know what the other one does.

[I_Love_Plasma]

Good question. I'm not sure, because mine is one wire so it obvious. They both may be power wires. Or one may be for 6volt and the other may be for 12. When I was researching it, I found a lot of those trucks had alts that were for both 6v and 12v. IDK how close you are to any town...but you could try a generator alternator repair shop. Or a garage that's been around more than a week. The repair shop should be able to tell you. If not, PM me everything you know about it and I can call my guy up here. or i can PM you their number whatever works sweet for ya.

Sorry Brad simultaneous-post. Very good information.

Brad mentioned: "Then you just need a beefy engine to keep it spinning under load." Remember there's 746 watts per 1 horsepower at 100% efficiency. So if it's 60amps times 13.8 volts = 828 watts assuming the alt is 75% efficient multiply 828 by 1.25 (25% waste) and that would give you 1035 watts. So it will take a bare minimum of a 1.4 HP electric to spin it. For gas rule of thumb is "double the gas to equal electric" Needing a 2.8 HP gas. then you engine ins't 100% efficient either, say 60% (40 waste). 2.8 X 1.40 = 3.92 HP..on and on.....belts eat up power... So 5-8 HP should get you started.

Sorry, as if all of us don't get enough math at school and jobs

[bobwills]

What about making one out of a generator. I have an old one laying around with a bad motor. Would there be a way to convert it or would it not even work

[blasphemy000]

No idea about the generator. But really before you go tearing it apart, take a battery charger and hook the positive and the ground to the 2 terminals inside the plug on the side of the alternator, spin it up with your motor and measure the voltage between the case and the terminal on the back. Report back with that voltage, that should tell us how it's regulated, some internally regulated ones if the fields are fed from an external source like you do when you weld with one then they will still work as there is no feedback current to the regulator.

[redbeard]

That one looks like an internal regulator. If memory serves, the way to tell on the old GMs is to look at the orientation of the plug terminals. If they are parallel with the shaft, it's external, if they are perpendicular, it's internal.

[bobwills]

yeah im definatly gonna hook it up first. See what she will do. If i had to guess from what it was out it will be about a 50 amp. Because it was out of a 70s truck. So it didnt have a whole lot of power consumption. And o i see what you mean. Without it hooked to a battery where the positive goes it might not activate the regulater. And I would really like to do that. Be really nice having that extra power.

[I_Love_Plasma]

What about making one out of a generator. I have an old one laying around with a bad motor. Would there be a way to convert it or would it not even work

Oh a power generator, like 120vAC gas powered genset. I totally thought you were talking a "generator" like wind turbines have or really old tractors (starter/generator). What wattage does your genset have? you could step down the voltage with a transformer..120v is way to high, and i dont think it will draw down as much like the alt would.

[bobwills]

Yeah that might work pretty good. Wonder if it would be easyier to take it apart and unhook it though cause that seems a lot more complicated

[DaveO]

A couple questions:
>>To permanently disable the regulator, I would slightly enlarge the D hole so as to make it round
When you enlarge this hole, presumably with a drill, do you run the risk of metal turnings from the drilling process getting into the regulator and shorting things out?

Does the end-product welder require a cooling fan? Blasphemy, did you incorporate a cooling mechanism in your welder?

[blasphemy000]

My alternator had a big fan on the front of it to start with, the little pressed metal one behind the pully, but its outside of the case.

That's not my alternator, but the fan is the same. Just for reference though my motor spins the alternator the opposite way it would normally spin on a car so instead of it sucking the air trough the alternator and blowing it out the front its sucking it in the front and blowing through the alternator. None of this was on purpose though as I didn't even realize it was spinning backwards till like a week after I built it. Most car alternators don't care which way they spin since they generate 3-phase AC internally anyways. As for the cooling, I'm really not sure which way works better as I never had any problems with it overheating. Like I said, at full power the case gets very hot to the touch but it's never gotten hot enough for the current to drop off so I don't think I'm over working the diodes inside. After I'm done welding with it I cut the power to the field and let it spin for a few minutes to cool down. It just seemed like a good thing to do.

[Rivets]

Bobwills,

My last post above has a significant OOPS, so you can't hook up as per Blasphemy's schematic, because I forgot about the diode trio.

Unfortunately, you'll have to open up the cases and dive in.
See schematic below. (The 12 Volt Doctor's Alternator Book - Edgar J. Beyn - Spa Creek Inc.)

Remove the diode trio, and while you're at it solder a lead to the test lug and route it outside the case where you can easily ground it. Then you don't need a threaded hole.

Also, the + charger lead goes to lug #1 and the - charger lead goes to the casing and NOT to lug #2.

You can also remove the regulator, but then you'll have to connect leads to the slip rings and bring them outside the case.


There is an even neater way.

If you keep the diode trio, and hook up the rheostat between the test lug and the case, then you need the battery charger (or a battery for that matter) for only 1 or 2 seconds after start up.

Cheers,
rivets

[Rivets]

[QUOTE=DaveO;15396]A couple questions:
>>To permanently disable the regulator, I would slightly enlarge the D hole so as to make it round
When you enlarge this hole, presumably with a drill, do you run the risk of metal turnings from the drilling process getting into the regulator and shorting things out?
QUOTE]

DaveO,

It could be an issue, but my thinking was to use a drill bit in a threading tap chuck and enlarging the hole by hand and blasting with compressed air.

No longer relevant since the cases have to be opened. Easier and neater to route grounding wire outside the case - see post above.

Cheers,
rivets