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Discussion Starter #1
Sorry in advance for starting yet another on-board welder thread, but there are questions that I have that I can't find good answers for in any search. Here goes...

I realize that there are two types of alternators; internally regulated, and externally regulated. If I use an internally regulated alternator I need to bypass it.

I also read the thread about using a NAPA gizmo to build a welder and that it’s not really necessary for an alternator that’s not connected to the primary charging system and can regulate voltage with the throttle. It is nice though because it has the power outlets for running tools.

This is what I would like to build: Using an externally regulated alternator of many amps I would like a DC welder and a couple of plug outlets for tools. The box mounted in the engine compartment with the meter, quick attach wire hookups, and the outlets looks cool.

Here are my questions:

1. Can I have regulated power outlets while regulating welder output with the throttle?
2. Is there any way to have 110VAC power outlets and still have a DC welder? I have heard that alternators output AC but don’t understand this stuff. Diodes?
Rectifiers? Please help!
3. Wiring up a simple welder seems easy enough, but I haven't seen any diagrams that explain how to hook up the outlets. Any ideas?
4. How is the welder voltage regulated using the NAPA box?

Thanks for any help
 

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K10gearhead said:
Here are my questions:

1. Can I have regulated power outlets while regulating welder output with the throttle?
2. Is there any way to have 110VAC power outlets and still have a DC welder? I have heard that alternators output AC but don’t understand this stuff. Diodes?
Rectifiers? Please help!
3. Wiring up a simple welder seems easy enough, but I haven't seen any diagrams that explain how to hook up the outlets. Any ideas?
4. How is the welder voltage regulated using the NAPA box?

Thanks for any help
1. Yes. You can have 110V DC output to run tools etc. Most alternators will put out about 150 V at full field excitation and about 3,000 engine RPM. Just regulate the engine speed.

2. No, you get DC. The alternators are all three phase. If you remove the diodes, you can get single phase AC between any two wires of the three, but you will only get 1/3 of the amps and the frequency will vary with engine speed (but it will be above 1000 hz at idle).

3. You mean the tool outlets? The B+ wire from the alternator goes to one side of the outlet plug and the other side goes to ground. For welding, the stinger goes to the B+ and the ground clamp goes to any ground (for welding DCRP, reverse the leads for straight polarity welding but you cant weld on your own frame in SP)

4. All the box does is regulate the current that goes to the alternator field to provide regulated 110V DC. You don't regulate the field when welding; you just run it at maximum field. For welding you don't need a box. You can just run a jumper wire from the battery + to the field terminal.
 

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Discussion Starter #4
Re: Re: home-made on-board welder

Pin Head said:


4. All the box does is regulate the current that goes to the alternator field to provide regulated 110V DC. You don't regulate the field when welding; you just run it at maximum field. For welding you don't need a box. You can just run a jumper wire from the battery + to the field terminal.
So, If I wanted to weld, and have the tool outlets, I could use a two position switch to set the field input to full for welding, and regulated for 110V? What does the NAPA box use to regulate the field?
 

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thanks rudezuk:flipoff2:
Thats were I got the idea of the napa box.

So it is napa auto parts? I wasn't sure after tring the p/n's either.:confused:

I'll call them when I get around to it them.:beer: thanks
 

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That is fn sweet! I am gona go get three car batteries together, and start welding my sas.:D
 

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The napa part numbers from Jeff's article are still good. I picked up one on Monday. However, there are several different AMP rated models, and one with voltage meter. Do a search on napa's web site for power supply.

-tim
 

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Re: Re: Re: home-made on-board welder

K10gearhead said:


So, If I wanted to weld, and have the tool outlets, I could use a two position switch to set the field input to full for welding, and regulated for 110V? What does the NAPA box use to regulate the field?
My experience is that you don't need theNAPA box to run tools. The voltage doesn't matter that much. Most brush motors will run on anything from 60V to 150V although they will run faster with the higher voltage. The same goes for incandescent lights: the higher the voltage the brighter they are. Just put a outlet box in the engine compartment and regulate the speed of the engine to run your angle grinder or chain saw. If you are running a SCR controlled variable speed motor, you will have to run it at full speed or it will overheat the speed controller.
 

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TRed said:
That is fn sweet! I am gona go get three car batteries together, and start welding my sas.:D
The problem with welding with just batteries is that there is no easy way of regulating the current. You can burn off the coating on your 1/8 inch rod before you weld off half of it. You could just discharge the batteries (not good) or use high resistance, skinny cables. The current changes as the batteries discharge. It is OK to use batteries if you have no other choice, but to do your SAS, I would just get a buzz box.
 

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Re: Re: Re: Re: home-made on-board welder

Pin Head said:


My experience is that you don't need theNAPA box to run tools. The voltage doesn't matter that much. Most brush motors will run on anything from 60V to 150V although they will run faster with the higher voltage. The same goes for incandescent lights: the higher the voltage the brighter they are. Just put a outlet box in the engine compartment and regulate the speed of the engine to run your angle grinder or chain saw. If you are running a SCR controlled variable speed motor, you will have to run it at full speed or it will overheat the speed controller.
Correct (I am building one now and have done way more homework than I care to have done) When powering anything with your OBW, it can be only a brush type motor or a resistive load. All of these loads are not highly sensitive to variance in the input voltage, and will function quite well even if you are exceeding their "normal" 110v operation, or for that matter, are below it. A common myth that I keep dispelling is, "A 110v outlet? Sweet, I can run a TV in camp (or other device)" No, these electronics are not so-called universal loads. They contain sensitive components that will burn out the first time you try to put 110v DC in them.

SLADE: I don't have the part number (just reloaded this computer last night and haven't restored everything from my server) but if you go to allelectronics.com and search under panel meters, you will see a digital LCD screen that is for 0-200mV. If you run a 1 megaohm resistor from positive to a 1 kilohm resistor to ground and then run your DC+ from the panel to the connection of the two wires, and the DC- to ground, it will step that down in magnitude so the 0-200mV is going to read as if it were 0-200 volts. PM me if you have any questions.
 

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Thanks for the info. I tried allelectronics and it must have shut down since I couldn't find it. I built a welder a couple of years ago with the big externally regulated Ford alternater and it works great. I'ts gotten us out of a couple of jams. I also wired in a AC outlet to run other tools like drills, angle grinders and most importantly the blender. I just thought it would be easier to wire in a guage rather than getting the meter out to set the voltage each time. At least I know what I'm looking for now and how to modify it. Maybe I'll try Radio Shack.
 
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