SERIOUS On Board Welder (OBW) If You Are Interested... -

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post #1 of 50 Old 01-16-2012, 09:10 AM Thread Starter
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SERIOUS On Board Welder (OBW) If You Are Interested...

I messed with On Board Welders for quite some time.
This IS NOT as 'Simple' as people lead you to believe in the one page write-ups,
So, like usual, I'm going to cover background so you know what you are looking at/for,
And then I'll get to the welder it's self.



(Direct Current, what your alternators and batteries produce)

'STRIGHT' Welding Polarity is a POSTIVE Work Piece,
And a NEGATIVE Electrode.

'REVERSE' Welding Polarity is a NEGATIVE Work Piece,
And a 'Positive' electrode.

'STRIGHT' Welding Polarity will DIG DEEPER, give you better PENETRATION into the metal you are welding.

'STRIGHT' Welding Polarity, Positive Work Piece with NEGATIVE Electrode is impossible on most vehicles using an alternator for a welder.

The reason is, The alternators commonly used for 'Weldanators' have a NEGATIVE GROUND THROUGH THE CASE.
The vehicle frame/body is a NEGATIVE, and there isn't any way to 'STRAIGHT POLARITY' weld for penetration on your own vehicle with a negative ground alternator converted for welding.

Light duty surface welds with 'REVERSE' polarity is all you will be able to do on your own vehicle with 'Common' alternators that 'Ground' through the case.


A well thought out and worded rebuttal from user 'Shiftface',
Take note, this is how you SHOULD disagree and/or complain!

Now, he's a welder by trade, so I will have to do a correction if I can confirm this, and I will have a long hard look at what he's written.

Originally Posted by Shiftface
DC straight polarity, workpiece positive-electrode negative,
Provides a less digging arc and less penetration.

For stick welding, using straight polarity can help when welding thin material such as body panels.

It also can increase deposition rates and reduce parent metal/electrode blending, helpful in many hard surfacing applications where speed and/or purity of deposit are a consideration.

Most fusion purpose electrodes run poorly on straight polarity.
It's more common to use DC 'Straight Polarity' in TIG and MIG applications.


DC 'Reverse Polarity',
Electrode Positive - Work Piece Negative,
Provides the digging, penetrating arc important in most stick welding applications and is by far the most common method of delivery.

The arc characteristics provide much better heat, puddle and deposit control as well as good parent metal/electrode blending which provides excellent fusion properties.

Almost all stick electrodes will run reasonably well in dc reverse regardless of polarity designation.
No personal slamming or insults, perfectly explained with no malice.

What I've been able to CONFIRM of this is...
What I've been reading about 'Stright' polarity digging deeper is for TIG and some MIG applications.
I haven't been able to confirm what was stated about STICK rods yet... But I'm still looking!

I can BUILD a welder, but I'm not the best welder or the last word on welding since I do very little of it, and I don't do it on a daily basis...

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post #2 of 50 Old 01-16-2012, 09:11 AM Thread Starter
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To control POLARITY,
You have TWO CHOICES...

Dual batteries wired correctly will produce 24 volts, and 24 volts from batteries will weld either 'Strigth' or 'Reverse' polarity on your own vehicle.

I cover this type of welding rig extensively on the links below for "Winch, Welding, 'Lend Power' Project" in my signature line below.

This has the added advantage of the engine NOT being running, and the batteries will be DISCONNECTED FROM THE VEHICLE,
So you have little or no chance of damaging you own electronics.


2. You need to start with an alternator that DOES NOT 'Ground' through the case.
The case MUST be 'Neutral', and there MUST be a insulated 'Negative' post on the alternator if you want to weld with 'Straight' or 'Hot' Polarity on you own vehicle.

Since the engine MUST be running, I do NOT recommend this if you have an MSD module or fuel injection!
Computers and MSD modules DO NOT TOLERATE anything above about 16 to 18 volts,
And since the engine MUST be running to weld,
You can do some SERIOUS damage to your electronics!

I STRONGLY recommend you DO NOT try to weld on your own vehicle with the engine running with 'Straight' polarity!


The most common and easiest to obtain HEAVY DUTY alternator I've used for this application is the Leece Neville.

It has ISOLATED Positive & Negative DC outputs, so you can connect directly to the alternator and weld in both 'Straight' & 'Reverse' polarities.

This particular alternator has the added advantage of being VERY easy to convert,
To take control of the rotor to produce welding currents.

These alternators were used on a TON of big trucks, ambulances, and they are all over big truck salvage yards,
They are fairly inexpensive if you buy a 'Remanufactured' unit at the parts stores.

They start at about 105 Amps, and the most common are 105 and 130 Amps, there is also a 160 Amp version that is fairly common.


This is an old version of the CONVERSION, worked about 10 years on a farm around fertilizers, worked on farm equipment for about 10 year before it finally give up.

This shows how you remove the regulator, take over control of the rotor with a piece of non-conductive 'Plexi-Glass' and brass flat head screws for virtually nothing...

This image shows the outputs from the regulator housing and what they do...

This alternator will do two things that the little units will not,
The AC taps on the back will power AC induction motors, like saws and drills.

The second is you can add an extra set of rectifiers onto the back of the alternator, doubling it's 'Duty Cycle' since it won't get hot nearly as fast.
(rectifiers are the finned 'Red' things showing through the back of the case)

It looks a little goofy with an extra set of rectifier bridges mounted on the back of the case, and it's a little award to mount, but if you weld a lot, this will REALLY make the welder work for it's living.

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post #3 of 50 Old 01-16-2012, 09:12 AM Thread Starter
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'ELECTRODES', Welding Rods, Patch Material.

Welding Rods (Electrodes) will be rated for POLARITY, AC and/or DC, and type of material.
The SIZE, or Diameter of the Rod will determine to a great extent what you can use with a 'Field' welder or 'Alternator' welder.

The smaller the rod diameter, the less electrical current it will take to sustain an arc.
Smaller rods take more passes to make the weld, but will be MUCH easier on the welder,
And since we aren't welding up 2" bridge beams here, you should probably stick with smaller rods so you can control the welding process and not overheat your field welder.



'All Purpose' Rods.

What I call 'Dirt Farmer' rods since they will make reasonable welds on about anything, clean, rusty, dirty, old metal, over heated metal where the carbon is an issue,
Vertical, Horizontal, even over head welding,
Work with AC, Straight DC, Reverse DC, doesn't matter, you can burn rod and get yourself clear of the situation you are in...


6013 Rods do about everything but 'Dig' for deep penetration.
6013 Rods work with AC, Straight or Reverse Polarity DC, work in all positions
(you can get the weld to 'Hang' so vertical and overhead are possible, but not 'Pretty')
PENETRATION isn't 'Deep', but for most 'Jeep' applications, they work fine.
They DO require some preparation, you want a reasonably clean spot,
But will weld new and old metal just fine.
Weld strength is about 60,000 PSI when metal is prepped correctly and you know what you are doing...

6013 Rod, 5/64" in diameter, will require about 50 Amps to do a reasonable weld.
6013 Rod, 3/32" in diameter, will require about 75 Amps to do a reasonable weld.
6013 Rod, 1/8" in diameter, will require about 100 Amps to do a reasonable weld.


7014 Rods do about everything, but faster, and they penetrate better.

7014 Rods lay a lot of rod into the weld, so you can use them as 'Filler',
work with AC, Straight or Reverse Polarity DC, work in all positions
They weld in all positions, but overhead can be tricky for an amateur like me.
Penetration is deeper than 6013 rods, and make reasonable, fairly high strenght welds (around 70,000 PSI if you prep the metal and know what you are doing)

The reason I don't use 7014 a lot more is they require a lot of amperage, which heats up the welder rectifiers pretty quickly, so your 'Weld Time' or 'Duty Cycle' is reduced...

7014 Rods, 3/32" in diameter, will require about 100 Amps to do a reasonable weld.
7014 Rods, 1/8" in diameter, will require about 125 Amps to do a reasonable weld.
7014 Rods, 5/32" in diameter, will require about 150 Amps,

(well outside the 'Safe' zone of the average alternator welder...)


7018 Rods do fast, smooth welds that don't 'Bubble' (Low Hydrogen),
LIMITATIONS ARE AC or REVERSE' (Positive Electrode) DC welding, AC spatters like crazy!

They don't work with low voltage AC welders and they DO NOT work well with 'Straight Polarity' (Negative Electrode) DC welders very well.

7018 Rods are fast, they do reasonably strong welds, and they work on all steels.

7018 Rods, 3/32" in diameter, will require about 85 Amps to burn efficiently with a DC welder.
7018 Rods, 1/8" in diameter, will require about 125 Amps to burn efficiently, with a DC welder.


6011 is the 'Ultimate' Dirt Buster Rod.

Has to be used Electrode Positive (Reverse Polarity), but burns through about anything, digs deep, spatters like crazy, but doesn't care what you use it on.
Welds are REALLY ugly, but since you can weld about anything, and use a POSITIVE electrode, the smaller alternators with Negative 'Grounds' burn them pretty well.
Lousy tack welding rods, so keep that in mind...

I've ALWAYS got some 6011 rods in my rod container, they are just that handy, especially in small diameter.

6011 Rod, 3/32" in diameter, Will burn fine with about 60-70 amps,
(meaning they will work with small output welders or give you a much longer duty cycle with a bigger welder)
6011 Rod, 1/8" in diameter, will usually burn fine around 100 to 125 Amps,
(doesn't matter what you are trying to burn in, this rod won't be pretty, but it will get the job done without killing your welder in the process...)

I'm not by any means the last word in welding, so if you have something to share, PLEASE DO!


User built MIG welder for projects...





When you buy a rod holder canister for your Jeep,
Get the best, most air tight one you can find!
Keep the 'O' ring at the top well greased (dielectric grease works well).

Rods are NOT cheap, and moisture kills them!
The better the weather seal you can get on your rod holder, the better.

Drop some thin walled PLASTIC tubing down in that rod holder.
Diameter of the tubing depends on what size and how many (Count) of rods are are trying to carry...
Small tubes for smaller rods with smaller counts, larger tubes for larger rods or higher counts.

This lets you use ONE container for all your rods without mixing them up.
It also keeps rods from rubbing on each other, larger rods hammering on smaller rods while you wheel, and keeps the flux on the rod and out of the bottom of the container.

Color codes plastic tubes with a legend on the outside of the container, or in the cap, make locating the rods you want to use MUCH easier than rooting around in that container 6 months or a year from now and not remembering which/what rod does what...

I made a little 'V' shaped leg for my rod container (Hose Clamp and stiff wire),
Keeps it from turning over and dumping the rods out on the WET/DIRTY ground.

'LEGS' sticking out make a good way to hang the rod holder container on bumpers, side body, steering linkage, where ever you need it without letting the rod contianer fall over and dump your rods out on the ground.

And dirty rods introduce contamination into your welds.
Not a big deal for a 'Patch Job' to get you out of the field, but a big deal when you are building something and want a good, clean, strong weld that looks good...

I put end plugs (not caps, caps take up too much room) and glued them into my plastic (PVC) tubing separators.
I can lift out what ever rods I want to use without dealing with the rods staying in the container,
Or having to tip the entire container to get one specific rod.

I tried that and TOTALLY screwed up some welds.
Copper and steel welding don't get along, even in trace amounts...


'Filler Material' & Welding 'Stock',

One 'Sneaky' way to take patching material in the field with you is to have a longer than normal Jack Handle.
You would be surprised how many times I've hacked a chunk of my jack handle off for this or that when trying to fix a 'Field Break' and get back.

The jack handle is HOLLOW.
A good place to keep some 'Stock' for welding in braces, brackets, filler, ect.

Welding down a Wrench or two isn't the end of the world, Deep well sockets make for Tie Rod break repairs when you don't have anything else around.
(Jack handle is cheaper, but you MUST have a hack saw)
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post #4 of 50 Old 01-16-2012, 09:14 AM Thread Starter
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Good welding CABLE has counter rotated strand bundles, all the wire isn't 'Twisted' in the same direction.
(Most people don't know the difference between 'Wire' and 'Cable', Now you know the INDUSTRY version of that definition...)

Most 'Wire' doesn't have a VIRGIN, or PURE copper conductor material.
Welding cable has VIRGIN copper conductor strands because pure copper conducts the amperage better without resistance and heating up the cable.

WELDING CABLE is specifically designed to move AMPERAGE.
Every part of the design is geared to that end.

Virgin Copper Conductors, Counter rotated wire bundles, Small strand conductors,
All that moves AMPERAGE better.

You also get the benefit of electrical insulation that is both flexible, abrasion resistant, chemical resistant, high heat resistant and just plan better for the job than 'Vinyl Wire' insulation is.

HEAVY JUMPER CABLES, at LEAST 4 Ga. WELDING CABLE for jumper cables, makes a good set of welding leads without having to carry both jumpers and welding leads.



I use high amperage 'Quick Connects' for my jumpers and welding cables ('Anderson' Type Connectors) so there i s no fooling with the connections at the welder with 'Welding Connectors'.
No sense in messing with 500 AMP Connectors when you are never going to surpass 150 Amps when welding.
175 Amp 'Anderson' connectors work REALLY WELL...

175 Amp capable connector on the LEFT,
350 Amp capable connector on the RIGHT.

I use an 'Anderson' connector in the front of my Jeep so I can plug in Jumper Cables and not be near the battery that is being 'Jumped' in case it explodes or something else goes wrong.

They make a good disconnect point also in case something goes wrong...

'Anderson' Type Connectors for this application are compact, keep polarity correct and make your cables MUCH easier to store.

An 'Anderson' connector on the welding alternator will produce a quick connect point for your 'Jumper' cables,
And since your 'Jumpers' are actually welding cable if you are smart, there isn't an issue with welding from them.



Don't shop at the $5 bin!

If they are made of 'Plastic', forget them.
If they have small gauge cable connection points, forget them.

When I welded a lot in the 'Field' I used COPPER JAWS in the clamps.
Copper doesn't burn to the rods or work pieces, where other metals can some times burn themselves to the rods or work pieces.

Keeping a rod working in a STEEL CLAMP takes a little 'Finesse'.
Most clamps that work for Jumper Cables make TERRIBLE welding 'Stinger' clamps,
And welding stinger clamps SUCK for Jumper cables...

I do two things to try and get this stuff working well together...

The first is a folded piece of fairly thick copper, or a copper block with a hole drilled in it (What ever you can come up with).
The copper block with a hole will hold the rod, then you clamp the copper block in your jumper cable clamps, it will then be large enough to get a good grip on.

Same with the fairly thick folded piece (usually for smaller rods), stick the rod in the fold, then get a grip on the copper with the clamps.

The second is drill a hole in one of the jaws of the jumper cables up near the nose.
Stick the rod though the hole, use the other jaw to get a grip on the rod.
Doesn't work well for high amperage without burning a little metal out of the hole or the rod sticking, but works in a pinch...
All you need is a drill and about one minute to get it working...

This works OK for 'Field' repairs, but you really need a 'Proper' rod holder if you plan to build something that looks good.

This thing will drive you crazy trying to change rods when they are hot.

Rod Changes don't matter in the field to get you in, but working on something where you want to keep the weld puddle hot, this doesn't work very well.
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post #5 of 50 Old 01-16-2012, 07:28 PM
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post #6 of 50 Old 01-16-2012, 07:34 PM
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Keep going, don't stop now.


1957 WILLYS pickup,
1973 J 4000,
1978 CJ7 DD.
1979 CJ7 360, TH400/Quadratrac.
1979 J20
1980 CJ5 trail Jeep.
1983 CJ7
1989 YJ the CJ to YJ.
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post #7 of 50 Old 01-16-2012, 07:36 PM
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I probably won't ever do this, but I'm really interested to see the write up.

Originally Posted by Ripper3494 View Post
i think we should chase him around with yjs, its like being chased by zombies, slow, crippled but for some reason still scary as heck lol
Red Jeep Club #614
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post #8 of 50 Old 01-16-2012, 08:47 PM
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I'm curious about the three-phase ac taps. Do the produce true 208? At what potential amperage and how hardy and reliable is it for a source?

Originally Posted by gpets View Post is perfectly acceptable to take a sawzall to anything you can't figure out, that is how we all learn.
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post #9 of 50 Old 01-16-2012, 10:54 PM
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Originally Posted by B52dude View Post
I probably won't ever do this, but I'm really interested to see the write up.
Ditto. I love these kind of threads, even though I know chances are slim to none that I will apply them.
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post #10 of 50 Old 01-17-2012, 05:41 AM
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Originally Posted by Shiftace View Post
I'm curious about the three-phase ac taps. Do the produce true 208? At what potential amperage and how hardy and reliable is it for a source?
Probably not near, 3-phase has nothing to do with voltage. The voltage on the alternator will depend on the speed and the exicitation voltage.
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post #11 of 50 Old 01-17-2012, 06:09 AM Thread Starter
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Originally Posted by RenoF250 View Post
Probably not near, 3-phase has nothing to do with voltage. The voltage on the alternator will depend on the speed and the exicitation voltage.
Correct. you will have one of the 3 phase 'Legs' dedicated as the 'Neutral', and one each (total of 2) 'Power' legs.

Output voltage will depend entirely on alternator/engine speed and how much current you apply to the rotor.

This is VERY HIGH frequency AC voltage output, so anything with a transformer is out of the question.
No computers, TVs, radios, ect.
You will just burn them up.
(I don't watch soap operas when I'm working, so it's no big deal, and since I went to dual battery welder, I can use an inverter for clean 110 volt power)

It will power simple induction motors, like drills, saws, ect.


NOW! If you DO NOT want to mess with AC taps and trying to balance output voltage when you run 'Power' tools.

The CHEAP alternative is to find 'Cordless' tools at yard sales, round them up when the batteries go dead and the replacement battery costs more than the entire drill/saw kit did new,
And put a cord on them.

12, 14 volt battery powered tools work great with a cord and 12 volt vehicle battery,
While the 18+ volt tools work good on a 24 volt vehicle wired for welding.

These things are CHEAP ($2-$5 each at yard sales and swap meets every day),
Easy to convert to a 'Cord',
Since they don't work away from your 'Trail Vehicle' they don't get carried off for other jobs,
And if you burn one up in the field, WHO CARES! It was $5, NO LOSS!

I've COMPLETELY got away from using generator AC power tools, the power has to be monitored so you don't burn the tools up, and having a generator that will produce that kind of power is large and cumbersome to mount under the hood...

You aren't getting a 110 volt 'Saws-All' or reasonable drill for $3 anywhere like you will with battery powered tools converted to a cord!
Economy all the way around...


I'm still going, got a couple of comments on what I said about 'Straight' and 'Reverse' polarity, and I'm waiting on clarification.
I'm a 'Gears & Wires' guy, not a Welder, so if someone has a logical argument, I don't want to mis-inform folks, so I'm waiting to revise if I was wrong...

I've been using what I learned from the welding shops around here for 30 years, and it's not failed me, but even if I'm 'Technically' wrong, I don't want to pass it along, or at least throw in a disclaimer and references so you can educate yourselves.
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post #12 of 50 Old 01-17-2012, 07:03 AM
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I have a 160 amp Leece Neville that I robbed out of an ambulance at the Pick and Pull several years ago and was going to do the same thing. It even has a variable output on the DC side with an adjustment screw on the back.

You can get them for about $20 used and they are awesome units.

79' CJ7 - 82' CJ8 - 94' YJ - 96' ZJ
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post #13 of 50 Old 01-17-2012, 07:18 AM Thread Starter
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Virtually all the Leece Neville alternators have a voltage output adjustment on the regulators also.
You can fine tune the unit for the voltage output you want, makes them VERY virsitle as a charging system.
I don't suggest you run out and get one because they are more than twice the size of a 10 SI alternator,
but if you have heady draw appliances you want to 'Volt Up' for,
These are a good choice.

This is not a 'Peak' amperage rating on the LN alternators.
When they say 105 amps, they mean 105 Amps all day long, every day.
The rating is NOMINAL operating amperage, not 'Peak' amperage.

They are VERY heavy duty and rugged, last for years with full on roller bearings instead of bushings.
All around a tough, long living unit, so they make good, serviceable, SERIOUS 'Field' welders.
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post #14 of 50 Old 01-17-2012, 07:34 PM
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If you have this set up separate form the vehicles charging system. Does it still mess up the MSD and Summit cdi boxes??
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post #15 of 50 Old 01-18-2012, 07:57 AM
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This is, with out a doubt, one of the most useful and informative threads I've found on JFrm..and I am still reading, but had to remark- Well done all.
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