Wiring/control for dual alternator setup in patrol

[BigRAWesty]

Cable size is fine, 70mm2 from memory and good connections. Its a simple case of 100amp supply to battery and 400amp drain by winch, so the battery volts drop and - you know the rest. Matching the in - to - out better is my aim.

Interesting regards the welding as I do have a 200a Uniwelder alternator here and have found it next to hopeless for welding, even on 1.6mm rods. It was sent back to Uniwelder in WA for assessment and they said its fine, however it burnt out the windings soon after, was repaired by an auto elc and has sat on the shelf ever since. i think it might have been operator error, but can't be sure as they are pretty straight forward to set up and other people swear by them. Anyway I moved to a 24V mig welder from the US for welding and that works fine.

Yea right. Definitely something wrong with it.
But yea 2.5 rods only need 70A for a good weld..
3.2 are around 100A.
We use cigweld 175 welders and I can run 4mm rods in it.. maxed but it welds nice

[dom14]

200 a is rediculous..
Most welding is done at 50-90 with 2.5 rods.

But apart from that..
If the winch is struggling is it supply sorce or the cable size?

Need a bit more than 12V at those amps, you reckon?
Just wondering, when we use batteries to weld in an emergency situation, we are basically
short circuiting them to the point of damaging the batteries, aren't we?
How do we avoid doing the same thing to a second alternator that is used for stick welding?

[BigRAWesty]

Need a bit more than 12V at those amps, you reckon?
Just wondering, when we use batteries to weld in an emergency situation, we are basically
short circuiting them to the point of damaging the batteries, aren't we?
How do we avoid doing the same thing to a second alternator that is used for stick welding?

Tbh not sure of the voltage. I'll have a look at the specs.
But yea thats all welding is.
Don't do long welds and your batteries will survive.. only like 30-40mm at a time and let the batteries cool a bit..

[PeeBee]

I have tried the direct connection to battery welder method and found I needed at least 24V to maintain the arc, and 25v gave a bit too much spatter, however if you were really after deep peno welds in a single pass it would be good. i only tried with 2.5mm rods. I have heard this is really not a long term or sustainable proposition as the shorting does eventually damage the batteries, however i am guessing for an emerg repair it would have little impact.

The Uniwelder Alternator i have and didn't have much luke with looks like a standard 80A Hitachi Frame alternator, however it has 3 big plates of diodes on the back of it and requires a cooling horn to funnel the air over the windings and diodes. When it was tested by the autoelec it would barely generate a spark with the rods, at any speed, so i am still guessing as to what the problem was, even after it was rewound. The literature and experiences of others attest to them being really good devices and they have a 240V output as well.

The mig welder also seems to operate better on 24v as well. It can run on flux core of gas wire.

[PeeBee]

Typo, 36V not 25V

[dom14]

I have tried the direct connection to battery welder method and found I needed at least 24V to maintain the arc, and 25v gave a bit too much spatter, however if you were really after deep peno welds in a single pass it would be good. i only tried with 2.5mm rods. I have heard this is really not a long term or sustainable proposition as the shorting does eventually damage the batteries, however i am guessing for an emerg repair it would have little impact.

The Uniwelder Alternator i have and didn't have much luke with looks like a standard 80A Hitachi Frame alternator, however it has 3 big plates of diodes on the back of it and requires a cooling horn to funnel the air over the windings and diodes. When it was tested by the autoelec it would barely generate a spark with the rods, at any speed, so i am still guessing as to what the problem was, even after it was rewound. The literature and experiences of others attest to them being really good devices and they have a 240V output as well.

The mig welder also seems to operate better on 24v as well. It can run on flux core of gas wire.

Can you post a picture of your 24V gas/gasless mig welder, please mate?

If I understood correctly, you still have that high amp(200A?) Uniwelder brand alternator, but it can't be used for welding. In other words it doesn't either generate enough voltage or amps to generate a spark?!

Thanx

[dom14]

Tbh not sure of the voltage. I'll have a look at the specs.
But yea thats all welding is.
Don't do long welds and your batteries will survive.. only like 30-40mm at a time and let the batteries cool a bit..

Yeah, I tend to use secondhand crankers that are still in good condition. I keep a couple of those el cheapos to use in an emergency situation. With the matching welding rod, you can do an acceptable quality weld in an emergency.

[GeeYou8]

I will start by saying my welding skills are pretty much nonexistent, I blame this on a career in electronics where sparks are bad & are to avoided.
I remember reading about using the 2x batteries & seem to recall that the electrode lead was best if quite long & was coiled to give it some inductance. The added resistance & the inductance limits the current & helps maintain the arc.
Also how to remember which way around for the leads, the 2x houses of parliament
SENate: Standard Electrode Negative
REPresentative: Reverse, Electrode Positive.
Graham

[johno90]

Just a quick note with using a switch to isolate the exciter circuit, depending on the wiring inside the alternator and nearly 70% of alternators once you give it some rpm they can excite them selves leaving the switch you put in useless.

[PeeBee]

Check out Readywelder.com. I am yet to read how to post photos - bit lazy.

The Uniwelder I have is now just the 200a alternator. the control box went to heaven a long time ago and I was unable to get the support for repairs out of the guys in WA - we are talking circa 1998 . The alternator itself was used /installed as a 200a supply 100% duty factor unit to support the electric winch. In all the time I had it it was never used for winching, so cannot attest to its ability to generate 200a or not. When it did die and was put in for repairs with the autoelec he cast all sorts of doubts about its capacity, showing me a 200a truck alternator and that was a big unit - this is the size of a typical hitachi but about 3" longer due to the diode packs.I seem to recall it was also slow off the mark voltage wise, meaning it had to be spinning at 2000rpm engine speed to get to 13V, below that barely a pulse out of it. The alternator was designed to run at 11,000 - 13000rpm for welding, which it never did either when I had it as I burnt out a couple of vee belts trying to get it to that speed - very small pulley on the alternator and not much driving circumference. The alternator is in the garage somewhere - having a clean up now and might come across it - if i do, and if I can work out the photo attachment process i will put a couple of shots up of it.