Welding with batteries

[sunchaser Member Find all posts View Profile Close sunchaser]

G'day all,

Was wondering if anyone out there who has done any bush welding with two batteries has ever used a generator to keep the charge in the batteries whilst doing the weld. Or is it not really necessary? Could it cause any problems to the batteries or generator?

Cheers Gaz

[LeighW Avid PP Poster! Find all posts View Profile Close LeighW]

Generally you'll have two or three batteries in series so a gen is
not going to work.

[D4Dforme Senior Member Find all posts View Profile Close D4Dforme]

It can't be good for the battery.........even a 2mm rod will need 50 Amps to run a decent weld......I know my mate had to link 2 x Honda 20i's to weld up his boat trailer using a 170A inverter running 3.2 rods.....apparently they struggled a little but got the job done.

Maybe look in to MAP gas they may have something portable but unlikely.

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

I've only had to do it twice in the past. After a total of 20 seconds of actual welding I had trouble starting from either battery. That wasn't 20 secs continuous... that would cause a massive issue with the batteries hehe. But it's amazing how much you can get done

[MidLifeCrisis Out of control poster! Find all posts View Profile Close MidLifeCrisis]

I watched some dude from Loxton do it. He says the batteries don't lose much charge at all. I guess its relative to how much welding you actually do. For instance, he used to weld Mitsubishi's, at the rate they fall apart I assume the batteries lasted a few months of welding without recharge

(all jokes aside, my vague recollection was you could weld for a while without effect, but i will check with him, depending on whether he sees the funny side of the above post.

[Mattfunk 120 Advanced Member Find all posts View Profile Close Mattfunk 120]

I watched some dude from Loxton do it. He says the batteries don't lose much charge at all. I guess its relative to how much welding you actually do. For instance, he used to weld Mitsubishi's, at the rate they fall apart I assume the batteries lasted a few months of welding without recharge

(all jokes aside, my vague recollection was you could weld for a while without effect, but i will check with him, depending on whether he sees the funny side of the above post.

http://www.pradopoint.com/showthread...h-Welding-Demo
This fella?

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

I have covered this quite a few times over the years, most recently in this thread http://www.pradopoint.com/showthread...l=1#post523361

Some other posts / threads related here.

http://www.pradopoint.com/showthread...l=1#post396092
http://www.pradopoint.com/showthread...h-Welding-Demo
http://www.pradopoint.com/showthread...l=1#post431102

I did a training day for our 4wd club a few years ago and had a heap of guys all have a crack at welding, we burned up about a half dozen rods and from memory the voltage drop on the batteries was around .1 of a volt, so bugger all, half a dozen rods is an awful lot of welding for a bush repair, more than most are likely to ever use.

You really need 3 batteries to weld, 2 batteries might just be ok if you have small rods and really know your stuff, but even then its marginal, we tested this at the training day I mentioned and it wasn't very good. A normal ARC welder plugged into the power will produce 32volts at the stinger, so 3 batteries is as close to correct as you can get.

Battery welding is DC welding which is generally easier than AC welding, if you can manipulate you amps to a suitable level an experienced welder should be able to produce excellent welds.

Yes I used to weld Mitsubishi's together, but I was smart enough to never buy one

Cheers Andrew

[sunchaser Member Find all posts View Profile Close sunchaser]

Thanks for the replies
I was actually looking at your last thread on the subject AJ which got me wondering if welding drained the batteries quickly and might need a gen to keep power up to them. But only a drop of .1 volt after half a dozen rods it wouldn't be an issue.

Cheers Gaz

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

Yeah that's my experience, we were all a bit interested in voltage drop so tested the batteries regularly over the afternoon of playing around and found it to be a non issue. Having said that, if I had a major repair to do in the bush and had to use my crank battery and had no jump start option, I would stop regularly and test battery voltage, just to be sure. Maybe your batteries might be not as good as the three I used during my practice, so if voltage drops more than you would like, stick one back in the car and run it for a while, hook the others up with jumper leads to charge them while your at it. Your doing a major repair so time time shouldn't be an issue, your staying put for a while regardless.

Worst case scenario, you flatten your batteries and don't have enough juice to start the engine, you have no other batteries and no one to jump start from, you have an auto so cant push start it. You have 3 batteries, put your crank battery back in, hook the other 2 up in series giving you a bit under 24 volts (as they are flat) get your jumper leads ready, get someone to crank the engine, quickly touch the jumper leads on the crank battery feeding it 24v and remove as soon as it fires, which should be instantly.

We do this all the time at work on Trucks with flat batteries, the trucks are all computerised the same as modern cars and its never caused an issue.

Cheers Andrew

[sunchaser Member Find all posts View Profile Close sunchaser]

Thanks Andrew
Some great information there. It's something alot of us are set up to do but have never actually done.
Cheers Gaz

[RanJ Avid PP Poster! Find all posts View Profile Close RanJ]

3 batteries at a minimum eh? Explains a lot. Like why my batteries are so drained after a short period and why is so difficult to get it started.

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

No not at a minimum, don't use more than 3 in series or you will just melt everything. 3 is the ideal number.

Cheers Andrew

[MidLifeCrisis Out of control poster! Find all posts View Profile Close MidLifeCrisis]

http://www.pradopoint.com/showthread...h-Welding-Demo
This fella?

That's him. Never around when you need him.

[Oscartangotango Lurker Find all posts View Profile Close Oscartangotango]

I have never welded with batteries but have done plenty straight out of the back of an alternator.
It was a 100 amp alternator on my old cruiser, all that was needed was to disconnect the wire out of the alternator to trick it into pumping out full current, jumper leads from the body to the work was the earth and another lead off the positive terminal on the alternator to the rod.
Start the engine, bring up the revs and weld away for as long as you like...... if you needed more amps you just wound up the hand throttle.
Got me and many others out of lots of sticky situations over the years.

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

I just watched Pat Callinan do a demo on battery arc welding, it was a very segment to show how NOT to do it he pretty much got everything wrong!

Cheers Andrew