Welding off the Grid

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Re: Welding off the Grid

Postby Gordon-Loomberah » Sat Dec 29, 2012 1:47 pm

Thats true, I've done heaps of welding with batteries at 24V DC. 17V is, I think, the minimum voltage to maintain an arc, under normal conditions.
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Re: Welding off the Grid

Postby Privatteer » Sat Dec 29, 2012 8:00 pm

Does not sound to healthy for the battery to me considering your essentially putting a short across it.
In an emergency yes but for normal use?
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Re: Welding off the Grid

Postby Gordon-Loomberah » Sun Dec 30, 2012 10:34 am

Using the starter motor isn't much different to a short either! ;)

I always had a generator (Honda motor + 30A truck alternator) charging the batteries when doing it if there was insufficient or no solar and wind power at the time, and did some reasonably big projects with that arrangement. Portable welding arrangement when up the hill away from my power supply was with a couple of 12V batteries and the generator.
I've also seen a similar arrangement under the bonnet of a builders small truck- 24V alternator and 2 batteries, and you just leave the motor running and connect your leads to the dedicated welding terminals under the bonnet- just drive to the job and lift the bonnet and you are ready to weld!

One thing I did learn was that some cheap 12V batteries have very thin walled hollow terminals full of gas from the cell underneath :x That became obvious when one melted through under high current and a poor connection, and the resulting spark recombined the H2 and O2 gas from a couple of cells very quickly with a bang! :o :shock:
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Re: Welding off the Grid

Postby Smurf1976 » Sun Dec 30, 2012 4:13 pm

This welding straight off the batteries idea.

Do you have any fuses etc in there somewhere?
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Re: Welding off the Grid

Postby Gordon-Loomberah » Sun Dec 30, 2012 4:26 pm

I never did- current was basically limited by electrode size, and lead thickness and length. With the leads I was using, there was too much current available for 2.5mm rods, 3.2mm was ok, and 4.0mm was very nice to weld with- the rods just flowed into the job very smoothly. My electrician father suggested introducing some sort of inductor into the lead may have helped in some situations, (perhaps with smoothing current flow, I forget the details now), but I never experimented with that, as I acquired a MIG welder shortly afterwards- in the mid 90s.

I'm pretty sure my 230V welder doesnt have a fuse on the output side though.
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Re: Welding off the Grid

Postby Smurf1976 » Sun Dec 30, 2012 4:48 pm

Fair enough. The idea of shorting out batteries with no easy means of "turning it off" does worry me a bit though.....
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Re: Welding off the Grid

Postby Gordon-Loomberah » Sun Dec 30, 2012 9:32 pm

Hopefully you have a good grip of the hand piece and can easily break the arc ;) Anyway, the welding rod itself is actually a good fuse equivalent- the arc will extinguish if you don't feed more rod into the job.
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Re: Welding off the Grid

Postby offgridQLD » Mon Dec 31, 2012 10:45 pm

There are a few battery powered portable mig and tig welders available off the shelf.

Here is an example of a 160A mig welder that's portable with self contained battery's capable of 100" on 1/8 inch mild steel from a charge.

Image

It most likely has a few tiny led acid battery's but with a lithium upgrade would pep it up a little.

Link
http://www.prweb.com/releases/battery/welder/prweb3024374.htm

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