Can I run a welder off a generator???

As long as the generator can supply the current the welder needs I don't see why not, most small welders use most of a 240v 13A supply so a generator rated around 240V 15A should be fine.

This will be a pretty hefty device around a 4KW engine.

Be carfull though a lot of them quote 4 or 5 kw but can only have  max if 2kw  per outlet, you will need at least 3kw.

Yes, I've had quite a bit of experience doing a huge amount of welding on my Carlton GSi in the garage in my allotment.

I used a 150A SIP transformer MIG.

A friend loaned me a decent size 5.5KVA diesel generator, which promptly ran on its own oil (max revs & impossible to turn off) and died, I was desperate to progress so risked my new 2.3KVA generator.
It worked, but after maybe 200mm of weld went up in smoke. 2.3KVA was definitely too small.

I then bought a used 3.8KVA generator (cant remember the brand, cheap one) and welded up the rest of the project over the next couple of years.
I don't think this is ideal, but it worked, I did take the precaution of never pushing it duty cycle wise, I always did some work, then let it run with no load to get plenty of cooling air through, then periodically turned it off for a while to cool.

My conclusion is that it definitely is possible without spending crazy money, my generator cost £100. I would buy the biggest you can, but experience says that 3.8KVA will manage.


Beware the misleading badged generators being sold currently, with some sellers telling lies, others just not being open.
My friend bought one of them last week, model number included 8500 and he was lead to believe it was 8500W. There was no labelling at all on it about output.
It could barely run anything so he investigated it, seems to be 2000W max, and as its supposedly 3 phase and has 3 240 outlets I suspect that the 2000W is all phases combined, so only a few hundred W from one outlet. Only any use for lighting.
To be honest it was obvious to me just by the physical size that it wasnt 8500W but he hadnt realised.

You should find the Q & A guide below quite useful even though its taken from the website of a manufacturing supplier of Invertor MIG machines for industry (which will be very expensive MIG's when compared to what you will find on the electronic media sales sites or what mates are using)

www.weldclass.com.au/blog/47-using-generators-to-power-inverter-welders-your-questions-answered

The issue is also raised on the MIG Welding Forum

www.mig-welding.co.uk/forum/threads/running-an-inverter-off-a-generator.12655/

Go and knock on any local houses and see if they'll let you run a extension lead for a few quid.

I recently tested my newly bought R-Tech 180 amp MIG running from my ‘Kipor’ 2800w inverter suitcase generator - worked fine...

A few things to note:
- The Kipor is a Honda clone, had it years, been reliable.
- Inverter generators create a stable sine wave electronically.
- Inverter generators usually have a ‘Smart Throttle’, and run the engine as slowly as they can, to reduce noise and fuel burn. The Kipor has a switch to override it, if needed.
- Most non-inverter generators (even AVR ones) use a mechanical governor, and attempt to run the engine at a constant speed to get a constant voltage/frequency output - and fail when loads suddenly come and go (like welding!) - I’ve tested a few with a volt meter and oscilloscope - nasty!
- I tested with Smart Throttle on, it coped ok.
- I tested welding car body thickness metal only, as I don’t need to weld thicker tin while running from the generator.
- Clearly the generator max output is below the current needed for the welder at full tilt, see above.
- The R-Tech is a (rather good) IGBT welder (not transformer).
- Open frame generators are noisy, crude things in my opinion!

Also, remember to buy a fire extinguisher or two to live at the garage, BEFORE you start cutting or welding.

If I can help further (eg test something), let me know.

I did some work for a couple of friends who have a small farm near where I live. Since then I have had numerous calls from other farmer in my area who want equipment welded up. Some of the implements are pretty good size and difficult to move to my house for the repairs. If I build a trailer and can run a couple of different welders off a generator than I can make shorttime of the fix.