How to / DIY > Generators

Welding off the Lister

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Hi All

So, four years into the barn rebuild I've got the Lister,CS 6/1  mounted on a couple of steel beams and driving a Stanford 8.1, alternator up here, I squeezed it into my homemade back box and the '84 Ford 6610 lifted it, I've no idea how much it weighs, but as I had to cover 2 k on the main road I backed it up with a couple of ratchet straps, just incase.....

It wasn't a comfortable couple of k!

My question is,

Could I weld using 2.5mm / 3/32" rods and a decent inverter with the above combination?


Hi Stef,
The CS 6/1 is a bit puny for a welding source.  3/32 rods will be right on the edge; they run about 26 volts at 95 amps,  2470 watts (just over the sustained output of the 6/1) but you must also allow some losses in the inverter so you'd really need near  3000W continuous; that's more than the 6/1 can typically do.

No harm in trying since you're engine and not generator limited. You might try bumping up the rpms slightly if your flywheels can handle it safely.

Hi Bruce

Thanks for yet another swift reply!

 I got to the same answer, but, given my well know lack of experience / knowledge / and confidence with all things electronic it's good to have my hand held, I imagine you worked it our a lot swifter than I did!

I know the CS is good for around 3000w 'cos I rigged a bank of 6 x 500w lamps as a test load some while back, it got smokey but didn't die. I've got room for a few more revs as I'm running at 50Hhz at the moment. The fly wheels are original Lister and have no apparent damage.

I guess it's which folds first, the inverter or the AVR. I also have a big old air cooled industrial welder it's been wired for 220v single phase since I've had it, would this be a better / safer option?


Hi Stef, I did a lot of welding using my ST2 7KVA SOM, no problems at all, except that the sudden demand for electricity when striking an arc was too quick for the governor and the genny would bog down a little.
In Australia, domestic electricity outlets are fused at 10 amps (2400 watts), the small inverter welders that are readily available will happily run on this and can use a 2.4mm welding rod but it can be hard to strike an arc.
Welding rods come in smaller sizes: 1mm, 1.6mm and 2mm your CS would certainly handle these and would probably cope with a 2.4 rod at a push. I am unsure how quickly the governor would be able to compensate for the sudden full output demand but the heavy flywheels should help prevent the sudden voltage drop than can extinguish your arc, just after you struck it.
Your Stamford should easily be able to handle 3KVA, just be very careful not to stall the engine with a heavy load on it. As the engine speed slows the output voltage drops, the load remains the same and so the current increases. I have seen a lot of burned out petrol generators caused by the fuel running out under a heavy load.
I don`t think it makes a lot of difference if you are using an invertor welder or the older transformer welder, the load will be very similar.


With every step of the thing, you incur more losses. Trying to run a spinny thing, to a generaty thing, to a con/in-iverter thing, to a transformer thing... And a "standard" of conversion efficiency is 80% So... 80% of 80% of 80% of 80%....

A 6/1 running at nominal is 6HP = 4474W or 4.7kW. (*0.80)   You can tap the motor out another few hundred RPM for more power. (minus the losses)
I think an extra 50 RPM gave the 3/1 another 50HP but sorry I can't remember the maths behind that.
I don't know what the stamford head will do, or how it's coupled.

Personally, with that engine I'd be looking to the hell rectifier setup (skipping inversion/reversion/conversion) and running DC welds straight off. I'd be surprised if you could stall it on 2.5mm rods.


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