Running a Welder off Victron Multiplus 3kw

[Checkthisout]

Good Morning. I have a few little repairs/modifications to make at the cabin. A small Lincoln welder runs off my inverter generator but I would say its nothing short of abuse of here-said generator when I do. It see-saws up and down rapidly and incoherently as the current draw rapidly fluctuates. Im ok to use it for some quick tacks or very short beads but I have some longer welds I need to do.

Now I have the same generator that runs through a mutliplus.

Would you run a welder off a multiplus? If so, would you run the generator at the same time along with power assist or just bag it altogether and run the welder off a regular gen. I have all these options available but the easiest is just the multiplus or multiplus and my inverter gen. Thanks.

 

[740GLE]

What’s the demand of the welder? 240v at 30a?

 

[Checkthisout]

What’s the demand of the welder? 240v at 30a?

20 @ 120V

It's not the peak demand I'm worried about, it's the sharp fluctuations in current draw you get. It drives my inverter gen crazy....just want to make sure it won't damage the multiplus.

Thanks.

 

[yodamota]

Is your generator on a eco mode where it "responds" to the load by matching the rpm? If so I would take it off that mode while welding. If you haven;t tried that already.

 

[Checkthisout]

Is your generator on a eco mode where it "responds" to the load by matching the rpm? If so I would take it off that mode while welding. If you haven;t tried that already.

No. High speed but even at that setting it still jumps up and down rapidly as it still has more RPM left and the fact that it throttles up to compensate then suddenly the load drops.

Most welders run a 22 HP twin cylinder engine and have lots of flyweight. A little inverter gen just can't do it. It provides power fine but I just think rapid rpm fluctuation along with the inverter tryiing to rapidly fluctuate output isn't good

 

[Tomthumb62]

No. High speed but even at that setting it still jumps up and down rapidly as it still has more RPM left and the fact that it throttles up to compensate then suddenly the load drops.

I would think that a battery and inverter would be able to meet a sharp demand better than an inverter generator. Just make sure cables are sufficient to avoid heavy voltage drop and connections are tight.

 

[Tomthumb62]

I would think that a battery and inverter would be able to meet a sharp demand better than an inverter generator. Just make sure cables are sufficient to avoid heavy voltage drop and connections are tight.

Adding to say, particularly with a lithium battery as they LOVE instantaneous high amp loads. Provided you’ve given them ample cabling and connections.

 

[RCinFLA]

Most all modern inverters use PWM to create AC sinewave. The problem is the output L-C filter to average out the PWM.

Impulse current loads on PWM filter causes it to ring near its cutoff low pass frequency which interferes with inverter ability to regulate its AC output voltage.

Same issue applies to an inverter-generator.

 

[Checkthisout]

Most all modern inverters use PWM to create AC sinewave. The problem is the output L-C filter to average out the PWM.

Impulse current loads on PWM filter causes it to ring near its cutoff low pass frequency which interferes with inverter ability to regulate its AC output voltage.

Same issue applies to an inverter-generator.

So give it a shot? The welder will tolerate the fluctuation. I just don't want to damage the fancy multiplus.

Fawk it, run it?

 

[740GLE]

Multiplus or Multiplus II?

I think the multiplus has a slightly larger toroidal transformer which might help.

I only say this because the Multiplus has a little bit more losses than the Multiplus II.

 

[Checkthisout]

Multiplus or Multiplus II?

I think the multiplus has a slightly larger toroidal transformer which might help.

I only say this because the Multiplus has a little bit more losses than the Multiplus II.

Multiplus original formula.

It has two transformers about the size of a cheese wheel.

 

[Madcodger]

Would I try it? Absolutely! I bought a Victron because I didn't want some sissy little wimp of an inverter! That said, I haven't tried it yet. But now I sort of want to... My Hobart mig welder can do 240 or 120. I've never run it on 120 as it's in the garage, and those little wheels on its stand are gonna be a bear to get across the gravel dooryard, near the building with solar. But you've got me thinking...

I think I'd turn on the generator just to give the inverter more to work with, but hopefully the Multiplus will use battery to "smooth" things a bit for you. And btw, if you do hurt it, don't blame me. But would I personally give it a shot? Yep.

 

[740GLE]

How much welding are you doing a few tacks? Or feet of it? I’d try it for a little bit then check the temp of the Multiplus, if it’s really stressing the unit heat build up will be evident.

Also if you were running the generator, can’t you programs the grid support value of the Multiplus, such that it only asks for 5-10a and let the rest come from the inverter?

 

[Bluedog225]

I wouldn’t put that much strain on the Victron. Cool if it works but is it worth it?

 

[Checkthisout]

How much welding are you doing a few tacks? Or feet of it? I’d try it for a little bit then check the temp of the Multiplus, if it’s really stressing the unit heat build up will be evident.

Also if you were running the generator, can’t you programs the grid support value of the Multiplus, such that it only asks for 5-10a and let the rest come from the inverter?

A few feet of bead.

So let me emphasize here, I'm not concerned about the power demand itself but the rapid fluctuation in demand that occurs during welding. Make the inverter chase its tail, possibly damaging it.

If I get around to it, I'll take a video using a welder off an inverter gen so you can see what I'm talking about.

Edit: I see. You're not thinking peak but maybe the inverter picks up the difference between what causes sudden loading/unloading of the Gen. I like this thought process.

I dunno. I'll give it a shot....I can't provide instant gratification here though as this will be over labor day weekend. (Remote cabin)

 

[740GLE]

I’ve never welded but I’ve always thought it was more ideal to be constant or consistent, this demand from the wall would be consistent as well?

What was the size of your inverter generator?

If the welder is 20a 120, and your inverter generator is only 3k, it might have been on the edge of the governer response to keep things happy voltage and frequency wise so it kept hunting. If anything the magnetic field of that Multiplus toroids will only help it deal with swings better.

 

[Symbioquine]

I pretty regularly weld with my Victron Multiplus 24|70|3000 units (now using 240 split phase but for a long time I just used one @ 120v). I've wondered the same thing whether the sharp changes in current demand will reduce the life-expectancy of the units, but so far so good. (About 18 months now of periodic welding usually at least once a week for >15 minutes.)

My welder is a modern inverter-type (AHP AlphaTIG 203Xi) so that might make a difference.

It might be worth checking with Victron support to see if they would expect any detrimental effect on the hardware long-term.

 

[Checkthisout]

I pretty regularly weld with my Victron Multiplus 24|70|3000 units (now using 240 split phase but for a long time I just used one @ 120v). I've wondered the same thing whether the sharp changes in current demand will reduce the life-expectancy of the units, but so far so good. (About 18 months now of periodic welding usually at least once a week for >15 minutes.)

My welder is a modern inverter-type (AHP AlphaTIG 203Xi) so that might make a difference.

It might be worth checking with Victron support to see if they would expect any detrimental effect on the hardware long-term.

Perfect! Thank you!!!