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isochronic
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Joined: 21/01/2012
Location: Australia
Posts: 689

Posted: 12:37pm 10 Jul 2018

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I am interested in using a little inverter welder as a grunt power supply.
It should be fairly obdurate but with a lot of hash, spikes etc. So, I am wondering how to clean it up. At first glance large capacitors / filters would do that but I think the welder will not like a capacitive load..If I put a heavy duty resistor, ie radiator element or similar, before the capacitors - will that protect the inverter output ? The rated output is 50 amps at 16 volts continuous, 48 volts open circuit, 100 amps in short bursts, so I think roughly a 1 ohm resistance should do ok. (?)

noneyabussiness
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Joined: 31/07/2017
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Posted: 05:52pm 10 Jul 2018

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I have one of those small inverter welder as a mains backup charger.. directly connected to battery.. 72v open circuit voltage(48v system). . Actually works flawlessly,as the voltage rises it puts less and less in as voltage rises..the "noise " on the output doesn't seem to be a issue, the battery is a pretty good filter..

I'm pretty sure OZ has covered this somewhere and he was of same opinion.

I think it works !!

Warpspeed
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Joined: 09/08/2007
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Posted: 12:31am 11 Jul 2018

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It depends on the type of welder and the welding technique it was originally designed for.

MIG welders would probably be the best because they are supposed to operate with a fairly constant dc output voltage. Current is adjusted by varying the wire feed in speed. So it should make a pretty good basis for a general purpose dc power supply, especially for battery charging.

Stick and TIG welders are completely different. They are a constant current source type of supply, where you set the "amps" on a variable control, and the output voltage varies wildly with the load.

Many of these inverter welders can be used for a variety of welding techniques by selecting the right mode of operation, and adjusting the controls accordingly.

Should work, but be aware that the inverter transformer and heatsinks can be quite small and not designed for continuous operation at full rated power.

Cheers, �Tony.

noneyabussiness
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Joined: 31/07/2017
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Posted: 07:16am 11 Jul 2018

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https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com.au%2Fulk%2Fitm%2F131818334056

This is the one i use... VERY well made..

I think it works !!

isochronic
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Joined: 21/01/2012
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Posts: 689

Posted: 09:22am 11 Jul 2018

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It is a mig, it has an output "welding voltage" control but that may be an aim point more than anything. Good value though (assuming it lasts

Madness

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Joined: 08/10/2011
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Posted: 09:55am 11 Jul 2018

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The Knob says current and is MMA, it regulates current. I have one that looks slightly different on the outside but probably the same chinese guts. To get mine to charge @48v it needed an extra turn on the toroidal transformer on the output.

As for using it as a power supply it does not regulate voltage, so might be okay for some things.

There are only 10 types of people in the world: those who understand binary, and those who don't.

isochronic
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Posted: 12:05pm 13 Jul 2018

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It is definitely intended for MIG use, it is hard-wired to a wire feed and cable and mig handpiece.
I'll do some trials with some junk components and report back, hopefully not charred

Warpspeed
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Posted: 10:07pm 13 Jul 2018

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Sounds good Chronic.

I have a three phase rectifier MIG, and it has switchable transformer voltage tapping steps from around 16 volts to 44 volts dc if I remember. I suppose the inverter MIGs are probably built to operate over a similar kind of voltage range.

Its just a bit high for a 12v battery, and and falls short for a 48v battery, but it would work very well on a 24v dc system with switched output voltage steps of around two volts.

Never played with an inverter type MIG myself, so will be interested to see how this goes.

Cheers, �Tony.

isochronic
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Posts: 689

Posted: 10:42am 07 Aug 2018

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I thought I should check a few things before risking the smoke..
To filter the output a bit, looks like it will take some chunk low esr capacitors so I have been looking for those, bit expensive at high values though.
In the meantime I took the cover off for a eyeball..bit surprising, as well as the main inverter toroid, it looks like there is an inductor (ferrite ring) on the return clamp cable which I guess is a regulation/filter function. So I checked continuity with a cheapo meter, apparently no plain connection between power earth and return clamp - so I guess the output is floating maybe ? Not surprising but it will complicate things a bit.

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