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Forum Index : Solar : Inverter welder to Battery charger

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ozfossil
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Joined: 09/01/2015
Location: Australia
Posts: 2

Posted: 02:36am 09 Oct 2017

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Hi Guys, I picked up a small inverter welder from the tip the other day (I am sure it does not work) but looked at it from a different light - as a potential solar battery charger with some grunt - it is rated at 130 Amps and weighs a few kilos and from reading other posts on converting AC arc welders - i.e. fitting bridge rectifiers and fans heatsinks etc, this would not be at all necessary since inverter welders already have these features - and would potentially be able to be modded so that constant voltage is possible and even going a little further and perhaps putting in some intelligence for flat batteries.

I have not studied any Welder Schematics to see how and what they do to convert the Mains, to 340 V DC (close to many Grid Connect Solar arrays) then invert down to 30-40VDC at high currents for welding purposes, but can see inside the welder and it has a 450V main storage capacitor/DC stage (where solar array input could be connected directly) and some understanding of the regulator cctry controlling the inverter should be able to be modded cheaply to provide say 26-28v for 24 volt systems and then run a standard offgrid inverter as a secondary source of power when the grid goes down.

For myself - I am planning to only use a few batteries to keep everything happy short term, but depend on using all that lost solar capability when our grid goes down (does that fairly often)and I have all those solar panels doing nothing and I can't use my espresso machine - even in bright sunlight!

I searched this forum as I was sure some of you brilliant guys have already done this - but could not spot this subject.

Any thoughts and or failures would be welcome - otherwise I will have some attempts at this idea and try not to get too burnt

joebog1
Senior Member

Joined: 07/11/2015
Location: Australia
Posts: 114

Posted: 03:11pm 09 Oct 2017

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Most of those "little welders" have the same fault!!!
Its usually the RFI filter capacitors that fail and blow the fuses for the control board.
Its usually easy to see, BUT you will need good light and good eyes (use a magnifying glass) I have found that they almost all use 630 volt ( the better ones have 2000 volt versions) greencaps ( standard ultra cheap polyester ), although today they are brown. This fools the audiophools who just hate greencaps.
Check for very slight burn marks around the leads in the circuit board (s).
You can also usually find them using an ohm meter.

Good luck
Joe

yahoo2

Guru

Joined: 05/04/2011
Location: Australia
Posts: 1166

Posted: 11:08pm 09 Oct 2017

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I have tried charging without putting a lot of effort into it on lincoln, CIG and WIA machines. The inverter migs will output power but some of the inverter stick welders wont. my welders have all the fancy stuff like arc strike and ground fault protection on them so that might be stopping them from charging. perhaps the cheapies would work.

I'm confused, no wait... maybe I'm not...

ozfossil
Newbie

Joined: 09/01/2015
Location: Australia
Posts: 2

Posted: 04:50am 10 Oct 2017

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Thanks Joebog1 - that will give me somewhere to start looking - I also have a Smooth Arc Welder (read expensive) that I put aside years ago when it stopped working just out of warranty - so will get all fired up and look at that one too.

Thanks Yahoo2 - that is something I had not factored into the equation at all - although the tip find is definitely a poverty pack design (ozito) - and if there are some failsafe or load triggers that need to be disabled - it might be a replacement for the control cctry and my thoughts to make a simple and inexpensive 400V to 24V DC buck converter charger device could be more trouble than buying the real deal - still I am tempted to give it a go and learn something along the way!

Cheers and thanks - will update this as I find out a bit more

yahoo2

Guru

Joined: 05/04/2011
Location: Australia
Posts: 1166

Posted: 03:35pm 10 Oct 2017

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ozfossil said and my thoughts to make a simple and inexpensive 400V to 24V DC buck converter charger device could be more trouble than buying the real deal - still I am tempted to give it a go and learn something along the way!

Honestly, most of the recent offgrid solar systems I have designed have no charger installed, if the occasion arises where we do need to charge (hasn't happened yet,fingers crossed touch wood etc) I intend to only bulk charge, no fancy stuff, just get the voltage up above 80% state of charge level and throw a contactor. it is just a case of dialing the welder output up till you are comfortable with the load on the generator.
if you need to get to 60 volts then it is possible to series connect two power supplies, if you need to equalise or balance a battery bank that can be done with cheap low amp chargers after the bulk charge is finished.

It might be a different story if I lived in the tropics, but I dont.

I'm confused, no wait... maybe I'm not...

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