Turn My Transformer Spot Welder to DC using Kweld?

[rg12]

I have a pneumatic machine that I don't like it's consistency and how it's affected by different grids and sockets.
I want to have the Kweld connected to my pneumatic head and be powered from a big LA battery.
The question is, how do I take the output to the transformer or the signal to send power to the transformer and use it as a signal to fire the Kweld?
In my welder when I press the pedal it doesn't instantly power the electrodes but first makes the head drop and then fire.

 

[john61ct]

Lead will need to be truly massive to output the current you can pull from a little LI pack.

 

[serious_sam]

In my welder when I press the pedal it doesn't instantly power the electrodes but first makes the head drop and then fire.

Either there is a proximity sensor/switch that triggers the weld function when the head is lowered, or it is a timer with a set delay from the initial pedal action. Most likely a timer though.

I would buy a cheap timer circuit off ebay. Trigger it from the same signal running through the pedal. Use the output of that timer (probably a relay) to trigger the kweld. Discard/disconnect all the original controls, except what triggers/actuates the pneumatics.

A couple of decent sized car batteries will be enough power, and if you keep them on float charge, won't go flat. I use a single 750CCA vw golf battery on my diy welder. Works fine, but a second battery would probably be better.

 

[nieles]

afaik the kweld has an 'automatic' mode. it senses for a connection between the weld probes and fires a pulse when contact is made.

 

[rg12]

afaik the kweld has an 'automatic' mode. it senses for a connection between the weld probes and fires a pulse when contact is made.

Perfect!
I guess this is how my current welder knows when to fire.
Wait, I know that those welders (probably Kweld amongst them too) fires on contact with a certain delay.
Can that delay be turned to zero? what is the range there?
EDIT: Can the kweld withstand an hour of intense welding? (let's say 3 welds per cell side for 300 cells?)
I see they sell this:
https://www.keenlab.de/index.php/product/kweld-ultracapacitor-module/
Will it make the Kweld better or worse for fast welding?
I see the cap bank is rated for about 2 seconds between welds which is very slow (at 50j which I have no idea how strong it is).
Also, if I use a car battery, what is a good size for it? Can I get away with 50Ah? and can it be charged while in use or will it blow my charger?

 

[jonyjoe303]

You just need a good battery that has a good CCA rating, myself I use a 8 year old 27ah fullriver fullthrottle agm battery to power my 12 volt malectrics, it works excellent. I tried using a 4s8p lifepo4 (A123 cells) and also a 3s6p li-ion(using sony vct3 cells) and all I got was weak welds. The fullriver never fails, I also use it to jump start a V8 carburetor engine using fullsize 10 foot jumper cables. I prefer using the agm because I weld inside and don't want any acid leaking etc.

As far as charging it, you can do hundreds of welds without draining the battery too much, after using the welder I rarely have to put more then 3 ah back into the battery. No need to keep the charger plugged in while in use.

 

[rg12]

You just need a good battery that has a good CCA rating, myself I use a 8 year old 27ah fullriver fullthrottle agm battery to power my 12 volt malectrics, it works excellent. I tried using a 4s8p lifepo4 (A123 cells) and also a 3s6p li-ion(using sony vct3 cells) and all I got was weak welds. The fullriver never fails, I also use it to jump start a V8 carburetor engine using fullsize 10 foot jumper cables. I prefer using the agm because I weld inside and don't want any acid leaking etc.

As far as charging it, you can do hundreds of welds without draining the battery too much, after using the welder I rarely have to put more then 3 ah back into the battery. No need to keep the charger plugged in while in use.

fullriver.jpg

Thanks alot!