I had to replace the Optima yellow top in my car; 6 yrs old and seems to have an open cell.
I thought it was prime for some welding experiments. I opened some of the top with a carbide burr, and soldered a copper tab to the center lead connector to make a center tap at 6V. Then cut a slit in the lid I removed for the copper tab and duct taped the lid back on. One 6V side had the bad cell (open under the slightest load but looks fine on volt meter) , as expected, but the other side is in great shape still.
Welding on 30V was an entirely different experience; long arcing is easy, but it's TOO HOT, easy to over penetrate, more spatter/spray. I need to see how it goes on 1/8" rods on 1/4 steel, and practice more with 7018 now that I can long arc and move the electrode around. I did try some 6011 and at 30V it's too hot for 3/32 6011; it eats up the rod fast and I can hardly keep up lest I burn through. On 24V 6011 just won't stay lit. I can see now why arc welders have adjustable current regulation...dialing it in for any rod and material sure would make things easier.
I may open up the Optima again and solder copper tabs at 2V and 4V (26V and 28V total) to give them a whirl.
Here's a thought for you, Bruce
This is something often done when you are welding and find that you have set the welder 5 amps too high but you're in the middle of something a bit critical, or just don't want to stop
It also used to be common when setting the amps wasn't as easy as just turning a dial
And it's a common technique in positional welding . . .
You can really only get away with it with Low Hydrogen rods as they won't leave you with slag inclusions
Now, as you're working, there's a point at which you have gotten 100% of the penetration you can with your weld, and the whole puddle is just about to turn too liquid and fall through - leaving a big hole. Just before this point, you normally keep moving forward with your weld/puddle, and that's how you know you have gotten a good penetration etc (I'm over-simplifying here, but you get it . . . )
If the welder is turned a bit low, you can sort of sit there moving the puddle from side to side and making slow forward progress and a so-so weld - within reason
But if it's too hot, your options are limited. What sort of happens is that, to avoid making a too-hot, too-liquid puddle and having it all just fall away, you tend to move forward faster than you might like - so that the new, cold metal is taking the heat away from the puddle constantly. You tend to end up with a thin, scrappy weld
But what you can do - if you have Low Hydrogen rods - is move ahead a bit to where new, cold metal pulls some of the heat out of your puddle - and then move back . . .
It only takes a small fraction of a second for your weld puddle to cool from liquid to plastic (sort of) . . .
So if you start your weld and work along, watching as it gets "too" hot - then quickly move the electrode forward, sliding along the metal so you don't lose that arc, about maybe a half an inch - then come back to your puddle which has cooled in the fraction of a second your arc was away from it, and is now just a perfect temperature to carry on welding for another second or so - then move forward quickly another half inch - then back to your weld . . . and so on . . .
What's happening is that you're depositing little bits of weld on the metal "ahead" of your weld and then coming along a second or so later and welding over them. If the whole thing is nice and hot and you keep your arc short and you're using Low Hydrogen rods - it's a controllable process and weld quality can still be very good
It's a technique often used on "vertical up" welding, where, because the "work" is vertical not horizontal, the tendency for the weld puddle to "fall down" is much exaggerated. When the puddle gets too hot - you just move away from it for a quarter or a third of a second or some such and then come back to it as it cools . . .
If you have a google, somewhere there will be temperature charts for the process of arc welding and, because your hot weld is surrounded by cold metal, that cooling from "too hot" to "just right" happens very very fast once the heat source (the arc) is removed
Once you get your head around the physics of what's happening (and you'll understand that better than I do) you can see that moving ahead a little or a lot is an easy way to do a good weld with an arc that's "too hot" and is quite a controllable process
If you watch a video of a pipeline welder "keyholing" a root run - basically blowing right through and then filling back in in one action , so as to be assured of 100% penetration, that's sort of the same process
Have a "play", you'll see
Cheers
As your weld puddle forms a