Malectrics user here…
This could be a couple things
-
tips not sharp enough
-when my tips get rounded at the top, I notice the weld is more of a hotspot then a weld, and it might not stick as well as a sharper tip would be. Nickel still gets red with this, but the area is too wide to weld unless you crank it. -
bad battery
-I started off using a boat battery with 850 cca and 14ms, but after 10k welds, I needed around 40ms+ for similar welds. I’m now at 15k welds and need 60ms. Batteries wear down over time, especially if it’s a used battery (like my lawn mower battery I used at first… that thing was awful but worked) -
bad connections
-Tighten everything down hard. If it’s not full contact you don’t get full Amps. Every 2k welds or so I have to check all my bolts because they loosen and make me have to bump up the ms a bit.
If you can, get another 12v battery and voltage match them, then connect in parallel to see if it’s just a weak battery.