I expect the honest answer.
I cut jumper cables down so that they can connected to battery terminals and deliver the necessary amperage. I have a super capacitor bank (got it pre tarrifs)
Honestly?
I'm willing to help you out if you want.
It's not good. I would dare say it's possibly even a hazard as it is.
The key to soldering is to heat both of the parts that you want joined, then apply solder to that.
Baeically, you mostly don't melt the solder with your soldering iron, the heated joint melts the soldering.
What you got here looks like a cold solder, which is basically melted solder applied to cold metal.
It makes a weak connection that will fail or even come apart.
Start by making a good solid mechanically strong splice that maximizes contact area.
Starting from 2 clean stripped wires, join them together in sort of a X shape.
At the same time, twist each wire clockwise around the other.
(Like cross both wires in a x shape, holding each half between your index and thumbs, twist in opposite directions, one thumb away, one thumb towards you.
Twist as tight as you can. Bigger gauge stuff like what I think you're working with might need pliers.
Once that's done it's already a strong connection even before solder. )
Then to solder, heat the whole splice.
Say you're heating the top of the splice with your iron, apply solder from the bottom.
It's the heat from the wires that should melt the solder not your iron.
I don't know how to explain better, maybe pictures or videos.
Don't give up.
