just a couple of pics of my[ state of the art ]battery cable soldering machine mk1
the first pic is the pot i use a torch to heat it up until the solder is melted.
the second pic is showing the solid solder rod i melt to keep the pot full
the third pic is of my crude but effective blue point crimp tool
fourth pic crimp tool different angle
fith pic is cleaning flux ,you need to dip the crimped terminal in the acid before you dip it in the pot and watch the splatter,it burns.
once its cooled heat shrink it and your done ,will last longer than most boats .
you can see how you can solder the closed end lugs now by dipping ,works great
ps ,use tinned battery cable,it is available.