I don't do this all the time, but with small projects, or when I need to consume way too many fuses I do this to lower cost of the project.
Step 1: Create a Weakest Link
Find the lowest power bearing wire, and strip off a short piece, short enough to pull threads out and long enough to solder in.
Step 2: Find Power Source
Add the previous piece to the positive end and use something rigid to hold in the higher voltage rating wire in place.
Step 3: Note
If you burnt something else instead... then either you failed to find the lowest wire, another wire got damaged and became weaker than this one, or some components were damaged or defective.
I made this tutorial strictly in the interest of lowering cost in a battery bank style project. I think it's so cool to have fuse on every cell like the tesla, but I don't want to buy so many fuse, so rate your wire, and pull some strings to make a weak link.（be sure to secure the positive wire to non conductive place, so if cheap fuse burn, other things don't short from wire falling.）