What is this wire

Fuse and inline holder/fuse block rated for just above ALT max amps or fusible link wire (3 sizes smaller than the correct wire gauge for circuit under continuous load and not in a bundle with other wiring. Link should be about six inches long, no more than 9, and not bundled with other wiring): McMaster-Carr

Direct solder or if your skills soldering are not excellent, reducing butt splice and heavy gauge heat shrink or good tape: McMaster-Carr

This traditional cotton tape holds better than common plastic tapes (also at hardware stores): McMaster-Carr