Best way to replace a Super Nintendo Game-Save cartridge battery?

[KungKras]

I've seen videos about soldering batteries onto SNES games.
If you have good precision, you should be OK, it doesn't seem too complicated.

I tried soldering once, in elementary school. It's really not that difficult. But you should practive on some crap cartridge before trying to solder.
Buy a few old crap games to practice on first.