Make sure to use resin core solder. My neighbor used acid core solder that is used for copper plumbing and other metals and ended up with lots of corrosion for his motorcycle battery. Don't be like my neighbor.
I have been restoring antique radios from the 1920's and the soldered connections are still fine. For our cars make sure the wires are twisted together or crimped in a barrel connector (copper is best) and soldered and protected with shrink wrap.
The factory had professional crimp tools and soldering everything on the line would take too much time.
