depending on the length of cable you have to run 1 gauge should be good. If you are running the length of a car using a 0 or a 00. The best thing you can do is buy some cable figure out the length you need and go to a welding shop or Electrical supply house and have them attach the crimp on lugs on to the wire with a Hydralic crimping tool. I know guys like to solder the ends on but crimping the lugs on with a 15 ton Hypress is far superior to soldering.