What Circuits For Relay?

I would lower that "current figure" a lot on these old girls if you are powering something off the key switch.

EXAMPLE.........it is well known that voltage drop in the "ignition run" circuit causes overcharging, because this drop lowers the voltage to the VR, and make it "think" the battery needs more. So in a FACTORY STOCK car running only factor loads in the engine bay, the "run" circuit in some cars (mine was one) can see a drop of 1 1/2V more or less. Guess what? You need a relay. That entire circuit is likely only about a 5A load.

Headlights. Factory stock headlights are somewhere around 60W. At 12V-14V that's somewhere around 5A ea, or 10A for two. It is also well known that factory headlight wiring is undersized. RELAYS One for high, one for low.