I know this has been asked before, but what gauge wiring is recommended for a late-1970s truck with a 100A alternator? When people start talking Big 3, they seem to go overboard and say 2/0 is required even for old vehicles. My starter cable is toast, and I'd like to replace the battery and alternator cables at the same time. From the charts I've seen, even 4 gauge would be plenty to handle short runs (<5 feet) of up to 200A current. The stock wires were 4 gauge. I'm thinking a 2 gauge upgrade would be smart and give some room for added electronics (e.g., modest stereo system, replacement AC with electronic controls). What do you think? Is 2 gauge plenty?


Starter cable: 45 years old and too close to headers. Bad combo!

 

2 gauge is plenty. The wire is open to air circulation, and like you said, the run is very short. Bigger is better, but I have found very large wire is not very handy to hook up and route.

 

^^^what he said^^^

 

Thanks, Dave! I ordered all the stuff last night.

 

Thank you!

 

I upgraded the major cables to 2 gauge. I also ran a secondary, 4 gauge, fused line from the alternator to the starter solenoid. It's surprising how small the stock feed wire is - looks like 10 gauge, maybe 8. It's only a 2-foot segment and a 55 amp alternator, but I would have expected a little beefier line.

 

The factory pushes it to the limit. The design it just large enough to do the job with the stock vehicle. Copper is expensive, and if you can save a dollar on each vehicle, and make 100.000 vehicles that year, you have saved 100,000 dollars. Since you are putting a larger electrical load on the system, you are doing the right thing by upsizing the wire.