"Big 3"ish electrical upgrade? | Ford Explorer Forums - Serious Explorations

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"Big 3"ish electrical upgrade?


Well-Known Member
January 15, 2011
Reaction score
City, State
Middle Georgia
Year, Model & Trim Level
1999 Ranger
In process on my V8 swap into the Ranger. Need/want to rebuild the battery harness. I have two harness, one looks like this on the starter end. The other doesn't look much better on the battery end of the ground, I could probably do a repair splice on it, but I'd rather avoid that.


I could take the two apart and build one cable, but if I'm doing all that work I'd like to upsize the starter, alternator, and ground cables. At this time factory sizing is adequate, but I would like to plan ahead for a larger alternator, audio and lighting upgrades in the future. Also think the starter could benefit from a cable upgrade, I know my 7.3 will and browsing would suggest that most starters would.

It looks like I have 4 main wires to contend with and what I'm guessing the gauges are:

  • Block to B- (4 AWG)
  • B+ to Mega fuse (6 AWG)
  • Mega fuse to Starter (6 AWG)
  • Alternator to B+ (4 AWG)
There's also a ground between battery and chassis (10 AWG) and a ground strap between block and firewall (??? AWG equivalent), but those seem to be adequate for now and fairly easy to upgrade later. Cable for the starter solenoid needs to be addressed too, but I don't think there's any reason to upgrade that one, just repair/replace.

What size is the question.

I don;t think I need to go all the way up to the 1/0 guage that seems popular for "Big 3" wiring upgrades. I would like to step up a size or two for each, but I'm not even sure on the stock sizing.

Maybe 2 AWG for the block ground and starter, and 4 AWG for the Alternator?

Can you verify the stock wire sizes or have recommendation on what to upgrade to for each?

I can say that I plan to go with OFC welding cable for ampacity and flexability. I think that stuff is supposed to have really good insulation as well. I'll be rounting along the same path as stock, but probably separated from the AC compressor harness for future serviceability. Looking at the repairs needed, I don't like the idea of having to remove/replace the whole harness to run new cables.