Start/Charge cable upgrade?

[JoshT]

This wiring is from a 2000 Explorer 5.0L and going into my 1999 Ranger as part of the engine swap. Need/want to rebuild the battery harness. I have two harnesses, one looks like this on the starter end. The other doesn't look much better on the battery end of the ground cable, I could probably do a repair splice on it, but I'd rather avoid that.


View attachment 450167

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, e-fan, and lighting upgrades in the future. Also think the starter could benefit from a cable upgrade, I know the 7.3L diesel does and browsing would suggest that most starters would. Might still repair what I have, but seriously weighing the option for upgrade.

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 Alternator (6 AWG)
• Starter 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.

What size is the question.

I don't think I need to go all the way up to the Ø sizes 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.

 

[franklin2]

If you are planning future upgrades including the alternator, your stock mega fuse is not going to handle the increase. I think I would keep the stock mega fuse and the stock size wiring, and for the later upgrades, just add another mega fuse and parallel wiring to feed the larger alternator and your other added fuse box or distribution system. So this would mean having a battery terminal that would accept more than one large wire.