upgrading my big three

Hi all!

I have read almost all the posts on the12volt regarding upgrading the big three, especially the sticky by DYohn, but figured I would ask this kinda newbie question anyway...

I am planning on ordering all my wires, fuses, etc for my install sometime over the next day or two, and I am planning on upgrading the big three before I start the rest of the install. I am planning on using DYohn's page as the recipe, including adding to the existing OEM wires. But I am curious as to what wire guage I should try to buy. I assume the biggest wire I can afford for the big three is the best way to go about it, correct? But, I have been having trouble finding 2 guage for sale anywhere around me, even online. I have found 3 guage. Or, should I just go for the zero guage?

This will be in a 2004 Jeep Grand Cherokee, with the stock 132 amp (I believe) Alternator. Unfortunately upgrading to a HO Alternator is way out of my budget right now - as this past Thursday I found some slight water seepage in my basement. Don't be too jealous of that!

I will be running an Alpine PDX-5 for my entire system and from what I can figure, an 80 amp fuse on the power cable.

Or, is it a better idea to just replace the OEM wires? I tend to over-think things, so pardon my babbling, please!

Thanks so much in advance!

Jeff

Overthinking? Yes - but that's better than underthinking. Besides, like me, you should grow out of it when the time is right (if ever!).

IMO - the more the merrier. Whilst the minimum grounding (Big 3) must handle maximum demand, above that it serves to reduce resistance hence reduce voltage drops etc.
Plus I like redundancy or backup - ie, 2 at least minimal cables so that if one breaks, you have the other. (The downside here being that that may be useless unless the break is noted before the next break...)

As to replacing OEM - not if still covered by warranty etc, or if it can impact insurance.
Hence why I like the extra cabling in addition to the existing stuff - and preferably using independent attachment points (further redundancy and less warranty/insurance hassles).

IMO the beauty of engine & gearbox (ie, alternator) to chassis/body grounding is that it can be done in several places. (Unless ground loops become a problem, but generally if anything the opposite should occur.)


Just note that redundancy means "complete" handling for each redundant path. It is not for example 2x30A cables for a 60A job - that is not redundancy but is instead DOUBLE the failure rate (with a a bonus hazard thrown in!).
[ LOL! I recall a 600kVA UPS project where the consultant recommended two 300kVA UPS for extra reliability. I immediately binned the recommendation & design. Yep - Australia! ]

I am very familiar with the Grand Cherokees, owned one and there's two more in the family. I'm also familiar with the PDX-5, installed it in my GC and it ran great.

For any reasonable install like yours, the "big three" cables are so short that using anything larger than about 4 gauge is unnecessary, more expensive, and harder to work with.    Afterall, you will be running 4 gauge to the amplifier. So using 0ga in the engine compartment does nothing special for you. You can run the PDX-5 without any trouble whatsoever even on factory wiring (ask me how I know).   If you want to upgrade the big three, and it's not a bad idea, use 4ga and some quality hardware for connections and at ground points.

Also, do you really need to upgrade the alternator? You will be fusing the amplifier at 80 ampres, so the factory alternator will be perfectly adequate.

-J

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Malcom: "This is the captain. We have a...little problem with our engine sequence, so we may experience some slight turbulence and then...explode."
Jayne: "We're gonna explode? I don't wanna explode.

Oldspark and Teenkertoy,

Thanks for the replies...Sorry for the delay in getting back to you. Had some foundation guys coming out for estimates. And, the overthinking thing - being in my profession, that's the best thing we can do!

I will definitely be adding cables to the OEM. After the replies, and thining some more, it just makes more sense. The only thing I will do is redo the factory grounding points if need be.

The only reason I was thinking 0 gauge is because I am having some dimming lights - even with the factory stereo! I think my alternator may be heading towards the "light" even though the voltage seems to be fine, staying at 14 volts consistently.

I actually called the guys at HO Alternators after I posted this initially to see what they had to say. The guy told me not to even bother getting a HO alternator as it would help, but be be overkill. He said the stock 132 amp should have no issues with my type of current demand. Very honest and I appreciated that, so anyone that may be in the market for an HO alt., I would definitely recommend them!

So, thats where I sit. I have ordered the wiring and all components needed for my full install, so, now it's just a waiting game until my box and door pods are complete!

Thanks again guys!

Jeff

Good of HO Alternators to know their stuff and provide good advice. I do hope others take note.

Dimming can be a reaction issue (alternator & battery delay) but is increased with poorer wiring. IE - avoid shared paths (typically the +12V side) and fatten all paths - especially shared (eg, ground).
But it can also be inrush currents - especially for halogen lamps etc.

And never assume metal to metal is an electrical contact.
Hence your proposal to redo the factory grounding points is good - even if merely a loosen & retighten - preferably with a "clean all surfaces in between".
(My Alpine display blew due to a poor earth at a very tight thumb-sized diameter bolt - the voltage drop could exceed 2V! I had to dismantle and clean both cable eyelets. Now if I had have had a redundant ground somewhere else...)

And thanks for your thanks...

Is there any way that you can get this on video?
This would really help me out a lot.

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chargers#1

sorry, but kinda new to these things... what's the pros and cons on the big 3?

Not doing big3 - severe electrical damage due to fused (open) grounds. Before that, poor performance due to brown-out situation.
Fire hazard.

Doing big3 - superior performance (better lighting etc).

Also burning up the alternator, from the demands put on the charging system. I burned up 3 of them back in the day, then I got a much larger alternator from a donor car. Never had that issue again.

Don't confuse the poor guy - that's not a Big3 issue. (Except if an older external regulator alternator with a ground fault.)

Bad wiring means LESS demand on an alternator since the wiring etc is a higher resistance (less current).