Offroad Trailblazers and Envoys

Big 3 Upgrade + 250AMP HO Alternator

Breaker 1-9, anybody got a copy? Any discussion or mods relating to electrons and wires go here.

by mikekey » Sat Feb 01, 2014 8:54 pm

BACKGROUND:

I know alot of us members have quite a few electrical components running off factory wiring and our factory alternator. Hid's, Amps, Winches, Aftermarket HU's, Off Road Lights, Power inverters, Refrigerators, CB's, Ham Radios, Laptops, etc. Our vehicle’s stock electrical systems were designed for such---stock electrical. When you start adding things like audio equipment (amplifiers), aftermarket lights, etc, you are increasing the demand put on your electrical system.

Most of the time stock wiring is right around 8 awg (give or take). It’s simply not designed for the extra current draw required by aftermarket items. Let’s use a garden hose as an analogy to electrical wiring. If you have a long, thin garden hose, the flow of water through it will be much less than a short, thick hose. Compare a 100-ft, 5/8” diameter garden hose to a 1-ft long, 6” diameter section of water supply PVC pipe. The flow will be much greater through the shorter, thicker section (less pressure). The same goes for electrical systems. The larger and shorter your wiring, the less resistance to the flow of current.

Even if you do not have any issues with voltage drops, dimming headlights, or anything like that, the Big 3 is still highly recommended. Stock electrical systems can benefit from the Big 3. It’s probably the cheapest upgrade one can do for their electrical system. While it’s generally recommended to use 4 awg or larger wiring for upgrading the Big 3, I highly recommend using 1/0 from the start. It’s the best option and only costs slightly more. Better to do it right the first time around.

Also note; no conductor is 100% efficient, but larger AWG wire helps to overcome resistance and transfer greater amounts of amperes throughout the system with smaller losses in energy. This is why people generally do the "big 3". It's pretty common for audio guys with massive 1000 watt stereo systems do this sort of thing.

One more thing; I know this is a readily talked about topic, but your alternators primary purpose is not to charge your battery. It is made specifically to run all your electrical components such that your battery doesn't need to. Sure, your alternator charges the battery when current is available, but that is not its primary purpose. This is why when your alt. dies, your battery can only run the entire system for a very short time (its not a deep cell). The batteries main purpose is to help regulate spikes in voltage coming from the alt, and to crank the truck. And only when your alt. can't supply the system does your battery get used.

The factory Alternator is a 150 amp unit that is connected to the battery with a 6 gauge wire. I decided to replace mine with a 250 amp alternator and run 1/0 awg gauge wire to the battery.

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Note: This information is all over the web. If you’ve done research on it then you will recall most of the things I mention here. This isn’t something that I invented--it’s what I have learned by researching. I haven't really written this up in a how to format, it's more of a "what I did"


WHAT IS THE "BIG 3" UPGRADE?

When someone refers to the Big 3 they are referring to upgrading the three main electrical wires in the vehicle’s system:
1. Battery (+) to alternator power wire
2. Battery (-) to ground (frame)
3. Engine block to ground (frame)

On our GMT360 there actually third ground which I ended up also upgrading, which is Battery (-) to the fender.


DOING THE "BIG 3" UPGRADE

Note: The following is the method I used and the materials I used. If you have a different tool or method feel free to use it---as long as it gets the job done safely.

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I highly recommend welding cable for this "how to"! It is super flexible and you do not need any plastic covers. It is highly durable and over 99% copper. Please be aware any wire containing ALUMINUM is not a good choice. Although the aluminum clad wire is cheaper, it does not conduct nearly as good as copper. So choose your materials appropriately.

**I used 8ft of flexible 1/0 gauge high-strand wire and 8ft of 4 gauge high-strand wire. Now, I use this much becuase I bought blue and red wire. If you wanted, you could just get one color and you'd only actually need 5ft of each.

First thing I did was remove the factory wiring and determine what I was going to replace by examining the way the factory wiring is connected.

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I decided against currently replacing the wire to the starter, just because I didn't have a terminal appropriate for it.

Some might wonder about this decision, but I decided to run 1/0 gauge wire from the alternator to the positive side of the battery and 1/0 gauge wire for the negative side of the battery as the main ground to frame.

For my battery terminals on the 1/0 gauge wire I used copper connectors rather than ring terminals.

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Which btw, if you do not have a crimper a big hammer and a chisel work just as well. If you want extra peace of mind, I cut up solder and insert it into the bottom, then place the wire in, and hit it with the acetylene torch, this solders the connection. then I crimp it and heat shrink it.

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After crimping all my wires, I made sure to hook my main positive lead to the back of my alternator and installed the alternator.

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After getting the alternator installed I ran all the ground wires to the factory locations. I made sure to clean and prep the surface with a wire brush and sandpaper for good ground contact. First up was the Battery Neg (-) to the frame, which is 1/0 gauge wire.

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From the frame ground I ran 4 gauge wire to the engine block ground.
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After that I connected the negative cables to the battery and proceeded to connect the positive to the battery. It's hard to see, but I also replace the battery positive wire to the main fuse block with 4 gauge wire.
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That's about it.

This is really just to give you an idea and isn't necessarily meant to be a guide. :thumleft:

Aside: BTW, if you want my opinion, a nice AGM style battery goes along with this setup well. I just recently replaced my old one with this K-Mart unit:

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by mikekey » Sat Feb 01, 2014 9:05 pm

First post reserved.

I am not an electrical engineer, so don't take my information as such.
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by Aries » Sat Feb 01, 2014 11:41 pm

Great post :thumleft: a 250 amp alternator his on my list for this spring when I do my roof lights.
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by DirtyBacon04 » Sat Feb 01, 2014 11:51 pm

Cool! You buy parts, i buy beer. I come over, we do this to my truck (i'll reimburse for parts)

Deal.
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by mikekey » Sun Feb 02, 2014 12:13 am

As soon as mine is on the road and garage is free!
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by TBYODA » Mon Feb 03, 2014 11:15 am

Should this not be under electrical?
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by Moots1288 » Mon Feb 03, 2014 11:47 am

It seems that iys everyone's job to suggest where threads should be.
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by Diacom » Mon Feb 03, 2014 11:20 pm

We're just trying to make sure it's easy to find relevant information.

That being said however, this one could be in either category. It is a completed upgrade, but it is also something people would look for in electrical.

So as usual, it will be up to the mods to decide the final resting place for this topic.
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by DustinC1989 » Mon Feb 03, 2014 11:32 pm

If people use the search button correctly, it will lead them here no matter what section it is in.
And from what I've seen, they either use it correctly or expect all info spoon fed to them and refuse to search
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by Trail X » Tue Feb 04, 2014 11:04 am

Moved. Thanks for writing this up Mike! I've got some 2 gauge wire just waiting for this upgrade.
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by mikekey » Tue Feb 04, 2014 11:50 am

If you know how to crimp wire, it's a fairly simple to do task. If you want to get über fancy you can throw a 200 or 250 amp inline fuse between the alternator and battery. :thumleft:

I'll probably add more to this when I get to the second half and add the dual battery and inverter. But I'm still reading and planning that part out. And have an axle swap to get to first. :drive:
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by redmaro42 » Fri Dec 19, 2014 12:11 pm

any way to get the pictures uploaded and working again? Looking to do this to my envoy soon
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by Trail X » Fri Dec 19, 2014 3:04 pm

Looks like Mike is re-imagining his website. I'd PM him directly.
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by mikekey » Sun Dec 21, 2014 10:47 am

BOOM, yeah I moved servers recently. One semi-colon out of place and my subdomain DNS doesn't work. Thanks for letting me know, because I've been doing even more how-to's on other sites and I host everything off that old file path.
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by MKETrailblazer » Wed Dec 23, 2015 1:30 am

It's a shame the pictures don't show up but I like the thread definitely on the to do list!
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by Rickalicka18 » Wed Dec 23, 2015 9:14 am

Awesome write up! I've wanted to do this so bad, but getting to our alternators isn't exactly easy. Crutchfield sells these. And Is pretty much a must for someone like me pulling more than 1,000 watts of power I opted for an agm secondary battery (that I bought from crutchfield for $150 and haven't had a flicker problem with since) to run my system though If anyone is looking for a where to buy the kit, I highly suggest crutchfield heres the link: http://www.crutchfield.com/p_122BIG3XP/ ... l?tp=36390
Greatest thing about this kit is the connectors are already crimped on. And $50 is a steal in my opinion for what you get out of it. The only part would be to buy a 250 amp alternator.

Trail X, I think the whole point of the big three upgrade is maximum current pull from a 1/0 guage wire, wouldn't the 2/0 guage defeat that purpose? ;) not trying to be a smart ass or anything but If I were to do this I'd want maximum pull for all my audio equipment. Go big or go home right?
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