How to Upgrade the Big 3
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’ve learned by researching.
What exactly is the “Big 3”?
Update: The original pictures are no longer available. I've taken new pictures and edited them into Post 27. These pictures are not as in-depth as the original ones, but I've tried to edit them in such a way as to make them understandable and easy to follow. The pictures missing are mostly from the process of creating the cables, which should be pretty straightforward if you follow the text.
Thanks for understanding and sorry for any inconvenience. I hope these new pictures help.
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
3. Engine block to ground
Why should I do this upgrade?
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. Upgrading the Big 3 decreases the resistance in the electrical system. Less resistance means better flowing current which means lower or even non-existent voltage drops.
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.
How to upgrade the Big 3
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.
What you need
Originally Posted by the12volt.com
Note: Realize that the "absolute ground" of the electrical system is not the battery negative terminal or the vehicle chassis, but is the case of the alternator itself. This is why perhaps the most important cable among the Big 3 is the engine ground strap, as this is what connects the alternator ground to the vehicle's chassis. Be certain the resistance between the alternator case (the engine block assuming the alternator is properly bolted to the engine) and the battery negative is minimized.
• Approximately 10 feet of flexible
1/0 high-strand wire (measure your vehicle’s existing wiring with a string to be sure, and overestimate)
• Six (6) 1/0 ring terminals
• In-line ANL fuse holder
• ANL fuse rated between 200 and 300 amps (I used 250A)
• Wire brush to clean contact points
• Extended battery posts for ring terminals
• Wire cutters large enough for 1/0
• Knife or wire strippers large enough for 1/0
• Crimpers large enough for 1/0
• Propane torch or soldering gun
• Socket set for bolted connections
• Allen wrench set for connecting fuse
Gather/Order your materials
I bought my wire, ring terminals, and fuse from KnuKonceptz. They have highly flexible, high-strand count 1/0 at a great price. I highly recommend the flexible 1/0---it makes the process so much easier. All the other materials I had laying around or borrowed from work.
Let’s take a quick look at which wires we are upgrading
I tried to color coordinate these to make it easier to see.
• Red - Power wire upgrade
• Yellow - Battery to ground (frame) upgrade
• Green - Engine block to ground (frame) upgrade (new wire)
• Blue – Not necessary, but part of what some people call the Big 4. It’s essentially upgrading the frame to chassis ground (I did it through the battery negative). The only reason I did this is because I had extra wire left over and it sure as heck doesn’t hurt. (There’s also a frame to chassis connection underneath the truck behind the front passenger tire.)
As you can see the power wire and frame to chassis upgrades are straightforward. The engine block and battery negative to ground (frame) go down and out of sight. They come down as seen in the second picture and connect here inside the passenger wheel well (very convenient). You should take your wire and lay it out over the existing wire to mark exactly where to cut it, as seen in the third picture.
Preparing the wires
Gather everything you see here: wire, ring terminals, cable cutters, cable strippers/knife, crimpers, propane torch, and solder.
I used cable cutters rated at 2/0, but this stuff is so flexible it cut it like butter.
Mark the approximate location of where you’re going to strip the wire at. To cut it, you can use strippers if you want, but I found it much easier to use a carpenter’s knife (razor blade). Just run around the wire slicing down to the wire. It was much easier than I thought it would be.