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.
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.
What exactly is the “Big 3”?
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.
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.
What you need
• 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.
Attach your ring terminal and crimp it down using either pliers or a vise. I had a vise available, so I used it. Crimp one side of the terminal first, then the other side. After crimping alone you should be able to give the ring terminal a slight tug and it won’t budge. (Don’t pull it off, though…)
After crimping gather your materials for soldering. You want to set the wire up so you don’t have to hold it while doing this (it gets HOT). I used the vise and lightly clamped the wire down (not so tight as to pinch it). You want to hold the torch so as it heats up the backside of the ring terminal. Then add your solder so it seeps down into the strands of wire inside the crimped section of the ring terminal. It should look something like the last picture when finished soldering. Rinse and repeat for the other wires.
The first thing you want to do whenever you work on your electrical system is disconnect the negative terminal. Here is where you want to add your post extenders if necessary (but don’t reconnect negative terminal). I picked up a cheap negative post to hold me over. I have another one on order at the moment, but I wanted to knock this out today.
The first one I added was the positive wire running from the (+) battery terminal to the alternator. I wanted to knock it out first since it required the most work (fusing). Go ahead and connect it to your positive terminal.
As you can see it’s a little longer than I wanted it (better to have leeway than to be too short). No problem, though, because we will be adding a fuse and can cut it to length.
So go ahead and cut the wire where you will be adding the fuse. Eyeball how much you want to strip off and use your knife to do so. Go ahead and do the other side after cutting the wire to your desired length. Then insert the fuse and connect it all together.
The second one I upgraded was the battery to chassis ground (again, Big 4, I did it with the leftover cable I had). Be sure to use your wire brush and scuff up the contact location. Do it enough to essentially remove all of the paint. You can see the chassis contact location in the background (slightly out of focus).
The third one was the battery to frame ground. The first thing I did was remove the mounting bolt in order to scuff up the mounting surface. I have sprayed rubberized undercoating on this section of my truck in the past so that definitely needed removed.
I went ahead and ran it down through the engine bay and bolted it up to keep it from moving. Since the negative battery terminal is disconnected I left the other end of the cable disconnected as well.
Here you can see the final upgrade, which is engine block to frame ground. There are many bolts you can use….just pick one and make sure the connection is clean. You can see this one in the lower left of the first picture. It was a tight fit to undo this bolt and connect the ring terminal, but I did that and then connected it to the frame ground location, as seen in the second pic.
Now reconnect your negative terminal and test everything. Here’s a final look at everything during testing (right before I finalized their locations and zip-tied them in place). You can see that I still used too much wire for some locations, but it’s better to have a little more than run short.
Before/after videos using Gryphon's voltage display
In both videos I did two things: rolled all four windows down at the same time and cranked the system up. In the first video it took me a minute to get the song playing (sorry) but I cranked it up about as loud as I'll ever listen to it. In the second video I cranked it way past what I would normally listen to and then dropped it back down to the loudest I'd ever listen to it. Sorry for the crappy sound but my D90 doesn't pick up bass well at all. Made it sound really choppy.
Note that in the first video, the voltage idles around 13.6. It drops to a minimum of 12.8 while rolling the windows down and back up. While fluctuating with the music it drops to a minimum of 12.8 as well.
Now in the second video note that the voltage idles around 14.1. It drops to a minimum of 13.5 while rolling the windows down and back up. While fluctuating with the music past my regular listening levels it drops to a minimum of 13.4. When I lower it back to regular listening levels it doesn't fluctuate at all except on the heaviest bass notes. All in all I consider that a success.
• Try to keep wires away from heat sources inside the engine
• Leave some slack in the new wires for the movements inside the engine bay
• Don’t bother disconnecting stock wiring if you don't want to—current takes the path of least resistance so it won’t hurt anything
• If you still have issues with voltage drops/dimming headlights/etc the next steps for you are to upgrade your battery and alternator (I'm saving up for this)
• This isn’t a difficult task to accomplish as long as you understand what you’re doing to your electrical system. After prep time (including gathering material, cutting wire, attaching ring terminals, etc) it should take an hour tops to install everything.
Hopefully this answers any questions you guys have about this. If not and you still have questions, please ask. Many of us here are willing to help you.
I will be putting wire loom on all the wires---I was just running short today and it's been a long week. I wanted to put this up while I had the spare time.
I used a 250A fuse because KnuKonceptz rates their flex cable at "over 300A". Some people say match the ratings, some say you don't need a fuse, etc, etc. First of all I used a fuse to be safe. Even though power flows both ways I don't want the wire to get overloaded. I chose a 250A fuse because in the case something happens I want the fuse to blow before the cable reaches its limits. Just staying safe.