Wire #6 continues up the fender well as a single wire, and is routed to its destination at the passenger side fender, where it is secured with a bolt to create the second of the "Big 3" connections, the "Engine Block (Alternator) Ground > Chassis Ground" connection. This provides a second ground path between the Alternator/Engine Block grounds and the vehicle's chassis, WITHOUT forcing the ground current to travel through the TINY stock Wire #5.
I then hooked up two of the Big 3 wires at the alternator side. The NEW Engine to Chassis ground (Wire #6) can be connected anywhere on the engine block to anywhere on the vehicle's chassis. Since the alternator case is the ultimate grounding point of the entire electrical system, I decided to hook up right to the alternator mounting bracket where I would be electrically closest to the alternator case. You can see the connection to the alternator mounting bracket at left (Wire #6, also notice the bent terminal, which I had to do to keep the wiring out of the path of the alternator drive belt),
The second connection was at the (+) Charging Post on the alternator. You can see the connection to the alternator charging post at center (Wire #8). The wires have been labeled according to the initial diagram at the top of the write-up.
Also, you can observe in the picture how the Alternator charging post now has TWO wires connected two it - Wire #8 AND Wire #3, as labeled in the photo.
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Topside, near the battery, things look like so:
Wire #8 continues up the fender well, where it feeds into a 120A circuit breaker. On the other side of the circuit breaker, Wire #8 continues on to connect to the (+) battery terminal. This completes the first of the "Big 3" connections, the "Alternator Positive to Battery Positive" connection. This provides an alternate path for the Alternator to send a charging current to the battery. The new path is again, made of 4ga. wiring, which has a current capacity of 150A. I chose to put a circuit breaker on this path for the same reason I choose to fuse all of my power connections for aftermarket electronics.... safety and fire prevention.
Wire #6 continues up the fenderwell as a single wire, and is routed to it's destination at the driver side fender, where it is secured with a bolt to create the second of the "Big 3" connections, the "Engine Block (Alternator) Ground > Chassis Ground" connection. This provides a second ground path between the Alternator/Engine Block grounds and the vehicle's chassis, WITHOUT forcing the ground current to travel through the TINY stock Wire #5.
Wire #4 is left intact, providing a redundant Engine Block > Chassis ground by flowing ground current from the engine block to the battery (-) terminal, across the terminal, and to ground via the new Wire #7.
Wire #7 REPLACES Wire #5, creating the third of the "Big 3" connections, the "Battery Negative > Chassis Ground" connection. By replacing the wimpy stock Wire #5 with a much larger and higher capacity Wire #7, we have strengthened the stock ground path from Engine Block > Chassis ground across Wire #4, AND created a much stronger ground path for all of the chassis wiring (ECU's, lighting, windows, radio, etc, etc) back to the battery.
Last but not least, I removed the paint from the metal at the two fender ground points for Wire #7 and Wire #6, to ensure that they would have a clean and solid connection to the chassis. I ended up using the stock ground location, and another unused bolt hole located about 2 inches rearward.
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I used crimp ends and put sauder in it for an extra strong connection.
I used 4 G Copper (in some cases CCA). I don't see the need for 2 or 1 gauge that's overkill. But 8 gauge would be too little.
If you are doing a dual battery setup then you may want to read some other threads. I don't know how the big three will affect your plans. Personally I don't think a dual battery is necessary. Its complicstedt and expensive.
Why not just run a single battery setup and add a dual battery only for trips.
3. Also why crimp the lugs if you are soldering really no need
Unless you are using a clamp of some kind then yes you need to crimp. The crimp makes the attachment of wire to metal end connector MUCH stronger.
Solder is not very strong and not a weld. It is not meant to hold things together.
Also, my end connectors had a smooth internal surface and that also makes the solder not hold very well. I'm surprised you don't realize this. Perhaps there is something I don't know about your plan.
The crimp is to hold the wire to connector so you can pull on it with 50+ lbs of force (say a loose battery) and the cable won't come apart from the connector.
I've actually had a loose battery before and the cables were strong enough to hold it in place because of their end connectors. If the cable end connectors had come apart (because for example you didn't crimp them) they might cause an electrical fire.
Maybe you are using different connectors but if you are using the ones in my pictures above then be smart and crimp them.
1. I know its called the big 3, but what gauge is the wire between the alternator and battery stock? I think for my case I will forgo adding and unnecessary circuit since I don't have a ho alt.... yet....
2. Why wouldn't we just replace wire #4 & #5 with some 2 awg and call it good and not clutter the engine bay any further. ( in my case i guess..)
3. Also why crimp the lugs if you are soldering really no need...
I would answer your questions, but from what I can tell, all three of them are rhetorical. Also, judging by your exchange with Brian you seem to believe that you have all the right answers.
That being said, good luck, and take my write-up for what it is... an account of my experience/methods/opinions and nothing more.
I'd also like to add to my earlier comments that I don't necessary think it is wrong to not crimp it, you're not wrong per say.
Its just that there is good logic behind crimping it and its important that whomever reads this it told that.
I tried to replicate putting cut up pieces of rosin solder in the metal battery lug in a C-clamp and putting a torch on it as BFAD did. The solder melts into hardness with the mini-torch instantly, so when you put the cable in, you are just pushing against hardened solder. You can't crimp anything at that point.