The Big 3 just turned into The Big 7

[octanejunkie]

I ordered the smaller 2 gauge

Can you measure each individual cables and post here?

Big favor, I know

 

[octanejunkie]

Gonna take the other route and say it's entirely unnecessary for 99% of rigs, let alone 99% of 4Runners. Big 3 is already pretty unnecessary with 1 or 1/0 AWG, you'll NEVER ever in 100 years see anything even close to warranting such heavy duty cable - not even if you were running triple winches all at once - and especially so considering these do, what? Upgrade your starter cables and fuse box wiring? Yeah $145 well spent alright, people definitely have loads of problems with those... :crazy:
And I say that as someone with a Big 3 made from 1/0 welding cable. The saying "just because it's sold doesn't mean you have to buy it" rings familiarly here to me.
To that, personally I think it speaks volumes when people try to sell these kits under the guise of "adding lights" down the road, because these people know very damn well how tiny of a load LEDs impart and how much of a non-issue that is. And if they don't... is that really someone you want to purchase and take advice from?

What about when upgrading to the CS144 alternator?

Wouldn't 1/0 AWG make sense between Alt and BAT+?

1 AWG to the starter, and 2 AWG everywhere else?

How about between battery and winch?

What if you were running an AGM battery?

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[Pyral]

Gonna take the other route and say it's entirely unnecessary for 99% of rigs, let alone 99% of 4Runners. Big 3 is already pretty unnecessary with 1 or 1/0 AWG, you'll NEVER ever in 100 years see anything even close to warranting such heavy duty cable - not even if you were running triple winches all at once - and especially so considering these do, what? Upgrade your starter cables and fuse box wiring? Yeah $145 well spent alright, people definitely have loads of problems with those... :crazy:
And I say that as someone with a Big 3 made from 1/0 welding cable. The saying "just because it's sold doesn't mean you have to buy it" rings familiarly here to me.
To that, personally I think it speaks volumes when people try to sell these kits under the guise of "adding lights" down the road, because these people know very damn well how tiny of a load LEDs impart and how much of a non-issue that is. And if they don't... is that really someone you want to purchase and take advice from?

Yeah, 2 GA is enough to run 7 induction cookers simultaneously. Even if you had a fridge, a winch, lights, a cooktop, and whatever else, it still wouldn't near the rating. Chances are you wont be running all those things at once anyway.

 

[octanejunkie]

Yeah, 2 GA is enough to run 7 induction cookers simultaneously. Even if you had a fridge, a winch, lights, a cooktop, and whatever else, it still wouldn't near the rating. Chances are you wont be running all those things at once anyway.

I've been poking around and found a few sources, American Wire Gauge Chart and AWG Electrical Current Load Limits table with ampacities, wire sizes, skin depth frequencies and wire breaking strength it seems 0 AWG can carry 150 amps maximally while 2 AWG only 94 amps...

If 2 AWG will suffice for most of the engine bay feeds why not run 0 AWG from alt to BAT+ if 2 AWG is rated at least than the output of the alternator?


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[JT1USA]

Wire gauge only needs to meet the demand of the amperage output by the alternator. So, 4 gauge is sufficient enough for a 150 amp alternator. If I remember correctly 1/0 is good for up to 250 amps. Also, the amperage output by the alternator is not the amperage output at engine idle speed, it is far less. So factor that in when choosing a bigger alternator for electrical demands. Most winching is done at idle speed. That CS144 probably has an output of 50-60 amps at idle.

 

[JT1USA]

For those of you who like to tinker and are looking for more consistent voltage but don't want to do the big three upgrade right away, or buy a bigger alternator, try this. If all of your main battery connection points are clean of corrosion try running a bigger main ground wire from the battery to the engine block first. With DC systems it is OK for your ground wire to be bigger than the power wire. As long as all the other wire sizes are sufficiently sized for the alternator output. It is "never ok" to run a power wire bigger than the ground wire.

Obviously do this at your own risk.

 

[Riceye]

Wire gauge only needs to meet the demand of the amperage output by the alternator. So, 4 gauge is sufficient enough for a 150 amp alternator. If I remember correctly 1/0 is good for up to 250 amps. Also, the amperage output by the alternator is not the amperage output at engine idle speed, it is far less. So factor that in when choosing a bigger alternator for electrical demands. Most winching is done at idle speed. That CS144 probably has an output of 50-60 amps at idle.

The other consideration is the length of the run for the cable. When consulting a chart for wire gauge decisions, find one that shows amp ratings that relate to cable length. For example, the cable from the starting battery to the starter of my '87 VW Westfalia is about seven or eight feet long. The same cable for my T4R is a quarter of that. My Westfalia needs a much larger gauge cable only to satisfy the length of the run.

Choosing the Correct Wire Size for a DC Circuit

 

[19963.4lsr5]

The other consideration is the length of the run for the cable. When consulting a chart for wire gauge decisions, find one that shows amp ratings that relate to cable length. For example, the cable from the starting battery to the starter of my '87 VW Westfalia is about seven or eight feet long. The same cable for my T4R is a quarter of that. My Westfalia needs a much larger gauge cable only to satisfy the length of the run.

Choosing the Correct Wire Size for a DC Circuit

Yes and it’s for DC circuits. Not for AC. It has more to with the watts going through the wire than the amps. 14vdc and 150a is a lot less watts than 120vac and 150a.


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[4Reak Show]

….It is "never ok" to run a power wire bigger than the ground wire. ..

Curious. Why? For any complete circuit, amp flow is the same anywhere in the circuit, start to finish, positive source to negative termination.

 

[brillo_76]

Curious. Why? For any complete circuit, amp flow is the same anywhere in the circuit, start to finish, positive source to negative termination.

The only thing I can think of on this one is Amp capacity of wires. Must be thinking the user will exceed the Amp rating if the smaller wire. Thus heat it up or melt it as a rule of them.

As you are correct it's all to do with Amp capacity of the circuit. You can run 12 gauge and only pull 1 Amp or less through it if you wish. As long as you don't carry more amps then the wire is rated for.

Also the current is always carried on the outer surface of the conductor on its surface area. As it cascades down the electrons on a wire.

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[octanejunkie]

Curious. Why? For any complete circuit, amp flow is the same anywhere in the circuit, start to finish, positive source to negative termination.

The entire vehicle, all the metal that's not specifically insulated, frame body and engine block are a ground plane and conduct negative current. You can't get a bigger conductor than that lol

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[19963.4lsr5]

An upgrade to a CS144 would require 1awg.


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[4Reak Show]

The entire vehicle, all the metal that's not specifically insulated, frame body and engine block are a ground plane and conduct negative current. You can't get a bigger conductor than that lol

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I’m curious why the person I quoted said it’s “never ok” for a bigger positive cable. Everything starts and ends at the battery (with alternator wired essentially in parallel) therefore all cables to/from battery carry the same overall amperage for the system as a whole. So I’m curious as to why a negative cable is allowed to be larger but the person I quoted said the positive is never ok.

I’m on board with these types of upgrades. I just find the overall misinformation astounding.

 

[octanejunkie]

I’m curious why the person I quoted said it’s “never ok” for a bigger positive cable. Everything starts and ends at the battery (with alternator wired essentially in parallel) therefore all cables to/from battery carry the same overall amperage for the system as a whole. So I’m curious as to why a negative cable is allowed to be larger but the person I quoted said the positive is never ok.

I’m on board with these types of upgrades. I just find the overall misinformation astounding.

Everything I have ever read suggests using the "correct" size wire for the load expected, sustained and burst. Bigger isn't always better, and too small is definitely not good.

Here's a curious chart I found specific to automotive wiring at "www.sherco-auto.com/battery-cable-starter-wire-10-awg-gauge.html"

For grins and giggles, I may use 1 AWG between my CS144 alternator and Bat+, and between the Battery and the winch, but again, that seems to be overkill when 2 AWG is rated to carry 150 amps up to 50 feet

 

[brillo_76]

Everything I have ever read suggests using the "correct" size wire for the load expected, sustained and burst. Bigger isn't always better, and too small is definitely not good.

Here's a curious chart I found specific to automotive wiring at "www.sherco-auto.com/battery-cable-starter-wire-10-awg-gauge.html"

For grins and giggles, I may use 1 AWG between my CS144 alternator and Bat+, and between the Battery and the winch, but again, that seems to be overkill when 2 AWG is rated to carry 150 amps up to 50 feet

Some truth to that. It really depends on the surface area and oxidation state of the wire. If the wire is black or green it's not going to conduct as if it was clean copper.


It's a good rule of thumb to gauge the wire to the circuit Amp load.

The main reasons for this is cost and diameter size of the wires.

I have seen oxidized wire burn itself right out of harness and melt it all together before.

Too small burns off and melts into other wires.

Another good rule of thumb is if you decide to go bigger wire you go one gauge larger amperage load..




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[octanejunkie]

In reality, I think 2 AWG is at the upper end of anything I'm going to do electrically on my 4runner.

Until/unless I relocate my battery to the rear, or add a second battery in the rear, 2 AWG seems fine, and it's just over 0.25" in diameter.

I am planning on ordering 10' of 2 AWG and 5' of 4 AWG, red and black, along with 3/8" and 1/4" copper lugs and heat shrink for each gauge wire.

2 AWG for
Alt to Bat
Bat to starter
Bat to winch
Primary engine and frame grounds


4 AWG for
Bat to factory fuse box
Bat to aux fuse/relay box
Secondary grounds


FWIW, looking for commercial winch wiring, all commercial options top out at 2 AWG with most being in the 6-4 AWG size range.

 

[JT1USA]

I’m curious why the person I quoted said it’s “never ok” for a bigger positive cable. Everything starts and ends at the battery (with alternator wired essentially in parallel) therefore all cables to/from battery carry the same overall amperage for the system as a whole. So I’m curious as to why a negative cable is allowed to be larger but the person I quoted said the positive is never ok.

I’m on board with these types of upgrades. I just find the overall misinformation astounding.

Sorry for the late reply...The main ground wire on a DC system is the return path between the alternator and battery negative. Because of this it needs to be as "big" or "bigger" than the power wire. For example, the current flows like water and if you have a 3/4" pipe feeding water down into 1/2" drain pipe the drain pipe wont keep up and there will be some resistance... However if the drain pipe was the same size or even over sized to the main feed it will keep up and provide some headroom. Too much resistance creates heat and a potential fire. That why I said the power wire should never be bigger than the ground wire. I don't understand how this appears to be misinformation to you? Wasn't trying to be controversial.

 

[octanejunkie]

Sorry for the late reply...The main ground wire on a DC system is the return path between the alternator and battery negative. Because of this it needs to be as "big" or "bigger" than the power wire. For example, the current flows like water and if you have a 3/4" pipe feeding water down into 1/2" drain pipe the drain pipe wont keep up and there will be some resistance... However if the drain pipe was the same size or even over sized to the main feed it will keep up and provide some headroom. Too much resistance creates heat and a potential fire. That why I said the power wire should never be bigger than the ground wire. I don't understand how this appears to be misinformation to you? Wasn't trying to be controversial.

So if you had two batteries, separated but sharing a common ground would you size the negative connections the same on each battery or sized the same as the positives of each battery, respectively?

 

[Spiker Engineering]

Sorry for the late reply...The main ground wire on a DC system is the return path between the alternator and battery negative. Because of this it needs to be as "big" or "bigger" than the power wire. For example, the current flows like water and if you have a 3/4" pipe feeding water down into 1/2" drain pipe the drain pipe wont keep up and there will be some resistance... However if the drain pipe was the same size or even over sized to the main feed it will keep up and provide some headroom. Too much resistance creates heat and a potential fire. That why I said the power wire should never be bigger than the ground wire. I don't understand how this appears to be misinformation to you? Wasn't trying to be controversial.

The problem is that this "supply pipe" and "drain pipe" analogy is flawed.

What matters is the overall electrical resistance, which is the sum of the resistances of the positive and negative cables. The bigger cable diameter you choose, the lower the overall resistance will be.

And without considering the length of the cable, the discussion of wire diameter is pointless. A long wire needs to have a larger diameter to have the same resistance/voltage drop as a short wire of a smaller diameter.

It does make sense to "match" the positive and negative wire diameters and resistances. There is no sense having a huge positive cable with a tiny negative cable, or vice versa. The tiny cable will become the choke point and will overheat if you push too much current through it. But if your negative cable is properly sized to handle the current, there is no issue whatsoever with having a positive cable that is twice as big. Not much benefit either, but no downside other than cost.

 

[4Reak Show]

Sorry for the late reply...The main ground wire on a DC system is the return path between the alternator and battery negative. Because of this it needs to be as "big" or "bigger" than the power wire. For example, the current flows like water and if you have a 3/4" pipe feeding water down into 1/2" drain pipe the drain pipe wont keep up and there will be some resistance... However if the drain pipe was the same size or even over sized to the main feed it will keep up and provide some headroom. Too much resistance creates heat and a potential fire. That why I said the power wire should never be bigger than the ground wire. I don't understand how this appears to be misinformation to you? Wasn't trying to be controversial.

In any closed DC circuit, amperage is the same no matter where you measure. So, every single amp produced via the alternator travels on both the positive and negative equally. At this point, one wire cannot simply “always be bigger” in comparison to the other. I think that rule of thumb is misleading to folks without education.

Unless you’re assuming the positives are going different locations and they all share a single larger ground, then yeah that’s fine.

The statement “you can always run a smaller power wire” or whatever was said was what I was hung up on.

If you don’t believe me, try it. Build a simple circuit with a battery and a light bulb. Use an amp clamp and you’ll see the positive and negative carry the same current, as long as the system is closed. Therefore, the wires should be sized the same in my opinion, or it becomes a potential choke point.