Big 3 Upgrade - NEED HELP!

[PaperweightNate]

I've watched all the big 3 youtube videos I can find. Ive seen Bigfishallday's tutorial. Here's my questions.

1. The original positive wire runs into the fuse box behind the battery. Does the fuse box get bypassed (the wire runs from the positive terminal directly to the rear bolt of the alternator.) ?

2. The original negative wire runs into a bundle of several other wires all wrapped together. Is that also bypassed ( the wire runs directly from the negative terminal to the front bolt of the alternator) ?

3. Do the original wires get reconnected to the battery or do they stay off? (can I remove them completely?)

4. Is a fuse necessary to be connected to the new positive wire like Bigfish did or do I only need the 3 upgraded wires?

Thanks, Nate.

 

[Swede]

1. The original positive wire runs into the fuse box behind the battery. Does the fuse box get bypassed (the wire runs from the positive terminal directly to the rear bolt of the alternator.) ?

Answer: No it does not get bypassed. The cable runs from the alternator output post to the 100 amp fuseable link in the fuse box then continues out of the box to the "+" post of the Battery.

2. The original negative wire runs into a bundle of several other wires all wrapped together. Is that also bypassed ( the wire runs directly from the negative terminal to the front bolt of the alternator) ?

Answer: Yes and No, this cable runs from the "-" post of the Battery into that harness and directly to the engine block behind the alternator. So yes it bypasses the fuse box but no it does not bolt anywhere to the alternator. Also, there is a second smaller gauge wire that runs from the "-" post to the body, this wire should be upgraded to the new gauge as well.

3. Do the original wires get reconnected to the battery or do they stay off? (can I remove them completely?)

Answer: You can do both if you like however I'm sure most will just remove the OEM cables.

4. Is a fuse necessary to be connected to the new positive wire like Bigfish did or do I only need the 3 upgraded wires?

Answer: Upgrading the 3 wires is all that is required unless you are upgrading the alternator to a higher amperage unit. The 100 amp (some are 120 amp) OEM Fuseable link is enough to protect the cable from over current when using the OEM 70 amp alt. There is no need to add another fuse.

Hope this helps.

 

[hrt4me]

OP, would you please take and post photographs along the way of your Big 3 ground wire upgrade/installation?

 

[BrianSD_42]

I'm still trying to figure out why in BFADs post about this he shows 4 wires ... ?

 

[BigFishAllDay]

I'll get you guys all squared away on this tomorrow...

 

[BrianSD_42]

I'll get you guys all squared away on this tomorrow...

NICE!

Especially since I plan on doing this on Saturday. Making the wires properly looks pretty easy and I'm sure the ones on the truck won't be too hard to disasemble but ... still it does look a bit daunting since I will be doing a hand trace by feeling how the cables connect to the alternator.

I will also be installing a new fuse box for my various electronics.

 

[PaperweightNate]

Thanks for all the responces. Id like to get my whole build up if I can figure out how to work the forum.. kind of hard to navigate to me, dunno why.. I think I can figure it out now but ill post the progress anyways for advice.. im trying to connect off road lights a sub and a winch so im running out of space to attach things to the terminals.. nate.

 

[Swede]

Quick question. How much wire do you guys estimate is needed. I have about 9 ft of 2 gauge left from my amp install. Im not running alot of power but I would like to upgrade anyway. I was gonna do this a while back but backed off when I wasnt sure where the chassis/engine block ground. Thanks.

I think you'll have enough. 9' should make it.

 

[hrt4me]

1. The original positive wire runs into the fuse box behind the battery. Does the fuse box get bypassed (the wire runs from the positive terminal directly to the rear bolt of the alternator.) ?

Answer: No it does not get bypassed. The cable runs from the alternator output post to the 100 amp fuseable link in the fuse box then continues out of the box to the "+" post of the Battery.

2. The original negative wire runs into a bundle of several other wires all wrapped together. Is that also bypassed ( the wire runs directly from the negative terminal to the front bolt of the alternator) ?

Answer: Yes and No, this cable runs from the "-" post of the Battery into that harness and directly to the engine block behind the alternator. So yes it bypasses the fuse box but no it does not bolt anywhere to the alternator. Also, there is a second smaller gauge wire that runs from the "-" post to the body, this wire should be upgraded to the new gauge as well.

3. Do the original wires get reconnected to the battery or do they stay off? (can I remove them completely?)

Answer: You can do both if you like however I'm sure most will just remove the OEM cables.

4. Is a fuse necessary to be connected to the new positive wire like Bigfish did or do I only need the 3 upgraded wires?

Answer: Upgrading the 3 wires is all that is required unless you are upgrading the alternator to a higher amperage unit. The 100 amp (some are 120 amp) OEM Fuseable link is enough to protect the cable from over current when using the OEM 70 amp alt. There is no need to add another fuse.

so you recommend a fuse if one were to upgrade the alternator (e.g. CS-144).... which one, i.e. would 120 amp be sufficient, or would 140 amp be better?

 

[Swede]

so you recommend a fuse if one were to upgrade the alternator (e.g. CS-144).... which one, i.e. would 120 amp be sufficient, or would 140 amp be better?

That would depend on the current output of the alternator and the wire size. If the CS-144 alternator outputs 120 amps (I can't remember what it was rated off hand) and you have 4 awg cable then a 120 amp fuse would be fine.

 

[hrt4me]

That would depend on the current output of the alternator and the wire size. If the CS-144 alternator outputs 120 amps (I can't remember what it was rated off hand) and you have 4 awg cable then a 120 amp fuse would be fine.

how would I calculate that?

 

[4Runner4TW]

I'm still trying to figure out why in BFADs post about this he shows 4 wires ... ?

He shows 4 wires because the Positive is connected to a fuse. It goes from Pos Alt to fuse to pos battery. Think of that as 1 wire when technically it is 2. This threw me off as well. He did a great second write up, if i was home i would post the link. I saw he responded so maybe that's what he is up to.

 

[hrt4me]

He shows 4 wires because the Positive is connected to a fuse. It goes from Pos Alt to fuse to pos battery. Think of that as 1 wire when technically it is 2. This threw me off as well. He did a great second write up, if i was home i would post the link. I saw he responded so maybe that's what he is up to.

How To Perform the "Big 3" Wiring Upgrade on a 3rd Gen T4R

 

[Swede]

how would I calculate that?

The Electrical Code to start. There are also apps for your smartphone. Tons of places actually. I use the CEC (Canadian Electrical Code) guidelines for conductor size and ampacities for free air single conductors. I'll punch in some #'s for you:

14 AWG = 20 Amps
12 AWG = 25 Amps
10 AWG = 40 Amps
8 AWG = 65 Amps
6 AWG = 95 Amps
4 AWG = 125 Amps
2 AWG = 170 Amps
1 AWG = 195 Amps
1/0 AWG = 230 Amps
2/0 AWG = 265 Amps

Again, the fuse is there to protect the conductor so if you have a 180 amp alternator and 4 AWG wire, since the wire is only rated to 125 Amps, it would be necessary to use a 120 Amp fuse. If you are in a situation where you need the 180 Amp current then it would be appropriate to run 1 AWG wire (195 Amps rating) and a 180 Amp fuse. :nerd:

 

[hrt4me]

The Electrical Code to start. There are also apps for your smartphone. Tons of places actually. I use the CEC (Canadian Electrical Code) guidelines for conductor size and ampacities for free air single conductors. I'll punch in some #'s for you:

14 AWG = 20 Amps
12 AWG = 25 Amps
10 AWG = 40 Amps
8 AWG = 65 Amps
6 AWG = 95 Amps
4 AWG = 125 Amps
2 AWG = 170 Amps
1 AWG = 195 Amps
1/0 AWG = 230 Amps
2/0 AWG = 265 Amps

Again, the fuse is there to protect the conductor so if you have a 180 amp alternator and 4 AWG wire, since the wire is only rated to 125 Amps, it would be necessary to use a 120 Amp fuse. If you are in a situation where you need the 180 Amp current then it would be appropriate to run 1 AWG wire (195 Amps rating) and a 180 Amp fuse. :nerd:

thanks, that was very helpful

 

[infamousRNR]

The Electrical Code to start. There are also apps for your smartphone. Tons of places actually. I use the CEC (Canadian Electrical Code) guidelines for conductor size and ampacities for free air single conductors. I'll punch in some #'s for you:

14 AWG = 20 Amps
12 AWG = 25 Amps
10 AWG = 40 Amps
8 AWG = 65 Amps
6 AWG = 95 Amps
4 AWG = 125 Amps
2 AWG = 170 Amps
1 AWG = 195 Amps
1/0 AWG = 230 Amps
2/0 AWG = 265 Amps

>>> the wire for the positive terminal connection to the alternator should have the fuse right??

so doing the "big 3" upgrade with 0 gauge would require a 230 Amp fuse, IF your alternator was a 180 amp output? what is the stock alternator output? and what would the stock alternative fuse need to be if using 0 gauge wire?