Big 3 Upgrade

[imjohnny]

Looking at going to a bigger alternator for Mabel and would like to do a big 3 with it. Going to add electric fans and want to make sure I am good power wise. But had a question.

Every post about the big 3 has the positive going from the alt directly to the battery, but on mine right now it goes back to the harness and then goes to the battery. Should I take directly to the battery or do I follow stock lines and go to the harness and then upgrade the wire from the harness to the battery too?

 

[Itali83]

I always leave my factory harness as is, and add a larger new cable direct from alternator to battery. All the wiring on my trucks have been “good” as in not hacked up by previous owners and everything has worked. I just like to add the extra hounds and powers basically on top of the factory stuff. Never had a problem and does make a big difference. Run a separate FUSED power from battery to bulkhead connection on firewall. Your cab power will thank you. There is always a lot of voltage drop between battery, starter connection and then up to the bulkhead which powers everything in the fuse box and beyond.

Ben

 

[Frankenchevy]

Yes and no. You should wire things in a way that they make sense. @Itali83 ’s suggestion is a good start; you should consider future loads, how your efans are triggered, etc. Some items make sense to integrate into the factory wiring, such as using your factory high/low beam wiring to trigger relays for headlights.

 

[imjohnny]

I always leave my factory harness as is, and add a larger new cable direct from alternator to battery. All the wiring on my trucks have been “good” as in not hacked up by previous owners and everything has worked. I just like to add the extra hounds and powers basically on top of the factory stuff. Never had a problem and does make a big difference. Run a separate FUSED power from battery to bulkhead connection on firewall. Your cab power will thank you. There is always a lot of voltage drop between battery, starter connection and then up to the bulkhead which powers everything in the fuse box and beyond.

Ben

Thanks for the info. So you are saying leave the current wire from the alt to the bulkhead connection, run a new one directly from the alt to the battery positive, and another fused connection from the battery positive back to the same bulkhead connection? Just clarifying before I start cutting up wire!

 

[Itali83]

Thanks for the info. So you are saying leave the current wire from the alt to the bulkhead connection, run a new one directly from the alt to the battery positive, and another fused connection from the battery positive back to the same bulkhead connection? Just clarifying before I start cutting up wire!

Yes, that’s what I’ve done to 3 of my squares that are daily drivers. I did check the original wiring over closely to determine its condition and make sure there were no chaffs or cuts first. Don’t want any shorts that’s for sure.

Ben

 

[imjohnny]

Yes, that’s what I’ve done to 3 of my squares that are daily drivers. I did check the original wiring over closely to determine its condition and make sure there were no chaffs or cuts first. Don’t want any shorts that’s for sure.

Ben

Thanks so much. Yeah, my truck is un messed with and in great shape, and the wiring looks to all be in great shape. Don't plan on adding much to it electrically, but would love to make sure my lights don't dim and have the ability to go to the electric fans with no issues.

 

[CalSgt]

All of the “Big 3 Kits” for late model stuff add to the factory wiring and leave it all in place.

I’m in the process of doing the upgrade on mine but trying to keep it super clean since I shaved the firewall. I’ll run the bulkhead from its own 4ga wire and abandon the factory alternator lead and the lead from the starter

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It’s not all in there yet but I ran a 0ga ground from the battery to the frame, and connected 4ga ground from the block and another from the alternator housing to the same lug. The fan controller grounds there too.

Also a 0ga positive from the battery to a fused distribution with 4ga to: the alternator, bulkhead, amplifier, and the fan controller will connect to the last open slot.

 

[imjohnny]

All of the “Big 3 Kits” for late model stuff add to the factory wiring and leave it all in place.

I’m in the process of doing the upgrade on mine but trying to keep it super clean since I shaved the firewall. I’ll run the bulkhead from its own 4ga wire and abandon the factory alternator lead and the lead from the starter


It’s not all in there yet but I ran a 0ga ground from the battery to the frame, and connected 4ga ground from the block and another from the alternator housing to the same lug. The fan controller grounds there too.

Also a 0ga positive from the battery to a fused distribution with 4ga to: the alternator, bulkhead, amplifier, and the fan controller will connect to the last open slot.

Very clean looking. That fan/rad combo sure will keep things cool.

 

[75gmck25]

Standard wiring for the alternator charge wire does not go back to a bulkhead connector for charging. The charge wire (threaded bat terminal on alternator) runs down the valve cover and the back of the engine and connects to the starter large terminal. The large cable to the battery positive is connected to the same starter terminal. It’s a relatively direct path, but the starter terminal is not easily accessible unless you lay under the truck.

The two-wire plug with two smaller alternator wires running to the bulkhead connector are the voltage sense wire (tells alternator when voltage has dropped and charging is needed) and the activation wire (ignition-switched to turn alternator on).

I have a higher 94 amp 12si alternator, so I ran a 2nd charge wire directly from the bat terminal over to the battery positive. IIRC, I got the larger wire from a GMT400 truck in the junkyard, so it already had a fusible link to protect it.

 

[CalSgt]

Standard wiring for the alternator charge wire does not go back to a bulkhead connector for charging. The charge wire (threaded bat terminal on alternator) runs down the valve cover and the back of the engine and connects to the starter large terminal. The large cable to the battery positive is connected to the same starter terminal. It’s a relatively direct path, but the starter terminal is not easily accessible unless you lay under the truck.

The two-wire plug with two smaller alternator wires running to the bulkhead connector are the voltage sense wire (tells alternator when voltage has dropped and charging is needed) and the activation wire (ignition-switched to turn alternator on).

I have a higher 94 amp 12si alternator, so I ran a 2nd charge wire directly from the bat terminal over to the battery positive. IIRC, I got the larger wire from a GMT400 truck in the junkyard, so it already had a fusible link to protect it.

My alternator charge wire T’d at the firewall bus bar, one lead went to the starter and the other to the bulkhead. A second hot wire went straight from the bulkhead to the starter.

Perhaps it wasn’t correct, we did do a I6 to V8 swap in 1997 and perhaps crossed them up. but everything worked fine.

 

[Ricko1966]

Moved to correct thread.

 

[SquareRoot]

What's the "Big 3"? My Powemaster 130 amp alternator uses a 4 gauge charge wire connected to the batt lug on the remote start solenoid. Does having a remote solenoid mean I have the " Big 4"?

 

[PrairieDrifter]

What's the "Big 3"? My Powemaster 130 amp alternator uses a 4 gauge charge wire connected to the batt lug on the remote start solenoid. Does having a remote solenoid mean I have the " Big 4"?

It means upgrading the factory battery wiring. Usually the main battery power, ground and charge wire. Those are the "big 3"