Alternator Wire Size?? - Chevelle Tech
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post #1 of 26 (permalink) Old Jan 14th, 08, 12:25 AM Thread Starter
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Brian
 
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Alternator Wire Size??

I want to change my external charging system to an internal style. I plan on using a conversion kit listed in the link..
https://0193647.netsolstores.com/ind...l=&strCompare=

I need to run a 140 amp alternator to run a Lincoln Mark VIII fan. Do I need to upgrade the main red power wire from the alternator to the battery, if it currently is in good shape??

Thanks...

1968 300 deluxe
15.9 @ 88.0 mph
1968 mailbu (383,th400,12bolt/posi)
13.52 @ 101.84 mph

"Just about the stupidest thing you could do, is to try and move a big block with your shoes untied."

"IF YOU HAVE A RACE CAR BUY RACE CAR PARTS"
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post #2 of 26 (permalink) Old Jan 14th, 08, 2:32 AM
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Re: Alternator Wire Size??

this is a partial chart from chevellestuff.com
Recommended Charging-Cable Gauge Size

AMPS To 4-ft 4-7 ft 7-10 ft 10-13 ft 13-16 ft
85-105 6 6 4 2 2
105-125 4 4 4 2 2
125-150 2 2 2 2 0

factory charge wire is only 10-guage, if your going to upgrade to this kind of set-up you should research the tech reference series on the tech tab above, and or visit the mad electrical site, ot the chevellestuff.com site, all have a lot of info on swapping altenators and wiring correctly to prevent overheating (fire) wires. i rewired the front of my car with the recommendations of the MADelectrical site and it works great like it should.....
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post #3 of 26 (permalink) Old Jan 14th, 08, 2:45 AM Thread Starter
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Brian
 
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Re: Alternator Wire Size??

Quote:
Originally Posted by VinceS427bb View Post
this is a partial chart from chevellestuff.com
Recommended Charging-Cable Gauge Size

AMPS To 4-ft 4-7 ft 7-10 ft 10-13 ft 13-16 ft
85-105 6 6 4 2 2
105-125 4 4 4 2 2
125-150 2 2 2 2 0

factory charge wire is only 10-guage, if your going to upgrade to this kind of set-up you should research the tech reference series on the tech tab above, and or visit the mad electrical site, ot the chevellestuff.com site, all have a lot of info on swapping altenators and wiring correctly to prevent overheating (fire) wires. i rewired the front of my car with the recommendations of the MADelectrical site and it works great like it should.....
Vince thanks, I have been reading through some of that stuff, very informative. I am very inexperienced when it comes to wiring, so some of the stuff is over my head right now. The only power accessory I run is the fan, no ac or stereo.

If I run a 2 gauge wire, does it need to be just from the alternator to the horn relay, or all the way to the battery?? Thanks for your help...

1968 300 deluxe
15.9 @ 88.0 mph
1968 mailbu (383,th400,12bolt/posi)
13.52 @ 101.84 mph

"Just about the stupidest thing you could do, is to try and move a big block with your shoes untied."

"IF YOU HAVE A RACE CAR BUY RACE CAR PARTS"
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post #4 of 26 (permalink) Old Jan 14th, 08, 2:53 AM
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Re: Alternator Wire Size??

Quote:
Originally Posted by nolimitpkr View Post
Vince thanks, I have been reading through some of that stuff, very informative. I am very inexperienced when it comes to wiring, so some of the stuff is over my head right now. The only power accessory I run is the fan, no ac or stereo.

If I run a 2 gauge wire, does it need to be just from the alternator to the horn relay, or all the way to the battery?? Thanks for your help...
it depends on where the battery is located and if you have (f*rd) solenoid in the starting system or just the regular gm-starter-solenoid set-up. also depends on if you have the short or long water pump set-up for which side of the engine the altenator is attached and if you will be running the power from the horn relay to the FAN-relay to provide power to the fans.....
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post #5 of 26 (permalink) Old Jan 14th, 08, 3:16 AM Thread Starter
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Brian
 
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Re: Alternator Wire Size??

Quote:
Originally Posted by VinceS427bb View Post
it depends on where the battery is located and if you have (f*rd) solenoid in the starting system or just the regular gm-starter-solenoid set-up. also depends on if you have the short or long water pump set-up for which side of the engine the altenator is attached and if you will be running the power from the horn relay to the FAN-relay to provide power to the fans.....
Battery is located up front, I do not run a solenoid, and its a long water pump, alt is on passenger side.

Here is how the fan is wired. I added an 60 amp fuse with 8 gauge wire from the fan to the relay and the relay to the battery..


Just curious on MAD they only use an 8 gauge wire, but that chart shows to use a 2 gauge wire for 140 amps??? AM I missing something here???

Thanks again....

1968 300 deluxe
15.9 @ 88.0 mph
1968 mailbu (383,th400,12bolt/posi)
13.52 @ 101.84 mph

"Just about the stupidest thing you could do, is to try and move a big block with your shoes untied."

"IF YOU HAVE A RACE CAR BUY RACE CAR PARTS"

Last edited by nolimitpkr; Jan 14th, 08 at 3:31 AM.
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post #6 of 26 (permalink) Old Jan 14th, 08, 3:32 AM
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Vince
 
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Re: Alternator Wire Size??

Quote:
Originally Posted by nolimitpkr View Post
Battery is located up front, I do not run a solenoid, and its a long water pump, alt is on passenger side.

Here is how the fan is wired. I added an 60 amp fuse with 8 gauge wire from the fan to the relay and the relay to the battery..
i think you will be fine with the 2-gauge from the alt. to the battery.
no need to run a larger wire from the battery to the horn relay unless you have a 3-wire altenator and will also need to run power for the headlight relays to provide more voltage/current to the headlamps for brighter lights. the 3-wire alt. has a sense wire that will sense the voltage at a point you want to monitor such as the horn relay buss-bar, also the 3-wire set-up will allow you to use the gen (idiot) light on the dash. it will come on if you are starting or throw a belt or have low charge conditions.
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post #7 of 26 (permalink) Old Jan 14th, 08, 8:20 AM
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Re: Alternator Wire Size??

The horn relay is the main power distribution. I would run the alternator output to it. Also I would connect the power feed for the fan relay to the horn relay not the battery.

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post #8 of 26 (permalink) Old Jan 14th, 08, 8:29 AM
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Re: Alternator Wire Size??

Quote:
Originally Posted by VinceS427bb View Post
i think you will be fine with the 2-gauge from the alt. to the battery.
no need to run a larger wire from the battery to the horn relay unless you have a 3-wire altenator
Quote:
Originally Posted by Elree Colby View Post
The horn relay is the main power distribution. I would run the alternator output to it. Also I would connect the power feed for the fan relay to the horn relay not the battery.
You definitely need a larger wire from the alternator to the power distribution point. The wire from the alternator to the battery doesn't need to be very large, as the battery only needs recharging current.
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post #9 of 26 (permalink) Old Jan 14th, 08, 9:28 AM
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Re: Alternator Wire Size??

Also upgrade the chassis grd wire, battery to passenger side front fender. This is the return path to the alt. If only the positive is upgraded you run the risk of burning up the chassis grd wire.

Hank

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post #10 of 26 (permalink) Old Jan 14th, 08, 3:18 PM Thread Starter
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Re: Alternator Wire Size??

Thanks for the help guys, I just have a mental block with wiring... This project could be beyond my knowledge, I guess I will just have to start tearing stuff apart and find out where it goes.

Does the main alternator power wire go to a splice before going to the horn relay??

I think I understand that the main wire will need to be upgraded to the horn relay(2 gauge), but no need to upgrade from the wire from the horn relay to the battery, is this correct??

Sorry if I am repeating myself, I just have trouble visualizing this type of stuff. I never understood Algebra until someone showed me step by step what to do, so thanks for your patience...

1968 300 deluxe
15.9 @ 88.0 mph
1968 mailbu (383,th400,12bolt/posi)
13.52 @ 101.84 mph

"Just about the stupidest thing you could do, is to try and move a big block with your shoes untied."

"IF YOU HAVE A RACE CAR BUY RACE CAR PARTS"
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post #11 of 26 (permalink) Old Jan 14th, 08, 3:41 PM
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Re: Alternator Wire Size??

I've got a CS-130 alternator in my '69. I put in dual 8 ga wires from the alt. to the distribution point. You don't need a system to handle 140 A. You should size the wire for the load required. You will normally only be using a fraction of that current. If you are actually going to be continuously drawing 140 A then you need an even bigger alternator.

Erik
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'68 Chevrolet C10 Stepside Project, 292, t-56, C4 IRS
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post #12 of 26 (permalink) Old Jan 14th, 08, 3:50 PM Thread Starter
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Re: Alternator Wire Size??

Quote:
Originally Posted by ehjorten View Post
I've got a CS-130 alternator in my '69. I put in dual 8 ga wires from the alt. to the distribution point. You don't need a system to handle 140 A. You should size the wire for the load required. You will normally only be using a fraction of that current. If you are actually going to be drawing 140 A then you need an even bigger alternator.
I am thinking of going to the 140 because the 100 amper I have now is only showing 13.20-13.60 volts when the fan is running and the car is idling. Is that enough volts to keep the battery charged? The system is on my bracket racing car and the last thing I want is to have a dead battery in the staging lanes...

Also can an external regulator handle the current load from my 100 amp alternator??

Thanks guys, TC ROCKS!!!!!!!!!!!

1968 300 deluxe
15.9 @ 88.0 mph
1968 mailbu (383,th400,12bolt/posi)
13.52 @ 101.84 mph

"Just about the stupidest thing you could do, is to try and move a big block with your shoes untied."

"IF YOU HAVE A RACE CAR BUY RACE CAR PARTS"
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post #13 of 26 (permalink) Old Jan 14th, 08, 5:02 PM
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Re: Alternator Wire Size??

Quote:
Originally Posted by nolimitpkr View Post
I am thinking of going to the 140 because the 100 amper I have now is only showing 13.20-13.60 volts when the fan is running and the car is idling. Is that enough volts to keep the battery charged? that should be enough to keep it charged, you should figure out about how many amps the car is actually using before making changes and buying a large amp alt.
The system is on my bracket racing car and the last thing I want is to have a dead battery in the staging lanes...

Also can an external regulator handle the current load from my 100 amp alternator??stock type external regulators are only rated to handle about 62-amps, you must not be pulling that many amps or you would have had problems already........

Thanks guys, TC ROCKS!!!!!!!!!!!
see above responses also the stock alt wire (red 10-gauge) goes to a splice on the harness and splits off to the horn relay and to the fuse box on the firewall. the alt. will only produce up to the amps rating when the load is large enough, meaning a 100-amp alt. may only put out 45-amps at idle and when engine rpms go up it will rise to the max draw of you car. that's why you should figure out total amps needed (lights. ign-box, fan, radio, gauges, fuel pump, etc.) hope this helps.......
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post #14 of 26 (permalink) Old Jan 14th, 08, 5:30 PM Thread Starter
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Re: Alternator Wire Size??

Thanks Vince......

1968 300 deluxe
15.9 @ 88.0 mph
1968 mailbu (383,th400,12bolt/posi)
13.52 @ 101.84 mph

"Just about the stupidest thing you could do, is to try and move a big block with your shoes untied."

"IF YOU HAVE A RACE CAR BUY RACE CAR PARTS"
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post #15 of 26 (permalink) Old Jan 14th, 08, 5:39 PM
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Re: Alternator Wire Size??

Quote:
Originally Posted by nolimitpkr View Post
I am thinking of going to the 140 because the 100 amper I have now is only showing 13.20-13.60 volts when the fan is running and the car is idling.
Where are you taking that voltage measurement at? The only place thats important is at the battery. Any readings from the fuse box will be lower because of voltage drop.

Greg U


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