C4 charging system upgrade
Thread Starter
Le Mans Master
Joined: Nov 2009
Posts: 6,882
Likes: 234
From: Bangkok, Thailand
C4 charging system upgrade
I've ended up rebuilding my 91 from the ground up pretty much. On my first C4 I was driving one day and noticed the volt meter bouncing. When I checked under the hood I saw smoke coming from the main lead off the alternator and the red insulation was black. That lead wire just seems way too small to handle the 105 amp factory alternator, much less an upgraded one like this: https://www.summitracing.com/parts/p...ette/year/1991
I'm upgrading to a Racetronix fuel pump their wiring harness since the stock wiring can't really keep up there either. I've also gone to 80w100 Xenon headlight bulbs and will be adding relays for those to avoid overloading that wiring as well. I plan on replacing the cheapie head unit with a better double din unit and want to add cameras front and rear as well. To help reduce draw I've upgraded all the exterior lights to LED. I'll probably end up replacing the factory fog lights with real (long range) driving lights as well.
That said, what I'd really like to do is upgrade/replace the main lead from the alternator to the battery. The existing one is already hard from age and I suspect from running too much current that it's gotten hot and started to weld itself together inside.
So, suggestions? My flame suit is on for all the "why upgrade to more output" questions. I am one of those who would rather go a little bit overboard and have a margin of error rather than run on the ragged edge.
PS, I'll be using a March 3 piece underdrive pulley set as well..........
I'm upgrading to a Racetronix fuel pump their wiring harness since the stock wiring can't really keep up there either. I've also gone to 80w100 Xenon headlight bulbs and will be adding relays for those to avoid overloading that wiring as well. I plan on replacing the cheapie head unit with a better double din unit and want to add cameras front and rear as well. To help reduce draw I've upgraded all the exterior lights to LED. I'll probably end up replacing the factory fog lights with real (long range) driving lights as well.
That said, what I'd really like to do is upgrade/replace the main lead from the alternator to the battery. The existing one is already hard from age and I suspect from running too much current that it's gotten hot and started to weld itself together inside.
So, suggestions? My flame suit is on for all the "why upgrade to more output" questions. I am one of those who would rather go a little bit overboard and have a margin of error rather than run on the ragged edge.
PS, I'll be using a March 3 piece underdrive pulley set as well..........
Last edited by mcm95403; Jul 21, 2021 at 12:20 AM.
Melting Slicks
Joined: Sep 2004
Posts: 2,847
Likes: 439
From: Spring Texas
Article borrowed from this site. Pretty much applies to any car.
As many of you know, upgrading the "Big 3" wires in your engine compartment can lower the overall resistance of your entire electrical system. The effects of the lower resistance are typically:
1) Reduced dimming and smaller voltage drops
2) More stable voltage and better current flow
3) Less strain on your vehicle's charging system
So for those of you looking to upgrade your system and help out your electrical system, this is the modification for you. If you have heavy dimming or are getting large voltage drops during loud bass hits, upgrading your vehicle's "Big 3" will usually help to reduce and sometimes even eliminate the problems. So without further ado, the "Big 3" wires are:
1) Battery negative to chassis
2) Alternator to battery positive
3) Chassis to engine
Now, I suppose it would help if I explained what each of these wires does, and to do that I would like to paraphrase an explanation by IMTfox from a while ago: Think of your vehicle's charging system as two different circuits, one consisting of your amplifier and your battery, and the other consisting of your alternator and your battery. The current in your electrical system flows from your positive battery terminal to your amp, from your amp's ground to the chassis, and then from the chassis back to the negative battery terminal. But how does it get to the positive terminal in the first place? That's where the alternator comes in. Current in the second circuit flows from your alternator's positive post to the battery's positive terminal, then from the battery's negative terminal to the chassis, and from the chassis back to the block, which happens to be the grounding point for your alternator.
So, from your battery, you have the power wire going to the power terminal on your amplifier and then your amplifier is grounded to the chassis of the vehicle. From here the current needs a way to get back to the negative battery terminal, and that way is through the first of the "Big 3," the battery negative to chassis wire. Upgrading this wire will "upgrade" the circuit between your battery and your amp by giving the current a larger path to flow through to get back to the battery.
Now, think of your alternator as the battery and your battery as the amp. From the positive post on your alternator, you have the second of the "Big 3," the alternator to battery positive wire supplying "power" to your battery. From there the battery, just like your amp, is grounded to the chassis through the wire mentioned in the previous paragraph. Again, the current needs a way to get from the chassis back to the alternator's "negative terminal" and that way is through the last of the "Big 3," the chassis to engine wire. Since your alternator is most likely mounted to your engine block using a metal or conductive mounting bracket, you can simply add your new wire from the chassis to one of the mounting posts for the alternator. Upgrading these two wires will "upgrade" the circuit between your alternator and your battery, again giving the current a larger path to flow through. Helpful hints:
1) Leave the stock wiring attached after you're done. Don't replace the stock wiring, add onto it. Current will take the path of least resistance anyway, so replacing the stock wire will only make more work for yourself.
2) When fusing your alternator to battery positive wire, fuse it toward the battery end of the wire. the battery will explode if it's overloaded, while the alternator will only burn out its regulator which won't cause much damage except to the alternator itself. Exploding batteries are no fun!
3) When crimping large gauge terminals for 1/0awg and sometimes even 4awg, a vice works well. Crimp one side of the terminal at a time, creating an overlapping edge. Put the boot around this and then wrap it in electrical tape if you want. the most secure connections will occur in this way.
4) Lastly, prepare all your materials and tools BEFORE you are ready to upgrade. Know what you are doing before you start so you can be done as quick as possible. The majority of vehicles have computers that will reset after the battery is disconnected for a long time and they can cause older vehicles to do strange things if they reset.
Hopefully this clears up most of the questions you had about why we upgrade the "Big 3" and how it helps to stop dimming and other electrical problems.
Helpful hints:
1) Leave the stock wiring attached after you're done. Don't replace the stock wiring, add onto it. Current will take the path of least resistance anyway, so replacing the stock wire will only make more work for yourself.
2) When fusing your alternator to battery positive wire, fuse it toward the battery end of the wire. the battery will explode if it's overloaded, while the alternator will only burn out its regulator which won't cause much damage except to the alternator itself. Exploding batteries are no fun!
3) When crimping large gauge terminals for 1/0awg and sometimes even 4awg, a vice works well. Crimp one side of the terminal at a time, creating an overlapping edge. Put the boot around this and then wrap it in electrical tape if you want. the most secure connections will occur in this way.
4) Lastly, prepare all your materials and tools BEFORE you are ready to upgrade. Know what you are doing before you start so you can be done as quick as possible. The majority of vehicles have computers that will reset after the battery is disconnected for a long time and they can cause older vehicles to do strange things if they reset.
As many of you know, upgrading the "Big 3" wires in your engine compartment can lower the overall resistance of your entire electrical system. The effects of the lower resistance are typically:
1) Reduced dimming and smaller voltage drops
2) More stable voltage and better current flow
3) Less strain on your vehicle's charging system
So for those of you looking to upgrade your system and help out your electrical system, this is the modification for you. If you have heavy dimming or are getting large voltage drops during loud bass hits, upgrading your vehicle's "Big 3" will usually help to reduce and sometimes even eliminate the problems. So without further ado, the "Big 3" wires are:
1) Battery negative to chassis
2) Alternator to battery positive
3) Chassis to engine
Now, I suppose it would help if I explained what each of these wires does, and to do that I would like to paraphrase an explanation by IMTfox from a while ago: Think of your vehicle's charging system as two different circuits, one consisting of your amplifier and your battery, and the other consisting of your alternator and your battery. The current in your electrical system flows from your positive battery terminal to your amp, from your amp's ground to the chassis, and then from the chassis back to the negative battery terminal. But how does it get to the positive terminal in the first place? That's where the alternator comes in. Current in the second circuit flows from your alternator's positive post to the battery's positive terminal, then from the battery's negative terminal to the chassis, and from the chassis back to the block, which happens to be the grounding point for your alternator.
So, from your battery, you have the power wire going to the power terminal on your amplifier and then your amplifier is grounded to the chassis of the vehicle. From here the current needs a way to get back to the negative battery terminal, and that way is through the first of the "Big 3," the battery negative to chassis wire. Upgrading this wire will "upgrade" the circuit between your battery and your amp by giving the current a larger path to flow through to get back to the battery.
Now, think of your alternator as the battery and your battery as the amp. From the positive post on your alternator, you have the second of the "Big 3," the alternator to battery positive wire supplying "power" to your battery. From there the battery, just like your amp, is grounded to the chassis through the wire mentioned in the previous paragraph. Again, the current needs a way to get from the chassis back to the alternator's "negative terminal" and that way is through the last of the "Big 3," the chassis to engine wire. Since your alternator is most likely mounted to your engine block using a metal or conductive mounting bracket, you can simply add your new wire from the chassis to one of the mounting posts for the alternator. Upgrading these two wires will "upgrade" the circuit between your alternator and your battery, again giving the current a larger path to flow through. Helpful hints:
1) Leave the stock wiring attached after you're done. Don't replace the stock wiring, add onto it. Current will take the path of least resistance anyway, so replacing the stock wire will only make more work for yourself.
2) When fusing your alternator to battery positive wire, fuse it toward the battery end of the wire. the battery will explode if it's overloaded, while the alternator will only burn out its regulator which won't cause much damage except to the alternator itself. Exploding batteries are no fun!
3) When crimping large gauge terminals for 1/0awg and sometimes even 4awg, a vice works well. Crimp one side of the terminal at a time, creating an overlapping edge. Put the boot around this and then wrap it in electrical tape if you want. the most secure connections will occur in this way.
4) Lastly, prepare all your materials and tools BEFORE you are ready to upgrade. Know what you are doing before you start so you can be done as quick as possible. The majority of vehicles have computers that will reset after the battery is disconnected for a long time and they can cause older vehicles to do strange things if they reset.
Hopefully this clears up most of the questions you had about why we upgrade the "Big 3" and how it helps to stop dimming and other electrical problems.
Helpful hints:
1) Leave the stock wiring attached after you're done. Don't replace the stock wiring, add onto it. Current will take the path of least resistance anyway, so replacing the stock wire will only make more work for yourself.
2) When fusing your alternator to battery positive wire, fuse it toward the battery end of the wire. the battery will explode if it's overloaded, while the alternator will only burn out its regulator which won't cause much damage except to the alternator itself. Exploding batteries are no fun!
3) When crimping large gauge terminals for 1/0awg and sometimes even 4awg, a vice works well. Crimp one side of the terminal at a time, creating an overlapping edge. Put the boot around this and then wrap it in electrical tape if you want. the most secure connections will occur in this way.
4) Lastly, prepare all your materials and tools BEFORE you are ready to upgrade. Know what you are doing before you start so you can be done as quick as possible. The majority of vehicles have computers that will reset after the battery is disconnected for a long time and they can cause older vehicles to do strange things if they reset.
