My 150A Holley alternator instructions state a new charge wire should be installed:
4-7’ length use 4ga wire
7-19’ length use 2ga wire
Anyone know the approx length of the charge wire from batt to alt on 80-82?

 

Around 4ish ft to the lug on the starter. That's the battery connection under the hood.

 

Did some of the newer C3s run a dedicated lead all the way back to the battery via the driver side frame? Or did I imagine that?

 

There is a 12ga charge wire from a lug inside the battery compartment to the alternator. It’s routed inside of the frame on the drivers side. There is also a 12ga ground wire routed with the charge wire. Both charge wire and ground look to be 8-10’ long using a tape measure. I’ll use 2ga for the charge wire based on the Holley instructions.

 

6 guage should be overkill. 4 feet.from alternator to solenoid. All the way back to the battery? Can be done. My EFI is wired that way. But charge wire? Why?

 

Yes, some did run all the way back and through the frame, my 82 CE is like that, and they have a fusable link in a hard spot to get at. I think I remember it having to do with what kind of radio was installed but I could be wrong...

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I have never seen anybody go right to the battery with the alternator output. That long run would make for an expensive length of wire. I use a "Welding Cable" style wire that is made up of tiny strands of copper wire and remains very flexible compared to standard 4 gauge wire. If there is a marine/boat store nearby they frequently sell the more flexible wire or just order it online. Marine/Boat Heat Shrink has glue inside the heat shrink that is heat activated which seals the connection better and longer.

Using the flexible 6 gauge wire I went from the alternator output terminal to the battery starter's Positive (12Vdc) post and that was enough to take all the power I am making directly to my battery without heating up any wires at full alternator output. It is better to use a larger than you need sized wire, than one that is marginal. Just never under-size a wire for the current it needs to be able to carry.

Why do you need 150 Amps when the cars were made with 63 amp alternators? What do you have that uses that much power? I switched to a gear-drive starter on my 12.25-1 compression BB and the current used to start the engine dropped dramatically. One thing I added to my C3 was a Marine/Boat Circuit Breaker that is the last line of defense for the electrical system and very easy to switch off to keep the battery from being discharged. When I add up all the accessories that use power, my alternator still has a safe margin for charging the battery completely.

I am a battery specialist/nut and that would be the "right" alternator for a really, really BIG Battery. I don't have A/C but I have never had a battery get low on my 1968 C3 with a ~100 amp Tuff Stuff Alternator. I am using a Deep cycle battery and it has not had any issues with the alternator on my C3. Bigger is not always Better when it comes to alternators as they can and do charge the battery differently. My battery has removable covers for checking the electrolyte levels and I check regularly as with my "Little" 100 amp alternator can boil out the water from the electrolyte. 150 amps would require an automatic watering system to keep up with the excess use of water from the electrolyte. If you are not using a Flooded Lead Acid battery you might have some issues there with the high charging capabilities of some of the larger alternators.

Harbor Freight has a great Hydraulic Wire Crimper that does an awesome job on battery connections. To keep corrosion down I like to "tin" my wires by dipping the wire and connector into a Solder pot which will allow the "tinning" all the way to the center of the wire and this keeps corrosion away for a while. After battery connections are made I put Battery Grease on the terminals to keep them from corroding. This just keeps the oxygen from getting inside the connection and corrosion following along.

 

The simple answer to your question is that this is an LS swapped C3 with Holley belt drive that includes a 150a alternator, ECU, big fans, modern sound system, upgraded gauges, etc.

The later 80-82 C3s do have a charge wire directly from the battery to alternator. The Holley manual clear states that > 7’ length of charge wire needs to be 2ga for their 150a alternator.

We’ve gone a bit off topic from my original question on length of the charge wire. However, I went ahead pulled it back through the frame and it’s 9’ long. I’ll install a new 2ga charge wire in its place along with a 175a fuse using Richard454 recommendation.

 

Thank you for the clarification there TorchZ51. I was not aware that you were talking about a LS swapped vehicle. I tend to stay away from any posts that are LS related as it is out of my area of expertise.

I would follow what Holley suggests you do. They seem to have a pretty good idea about what they are talking about. I am using one of their EFI system and have been very happy with my contacts who sell and maintain the Holley EFI products. Next I want to try a Holley Terminator and set up a multi-port fuel injection system for my BB.

You might consider using the more flexible "marine style" 2 gauge wire as it is way more flexible and that might help you in the routing. It is available on Amazon as are the Fuse and circuit breakers.

Using a fuse or circuit breaker near the battery is always a good idea. I have one that has a one button opening to stop the juice when you leave the car.

Good Luck and I hope it all works out for you!

Regards,
Chris

 

LOOK HERE...!!!

Now you have...lol...They ran some down the inside under the drivers side rug, and others went through the frame.... You are not alone, the mechanics at a well known Corvette shop around here did not believe me when I said mine was in the frame...I won some drinks over that and made some friends...

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Thank you 1860army for your informative and friendly post!

This idea of running the battery cable all the way from the alternator to the battery was "new to me". I have an early 1968 C3 and a 1988 C4 so you are in between those two and "out of my area" of knowledge. The C4's put the battery up front again and this solved the long battery cable issue. Then the car thieves found out you could punch a hole in the battery and let it drain out before stealing the Corvette. The battery would probably last longer away from the heat and vibration from the engine. I prefer the rear mounting the battery in my Corvette and the longer cable run. As long as the cable is up-sized enough then you should have no troubles with the charging system. Too small a gauge and it might have a voltage drop that you really don't want to deal with.

Thank you also for providing the link to ZIP to let me see the part in real life. I trusted you and believe that you are correct as I simply don't have any experience with those particular years.

Having a 1968 C3 we have a lot of things that are unique to our Corvettes. I have fun with other Corvette owners because my car is soooo different. My 1968 interior may be a bit more snug than the cars that followed but my C3 was made with a 427 and just the "go-fast" goodies that Zora had intended to put in these cars for us.

Thanks again 60!

Best regards,
Chris

 

Thanks for the feedback. Glad I did not imagine that. ​​​​​​​