I'm cleaning up some wiring mess in the engine compartment and Bubba ran a wire from the alternator rather randomly over to the starter. It does work but will need a new wire as the insulation is brittle from being next to the exhaust manifold.

I can at this point very easy run a 10 gauge wire back to the battery and connect it up to the terminal that goes to the hot side of the battery. In fact it might be easier to do that than try and snake the wire behind the wiper motor and down to the starter hot terminal.

Is there any reason to not just run it back to the battery?

JT

 

I'm not an expert on 82's. But I thought all 82's ran the alternator charge wire through the frame and directly to the battery.
In answer to your question. No, there is absolutely no reason not to run the charge wire directly to the battery. It is the very best way.

 

That's how GM did it on the ETR cars. It also has a 10GA ground wire running from the alternator back to the battery.
In fact Zip Corvette makes a replacement harness to do just that.
https://www.zip-corvette.com/80-82-a...g-harness.html

 

The service manual shows the hot from the alternator going to the starter.

JT

 

That's not how I read it. My 80 certainly has the alternator going straight to the battery (well, in stock configuration). There's a junction block inside the battery compartment behind the seat.

At any rate, 10 gauge is kinda thin, if you are going to be adding any other electrical loads in the future (electric fans, etc), or even just upgrading the alternator.

 

Interesting the service manual shows a different route but there are many typos in both lol.

I don't plan on adding any electrical loads at all.

JT

 

82 with optional radio has the charge wire directly from alternator to the battery. It’s routed through the frame on the drivers side.

 

Perhaps they just didn't update that part of the manual. It happens. Earlier cars did run to the starter. From a junction first however.
Going straight to the battery is a definite upgrade any way you look at it.

 

How did they route the wire through the frame? I'll have to look but don't recall any openings in the battery compartment except to the center console.

I "think" I remember reading somewhere that was done to reduce static on the radio... probably not needed with a modern radio.

JT

 

If I need a size 10 wire then I will regularly up size it at least one size for safety. I have a 100 amp alternator that feed the battery Positive terminal on the Starter motor through a #6 (?) wire. It never gets warm from current going through it nor do I exceed the wire's capacity.

For my cooling fans and other electrical loads I ran a #6 wire to the right inner fender to a post where it is distributed. I have a 100 amp Marine (Weather resistant) circuit breaker that protects the loads for me from near the battery. Between the marine grade electrical wire and circuit breakers it made the system safer and being weather resistant should help the parts survive in my convertible.

I don't see any reason to run all the way to the battery when such a large wire connection is available right there on the starter motor. The battery cable is sized large enough to handle a lot of current. With the gear drive starter my engine uses less current to get it started and running which makes the battery Positive cable from the battery to starter motor way oversized for the loads on it.

For the aftermarket EFI systems it is critical that you run the power from the battery directly. For this I ran a pair of 10 gauge wires from the battery to the EFI controller. The power wires were twisted together to help control electrical noise getting into my EFI system. That is separate from the wiring. All the rest of the electrical loads run off the "aux" battery post on my right inner fender.

 

The thought on up-sizing - I have always been told- under the hood temps. As electricity slows down as the wire gets hot and adds resistance
. "Under the Hood Temps" = Increased Resistance

• The Physics: The resistance of a metal conductor (like copper) increases as its temperature increases.
• The Problem: Under-hood temperatures are high, and ambient heat soak causes wire resistance to rise. When a wire is hot, it struggles to carry the same amount of current it could when cold.
• The Result: A wire that is perfectly adequate in the passenger compartment might be undersized in the engine bay.

. "Electricity Slows Down" (Higher Resistance)

• The Cycle: When a wire is too thin (or gets too hot), its resistance rises. This higher resistance makes it harder for electrons to flow.
• Thermal Runaway: The increased resistance creates more heat through Joule heating, which makes the wire hotter, which increases the resistance further.
• The Impact: This cycle leads to voltage drops (low power to components) and can melt insulation, causing short circuits or fires.

aftermarket EFI systems it is critical that you run the power from the battery directly.

Exactly- the battery filters "dirty " power as the alternator's power has some AC ripple left over from the it's simple diode conversion design. The battery also provides a more stable power- not surging.
Electronics like that!

The power wires were twisted together to help control electrical noise getting into my EFI system

I believe it was BMW that first started doing this in the 80's with their speaker wires to keep out noise- albeit Alexander Graham Bell patented twisted pair wires in 1881 for telegraph!




Here's a guesstimate for what size wire to run - and fuse appropriately-
Fuse are designed to protect the wire before it melts- not save the device-

 

From the assembly manual.....

 

The 82 factory assembly manual shows the same thing. I'll probably reroute it after I get it running again.

JT