AAW Classic Update kit -- ALT, BAT, and panel feed wiring

[MikeB]

I'm trying to decide how I want to wire the charging and panel feed circuits on my 69 C10. The kit comes with a "charging" sub-kit with 6 gauge (!) wire and 175 amp fuses that is total overkill for me. I'm actually considering using 10 gauge wire, which is one size larger than stock, or possibly 8 gauge, which I used on an 82 C10.

As for routing, I may just duplicate the factory routing from battery to alternator, but use a maxi-fuse instead of a fusible link near the battery. I do not want to feed the alternator and fuse panel off of the starter BAT terminal, because things are very tight down there with my headers.

What have you guys done?

The truck probably draws no more than 30-35 amps through the fuse panel with everything turned on. No killer stereo, power windows, or radiator fans. The Vintage Air system is powered directly off the battery through a breaker.

[jeffahart]

I installed a classic update from AAW also. Here's what I've done, and it's in anticipation of heavy amp draw.

I ran a 4 gauge alt wire. I bypass the starer and go straight to the battery. I have a 200 amp breaker inline to the bat. I also grounded the crap out of everything winch related with heavy gauge welding wire. I know you're not running a winch but this is my deviation from stock. I would go ahead with their instructions if no need to deviate. Then you will have instructions to pass on to the next owner, or even yourself a few years down the road. But I'm always a fan of overkill whenever I have my hands on someting... But I often find myself scratching my head a few years down the road wondering why I did things off the beaten path!

j

[RustyPile]

Originally Posted by MikeB

I'm trying to decide how I want to wire the charging and panel feed circuits on my 69 C10. The kit comes with a "charging" sub-kit with 6 gauge (!) wire and 175 amp fuses that is total overkill for me. I'm actually considering using 10 gauge wire, which is one size larger than stock, or possibly 8 gauge, which I used on an 82 C10.

As for routing, I may just duplicate the factory routing from battery to alternator, but use a maxi-fuse instead of a fusible link near the battery. I do not want to feed the alternator and fuse panel off of the starter BAT terminal, because things are very tight down there with my headers.

What have you guys done?

The truck probably draws no more than 30-35 amps through the fuse panel with everything turned on. No killer stereo, power windows, or radiator fans. The Vintage Air system is powered directly off the battery through a breaker.

Although others will disagree with me on this, I'm not a fan of replacing fuse links with those maxi-fuses. Fuse links are by design, a slow blow fuse, while maxi-fuses are not.

By feeding the Vintage Air system directly from the battery does not take any load off the alternator. Any current draw taken from the battery HAS to be replaced by the alternator, no matter where the "draw point" is located. All current consumption is "replaced" through the wire connecting the alternator to the battery. Not to sound argumentative, but I find it hard to believe there is only a total of 35 amps going through the fuse panel. Besides that, headlight current doesn't pass through the fuse panel. The headlight switch is feed directly, but separately, through a fuse link from the battery.. On average, and I don't know exactly how much current your system draws, but I'd guess more along the lines of 40 - 55 amps.

Remove the main feed wire from the starter and move it to a buss bar mounted near the battery. I suggest you run an 8 ga. wire between the alternator and battery. Run a 10 ga. wire from the battery to the fuse panel. If you're running an internally regulated alternator, connect the voltage sensing wire to this wire near the bulkhead connector. Tie these circuits in with the existing feed to the headlight circuit and you should be fine.

[MikeB]

Originally Posted by jeffahart

I would go ahead with their instructions if no need to deviate. Then you will have instructions to pass on to the next owner, or even yourself a few years down the road.

Yeah, I'll at least need some notes a few years down the road. Sometimes I can't even remember what I did yesterday!

[MikeB]

Originally Posted by RustyPile

Although others will disagree with me on this, I'm not a fan of replacing fuse links with those maxi-fuses. Fuse links are by design, a slow blow fuse, while maxi-fuses are not.

I've heard that before on other forums. Then again, Ron Francis says it's a fire waiting to happen! My truck's original 12 gauge wiring was protected by the appropriately sized fusible link for the past 30 years. Can't remember why I replaced it back then, but I think it was getting kind of tattered looking.

Originally Posted by RustyPile

By feeding the Vintage Air system directly from the battery does not take any load off the alternator.

Correct, but my point was that AC current does not run through the panel feed wire that I'm trying to size.

Originally Posted by RustyPile

I find it hard to believe there is only a total of 35 amps going through the fuse panel. Besides that, headlight current doesn't pass through the fuse panel.

I came up with that number based on previous vehicles with comparable loads. I measured it on the feed wires to fuse panel and Vintage Air system using a DC current clamp.

As for headlight current draw, you're correct that it's not through a fuse, but it is through the fuse panel BAT bus which is fed by the single fuse panel feed wire. The switch itself has an internal breaker.

Originally Posted by RustyPile

Run a 10 ga. wire from the battery to the fuse panel. If you're running an internally regulated alternator, connect the voltage sensing wire to this wire near the bulkhead connector.

Tie these circuits in with the existing feed to the headlight circuit and you should be fine.

Good idea on 8ga between battery and alternator, and the 10ga to rest of world. Yes, I usually run the sense wire to a location near the panel feed.

Not sure what you mean by the second statement. As I mentioned above, the headlight switch gets power from the fuse panel BAT bus.

But thanks for your comments and suggestions.

[RustyPile]

Originally Posted by MikeB

<<<<<<<<<<<SNIP>>>>>>>>>>>>>
Not sure what you mean by the second statement. As I mentioned above, the headlight switch gets power from the fuse panel BAT bus.

But thanks for your comments and suggestions.

Mike, you mentioned that there's 30 - 35 amps going through the fuse panel. I was pointing out that any amperage passing through the headlight switch, or any other circuits would be additional to that figure. In a factory harness, the main feed wire splits with one "leg" going to the fuse panel, one going to the headlight switch.. The wire coming from the alternator also joins this wire.. All of these wires are typically 12 gauge wires from the factory.. Every single drop of current used by the electrical system has to pass through these wires at some point. If any aftermarket electrical items are added, the gauge of the wire section between the alternator and battery should be increased, no matter where the item is "married" to the original system.

The idea for the modifications is to provide sufficient wire sizing in the charging circuit to handle the higher output produced by the alternator.

Current flow through a wire is similar to water running through a hose.. The hose can very easily be too small to provide sufficient flow for the job at hand, but there won't be any problems if the hose is too large. As you mentioned, the 6 gauge wires are probably "overkill" for your application, but on the other hand, 10 gauge might not be big enough..

[MikeB]

Originally Posted by RustyPile

I was pointing out that any amperage passing through the headlight switch, or any other circuits would be additional to that figure. In a factory harness, the main feed wire splits with one "leg" going to the fuse panel, one going to the headlight switch.

From the factory, my 69 has a single 12 gauge wire that runs from the battery through a #16 fusible link, across the radiator support, and into a "splice" where it was crimped and soldered together with two other 12 gauge wires -- one running to the alternator, the other to the fuse panel. That is the only 12 volt feed wire running to the fuse panel.

I just confirmed the above on my old stock harnesses, which are now laying on the floor and not connected to each other. One red wire from the "splice" feeds the battery buss. Then the headlight switch and ignition switch are on the same buss. No separation at all.

Maybe that isn't the case for a 67-72 C20??? I do know that on my old 82 C10, there were two separate 12 volt wires feeding the fuse panel, and maybe the configuration is as you described, but I never looked at it.

Photo shows the GM "splice". Just a little crude, huh? It was wrapped in a thick rubber-like tape. The black wire was one of two used used to send a voltage drop to the stock ammeter (which is really a -/0/+ voltmeter).

[RustyPile]

Originally Posted by MikeB

From the factory, my 69 has a single 12 gauge wire that runs from the battery through a #16 fusible link, across the radiator support, and into a "splice" where it was crimped and soldered together with two other 12 gauge wires -- one running to the alternator, the other to the fuse panel. That is the only 12 volt feed wire running to the fuse panel.

I just confirmed the above on my old stock harnesses, which are now laying on the floor and not connected to each other. One red wire from the "splice" feeds the battery buss. Then the headlight switch and ignition switch are on the same buss. No separation at all.

Maybe that isn't the case for a 67-72 C20??? I do know that on my old 82 C10, there were two separate 12 volt wires feeding the fuse panel, and maybe the configuration is as you described, but I never looked at it.

Photo shows the GM "splice". Just a little crude, huh? It was wrapped in a thick rubber-like tape. The black wire was one of two used used to send a voltage drop to the stock ammeter (which is really a -/0/+ voltmeter).

Mike, you're missing the point and also getting off subject. Never mind what's on the '82, that's another vehicle for another thread.. Dig deeper into that old harness.. Somewhere along one of those red wires is another splice or connection for the feed to the headlight switch. This main power distribution circuit begins at the battery + and runs all over the place. Open the harness at the headlight switch and follow that red 12 gauge wire and see just where it joins the main feed wire.. It could possibly join at the starter solenoid or maybe at a junction post connecting to the + cable at the battery..

The point I'm making and trying to phrase it so you understand, is that every single electron of current (amperage) used by an electrical system has to be replaced by the alternator or the battery will run down.. The wire feeding the current from the alternator back to the battery has to be heavy enough to handle those electrons. You seem offended because I didn't agree with your total electron count (amperage of 35 amps).. It wasn't my intention, and I so stated at the beginning of that statement, to argue the point or start a pissing match.

[MikeB]

I mentioned the 82 truck wiring as an example of a fuse panel fed by two 12-volt feed wires.

Just in case my eyes and ohmmeter were deceiving me, I went to a factory wiring schematic. It shows a single 12R (red, 12ga) 12-volt feed wire running from the battery, through a fusible link, to the bulkhead panel. Along the way, on the driver's side of the radiator, it connects to the alternator via the splice I mentioned earlier in this thread.

However, the 12-volt feed wire does not connect directly to the fuse panel battery bus, as I said or implied, but instead it runs through the dash harness to another splice (buried in the harness). From that splice, 12ga red wires run to the panel battery bus, the ignition switch, and the headlight switch. So yes, headlight current does not run through the fuse panel battery bus, but it does run through the single 12ga wire feeding the fuse panel, headlights, and ignition switch. So, that feed wire IS a valid place to measure current draw, including headlights, unless relays are used.

Do you have a factory schematic showing two 12-volt red feed wires used on late 60s/early 70s cars and trucks? All I can find is variations on the routing I mentioned above. The two main differences are where the horn relay was mounted, and where the 12-volts was picked up -- starter terminal, horn terminal, or splice.

Happy Motoring!

[RustyPile]

Originally Posted by MikeB

I mentioned the 82 truck wiring as an example of a fuse panel fed by two 12-volt feed wires.

Just in case my eyes and ohmmeter were deceiving me, I went to a factory wiring schematic. It shows a single 12R (red, 12ga) 12-volt feed wire running from the battery, through a fusible link, to the bulkhead panel. Along the way, on the driver's side of the radiator, it connects to the alternator via the splice I mentioned earlier in this thread.

However, the 12-volt feed wire does not connect directly to the fuse panel battery bus, as I said or implied, but instead it runs through the dash harness to another splice (buried in the harness). From that splice, 12ga red wires run to the panel battery bus, the ignition switch, and the headlight switch. So yes, headlight current does not run through the fuse panel battery bus, but it does run through the single 12ga wire feeding the fuse panel, headlights, and ignition switch. So, that feed wire IS a valid place to measure current draw, including headlights, unless relays are used.

Do you have a factory schematic showing two 12-volt red feed wires used on late 60s/early 70s cars and trucks? All I can find is variations on the routing I mentioned above. The two main differences are where the horn relay was mounted, and where the 12-volts was picked up -- starter terminal, horn terminal, or splice.

Happy Motoring!

No, that's not a valid way/place to measure total current draw/demand.. The only place to do that is where the system main feed connects to the battery.. Everything originates there.. Measuring current at any other location could indicate "overlapping" current flow, and/or leaving some out.

Mike, what is it you're trying to accomplish? In your original post you asked about the gauge requirement on the charging circuit.. I've answered that question.. If you're wanting to debate current flow, how or where to take the readings, then, I'm sorry... I'm done here..