Alternator help…

[AuroraGirl]

Often, the starter solenoid IS the junction point. Some older GMs used the horn relay as a junction for most loads other than the starter motor.


Consider "duty cycle". That "125 amp" alternator is putting out twenty amps most of the time; and almost never puts out 125. That's why it's the size of a softball. It's a 30-amp alternator with delusions of grandeur. It can throw 125 amps +/- 10%...for a few seconds.

OTOH, I used to install 100+ amp alternators onto City Buses, and the cabling was enormous, and the alternator was oil cooled and weighed 80 pounds. That alternator put out it's rated power for hours on end driving racks of lights, multiple heater/ac blowers, etc.

I have a suspicion that the chart was intended more for constant loads (City Bus) than for intermittent loads (automobile/light truck.)



A lot of truth to that. Vehicle wiring often does not follow proper standards for voltage drop in a circuit. I was surprised when I took after my Luminas with a voltmeter looking for the three volt loss in the fuel pump circuit. I expected to find a 2+ volt loss somewhere. Instead, I found .1 and .2 losses...everywhere. The wiring was just too damn small for the amperage it was carrying and the length of it all.


The guy is nuts. He's pushing multiple ground cables and an alternator output cable that are bigger than the starter cable.

His 2-gauge starter cable is fairly reasonable. A little excessive, just like we like it. So a 2-gauge engine ground is similarly reasonable because the engine ground and the starter power cable carry approximately the same load--but he's using 0 gauge grounds. The body and frame don't see squat for amperage compared to the starter draw, he's using 0 gauge when 4-gauge (and maybe 6-gauge) would be overkill. And he's using 0-gauge for the alternator output, which is more cable than you could safely hang off the stud on the back of the alternator without additional support. The friggin' stud is threaded for a nut that takes a 10mm wrench! How can you need 0-gauge copper connected to a skinny-ass output stud?

Take the GM-spec cables, increase by "2" gauge numbers. What was 10-gauge becomes 8-gauge. What was 8-gauge becomes 6-gauge, what was 4-gauge becomes 2-gauge. That's all you need most of the time, unless you've got some enormous non-stock electrical load.

Or cable runs* on your last point. A buick lesabre has the battery under the back seat and the alternator can be 127amp AD237

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That car has a LONG wire and high loads are possible, GMs answer to too many loads on their subpar wiring was just having Load Management and Shed features in the DIM as shown above

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My park aveneu goes like 3 feet to the underhood box, like 1/5 or so the distance the box to the battery on a lesabre, and its the same gauge LOL and those also had AD230s more often than a park avenue (105 amps)

I always advise checking those cables and probably like you said going up 2

Old GM ground cables for battery post can be cleaned up to a decent lug to lug cable if they are in ok shape
Power cable probably too, this was a power Iirc

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It was 4 maybe 5 feet long and It had very very low ohms reading and then in a alternator charge wire spot it was .02 drop at the worst , maybe it was .01 but I didnt have a lot of loads on Just Idling. I had to quick repair and the stack of lugs was kinda ghetto looking but seemed to be ok. it switched to chassis ground cable when I got that sorted. The chassis ground was too shot for my liking. lol

 

[AuroraGirl]

I disagree. Batteries should never be in such a condition to pull a full amp rating from the alternator. I can understand needing a heavier charge wire on a semi with mulitple huge batteries, out behind fuel tanks, but not a single battery right next to the alternator in a pcikup.

also I said subpar because GM cables seem to me low quality in the 80s 90s and usually has to do with the crimp fr the lugs, tension on the wire not from gm fault but owner making a damaged spot potentially in insulation, the lugs liking to rust and then resistance builds up etc etc.. plus some are just subpar. 105amp cs130 in a 1992 silverado that uses the heater in winter and radio for low volume fm on the smallest sspeaker package with stock lighting is fine. infact, the alternator could go down in size and still be fine probably.

I have a loaded car and my truck has a 10si on it(GMC) but its getting a good upgrade after I get new plow a frame and sector for the snow plow and fix some wearing u joints etc. Electric plow pump and low speed operation with high spike loads and not super amounts of off time to charge up leisurely, It would also be good to have 2 batteries so the spikes dont ding so much off one
But, of course, thats not most people. Ive had my chassis ground kinda blow in half but it was kinda surprised it lasted so loing

I dont have a pic of it but it was my gpas work
This is some household example of his electrical

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Ive checked. Only one electrical box in the suspended ceiling for the basement, which is most of them in the house, have covers.
Im frankly shocked he used them at all junctions... lol.
He was not worried about fire or longevity or "the next guy" as evidenced by the 11 pieces of rebar he reinforced the wood chute with in the basement wall. Wasnt ever going anywhere in his lifetime.
He was right, and that took a lot of cutting blades LOL

 

[AuroraGirl]

What junction point should you run the cable that goes from the battery to the starter? Every GM I've seen has a straight run to the starter.

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this is an LT1 roadmaster which I have no experience on but apparently they did go to the battery for that one. CS130 probably. Hmm.

 

[Erik the Awful]

I disagree. Batteries should never be in such a condition to pull a full amp rating from the alternator. I can understand needing a heavier charge wire on a semi with mulitple huge batteries, out behind fuel tanks, but not a single battery right next to the alternator in a pcikup.

If the alternator can put out 150 amps, you use wire that can handle 150 amps. Don't under-size your wire.

Take the GM-spec cables, increase by "2" gauge numbers. What was 10-gauge becomes 8-gauge. What was 8-gauge becomes 6-gauge, what was 4-gauge becomes 2-gauge. That's all you need most of the time, unless you've got some enormous non-stock electrical load.

Agreed. I have a 0 gauge wire going to my starter, because that's what I had on hand. If I were buying wire, I'd get 2 gauge.

 

[454cid]

If the alternator can put out 150 amps, you use wire that can handle 150 amps. Don't under-size your wire.

Not for a charge wire. You do remember that not only is the wire smaller, but it's also a fusible link?

 

[AuroraGirl]

Not for a charge wire. You do remember that not only is the wire smaller, but it's also a fusible link?

for clarification, the vehicles which I was talking about use Max- i- Fuses instead of fusible links

 

[Frank Enstein]

Looks like I hook up the sense wire the next time I'm under Frank's hood!

I'm thinking I might try hooking it up to the gauge positive and maybe they won't pulse with the turn signals.

Anybody have any thoughts about that?

 

[454cid]

Looks like I hook up the sense wire the next time I'm under Frank's hood!

I'm thinking I might try hooking it up to the gauge positive and maybe they won't pulse with the turn signals.

Anybody have any thoughts about that?

I've wondered about this too, ever since I started reading about 60's Chevys using the horn relay as a main junction. I wonder how our trucks are wired. I haven't looked at the schematic. I kind of expect to go cross eyed with all the wiring our trucks must have compared to a 60's vehicle. I suspect our main junction would be at the underhood fusebox. When I swapped alternators on my Buick, I went from a 10dn with remote regulator to a 12si with internal regulator, I connected the sense wire to the main positive stud on the alternator, which connects it to the starter which is used as the main junction.... Buick being a GM division back then, and not just a marketing brand, didn't do things the Chevy way.

I'm kicking around the idea of getting an ad244, so wiring kinda comes up in that, since I'd need to swap connectors anyway... my stock CS144 uses the rectangular connector, not the oval. I don't really need to do it... The CS still works, and I already have a spare, so buying an AD244 at stock output really does not get me much except being a neat little project. Instead, I may just upgrade the rectifier in the CS144 and call it good.... check on the bearing too.

 

[Erik the Awful]

Not for a charge wire.

Absolutely for any wire. If you need fusible link (I installed a fuse block), get the appropriately sized fusible link, but don't skimp on the size. If your alternator can provide 85 amps or 105 amps, or you threw a 200 amp alternator in there, you need the wiring to be able to handle the current longer than the alternator. Mine's the factory 105 amp, so I'm good with 8 gauge.

12 Volt Wiring: Wire Gauge to Amps – Offroaders.com provides information and entertainment to 4×4 enthusiasts worldwide

www.offroaders.com

 

[454cid]

Absolutely for any wire. If you need fusible link (I installed a fuse block), get the appropriately sized fusible link, but don't skimp on the size. If your alternator can provide 85 amps or 105 amps, or you threw a 200 amp alternator in there, you need the wiring to be able to handle the current longer than the alternator. Mine's the factory 105 amp, so I'm good with 8 gauge.

12 Volt Wiring: Wire Gauge to Amps – Offroaders.com provides information and entertainment to 4×4 enthusiasts worldwide

www.offroaders.com

LOL, and I too am fine with my factory 8 gauge wire at the 150amps you mentioned. My alternator is more like 120/140.

I was wrong in my thinking as to why the charge wire is always smaller than the others.... it's not because that battery should not require a ton of current to keep charged, it's because the sources are different. For the charging wire the alternator is the source, and for the starter the battery is the source, which can supply a much higher current, requiring heavier wire. My point was that people don't need these giant wires that they tend to buy/recommend, especially for a charge wire that is much more current limited. Thanks for getting me to rethink that.