How do I identify what alternator I have in a '04 Yukon Denali

the same thing applies to many things
say you have a laptop and it came with a 180w charger
and you plug in a 90w charger it will work (or should) but it will take longer to charge and that charger is going to get really hot because it is being worked 100+ % of what it was designed for.
and if you plugged in a 240w charger it is going to still charge the same time or very close to what it did with the 180w only now the charger is under less strain and won't get very warm.
electrical devices are normally designed to only "draw" a specific amperage, to a certain degree, if you plugged in a 600w charger to that same laptop it's going to overload and melt the inverter and likely start burning.

talkyukon said:

I figured it out.
There is a serial number and a stamp that says 145amp on it on the alternator
So its a bosche delphi 145 amp alternator

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The OE 145A alternator has a black "spacer" between the case halves; the 105A one does not have the spacer. Glad you found the numbers on it.

Doubeleive said:

*do not ever increase the fusible link
why? because the fusible link is built to prevent everything behind it from burning up, increase the link and you risk destroying modules, wiring, as well as a risk of fire.
upgrading the charge cable is standard

i should add that simply increasing the alternator amperage does not increase how many amps the vehicle will use, the extra amps just makes it a lighter load on the alternator.
any external/aftermarket equipment requiring more power should be wired separately with it's own wire and fuse's, relays, etc i.e. amps, high power lighting, cb, ham, etc

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Yes. A fuse/circuit breaker in a car, home, factory, spacecraft is there protect THE WIRING. The fuse/circuit breaker is sized to the wiring. The wiring is sized for the load(s) which is anything connected to the wiring that consumes power. If a vehicle came factory with a 145a alternator and you stick a 160a or even bigger in, it will be able to charge the battery up faster than the original 145a alternator because the 160a+ puts out more current (power). Remember power is equal to volts x amps and since the voltage will be the same on the output BUT the higher output current of the "bigger alternator" raises a number up in that power equation which is the current.

As an example:
145a alternator at nominal 13.8v = 2001w
160a = 2208w
200a = 2760w

The bigger output alternators need more stator coils so to be able to house those the rear case halve of the alternator has to be moved further back from the front case halve and spacers are added in between. Some fancy really high output alternators physically are bigger and/or thick front to back and may even require a custom mount for installation.

As @Doubeleive stated, any high power aftermarket devices should be directly connected to the battery (and not run through the fusible link circuit) with its own properly sized fuse, and the fuse should be located near the battery.

Joseph Garcia said:

As @Doubeleive stated, any high power aftermarket devices should be directly connected to the battery (and not run through the fusible link circuit) with its own properly sized fuse, and the fuse should be located near the battery.

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Reminds me of one time EON's ago young and dumb around 1985 or so I had installed a amp in my chevy Cavalier in the trunk and I had probably installed a overrated fuse (best guess)
and me and some friends were cruising the ave and all of a sudden the whole car filled up with smoke like a bomb had gone off. Pulled over and we all jumped out wondering WTF? and discovered my power wire that I had tucked under the carpet front to back had burnt from end-to-end, a big black mark in the carpet all the way down the floor and then across the engine bay to the battery. luckily that's all it did was burn and go out, it was kind of weird in the sense that the entire wire was burnt to a crisp. That was one of those learning experiences that life teaches us.
It went off like a military breaching device is the best way to put it

Joseph Garcia said:

As @Doubeleive stated, any high power aftermarket devices should be directly connected to the battery (and not run through the fusible link circuit) with its own properly sized fuse, and the fuse should be located near the battery.

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Yes, fuse... mis-statement on my part...

Doubeleive said:

Reminds me of one time EON's ago young and dumb around 1985 or so I had installed a amp in my chevy Cavalier in the trunk and I had probably installed a overrated fuse (best guess)
and me and some friends were cruising the ave and all of a sudden the whole car filled up with smoke like a bomb had gone off. Pulled over and we all jumped out wondering WTF? and discovered my power wire that I had tucked under the carpet front to back had burnt from end-to-end, a big black mark in the carpet all the way down the floor and then across the engine bay to the battery. luckily that's all it did was burn and go out, it was kind of weird in the sense that the entire wire was burnt to a crisp. That was one of those learning experiences that life teaches us.
It went off like a military breaching device is the best way to put it

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So you Cheech and Chonged your car but without the pot????

rockola1971 said:

So you Cheech and Chonged your car but without the pot????

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100%

.

Doubeleive said:

upgrading the alternator with a standard system and no changes otherwise may have benefits such as
improved battery charging
maybe a tiny tiny bit brighter headlights and interior lighting
radio may sound slightly more crisp (questionable)
maybe less dimming when the brake pedal is applied.
ac fan might have a smidge more kick
engine "may" maybe run tiny bit better, nothing you would probably ever notice but could perhaps show up on a oscilloscope.
perhaps a .000004 hp increase from less alternator strain
that's really about it, battery health plays a big part in all of that.

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No, none of that. You're just guessing. That would require the tiniest battery and undersized alternator with additional loads that are too much for the stock electrical.
Electrical/THE LOADS, are a pull (what they need, not a push from the battery).


OP
The factory cable from alt to batt + is a fusible link. It is sized for the factory size alternator. If it has too much amperage/resistance then it is designed so that it will burn and break inside the casing, but the case/sheathing will stay intact, in order to prevent a bare wire from connecting off the amp to metal, arcing, and burning your pickup to the ground.
If you're going to upgrade your alt to something larger, you would need to upgrade the charging cable to get the benefit. You would then fuse that cable, and you would want a protected fuse holder.


The cable can be as large as you want. The fuse on the cable, needs to be less than the cable's capability. The point of the fuse is to intentionally create a weak point, that can be controlled, and easily fixed.


I'm mostly pickups, but there are two sizes of alternators, 105 and 130. 105 is a small case, and 130 is the large case. The 130 large case is also, 145, 160, 180, and just about everything else aftermarket. The shape of the two alts are different, and the pulley is in a different spot. The large case uses a serpentine belt that is 3/4" longer than the 105 amp small case. The smaller belt will physically install, on the larger case alt, but will cause more pressure on the alternator, and leads to: hard starting, whining at higher rpm, belt slipping at higher rpm, and poor charging issues. THIS is really why you need to know which alt you have. Personally, you should take the time to find the part number on the belt, and if you wanted, you could always see how to test the output on the alt if you didn't buy it, or own the vehicle since new.
105 came on 99-04, and then in 05 they went from clutch fan to electric fans, and needed a larger 130 amp alt, (might be a little higher on SUVs, the 3 digit K code in the glove box should be your alt size). If you are having bearing noises from the alt, someone may have previously upgraded the alt and not the belt. Replacing the belt to the correct size might solve your problem and be cheaper.

Unless you have aftermarket amps for subs, or have larger draw items in your vehicle like a fridge, or a pump, there's almost no other reason to need a larger alt than factory. If you're not getting voltage drops, then you have all you need.