Any differences with alternators?

[Mike534x]

I'm going to attempt replacing my alternator one more time, but I do have a question since this pertains to the 5.3.

Why I'm looking to replace;

My current one seems to be overcharging the battery, as I found out last week where I discovered battery acid was coating my inner fender and the battery holder. The shop looked over the battery, and replaced whatever fluid was lost and it seems to be in working order. Both keep passing the tests from Advanced Auto, and the shop tested it and found it to be working out as well. I'm honestly at a loss, I bought the battery, an Interstate T7(?) series that comes with a 4 year warranty that seems to cover it. I've taken it to an Interstate battery center, and they won't replace it unless its showing failure. Since it was installed, I've been dealing with issues where it'll drain over the course of 3 days. I've checked and cleaned the grounds in and around the engine bay, by following the manuals in Mooseman's sig. It's honestly becoming a pain, especially Sunday morning while working on the Envoy. It was a little low when I went to the gym, and during the course of starting her up, to turn the wheels while replacing my hub assembly was enough to deplete it. Which resulting in the starter just clicking. So I hooked up the Battery Tender and let her charge over the course of the day. So I'm not sure if the alternator is just not charging the battery enough throughout the drive, or the battery has a weak cell that is just not registering.

The current alternator is a ACDelco 334-2529A refurb, I was looking at Remy or DB Electrical. This is alternator #3, the previous one kept causing my headlights/dash to dim whenever I opened/closed the windows or made my headlights flicker while driving. (I have another thread from 2-3 years ago about voltage fluctuations). Though one thing has me wondering, why is there such a price difference between the AC Delco Alternator for the 360/370 platform versus the ones you get in the Yukon/Tahoe? (if they're interchangeable).

 

[Reprise]

IIRC, the one for my Envoy was 145A, while the one for my Sierra CCSB is 105A. And the Sierra has just about the same 'goodies' that my Envoy has - Bose, full power, heated seats, rear climate, etc.

So there is a difference between those two, at least.
Another reason could be the aftermarket supply -- GM sells 500,000 pickups a year, every year, and an alternator is a wear item -- so maybe there's warehouses full of them - ?

The one I took off my Envoy was still working; I just decided to replace it while I had it off, and it's a spare part now. If the one in the Sierra went (it's a Remy, and I think it's a refurb), I wouldn't have an issue with putting on the old one from the Envoy, until I could get a new one for the Sierra (as long as the pulley was the same size / width, etc.)

 

[Mike534x]

I noticed the amp differences between the models, and I saw GM had a few in the full size trucks that had the same output as the one that came in the Envoy. When I still had my Avalanche, I contemplated swapping the two around to see if the problem followed over to the other truck. From a visual standpoint, and putting them side by side it looked like the pulley was the same size/shape. But I never did the change, since I wasn't exactly sure if they were compatible between the models as long as the specs lined up.

After seeing the price differences, and how the ones for the full size trucks appear to be cheaper was starting to wonder if its worth going for one of those as long as the pulleys matched and the amp met or exceeded the factory one.

 

[northcreek]

There may be other issues besides mounting and pulley size when swapping units since these are not stand-alone alternators. They work in concert with the ECM and are more vehicle specific.

 

[Mooseman]

If you do swap them to something from another year, check the connectors as they did change at some point even if the alternator body is exactly the same.

Is yours equipped with a SARVC on the negative battery cable? If so, try disconnecting it and the alt should work like a normal one. It's suppose to lower amps/voltage when the battery is fully charged and demand is low. Are you keeping an eye on the voltages? Is it higher than normal?

 

[Mike534x]

There may be other issues besides mounting and pulley size when swapping units since these are not stand-alone alternators. They work in concert with the ECM and are more vehicle specific.

I see, so running a full size trucks alternator could in theory wreck havoc on the electronics or at the very least screw with the batteries charging and how the PCM handles everything?

If you do swap them to something from another year, check the connectors as they did change at some point even if the alternator body is exactly the same.

Is yours equipped with a SARVC on the negative battery cable? If so, try disconnecting it and the alt should work like a normal one. It's suppose to lower amps/voltage when the battery is fully charged and demand is low. Are you keeping an eye on the voltages? Is it higher than normal?

I think the connectors changed in 06 or 07, mine does not have the SARVC. My Avalanche did, which made me wonder if that mattered in whether the alternators could be swapped out or not. As far as I can see, the voltage hugs the 14-14.5 mark on the dash. It doesn't experience the 12.5 to 13 drop the old one did, before swapping for the one in place now. The issue itself is very sporadic, it can sit for a few days and be fine and then the battery could be dead or nearly fully drained the following one or two nights after sitting. Each visit to Interstates battery center has shown the battery is low, and they refuse to test it unless its fully charged. It's like a never ending uphill battle Haha.

 

[Sparky]

It sounds to me like the root issue is elsewhere. Battery drain suggests some sort of parasitic draw, but maybe sometimes bad enough that when the vehicle is running it sees it as a large electrical load and is pumping up the alt to try to compensate. Maybe. Just a theory.

I'd test for parasitic draws. Multiple times if needed if it may be intermittent (like a resistive short due to a cracked coupler for example).

 

[Mike534x]

It sounds to me like the root issue is elsewhere. Battery drain suggests some sort of parasitic draw, but maybe sometimes bad enough that when the vehicle is running it sees it as a large electrical load and is pumping up the alt to try to compensate. Maybe. Just a theory.

I'd test for parasitic draws. Multiple times if needed if it may be intermittent (like a resistive short due to a cracked coupler for example).

Are there any usual places I should check first? I did clean and check all the grounds already. Also tackled the ignition switch, as a precaution incase that was the culprit.