Alternator charging

[SpareParts]

I have a curious issue and it's the same on my sig rig and the wife's 2014 Avalanche, 5.3L
Been going on for months with the wife's truck and had to low of charge to start once a few weeks ago. Jump it and the gauge showed well past 14V for a while. Starting fine ever since.
I notice mine appears to not be charging sometimes but has always started. It does have a new 160A alternator
All battery/alternator connections appear tight and clean on both trucks.
The volt gauge usually shows a hair over 14V on the gauge when they are running. Sometimes they will show under 14V on the gauge. When the gauge shows under 14V i can still hear the alternator making that sound they do when charging.
This is intermittent and i have not been in a position to check voltage with a multimeter when i notice it happening
Until i can diagnose this when it's happening im unsure what it is.
If it was a bad battery it would get worse i believe. I refuse to believe 2 alternators are bad the exact same way with one being new.
Maybe bad connections but i can't find any loose, they all appear clean and none feel hot to the touch.

Anyone else have a problem like this?

 

[Fless]

Do some homework on "RVC." Maybe that's what's going on here.

07 tahoe 5.3 voltage randomly dropping

So my 07 tahoe LT has gone through 2 alternators in the last 3 months. The first one was the original from the factory, so I'm not too surprised on that one going out. The second was a remanufacterd duralast Delco alternator. And that one went out after 3 months. Have my 3rd one on it now, and...

www.tahoeyukonforum.com

 

[tom3]

Yeah, I like this RVC high tech charging system about as much as the AFM engine deal. I'm never sure f it's working correctly or if it just quit charging or overcharging a failing battery.

 

[SpareParts]

I had a 2008 Escalade EXT that would randomly have a too low to start battery. Battery and alternator were new trying to solve the problem.
I did buy a new sensor for that but never installed it as I sold it before I installed it. Maybe I still have it around here to try.
I don't like the system after reading about it but I'm a little leary of just unhooking the sensor but might be worth a try for a few days as a test.

I don't recall if i read it or not but if the sensor is unhooked will the alternator act normally with the demand, (IE) varying the output to match the load?
Think ill brake out the multimeter today or tomorrow and get some factual data on how it works on my 07.

 

[PG01]

 

[Doubeleive]

I had a "similar" issue once, after a bunch of troubleshooting I determined it was a bad battery, but it wasn't completely bad it was just bad enough to make the charging system think it was fully charged but it wasn't. I could turn every single thing on in the vehicle that you can turn on and the alternator refused to increase the output.
had the battery tested and it passed testing, but they said it was "borderline" meaning they wouldn't warranty it. Replaced the battery and everything went back to working normal.
the RVC system works by reading the sensor data and calculating the battery state of charge based on a estimated temperature. In my case even "bypassing" it didn't work.
this was after replacing the sensor and alternator and cables.
If you have a tech2 you can monitor all the charging data and see what it is doing
I had all the data up on the screen and could see it was still in economy mode with the old battery with everything turned on
then with the new battery installed I monitored it again and economy mode was not commanded.
that was 5 years ago, the replacement battery was still working but I could tell it was getting weak when the weather changed this season and I just replaced it again about week or so again. It's pretty common for a battery to start showing it's age or give up the ghost when the weather changes either in the fall or in the spring when the temperature swings up or down.
just food for thought

 

[SpareParts]

I would also be leaning to two weak batteries.
I have a Snap On Solus Pro that should read all the data also. Likewise, I will try the same you have posted above Monday or Tuesday.

 

[swathdiver]

Doesn't sound like a problem at all. If you do lots of short hops, the battery will soon become depleted.

If the battery is tired and not holding a charge, the alternator will run at full output almost all the time to keep you from getting stuck.

When you put a new battery that's been sitting on a shelf for a few weeks, the alternator will run at full output for a few hours to get to know it and to get it fully recharged.

A battery that's been sulfated, can be rejuvenated with a battery tender when the truck is sitting. I got 48 months out of a 30 month battery by doing that once.