Regulators regulate.
12.8 to 15 sounds like what I was reading when I was monitoring mine.
The place that tested the battery could have tested the alternator and starter at the same time same machine.

I think you should be checking the ground connections before you spend more money.

 

A fluctuation in battery voltage doesn't always mean the alternator.
And FWIW. The regulator is NOT in the alternator. It is controlled by the BCM or ECM. (can't remember which )

You could have a ground issue, or the alternator or battery possibility. Not sure how you got the battery tested without a full cycle charge on it. (i.e. it was dead. You jumped it off, then only drove it to get it tested ? )

Anyhow. If you pull the alternator anyway, I would suggest having it bench tested to avoid replacing it for no reason.

 

I have my own tester I'm going to use on friday. Resting batt voltage is 12.8. After thinking about it I think I'm going to check grounds. Do you know where the main is. I haven't looked in search yet but I will soon

 

It's near the battery in the spare tire well.

 

That's a very important piece of info. I thought it was off the alt.
I'm going to do a bench test on the battery friday to be sure. I have the Alt if needed so I'll be checking grounds and the batt as I normallywould. Full charge then load test

 

I believe I remember reading in a thread there is one up front also, I assume it's the engine ground maybe one for the fuse box?

 

https://www.chevyhhr.net/forums/how-...cations-56504/

 

Thank you. You saved me time

 

So I ended up needing a battery. Funny thing is now driving voltage is back to 14.5 pretty constant. No once has it dropped to 12.6v. Pretty odd the way these thing regulate voltage in my opinion.

Did check some grounds also while I was at it and they all look secure.

Thanks guys for your help.

 

You're welcome, drive on!