Rough idle + voltage mismatch = alternator failure?

[saurabh_goyal93]

Hey all, had a quick question. My car was running a little rough on idle sometimes, very intermittent so one of the mechanics put a scan tool on it and while there were no codes, he noticed that the scan tool was reading battery voltage as 12.5v. I got the battery checked by Supercheap Auto & Battery World, and both said that the battery was fine. However, this is where it gets weird. When testing the battery from the boot, it reads 14.5v but when testing it from the positive & negative terminals in the engine bay, it reads 12.5v. Could it be the alternator or should I get something else looked at?

If it is the alternator, does anyone know the part number of the OEM alternator? or is a high amp alternator the way to go?

It's a 2016 Caprice w/ 6.2L LS3 Auto with 260k kms.

 

[Immortality]

That sounds like a wiring problem. Voltage should be almost identical anywhere in the system.

Start by checking/cleaning the battery terminals etc.