3rd alternator need help

[Franksauto]

Hi there, I was an auto mechanic and had my own shop for just over 23 years before getting out of it almost 8 years ago. I had very little BMW experience then and even less now. I'm having an issue with my daughters 2010 BMW 328 I X-Drive. About 6 months ago her car died, never did get the full details out of her. anyway the tow truck driver told me it was the battery. Like a fool I went ahead and bought a new after market battery. Well that was my first mistake! Find the problem first and if it is the battery stick with BMW! Found out the battery was only 2 years old and that the alternator was not charging. The parts store where I had done hundreds of thousands of dollars in business in the past had no problem taking the battery back. I replaced the alternator with a brand new aftermarket brand (TYC). Probably another mistake! My Mid-tronics tester was saying excessive ripple detected however the alternator was charging fine at 14.5 volts so I let it go. 2 months later the alternator dies. I replaced with another one and Mid-tronics tester is giving me the same reading, excessive ripple detected still charging fine. That one lasted a week. Now I replaced with a third and ran a ground wire from the alternator to a good frame ground. Same thing excessive ripple detected.
I tested the battery again with the battery disconnected and it says load noise detected, turn off all loads. Battery health is at 50% and charge is low. Can the battery be cooking my alternators? I am going to pick one up anyway (BMW of course) and probably never have to worry about the battery again.

Any thoughts or answers would be greatly apriciated.
Thanks in advance,
Franko-

[RocketSurgeon]

Ok, I'll start by saying that BMW and aftermarket parts don't get along. I'm not familiar with that alternator brand, I think Bosch is OEM.
The charging system is pretty complex. The battery must be coded for capacity and chemistry, and registered. An unregistered replacement battery can cause all kinds of weird issues. The alternator is controlled by the bit serial data bus, so a bad component on that bus could cause bad alternator behavior. Do you have software to read out the BMW codes? You might have a bad intelligent battery sensor or something causing a problem that wouldn't throw a light. I would suggest pulling codes with a BMW specific scanner like ISTA+.