Battery light is on after Two alternator changes?

I had the alternator replaced TWICE yesterday and still having problems....



I had replaced it only because it was making one heck of a noise.. (bearings went out)... So I took it in and had it replaced today with a 80 amp BOSH alternator. It was charging and checked out ok so I drove home. I made a quick stop (about 20 min) at the store and when I came out and started it up, the Battery light was on..

So I took it back and they changed out the Alternator with another new one, tested it, yep charging.. So i went home again.. came out tonight about 5 hr later, and the Battery light is on again... It's not charging...



What is going on...?? The battery is 2 years old and the only reason for changing the Alternator was because of the bearing noise... Belt is new, Idler pulley is new, engine is quiet at idle.



Any ideas..?? I am stuck until Monday unless I can fix this...



BMW '96 328i e36



Thank you
Battery light is on after Two alternator changes?
Could be damage to battery because of the prior failing alternator/voltage regulator.
Battery light is on after Two alternator changes?
A bad batch of alternators OR a defective battery.



Every year 1.6 million alternators are replaced when it was the battery that was the problem.



Infrequently - a battery cannot be charged.



Quick test: Connect a portable,automatic battery charger, (one with a meter) and watch the meter. If it is set on 8 amps and does not rise to a 4 to 8 amp charging rate or does not show ANY charging rate - then look at a defective battery.



Only if the battery has a full charge of 12.66V - OR - is defective - will the charger not charge.
First open up the battery cap, and check if water is in the cells.

The battery could be the problem.



Next check your belts, are they tight?



I'd go with the battery and have the battery checked out.
I am guessing those were aftermarket alternators rather than new OEM from the dealer. Your experience is why I gave up on aftermarket alternators about 15 years ago. The very high failure rate in the first day of service was too much to stand. From your description it is hard to blame the problem on anything except the alternator - put one in, it works for a while.



At this point a battery charger may be your best friend. Modern chargers are much kinder to batteries than earlier ones and $50 or so can get you a beauty if you don't have one now. I had to replace my old clunker and I am very happy with my Schumacher SE-5212A. As long as you are just driving in town and not running the fan on high with headlights the battery should keep you going.



The alternative is another of what you have... unless they still have your original. At least it worked.