Charging confusion l322

Hi all
I've had my first real issue with the l322 supercharged after 2 years of owning (I know I've done well) so last week my alternator died although I think it had been going for several months intermittently. So I've put a new alternator on at first all seemed good until I left the car idling for 10 mins then I got the red battery symbol and low voltage 11.8v. which varied upto around 13v when running. so I've had a look today to try and figure out what's going on alternator seems as if it's charging OK but after loading it drops off as if its not charging at all I tested all cables they seem OK and even though it didn't seem like or show any symptoms I changed the battery just to rule it out. Could the bms cause the issue after changing the alternator/battery? is it just learning to charge the new battery? Or could it be more sinister like a fault with the stimulator feed to the alternator?

any ideas, clues or information would be greatfully recieved as it has my head firmly stuck in the shed

Have you told the car or has a new battery and it's capacity?

kermit_rr said:

Have you told the car or has a new battery and it's capacity?

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No I haven't would that cause the charge issue

The car will request a different charge profile depending on the age of the battery and how well it holds charge. If you don't tell the car it has a new battery then can over put under charge and generally get confused, though it might learn the right profile eventually.
Will it cause the battery light to come on? Honestly don't know. On the flip side, i would expect the bms/alternator to either fail or not