540 Rough Idle vs Alternator Charge Rate

[bmw540]

Has anyone experience a rough idle when the alternator is not charging.

I found my idle became very rough to the point the whole car began to shake and loss of power. A friend said to check my battery. I noticed that the battery was in charging mode. i.e. the battery status window is black and not green. I have had no starting issues but to be safe a purchased a new battery and everything including the idle was perfect again.

Yesterday after 3 weeks I have the same problem again and noticed the new battery is in charging mode. I am thinking I should go to an auto electrics guy to get the alternator checked.

Has anyone had this issue and what was the fix.

[BillionPa]

alternator voltage regulator with bushings is my suspect, but the whole thing could be shot. my M60 runs like ass when the battery voltage is even a bit low, i use a trickle charger whenever i can.

i do have a new regulator, but its a total bitch to get to the alternator, so.... maybe when i fix the other engine mount and the steering box.

[bmw540]

yeah will wait to see what the sparky says.

My old man has a 735 e32 which does the exactly same rough idle.

Found some interesting points to check in the bentley manual if I get some time to play.