Dead Battery!

Bat Drain

The new regulator will take care of the main drain.

Unfortunately, E9s charging system is a crossover. That means the diodes are inside the end of the Alternator if original type. Check yours and see. One of the many diodes ( excitor) is causing the red light to stay on. You can have it repaired ( New diodes are still available from BMW) or a rebuilt from Autozone shows up as about $45. Napa was higher.
 
Thanks for the info. Will the alternator still charge if the diode is bad? I can live w/ the light for now. I just don't want to have to get a jump every time I go out w/ the car.

Just my opinion - I don't buy anything from Autozone - typically cheap parts and inexperienced personnel. Everyone in my NAPA store has worked in the business for 10+ years and are true professionals in addition to the fact that they can get a decent amount of the basic OE parts for my cars. I would pay a lot more just for the experienced personnel and I really don't mind paying a little more for a premium part.

Sorry for the rant...
 
bat/gen

Check your voltage again running. Anything over 13v means good things.

The light is a minimum draw-.5watt or less. If you wanted to use the car until you got the alternator fixed, I don't see why not. The caveat is if the car's sitting for long- pull the black plug to stop the slow drain. PIA, but heh, i understand you want to have fun with the new toy/car.

Good luck.
 
Alternator is pumping 13.7 with plug in and running - whoohoo!

So, if I've read everything correctly - I either need to get this diode fixed in the alt or buy a new alt and I will lose the red "L" light - correct?
 
Charging Red Light

Charging! That's a beautiful thing.

Yes. Fix or replace the alternator to make the red light disappear.95% or greater.

On a chance, check/ clean the black plug connections and wires to make sure everything there is making proper contact. 5% or less.

I assume it's a bright glow and not very faint... faint means resistance somewhere in the circuit whereby you can measure the drop in voltage somewhere along the circuit. Cleaning up/ partial connections/ etc.
 
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