Just picked up my first mini, 06 S with 70k. Service has been kept up fairly well. Prior to my purchase the alternator was replaced for a 2nd time in the 70k. The battery was replaced 2 years ago with a DieHard platinum AGM.

When I hard accelerate with the AC on the battery light kicks on until I let up. If the AC is off l, no battery light. The light doesn't come on at idle. Power steering seems fine.

I checked the voltage with a gauge in the cig lighter. 13.7 at idle. 13.1 with AC on, sometimes dropping down to 12.5. I charged the battery up to 12.75, shortly after it settled at 12.3. After a drive it settles at 12.3.

I have a 15% reduced pulley. it seems like the car was built with having an underpowered alternator - cases of PS pumps going out when the alternator dies. So is the issue with the new alternator or something else?

Thanks all!

 

Slipping belt???
Just a guess.

 

+1
Sounds like a slipping belt.
With the reduction pulley, you need a belt that is shorter than stock. Make sure you have the right one installed.

 

I also have a few modest performance mods on my 04 R53 including a 15% SC reduction pulley.
If you come to determine that your belt might be slipping; here is I've been running with great results with my setup for the past 3years.



Best of luck.

 

Yes, if it has the stock belt, it will be too loose. I have had the same Alternator since 2005 ( 170K ). I run a Dinan 17% Pulley with the correct belt. It may also be a bad tensioner. Get a new belt, and new Tensioner, do them together.

 

Thanks all, you rock. I actually just purchased the K060535 belt and the belt tool. I will get a new tensioner.

Speaking of tensioner - is the best/easiest way to remove the PS mount and raise the engine up 4 inches or so to access all the bolts holding it on?

 

Have the battery load tested. On the e46, an 11 month old Die Hard Gold ( non agm ) died hard.

 

Have the battery load tested. On the e46, an 11 month old Die Hard Gold ( non agm ) died hard.