High output alternator option for E46 M3's with S54

[CMM3]

With the addition of fans for oil & engine cooling along with an electric power steering pump my alternator was repeatedly failing. With an estimated current draw of around 130 amps it appears that the stock 120 amp alternator was overloaded. I searched the forums and there was some mention of a 140a upgrade that required the connector to be changed.

Working with a great shop locally called Chelmsford Auto Electric located in MA. they where able to find me a brand new BMW OEM Valeo alternator that outputs 160a @3k rpm's, 170a @3.5K rpm's and 180a @ 5k. They were able to cross to the alternator using the voltage regulator part number and told me it was from a 2005 X5.

I tried to find it on Real OEM and could not. But the one they sold me fits perfectly and has the same square plug on the regulator. The only thing that needed to be swapped over was the plastic cover on the back which took about 10 seconds to do with just 2 screws holding it in.

I now see a solid 13.8 to 14.2 volts at the battery with the engine running and all the fans and power steering on, problem solved.

I don't have a BMW part number but if should anyone be looking for to upgrade their alternator you can give this shop a call at 978-649-4448. Ask for Brian and tell him Dan with the BMW Z3 sent you. The part number for this alternator on my invoice is 88004004J and it cost $339 which is a great price.

There may be a core charge but I'm not sure as they took back the 120a output stock version that I bought from them early that failed.

[Onizukachan]

Interesting.
You can also use the 155 amp alternator from a SULEV or 03-04 530. Some 330verts also had them.