Sometimes alternator does not charge battery on startup
New Members
Joined: May 2022
Posts: 316
Likes: 51
From: Mesa, AZ
My Ride: 2006 530xi (Touring)
Be careful when doing ANYTHING in the engine compartment with a running engine (they can bite!) but there's no reason that moving the cables around would be a problem. The one possible exception is if the stud that connects the "big red wire" to the alternator is loose and jiggly, and then snaps off, leaving you with a direct connection to your battery floating around loose. ;-)
Thread Starter
New Members
Joined: Jun 2022
Posts: 11
Likes: 1
From: Romania
My Ride: e60 525d lci
Thread Starter
New Members
Joined: Jun 2022
Posts: 11
Likes: 1
From: Romania
My Ride: e60 525d lci
Voltage changing is normal, though having it drop to 12 volts or below with the engine running isn't. ;-)
I just went through my E60 power management service document, and "it's more complicated" than I thought, with the DME being a pretty large part of the secret sauce that makes a BMW alternator wake up and start working (it contains the "programming" to tell it what to do). The IBS does provide some info, though I wouldn't swear it could cause the symptoms you're seeing. Is the IBS still unplugged?
I can send you the service document so you can get a feel for just how complicated BMW has made the charging / electrical load systems in these cars (kind of astonishing). The document is about 700kb in size (I think that's OK to send as an attachment in the messaging function here).
That said, the most common failure IS with an alternator, and my "wiggling cables" is still a very valid suggestion. If you can cause the symptom to cut in and out by moving a given cable, you're close to finding the culprit.
I just went through my E60 power management service document, and "it's more complicated" than I thought, with the DME being a pretty large part of the secret sauce that makes a BMW alternator wake up and start working (it contains the "programming" to tell it what to do). The IBS does provide some info, though I wouldn't swear it could cause the symptoms you're seeing. Is the IBS still unplugged?
I can send you the service document so you can get a feel for just how complicated BMW has made the charging / electrical load systems in these cars (kind of astonishing). The document is about 700kb in size (I think that's OK to send as an attachment in the messaging function here).
That said, the most common failure IS with an alternator, and my "wiggling cables" is still a very valid suggestion. If you can cause the symptom to cut in and out by moving a given cable, you're close to finding the culprit.
Members
Senior Members
Joined: May 2005
Posts: 1,523
Likes: 53
From: Denver, USA
My Ride: 2006 BMW 530xi 6MT
Model Year: 2006
Engine: N52
New Members
Joined: May 2022
Posts: 316
Likes: 51
From: Mesa, AZ
My Ride: 2006 530xi (Touring)
Yep. I'd disconnect everything (after removing the "big red wire" connecting the battery to the engine compartment), clean the connections, and re-fit them. Otherwise, you're going to most likely have intermittent issues again in the future.
Super Moderator
Joined: Apr 2008
Posts: 2,504
Likes: 220
From: San Diego, CA
My Ride: '06 530i N52
Since the IBS isn't connected, it is going to be random charging (open loop). You need to view the battery charge histogram in order to get an accurate assessment.
