Possibly BAD battery??
#31
Super Moderator
Joined: Jul 2011
Posts: 3,707
Likes: 328
From: Augusta, GA
My Ride: 05 530i M54
Model Year: 05 530i
Engine: 3.0 M54
Originally Posted by pavjayt
Thanks Sean for all your leads.
I am a bit confused. At the battery, there are two hot wires, one goes directly to the fuse box in the trunk above the battery and the other one goes to the front. While trying to isolate the drain, I left only the hot wire going to the trunk fuse box overnight while there is no current draw reading I can see on my meter, the battery voltage hasn't changed much by morning. Next day, left the other hot wire going to the front connected to the battery, constant drain of 5A and battery went flat by the morning.
At this point, charged the battery full, kept the hot wire going to the front connected and started with the fuses in glove box, the drain hasn't changed with the same result for the fuses in the engine bay.
Now my question, how do both of these fuses boxes get power? Is it from the same hot wire going to the front from the battery or is this cable solely the one that is being connected to the jump start clamp in the engine bay?
After looking at the wiring diagrams, the second hot wire at the battery is solely going to that jump starting terminal in the engine bay (with probably one connection point in between X2219), but from the symptoms that I am seeing, that is not at fault. Then the cable that I am connecting/disconnecting at that clamp is the only one that goes to starter and alternator. So, it should be somewhere in between, time to trace that cable.
Also, could you please elaborate on what modules you are talking about in the spare wheel well area? Will go through your link now
I am a bit confused. At the battery, there are two hot wires, one goes directly to the fuse box in the trunk above the battery and the other one goes to the front. While trying to isolate the drain, I left only the hot wire going to the trunk fuse box overnight while there is no current draw reading I can see on my meter, the battery voltage hasn't changed much by morning. Next day, left the other hot wire going to the front connected to the battery, constant drain of 5A and battery went flat by the morning.
At this point, charged the battery full, kept the hot wire going to the front connected and started with the fuses in glove box, the drain hasn't changed with the same result for the fuses in the engine bay.
After looking at the wiring diagrams, the second hot wire at the battery is solely going to that jump starting terminal in the engine bay (with probably one connection point in between X2219), but from the symptoms that I am seeing, that is not at fault. Then the cable that I am connecting/disconnecting at that clamp is the only one that goes to starter and alternator. So, it should be somewhere in between, time to trace that cable.
Also, could you please elaborate on what modules you are talking about in the spare wheel well area? Will go through your link now
#33
Anyways, here are my observations, with everything shutdown there is constant 5A drain and if I leave the battery connected, it drains the battery to ~2V by next morning. Anyways after tracking down, it comes down to this cable in the engine bay. If I disconnect it, drain is ZERO, once I connect it back, it goes to 5A.
#34
Thread Starter
New Members
Joined: Oct 2016
Posts: 216
Likes: 1
From: El Cerrito
My Ride: E61
Model Year: 2009
Engine: N54
#35
If it's the alternator, the brushes can be replaced independently of the entire alternator. So, if it's the alternator you can pull the brushes and see if the draw goes away to rule that in/out as well.
The following users liked this post:
pavjayt (02-15-2021)
#37
I can imagine faults in both the alternator and the starter that could cause a 5A draw. Disconnect it at either one, whichever is easier to get to, check again. I would probably bet on the starter if I had to bet.
#38
Thread Starter
New Members
Joined: Oct 2016
Posts: 216
Likes: 1
From: El Cerrito
My Ride: E61
Model Year: 2009
Engine: N54
Ok, I just did a quick check, removed the cable from alternator, drain went down to 0 and as soon as I touch it to alternator, drain went up to 5.6A.
At the moment searching internet on how to test this particular alternator model
At the moment searching internet on how to test this particular alternator model
#39
Thread Starter
New Members
Joined: Oct 2016
Posts: 216
Likes: 1
From: El Cerrito
My Ride: E61
Model Year: 2009
Engine: N54
Quick update
Following up from above, I unplugged the DME connector at the alternator just to rule out this as faulty as well, the drain (5.6A) is the same when I connect the red cable to alternator vs disconnecting it drops to 0A. Proceeded with removing the brushes as Josh above suggested and tested again and the drain dropped to 0A. Here are some pictures of the brushes for reference.
Going to order a replacement now.
If you have any other suggestions, please let me know
Following up from above, I unplugged the DME connector at the alternator just to rule out this as faulty as well, the drain (5.6A) is the same when I connect the red cable to alternator vs disconnecting it drops to 0A. Proceeded with removing the brushes as Josh above suggested and tested again and the drain dropped to 0A. Here are some pictures of the brushes for reference.
Going to order a replacement now.
If you have any other suggestions, please let me know
#40