Dead battery

Fred Owner/Technician California Posted   Latest   Edited  
Resolved
Electrical
2005 BMW 645Ci 4.4L (N62) 6-spd (A6HP26Z) — WBAEK73435B326472
Dead Battery

This BMW will sit for a week the car starts right up. The next day or two the battery is dead. The customer states it has to be jumped every couple days. Our experience has been after a week it starts then perhaps the next day or two it's dead.

Every time I test it for a draw it's fine. Using a current clamp or in series amp meter. 

We had one time the doors locked after a week it was dead, the other time doors were not locked after a week it was dead. 

Odd thing is the alarm would go off sometimes. This happend twice within a hour of locking the car ( battery fully charged) other times after a week of sitting the alarm went off but the car was still able to start fine, then two days later the battery was dead. 

Possible connection between the alarm and dead battery?

Anything you can add would be appreciated 

Fred

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Jesse Owner/Technician
Delaware
Jesse
   

Final stage. Make sure it has proper battery and AH rating. Oh and check with a FLIR camera. Might be easier to spot a hot spot.

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Gary Owner/Technician
Colorado
Gary
 

I'm not a BMW guy, but when I get intermittent battery drains, I connect my old Fluke 187, which has a 24-hour min/max monitoring capacity, to determine the amperage of the drain. If it's 6-8 amps, we're looking at an HVAC, seat, wiper, or similar motor activating. Similarly, if we're looking at 200 mA, probably we're looking at a module. You can do the same with any device capable of…

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Dan Diagnostician
New Jersey
Dan
 

I’d have a focused look at all of the latch and handle inputs to the modules. It’s possible to have a door / hood / trunk switch intermittently sending an ajar message and waking modules and or triggering an alarm.

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Dennis Mobile Technician
Pennsylvania
Dennis
   

Fred, Have you scanned the car (all modules) for fault codes to this point? What kind of draw are you seeing when you have tested it? Its certainly possible something is waking the car up intermittently. A good scanner for these cars should have functionality to perform an “Energy Diagnosis” (BMW term) to tell you which modules have woken the car up over a certain number of key cycles to give…

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Fred Owner/Technician
California
Fred
 

This has a lot of codes, I posted pics. Every time I test for a draw it is .01 or .0 I cleared the codes they don't come back, but after the battery goes dead there are a lot of codes again

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Dennis Mobile Technician
Pennsylvania
Dennis
 

Fred, That DWA code is suspect, I’d have a closer look there. Someone else in this thread mentioned one of the common ways the siren controller fails. Those remaining under voltage faults are most likely caused by the battery voltage itself. Also - your Autel should have the functionality to perform the Energy Diagnosis test. Ones I have used in the past have had it. This will give you a…

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Travis Diagnostician
Texas
Travis
 

I think I’ve seen hood switches cause those issues on that body, driver side up near the strut tower under hood, disconnect and see if the issues continue. Also when you say draw is OK it should be 40 milliamps after 70 minutes

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Louie Technician
New York
Louie
 

Hi Fred check or just replace the engine ground strap also check the aluminum motor mount bracket that the ground strap bolts to for cracks .as These straps age they develop excessive voltage drop that affects both cranking and charging

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Rick Technician
New York
Rick
 

I’ve had quite a few BMW’s with parasitic draw caused by door handles, if it has convenience/comfort access. usually but not always driver’s front. You can tell by which one stays warmer than the others

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Justin Mechanic
Tennessee
Justin
 

The fault code in the DWA (anti theft system) that you have needs to be investigated. It says the fault is currently present and the internal batteries are depleted. There is a siren module on this car that is located behind the rear bumper i believe. It can cause false alarms and also current draws intermittently. Sometimes, the batteries leak out acid onto the circuit board of this siren…

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Richard Technician
New York
Richard
 

I would try running the car on and off with the blower on and then shutting the car off and see if the blower stays on. If so, the final stage is faulty. Could try it several times and maybe you will catch a break and see or hear it fail.

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Timothy Owner/Technician
Wisconsin
Timothy
 

The BMW tooling has the stuff you need. It has the capability to tell you who woke up, and when it happened. I quit trying to do intermittent draws on these. Had one that no-one could solve. Dealer solved it. Tooling (or maybe luck?) solved it. By that time, I learned never to try to find an intermittent parasitic load on a BMW!

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Fred Owner/Technician
California
Fred
 

Thank you for your input, it's definitely intermittent, it sat since Wednesday until today, (Monday) it started fine The customer did take it to the dealer in the beginning with no results. Thanks Fred

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Fred Owner/Technician
California
Fred Resolution
 

This BMW has not acted up for 17 days, alarm has not gone off as well. There is no resolve for this one. Thanks for your help

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