BMW X5 | Battery drain

Pete Arthur
May 12 2016

Thank you Nick for a well-written and informative article.  Your level of expertise is far greater than mine but I was able, for the most part, to understand and follow your narrative.  I have a 2016 X5 that is six months old, but has only 250 miles on it.  Since I drive it infrequently I keep a float charger attached to the battery terminals in the engine compartment.  (I still haven’t located the battery; I have read that on the older X5 models it is located under the spare tire.  This vehicle has run-flat tires and no spare.  I have looked behind the second row seats, but if it’s there I haven’t found it.)  When I brought my X5 home from the dealership I noticed the battery was heavily discharged (it drew a ten amp charge for about ten hours, then a two amp charge for a few hours after that).  However, even if I leave the garage with a fully charged battery and drive the vehicle for any length of time I have noticed that the battery will still accept a charge after I bring it back to the garage.  This leads me to believe that the battery is experiencing a net negative charge while it is being driven.  I know that the utilization of electricity to power certain components (e.g. electric power steering and totally electric climate control) has increased substantially in newer vehicles; however, I wish the designers and engineers had incorporated an ammeter in the instrument cluster so I could monitor the battery’s state of charge (or discharge) while it is being driven.  Just verbalizing my thoughts and concerns here.  Thanks again for your article.

Jaima
November 14 2011

I too have the dreaded battery drain (2003 bmw x5 auto) I replaced the blower regulator aka fsu but still have a power drain?
I have read that there is another 2 possible causes, 1) the telephone module and 2) the radio/satnav unit, for number “1” pull fuse 74 in the boot/trunk and see how you get on.

terryg
August 27 2010

Nick i like your style,great article!

Nick Hibberd
August 16 2009

With repeated interest over one particular question I thought it appropriate to respond.

If you haven’t guessed by now the focus of these articles is the oscilloscope and its role played in a particular fault-find. With each article I try to include all the key points related to the investigation and make sure these technical facts come across in a reader friendly fashion, at the same time keep them light enough to be enjoyed by readers from all competency levels; this can be a hard balance to achieve. To include everything about everything in a short article just isn’t realistic.

To expand a little on chasing a parasitic draw; there’s no magical quick check here I’m afraid just good old fashioned leg work and thinking the problem through. In this example to get a trustworthy result I relied on many factors which include some of my past recorded notes, time spent determining a normal shut-down pattern, studying the wiring diagram, prioritising test routes where a 5+ amp draw would be possible, and yes isolating circuits by removing their fuse and dealing with the inherited problems. Not forgetting when the fault was absent trying different methods to recreate the fault. This whole process has little contribution to helping someone’s scope proficiency so for good reason it wasn’t elaborated on too much.

I hope no-one was expecting me to reveal a magic wand with a part number, I only need that on French cars.

Enjoy scoping,

Nick Hibberd

Dan Spatig
August 10 2009

I would also like to hear what techniques were employed.

Very interesting article, Thanks.

Pete Boyes
August 05 2009

We had this exact same fault on an 03 X5. I have a friend who is a BMW Master Tech and apparently it is common on early models. Later cars have modified motors.

colin
August 05 2009

once again nick proves the scope is as good as he is

steve jones
August 04 2009

Are you not really talking here of a data logger rather than a true oscilloscope?

Irving
August 04 2009

I too would be interested in these techniques.  I have an Audi TT that exhibits a similar problem.  Only really used at weekends, sometimes can be left 2 weeks and starts fine, other times a day or two and no juice in the battery. So far attempts to track the fault down by the garage have been NFF (typical ‘the computer says there’s no problem’ response).

Shaun O'Neill
August 04 2009

I would like to hear those techniques as well!  You mentioned pulling fuses would not be wise on this application due to all the modules that would go off line then re wake up causing a longer wait. How did you isolate the ac system?  Thanks for a great case study though!

Stewart Horn
June 30 2009

You have stated that Through different tracing techniques you narrowed the search to the AC system. Please can you tell me what these techniques were.