Battery drain from Nav

[ANILE8]

I have had this problem for years and my battery would go flat if not charged every few days. So I finally got around to investigating it further while the vehicle is off the road.

This is a real common issue if you do a search. Not just in our cars but all BMW models. My problem was that I was getting a parasitic draw of around 0.5A.

By pulling fuses, I tracked the offending circuit to Fuse 49. This controls the Nav and TCU circuits. Then by pulling modules I found that it was the SatNav drive that was not going to sleep.

Although I no longer use it, I could not pull the Nav Drive because that controls the display screen with other vital info. As I mentioned it was pulling >0.5A when the ignition was off as the module would not go to sleep sometimes.

My solution was to wire in a 5-Pin relay on a switched ignition circuit (I had a spare slot of Fuse #2) to the offending Fuse #49. Now, she sits at 50mA which is considered normal for these cars.

Pin 85 Ground
Pin 86 Switched 12V
Pin 87 Fuse #49
Pin 30 Fuse #49

Hope this helps someone.

[XMetal]

Thanks for posting this - I may need to do this someday.

[Vanne]

Couldent you have just disconnected the Rom drive? Pulled the cable from the back of the drive? or would that have caused an issue? your way works too.

[ANILE8]

Originally Posted by Vanne

Couldent you have just disconnected the Rom drive? Pulled the cable from the back of the drive? or would that have caused an issue? your way works too.

Hi, that was my first preference. But because I have the BMW Professional Nav system with the flip-up screen in the dash that was not really a viable option.

Let me explain; if you disconnect the ROM drive you lose the entire interface to control vital functions such as DSP control, audio preferences, TV Tuner function, trip computer functions, setting of the date, time, fuel consumption data and mobile phone pairing functionality.

From my testing, some of the 'smarts' of this flip-up display system along with the audio system must be located within the Sat Nav ROM drive so if you do remove it you will also lose all of the afore mention functions.

The Sat Nav ROM drive in our cars (if you have this option) is actually more than just a ROM drive if that makes sense. As I remember you could not order the NAV option without the Professional Audio so they obviously designed it as a complete system.

Having said that, I was able to ditch the 6 Disc CD Stacker which didn't seem to affect anything, so I am 2kg better off at least.

[Vanne]

Thx mate, i didnt know that. I used to have that on my car aswell, but pulled the whole thing when the flip up screen lost its backlighting.. I absolutely HATED that nav.. just rubbish..

[XMetal]

Originally Posted by Vanne

Thx mate, i didnt know that. I used to have that on my car aswell, but pulled the whole thing when the flip up screen lost its backlighting.. I absolutely HATED that nav.. just rubbish..

Agreed. I have mine down 95% of the time. But it does come in handy in the boonies on some of my road trips - it doesn't look pretty, but it gets the job done and that's all that matters

[XMetal]

Originally Posted by ANILE8

I have had this problem for years and my battery would go flat if not charged every few days. So I finally got around to investigating it further while the vehicle is off the road.

This is a real common issue if you do a search. Not just in our cars but all BMW models. My problem was that I was getting a parasitic draw of around 0.5A.

By pulling fuses, I tracked the offending circuit to Fuse 49. This controls the Nav and TCU circuits. Then by pulling modules I found that it was the SatNav drive that was not going to sleep.

Although I no longer use it, I could not pull the Nav Drive because that controls the display screen with other vital info. As I mentioned it was pulling >0.5A when the ignition was off as the module would not go to sleep sometimes.

My solution was to wire in a 5-Pin relay on a switched ignition circuit (I had a spare slot of Fuse #2) to the offending Fuse #49. Now, she sits at 50mA which is considered normal for these cars.

Pin 85 Ground
Pin 86 Switched 12V
Pin 87 Fuse #49
Pin 30 Fuse #49

Hope this helps someone.

Did you run an in-line fuse to replace the removed fuse #49? Your current setup appeared to have removed the fuse in the circuit for the NAV?

Also, how were you able to measure the parasitic draw? Did you just removed fuse #49 and insert an amp meter in it's place?

Thanks.

[ANILE8]

Originally Posted by XMetal

Did you run an in-line fuse to replace the removed fuse #49? Your current setup appeared to have removed the fuse in the circuit for the NAV?

Also, how were you able to measure the parasitic draw? Did you just removed fuse #49 and insert an amp meter in it's place?

Thanks.

You will note the relay is powered by Fuse #2 which is fused. Power in our fusebox flows from the top to the bottom terminal.

Therefore I tapped into the bottom side of the fuse and made sure to put this connection back at the bottom side.

To do this I ground down one side of the fuse with a Dremel and soldered a wire.

Alternatively you could just use an inline fuse if you are more comfortable with that. Both methods will provide the same outcome.

Parasitic draw tests should always be performed by putting a DMM in series between the negative battery terminal and ground.

THIS video will give you a good visual on how it is done.

[XMetal]

Note that fuse #2 doesn't actually supply power to the NAV unit, it only energize (trigger) the relay to close the switch and complete the connection (between pin 30 and pin 87 of the relay) that will ultimately power your NAV unit. If you look at the attached relay diagram, fuse #2 will only provide protection for the relay trigger itself since it is in-line with the inductive part of the relay. Your wiring shows no protection for the NAV itself (between pin 30 and pin 87 of the relay) since the original fuse #49 had been removed. You may want to rewire a fuse in-line between pin 87 of the relay and the fuse box to replace the original fuse #49 that was removed in order to protect the NAV.

Thank you for the video link BTW