Potential Parasitic Draw 2003 2.5L

[Z4Will]

Hello Z4 Forum! I haven't had the time to formally introduce myself, I'm Will, I'm new to the forum and to BMW ownership. I recently traded my Stage 2 2005 Subaru WRX for a beautiful 2003 BMW Z4 2.5, this car has been a blast to drive so far. Unfortunately, since my recent ownership I have been hit with a few issues related to the car.

Problem:

Wake up in the morning to go start the car and I get nothing. No clicks, no power whatsoever. Of course I have a few choice words in my head at this point.

Solution:

Swapped out battery, clean terminals, problem solved. I Identified the console box light was not turning off, a little bit of duct tape later to tape the switch shut, no more light problem.

2nd Problem:

Same exact thing, no power, interior light manages to light up, but not enough juice to start.

I immediately check to see if the console light was the culprit, there is no indication that this was the issue. I push the car out of the garage and try to get my gf's Volkswagen Beetle to jump it, wait 20 minutes, not enough power, wait another 20 minutes still not enough power. I give up and move on. I purchased a 2nd battery, installed it, everything works fine again.

3rd Problem:

Wake up today same issue, I take my previous "dead" battery, hook it up with some jumpers, my old dead battery from a Lexus I used to have, and used another set of jumpers to connect both of these old batteries to jump it. Wait 20 minutes. Start. Sure enough it fires right up.

After conducting some preliminary research I believe I may have a parasitic draw. I look around on forums, it looks like most of the individuals that posted about an issue with similar symptoms corrected it without informing the internet =(
From what I gather these 2003 BMW's have been known to have head units that stay on by themselves which could be the problem, so I immediately disconnected a fuse related to the cd player. I have no idea if this fixed the issue or not or if I'll wake up tomorrow with another dead battery, I will be looking around for a trickle charger today.

So from what I gather here are some of the potential causes:

Head unit staying on after car is off.
FCR connected to blower
Trunk light sensor?
Bad ground wire?
Shoddy car radio amplifier?

Info about the car:

Manual Soft Top
Manual Seats
Manual Transmission
70k miles
Makes whoosh sound after car is turned off
Slightly hesitant idle (small hiccups, I'm guessing spark plug replacement)


I have no clue, I wanted to believe that it was a bad battery but now on the second new one and this problem still exists. I think a lot of people have been suffering from this same issue. I might be completely off here and have misdiagnosed it, it's looking like I'll have to do a parasitic draw test but I'm not really sure what I'm supposed to do when I identify the problem. I will continue doing research, but I really hope that someone here who has beat his/her head against a wall like I am now can share their experience and help me through this arduous process. Help me get this beautiful black E85 back to its former glory =)

~Z4Will

[bladeowner]

Hi, Welcome!

You could try to see what is drawing the current. - Keep Ignition off. Disconnect battery positive, connect a multimeter on current range (10A) between battery and positive lead. Measure current being drawn and reduce range accordingly. Make sure internal lights etc are off and then pull fuses out one by one to see what's drawing current that shouldn't be.

[BMWZ4MC]

If your car has the same heater blower as the E46 three series then the final stage resistor (aka hedgehog) may be the culprit. When this resistor is faulty, it may manifest itself as the heater fan running at variable speeds or alternatively by allowing the fan to run on after the engine is off flattening the battery.

http://forum.e46fanatics.com/showthread.php?t=713544

[Z4Will]

Update!

Ok, so I have purchased a battery tender and a portable jump starter as well until I can get this sorted, I have noticed that the 10 amp 2 amp maintainer battery tender took approximately 15 minutes to fully charge the battery from the yellow to the green light. I took it out for a spin tonight, there was about a single second of delay in the ignition, but it fired up. I noticed while driving after turning on the AC while it's on a cold setting that there is some variance in the speed, the ac/heater motor definitely makes slightly excessive noise, a steady noise, sounds almost like one of those old wind up toy trucks, I'm assuming the blower motor. It seems intuitive that based on the funny noise from the ac vents, the variable blower motor speed from startup to warm, and the parasitic draw point to the FSR as being the cause. I think this will be my first step. Am I off here or suffering from confirmatory bias?

[Finisterre]

I have a similar problem with my 5.

keep chuntering on. It is helping me work out what approach to take.

currently (npi) I disconnect the battery after use, which is a pain.

[nfarmer]

If your car has the same heater blower as the E46 three series then the final stage resistor (aka hedgehog) may be the culprit.

Our cars dont have a hedgehog

[Danderton]

For the heater issue I had an issue in a previous 3 series which turned out to be a known common issue with a resistor. A bit of googling for bmw heater resistor may be an interesting read.

Also if you think it may be a particular light staying on and draining the battery how about removing the interior bulbs one at a time. Say remove the glove box light bulb and leave it a week or 2, see if battery still dies. If it does try removing another bulb? Long winded I know.


Sent from my iPhone using Tapatalk

[BMWZ4MC]

For the heater issue I had an issue in a previous 3 series which turned out to be a known common issue with a resistor. A bit of googling for bmw heater resistor may be an interesting read.

See the posts above Great minds think alike perhaps

Also if you think it may be a particular light staying on and draining the battery how about removing the interior bulbs one at a time. Say remove the glove box light bulb and leave it a week or 2, see if battery still dies. If it does try removing another bulb? Long winded I know.

Another alternative is to use your phone as a video camera and see if the glovebox or boot light stay on that way

[andrewr]

Are you sure that the alternator is working correctly? If not, your battery will never get recharged and will quickly drain.

Andrew.

[Bing]

Another alternative is to use your phone as a video camera and see if the glovebox or boot light stay on that way

Every once in a while a really bloody good idea falls out your head

Please tell me you've not used that technique to double check an internal suture after surgery though

[scotty597]

I've had 2 problems with my 2005 Z. One you have found already, the centre compartment light....the plastic spigot had broken off leaving the light on all the time. This was never enough to draw down the battery over night.

The second was my business Sat Nav running all the time, only noticed after months or whiring and buzzing after the car was switched off whilst investigating the console light. I pulled the fuse and have not fixed the unit.

Neither of these issues drew enough current to draw the battery down over night. The car even sat for 2 weeks on hols like this and it started ok.

The current draw of any of the courtesy lights, boot/ glove box will not kill the battery overnight.

Have had a boot light help kill a battery in the winter over a number of weeks, coupled with lots of short journeys with heaters, demisters etc all on and the battery never getting a charge to replace what was lost after each cold start. Again this was weeks not overnight.

Its a substantial draw to kill the battery over night, even sidelights left on overnight wouldn't completely kill the battery (My wife did it honest).

Good luck.

[BMWZ4MC]

Another alternative is to use your phone as a video camera and see if the glovebox or boot light stay on that way

Every once in a while a really bloody good idea falls out your head

Please tell me you've not used that technique to double check an internal suture after surgery though

Think yourself lucky I'm not a proctologist.....although if you provide the phone, I'll provide the expertise

[Z4Will]

Update!

Ok so from further observation I noticed that the times when my battery drained were times when I didn't lock the car (garage kept). I listened to my car after a drive from the university and found out that when it was left unlocked I heard a really subtle buzzing noise coming from the left side of the engine bay (if your facing the engine), not on the surface, but a bit lower to the ground, I didn't identify the exact location, just noticed it generally. The sound persisted which I assumed that whatever it was was requiring some sort of power in order to make the noise in the first place. Then after reading some research on individuals with X5's (around the same year range) with similar problems I found that some of the X5 owners had issues with battery draw when their X5 wasn't locked as well as some issues with bluetooth as well. I'm assuming that locking the car allows the car to realize that it needs to start/stop certain processes. I tested this hypothesis, I locked the car while the sound was still going and sure enough about 5-8 seconds after lock the buzzing sound went away. I hope some of this helps our Z4/BMW community a bit. I'm still a bit iffy on whether this problem is the head unit or FSR, the car is not equipped with sat/nav so I can at least eliminate that as a potential cause of this problem. I'm still assuming the FSR since I believe that the location was close to where the sound was coming from though it was rather close to the head unit as well. In January I will have sufficient time to replace the DISA (potentially unrelated) and the FSR, though I have still yet to do a parasitic draw test due to time constraints. So lock your cars everyone, even if your in the garage. The battery tender works great as well to at least alleviate the issue, I feel that it may just be a bandaid but it has been working thus far at least. I may have already solved the problem by locking the car but I have not tested this theory yet by removing the battery tender out of the equation.

[Z4Will]

I can also assume that this is not normal, it seems intuitive that leaving the car unlocked should not drain the battery, but it does at least in my situation and I'm sure others.

[Ewazix]

If your car has the same heater blower as the E46 three series then the final stage resistor (aka hedgehog) may be the culprit.

Our cars dont have a hedgehog

The FSR (part 2) is a well known issue worth eliminating on the E85 as a source of drain