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2002 BMW 530I E39
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Discussion Starter · #1 ·
Hey,
2002 530i

I have been having a battery drain on my car. I keep the charger in my trunk, and when I know I am not going to be driving for awhile, I disconnect the battery and put it on a charger. Nonetheless, if I don't put it on the charger it will die.

I was doing some research online about bmw battery draining, and the BMW Intelligent Battery Sensor was the most popular response. I also saw online that it was part of the negative connection for the battery. To my surprise, my negative connector is a standard connector with nothing extra.

So where is my Intelligent Battery Sensor? Do I have one? If not, what is causing my drain!!!

Thank you,
Stephen
 

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2001 BMW E39 540i Automatic Sedan, 195 K miles
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If possible and practical, do NOT disconnect the battery. Just connect the charger to the posts under the hood, but keep the battery connected.

Best to use a "smart" charger : a charger that automatically switches from charging mode to maintaining mode or winter mode after it fully charges the battery. That is what works for me.
 

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2002 BMW 530I E39
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Discussion Starter · #5 ·
If possible and practical, do NOT disconnect the battery. Just connect the charger to the posts under the hood, but keep the battery connected.

Best to use a "smart" charger : a charger that automatically switches from charging mode to maintaining mode or winter mode after it fully charges the battery. That is what works for me.
good idea, I do use a smart charger
 

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Hey,
2002 530i

I have been having a battery drain on my car. I keep the charger in my trunk, and when I know I am not going to be driving for awhile, I disconnect the battery and put it on a charger. Nonetheless, if I don't put it on the charger it will die.

I was doing some research online about bmw battery draining, and the BMW Intelligent Battery Sensor was the most popular response. I also saw online that it was part of the negative connection for the battery. To my surprise, my negative connector is a standard connector with nothing extra.

So where is my Intelligent Battery Sensor? Do I have one? If not, what is causing my drain!!!

Thank you,
Stephen
You don't have an Intelligent Battery Sensor, E39 models were not equipped with that.
The Intelligent Battery Sensor (IBS) was added to the new BMW E60 5 series in 2004.
 

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2002 BMW 530I E39
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116 Posts
Discussion Starter · #7 ·
You don't have an Intelligent Battery Sensor, E39 models were not equipped with that.
The Intelligent Battery Sensor (IBS) was added to the new BMW E60 5 series in 2004.
that make me feel better as I looked for it to no avail. I will hook up the multi meter
 

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What ever happened with the no heat situation with your car, you never posted again regarding that issue.
Did you find out what was causing the no heat problem or not.
 

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2002 BMW 530I E39
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116 Posts
Discussion Starter · #9 ·
What ever happened with the no heat situation with your car, you never posted again regarding that issue.
Did you find out what was causing the no heat problem or not.
Hey Blue, that is a journey I have not completed. I flushed out my heater core and everything looked good. It appears as though hot water is going into it and coming out of it, which is weird as no heat is coming out of the vents. I have noticed that it appears a bit warmer though not really warm on defrost. This is still a work that is driving me crazy. I am convinced that this bmw is a female and demands my attention :)
 

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A failing Final Stage Unit or (FSU) seems to be the cause of most battery drain situations in E39, E46 and so on equipped BMW vehicles from what I have read. I preemptively replaced mine about a year after having bought my E39.
Does your heater fan actually blow air.
 

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2002 BMW 530I E39
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116 Posts
Discussion Starter · #11 ·
A failing Final Stage Unit or (FSU) seems to be the cause of most battery drain situations in E39, E46 and so on equipped BMW vehicles from what I have read. I preemptively replaced mine about a year after having bought my E39.
Does your heater fan actually blow air.
My heater does blow air though it is cold. I replaced my FSU last year, my fan wasn't turning off when I turned my car off. Did some homework and they said to replace the FSU, so I did and it fixed the fan staying on. I hope it hasn't gone out again.
 

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Wingnut
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if i understand your original post correctly, if after disconnecting the battery, does it discharge on its own? id so, the battery itself is the suspect.
does the car go to sleep after about 16 minutes after shutting down? the way to test for that is to close the doors, windows closed, everything shut off of course, open the trunk and leave the car alone, no door opening, no remote fob usage. the trunk light should go out after 16 minutes or so. if it doesnt, some module isnt allowing sleep mode. do you have the factory radio or aftermarket? or any other aftermarket electronics? if your car is an auto trans, another indication of the car going to sleep is the "P" indicator will go out after the time expires when viewed a window.
 

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Under the lift arms
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So e39's Dont have IBS's *which kindda makes it simpler

what you need to do is a amp draw test
then isolate the circuit that is pulling to much power after it goes to sleep

So how i like to do it is this..

Drop the drivers window, open the trunk, get the battery ready to be worked on (*remove the panel)

walk away for 15 min, when you come back the trunk light will be out

amp clamp the positive terminal



you can either use a clamp, or you can use your terminals, between the battery and the connector *ive seen this done, Id have to mess with it to get it right

but you want the car to go to sleep, and you want to be able to view the amount of amps being drawn after its asleep..

THen you can start pulling fuses to isolate circuits (*probably should have added that the passenger side door should be open the glove box open and the hood lol)

its been a while since ive done this, but you need to figure out whats still pulling power, after its commanded to go to sleep then you can pull that fuse, and figure out what is shorted or what module is smoking crack at night

its kindda time consuming, but not entirely complicated
 

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Wingnut
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or another way is to measure the voltage drop across each fuse to see which one(s) are drawing the most power after the car goes to sleep. that way youre not risking awakening the car by pulling fuses. all that is required is a DMM set to read DC millivolts. linked you to a good site that explains how to do this. and has the chart that tells you what the current draw converts to based on fuse amperage rating.its time consuming, but it works. did this last year on a friends E60, he had the same issue, was able to isolate it and fix, jut took me a whole afternoon in 95 degree weather 90 percent humidity outside in the sun..oh what fun that was.

 

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Hey,
2002 530i

I have been having a battery drain on my car. I keep the charger in my trunk, and when I know I am not going to be driving for awhile, I disconnect the battery and put it on a charger. Nonetheless, if I don't put it on the charger it will die.

I was doing some research online about bmw battery draining, and the BMW Intelligent Battery Sensor was the most popular response. I also saw online that it was part of the negative connection for the battery. To my surprise, my negative connector is a standard connector with nothing extra.

So where is my Intelligent Battery Sensor? Do I have one? If not, what is causing my drain!!!

Thank you,
Stephen
My e60 2004 was draining through the starter motor had to get a new one That was back in 2009 no problem ever since
Good luck
 

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Pull the fuses to your radio, I think there are two of them. See if that helps the battery drain issue. I ate two batteries and had countless drain issues that turn out to be the ground circuit that ran through the battery. Was setting up to do a draw test and when I pushed back in one of the radio fuses I could hear an arcing sound from behind the dash. New radio, never had and issue. Not saying it is your problem but BMW does some strange things with their ground wiring.
 

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So e39's Dont have IBS's *which kindda makes it simpler

what you need to do is a amp draw test
then isolate the circuit that is pulling to much power after it goes to sleep

So how i like to do it is this..

Drop the drivers window, open the trunk, get the battery ready to be worked on (*remove the panel)

walk away for 15 min, when you come back the trunk light will be out

amp clamp the positive terminal



you can either use a clamp, or you can use your terminals, between the battery and the connector *ive seen this done, Id have to mess with it to get it right

but you want the car to go to sleep, and you want to be able to view the amount of amps being drawn after its asleep..

THen you can start pulling fuses to isolate circuits (*probably should have added that the passenger side door should be open the glove box open and the hood lol)

its been a while since ive done this, but you need to figure out whats still pulling power, after its commanded to go to sleep then you can pull that fuse, and figure out what is shorted or what module is smoking crack at night

its kindda time consuming, but not entirely complicated
I like the amp clamp! How much does one of those bad girls run?

Sent from my ONEPLUS A6000 using Tapatalk
 

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If you get a clamp meter, make sure it does DC current. Most are AC current only. The Uni-T UT-210E is kind of a bargain for a low-range DC current meter. It's take some care and you'll notice things like changing it's orientation in the earth's magnetic field will induce an offset, but if you're careful it can read to <10mA.
 

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Hey Blue, that is a journey I have not completed. I flushed out my heater core and everything looked good. It appears as though hot water is going into it and coming out of it, which is weird as no heat is coming out of the vents. I have noticed that it appears a bit warmer though not really warm on defrost. This is still a work that is driving me crazy. I am convinced that this bmw is a female and demands my attention :)
The no heat issue still sounds like air in the cooling system. Are you absolutelypositively100%certain that you've purged the cooling system of all air?
 
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