Jump to content
Sign in to follow this  
bmwNewbe

e46 320d flatening batterys

Recommended Posts

hey guys new to the site and new to bmw in genral so hope this is posted in the rite place, bought my first bmw an e46 320d but my problem is that if it sits for 2 days then the batterys dead. if i start and give it a drive every day then its slugish to turn over but it starts. i do work on cars but have very little exp on bmw,so i checked the usual suspects, nothing i can find staying on door lights etc,the charge rate from the alternator is good and only about 0.06volt drop down to the battery which is good,discharge from the battery itself is ok plus ive also tryed it with 2 other batterys and sill happens. all in all im a bit stumped as i dont relly know the common faults for this car yet. any help would be great.thanks.

Share this post


Link to post
Share on other sites

You need to do a battery discharge check, which is not straight forward. Also scanning the vehicle may also lead you in the right dirrection. Where are you from ?? might pay to update your profile... it does help

Share this post


Link to post
Share on other sites

You need to do a battery discharge check, which is not straight forward. Also scanning the vehicle may also lead you in the right dirrection. Where are you from ?? might pay to update your profile... it does help

discharge rate from the battery is ok i have a hevy duty tester for diong that and its pritty spot on every time and ive tryed 2 other batterys in the car,ment to say they were both new ones. id be a wee bit to far away from some of you guys,live in nothern ireland,lol.. while looking through the differnt bmw sites this one seamed the best and most helpfull so i signed up.lol.. pluged in to a code reader but nothing came up so ill hada find someone with diagnostics to run checks.. do you know if the carsoft software is any good,if its ok i might buy myself it. thanks.

Share this post


Link to post
Share on other sites

Discharge check has to be done in sleep mode. You need to do this with a clamp meter and it can take up to half an hour for the vehicle to go into sleep mode.... car locked with nothing on and should be <20 mA. If its higher you need to start disconnecting modules to find the fault. Alternators even if they charge correctly can cause this and so do the heater fan resistor blocks.

Share this post


Link to post
Share on other sites

Discharge check has to be done in sleep mode. You need to do this with a clamp meter and it can take up to half an hour for the vehicle to go into sleep mode.... car locked with nothing on and should be <20 mA. If its higher you need to start disconnecting modules to find the fault. Alternators even if they charge correctly can cause this and so do the heater fan resistor blocks.

it was only the battery itself i checked whilst out of the car,the alernator i removed and took to a fella that recons them for me and he found it ok but tidyed it up ect for me before refitting so id say its ok. that leaves modules and the heater resistor, is there any that would be more common to cause discharge.??

Share this post


Link to post
Share on other sites

You must do the discharge check properly with the battery in the car to determine the fault. Doing this properly can be quite time consuming. If you are unsure how to do this I suggest getting your local dealer to do it for you.

Using a carbon pile battery tester will not check what is happening in the vehicle

Edited by *Glenn*

Share this post


Link to post
Share on other sites

You must do the discharge check properly with the battery in the car to determine the fault. Doing this properly can be quite time consuming. If you are unsure how to do this I suggest getting your local dealer to do it for you.

the dealer prices here are quite expencive compared to most other countrys, i do have a doner car i can borrow parts off if theres any common parts you could suggest to change.

Share this post


Link to post
Share on other sites

You might be missing my point.... you must do a discharge check in sleep mode.

Share this post


Link to post
Share on other sites

You might be missing my point.... you must do a discharge check in sleep mode.

i totaly understand glenn and i know thats what i should do but my main perdicament is i most likly dont have all i would need to do the test and the method, most cars here never need this done and the dealers here is total daylight robbery well over 100 pounds an hour. but i have the doner car which is same year and same spec but a total loss so i have bought it for spares and it runs perfect it sat for 2 months never started so has not got this problem as started it yesterday 1st turn of the key, so i am able to change one part at a time to it stops,also have another car so have no need to drive the bmw also. plus bing new to bmw its perfect opertunity to learn the parts inside out.

Share this post


Link to post
Share on other sites

I understand what you are saying, but you really need to determine what is causing it first. Depending on build, the control units from one car to another can be different, even a month build difference can make a difference.

Share this post


Link to post
Share on other sites

i totaly understand glenn and i know thats what i should do but my main perdicament is i most likly dont have all i would need to do the test and the method, most cars here never need this done and the dealers here is total daylight robbery well over 100 pounds an hour. but i have the doner car which is same year and same spec but a total loss so i have bought it for spares and it runs perfect it sat for 2 months never started so has not got this problem as started it yesterday 1st turn of the key, so i am able to change one part at a time to it stops,also have another car so have no need to drive the bmw also. plus bing new to bmw its perfect opertunity to learn the parts inside out.

A few things you can do youself:

1. Ensure the car is entering sleep mode.

How to tell? open the boot so the boot light is on. Close and lock car, and wait. Check how long it takes for the boot light to go off. When it goes off, car is in sleep mode. Note it can take 15min for this to happen

2. Check navigation is powering down. Whilst waiting for car to go in sleep mode, observe the nav unit. The RED LED stays on until 60s after last ibus activity. Then it flashes rapidly (writing to flash) and goes off. If nav never shuts down, this can be a cause of high battery drain.

Alternatively, use my NavCoder and monitor the databus in real time.

3. Disconnect a some non-critical systems and observe response. Eg: disconnect entire audio system by removing all audio system fuses. Observe what happens. Is battery drain still a problem?

4. Check alarm system. Check especially bonnet switch, try disconnecting the bonnet switch and observe what happens

5. Buy a clamp meter ammeter, and clamp to the battery cable.

Wait for car to go to sleep, documenting the current consumption in on, off, and sleep mode

Report your findings here

Share this post


Link to post
Share on other sites

I don't think he has the gear or understands how to do all this Jochen

Share this post


Link to post
Share on other sites

had a call today for the same fault, turned out to be the ecu.

Share this post


Link to post
Share on other sites

Don't want to poke my dumbass nose in here but does the ECU on the E46 have a cooling fan? Is it powering off?

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...