bmwNewbe 0 Report post Posted April 14, 2010 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. Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted April 14, 2010 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 Quote Share this post Link to post Share on other sites
bmwNewbe 0 Report post Posted April 14, 2010 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. Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted April 14, 2010 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. Quote Share this post Link to post Share on other sites
bmwNewbe 0 Report post Posted April 14, 2010 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.?? Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted April 14, 2010 (edited) 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 April 14, 2010 by *Glenn* Quote Share this post Link to post Share on other sites
bmwNewbe 0 Report post Posted April 14, 2010 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. Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted April 14, 2010 You might be missing my point.... you must do a discharge check in sleep mode. Quote Share this post Link to post Share on other sites
bmwNewbe 0 Report post Posted April 14, 2010 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. Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted April 14, 2010 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. Quote Share this post Link to post Share on other sites
jochen 4 Report post Posted April 16, 2010 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 Quote Share this post Link to post Share on other sites
*Glenn* 854 Report post Posted April 16, 2010 I don't think he has the gear or understands how to do all this Jochen Quote Share this post Link to post Share on other sites
kerry 10 Report post Posted April 16, 2010 had a call today for the same fault, turned out to be the ecu. Quote Share this post Link to post Share on other sites
deeveus 81 Report post Posted April 16, 2010 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? Quote Share this post Link to post Share on other sites
