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Discussion Starter · #1 ·
Hi, after a circus of trying to diagnose other problems I have come to find the issue is a battery drain problem. For background, car runs great and have just installed and registered a BMW battery.
Fitted the battery yesterday and went for a 30min drive. Checked ISTA voltage and alternator current. Got home, with car off battery was 12.6v.
Today checked the battery and the voltage is 12.2v.
Any idea or suggestions on what to check and what to look for is very welcomed.
Will plan to do a battery amp test next Monday over a 4 hour period and see what is found.
 

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Munich Mark - 2014 535XD
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#1 Culprit seems to be the Comfort Access Door Handle/s (If you have). You can usually see some Codes generated when this is happening.

Not knowing what Model you have other items are main wiring issues where some Wire Strands are broken causing loss of good current flow be it + (usually) or - .

I also assume the new Battery was properly registered ?
 

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Discussion Starter · #3 · (Edited)
had some spare time today so performed a current draw test. 12.7v at battery. current draw with everything closed and locked was
0min - 10a for a couple of seconds when I lock the car
0.5min - 7.3a
4min - 3.2a
5min - 0.35a
5.2min - 0.03a to 0.04a
bugger me what is going on. I have a gopro, thinking of recording if over night, what do you think?

updated - spoke too soon, just went out and noticed amp 0.01a but battery voltage down to 12.2v. Am I missing a trick here? New BMW battery just fitted. Have connected the battery charged to the engine bay charge points.
 

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Discussion Starter · #4 · (Edited)
update - checked alternator diode, 0ohm one way and 0.56 the other so have left it disconnected for testing. Also disconnected IBS. Have left the car unlocked and flicked the boot lid lock. Battery is 12.6 and is drawing 0.01a. It has been 53min and no reduction in battery voltage so far. Wonder if it is only when locked.
 

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Discussion Starter · #5 ·
#1 Culprit seems to be the Comfort Access Door Handle/s (If you have). You can usually see some Codes generated when this is happening.

Not knowing what Model you have other items are main wiring issues where some Wire Strands are broken causing loss of good current flow be it + (usually) or - .

I also assume the new Battery was properly registered ?
Hi Munich, yes new battery and registered. It is a F10 525d. Not getting any errors unless battery is flat which causes crank no start.
 

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update - checked alternator diode, 0ohm one way and 0.56 the other so have left it disconnected for testing. Also disconnected IBS. Have left the car unlocked and flicked the boot lid lock. Battery is 12.6 and is drawing 0.01a. It has been 53min and no reduction in battery voltage so far. Wonder if it is only when locked.
0.01A or 10mA is not a lot of current. Your battery is about 100Ah so it would take 10,000 hours to discharge the battery.

If you want to use battery voltage to indicate the state of charge, you need to disconnect the battery. All the voltages you see on tables are for no load. Another rough way to measure the state of charge is connect a charger and measure the time it takes to recharge the battery. If you connect a 4A CTEK charger, and it would charge in a 5 hours. It works out be about 10Ah or so that means your battery is about 90% full (assume you have a 100Ah battery).
 

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Discussion Starter · #7 ·
Hi smokeyy, I have noticed a fully charged battery go flat in 4hours but then sometimes not at all. I have a fully charged battery, disconnected the alternator and IBS, locked the car and will check if the battery drain happens over night. Battery is 105Ah
 

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Nuclear engineer
02/2012 X5 35d M57Y CPO 105K miles NOKIAN WR G3 20K miles
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Hi, after a circus of trying to diagnose other problems I have come to find the issue is a battery drain problem. For background, car runs great and have just installed and registered a BMW battery.
Fitted the battery yesterday and went for a 30min drive. Checked ISTA voltage and alternator current. Got home, with car off battery was 12.6v.
Today checked the battery and the voltage is 12.2v.
Any idea or suggestions on what to check and what to look for is very welcomed.
Will plan to do a battery amp test next Monday over a 4 hour period and see what is found.
BMW provides battery drain analysis in Advanced Vehicle Diagnosis.

DIY electrical troubleshooting is shooting blanks unless one is experienced
 

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Munich Mark - 2014 535XD
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Doug is great ! Sometimes a little hard to understand unless you first take the time to understand the Why before the What ;-)

Page 216+ talks about Parasitic Current Draw really well !

Well done Doug !
 

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Hi smokeyy, I have noticed a fully charged battery go flat in 4hours but then sometimes not at all. I have a fully charged battery, disconnected the alternator and IBS, locked the car and will check if the battery drain happens over night. Battery is 105Ah
I am probably stating the obvious. What condition makes the the battery go flat in 4 hours? If you can answer this question, you can follow this path and find out which part of the car is not shutting off properly.
 

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Discussion Starter · #11 · (Edited)
Left it over night with locked, alternator and ibs disconnected, and voltage has not dropped. Have now connected the ibs and alternator again to see if I can simulate the drain. It is very hard to find out what is going on. Will read the section you are referring too and will perform AC voltage test across battery with engine running. As much as I don't want it to be the alternator will be happy to know the issue.

So after reading noticed the following, turn on all accessories, short drive, unlock and lock, do not disconnect battery to perform current test.
- All F-Series vehicles 9-22 milliamps after 30 minutes
 

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Left it over night with locked, alternator and ibs disconnected, and voltage has not dropped. Have now connected the ibs and alternator again to see if I can simulate the drain. It is very hard to find out what is going on. Will read the section you are referring too and will perform AC voltage test across battery with engine running. As much as I don't want it to be the alternator will be happy to know the issue.

So after reading noticed the following, turn on all accessories, short drive, unlock and lock, do not disconnect battery to perform current test.
- All F-Series vehicles 9-22 milliamps after 30 minutes
The alternator output voltage is controlled by the DME through the IBS. If you have INPA or ISTA, you could change it through the software.
 

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Discussion Starter · #13 ·
so after fitting a new BMW battery, registering the battery, then a couple of long drives, I watched the battery voltage and alternator current on ISTA it looks good with no issues. Then leaving the car over night it goes flat. I have connected my multi meter for an hour and there is not excess current draw. I tried a members suggestion to check the blower resistor and noticed mine was not looking great, so got a second hand one from a wreaker and now the battery does not go flat...weird! So cleaned out the blower box which was full of crap and cleaned the black filter but now have a new problem, the aircond does not work any more.

Any ideas on why aircond does not go cold? if there a reset option or have I blown a fuse or relay?
 

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Munich Mark - 2014 535XD
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Well, I guess backtrack on the Resistor work you did, some sensor or connector must have been disturbed... No codes ?
 

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Discussion Starter · #15 ·
The resistor was really simple to change and checked the vent movements before tightening it all in. I hope it is not an O ring, but a software or electrical issue.
 

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Discussion Starter · #16 ·
i spoke too soon when out to the car and the battery is 12.2v flat. there is something really £$%^ me off with either the climate control or some weird intermittent drain. Its like it drains the battery to 12.2v each time and stops. I am sure there is something triggering it but having trouble in finding out what it is.
 

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Munich Mark - 2014 535XD
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Per Posts #1 is the Comfort Access Door Handles, usually the most used = Drivers Door - wrong side which is right down under ;-) Maybe try pulling that Fuse or measure Amperage across and see what happens... that's if you have that option of course.
 

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How old is this new battery?
Are one of your door handles warm to the touch?
Does your meter have a MIN/MAX button?
How are you doing this draw test? Snap a photo of the setup your using. If your just using a meter then are you disconnecting the battery before the test? This is not a good way to find a draw.
1-take car out and drive for 15 minutes and play with everything.
2-pull car in garage and open but latch all doors including trunk and hood button ( if equipped )
3- hook up DVOM in series.
Hook positive DVOM lead up to battery negative post. Hook DVOM negative up to a good chassis ground free of paint.
If needed you can run a wire from the negative jump post under the hood to the back of the car.
remove the 13mm negative cable connection on the body and leave the battery terminal alone. The goal is not to ever totally break the circuit and also to not disturb the DVOM setup.
if you normally lock the car then lock it. If not then don’t.
Whats your reading?
After car goes to full sleep mode then press MIN/MAX and leave it alone overnight.
In the morning come back and press MIN/MAX again to see the highest and lowest amperage draw readings.

if you find nothing after one or 2 of these tests then hook up the meter to read voltage and drive the car for a while. Sometimes alternators stop producing after they get hot. Lastly voltage is NOT amperage. Have you performed voltage drops on your battery and alternator connections? OEM alternator?
 

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Discussion Starter · #19 · (Edited)
Hi HotGrbg, thank you for the advice and think that by me disconnecting the battery to perform the test is not helping. I disconnected the climate control blower and heater valves and went for a drive and noticed the alternator volts drop only for a second. So went from 14 down to 12.4. Noticed the amps also dropped from 20 to 0. I pulled over and the issue did not come back, everything was fine 14v and 15-20amps, temp 80 and fan on low. Decided to go back home and sure enough it happened again this time drawing the battery down to 12.2 and thus my issue. I then spent the next 4 hours trying to get the alt out but had to also remove the inlet manifold. Noticed the brushes were worn down. Have ordered a second hand alt and lets see if this resolves it... fingers crossed.
 

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Discussion Starter · #20 · (Edited)
ok update, got a low km alternator from wreaker for $350 plus shipping. Was a nightmare to fit but all done. Went for a drive and the voltage drop issue has been resolved but the crank no start happened again. I checked the voltage and it was 12.56v so that should be ok. I noticed after about 6 attempts of trying to start and then waiting for about 5-10min for it to power down I noticed a click or thud sound from the center console, then it started.

1.tried to start and it cranks but no start without any errors
2.wait for car to go to sleep with all lights off including park selector and dash
3.get a click/thud noise in the center console around the gear selector and then try to start and it works. Without the click/thud it does not start

Any idea what this could be.
 
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