Another discharged battery post (F15 Sdrive35i)

[RossBMWZseries]

Before anyone suggests I take the X5 to a shop, I haven’t simply because I tested positive with Covid. I’ve been told to stay home from work and I’d hate to spread the virus to anyone I come in contact with so trying to resolve the issue at home while I got the time.

About 3 months ago, I started having issues with the Heads Up Display (HUD) intermittently; sometimes it would come on, sometimes not. At times, the X5 would have a week start, but it was very random and rare when it would do that. I figured it’s a 2014 model and 7 years later, a battery upgrade was due. One day it finally died in the driveway. I went to Oreillys and bought an H9 AGM battery, same specs as OEM. Came home and installed it. New battery died within an hour. Perhaps I got a bad battery so I went back to oreillys and got it swapped for a new battery. Went home and installed it; died again within 3 hours.

At this point I’m thinking it’s the alternator. I couldn’t find my Foxwell scanner to check for codes so I bought an OEM alternator and changed it just yesterday. The battery was weak so I gave it a jump and it worked fine. After a few hours, battery died again. I went to oreillys and they gave me a NEW battery again, came home and installed it: died within an hour. I’m thinking it’s the Intelligent Battery sensor (IBS) in the negative terminal as I read it could cause symptoms as exactly what I’m having. I found my Foxwell scanner and pulled these codes below;

8040B1/permanent - Wake-up line to the intelligent battery sensor IBS:short circuit to B+ or line disconnection
CD8E10/permanent - LIN bus: communications fault
805E71/intermittent - under voltage detected

I’m unable to check my tire pressure, TPM is disabled apparently. My date/time resets as well. My only guess it’s the IBS that discharging the battery this quickly. It also didn’t allow me to register the new battery, I believe the IBS is preventing me from successfully registering it.

I want to buy the IBS as it’s really not too pricey but everything adding up, ive spent quite a penny and haven’t resolved the issue. This is my wife’s SUV where we have the car sets for my baby girl, my other cars are not “baby friendly” so I need the X5 to run again once this virus is out of our house. Any insight helps, thank you!!

[Qsilver7]

If you haven't already...click the following link and paste your error code into the "error fault code" search box.

If you get any hits...click on the VIEW link in the FAULT INFO column...perhaps it will help point you in a direction to help with your diagnostics: https://bmwfault.codes/

[RED_Y_]

And you registered the battery, right? Also do you have second aux battery?

[RossBMWZseries]

Thanks Qsilver, let me look it up.


I tried registering the battery but it didn’t let me. It gave me a message saying something about not being able to communicate with the IBS.

My X5 only came with one battery.

[scotty339]

Don't even think alternator until you have the battery registered. The IBS is holding back voltage as it thinks you have a very old battery and is not charging at max Amperage.

Cant even troubleshoot this further until you have a new battery that's registered.

[RossBMWZseries]

Originally Posted by scotty339

Don't even think alternator until you have the battery registered. The IBS is holding back voltage as it thinks you have a very old battery and is not charging at max Amperage.

Cant even troubleshoot this further until you have a new battery that's registered.

My understanding was that even if I didn’t register the battery, it would function anyway but would just shorten the lifespan of the battery by a few years, not actually drain it within an hour. I’m gonna try registering it again but if I’m unable to due to the IBS, doesn’t that mean I’d have to replace the IBS first and then register the battery?

[scotty339]

Your battery has a life. Numbers for example only.

New battery, car will give it 14V or so.
Over time, it goes down as the battery ages. 13.8V... 13.6 ect ect.
Eventually your battery has say 80% and the IBS has said I'll only give you 13.0V because your old.

When you register the battery, it tells the vehicle, okay, new battery, give me all the voltage.

Without knowing what your old battery capacity was at and what state it was in, who knows what the charging system is outputting.

Once you have that all sorted and know you are good to go, then, you can charge up your new battery while in your vehicle and check voltage. Fire it up and check idle voltage. Then do some logging or use your code/sensor reader to do some logging while driving and see what voltages the alternator is putting out while driving.

When you say it goes dead.... is it not clicking over and starting up.... or?
Also, batteries sit on the shelf for a while and the F15 X5 platform is not a great vehicle to charge up a somewhat dead shelf battery.

Can you give these a charge on a bench charger or something else before putting it in?

[RossBMWZseries]

Ahh I see what you’re saying. I’ll do that then. Yea the battery is totally dead, like it won’t even unlock the car. I have to open the door manually, try to start it but does nothing, no lights, no crank, nada, so I then pop the hood, give it a jump at the engine posts, then once it gets juice immediately, I deactivate the alarm and start the vehicle, open the trunk and access the battery. I did tell oreillys to check the battery life before handing it to me. They checked it right in front of me and I had 98%

[RED_Y_]

So far it sounds like you have a faulty IBS which doesn't charge your battery properly and drains it fast, the fact that you can't register new battery confirms it so you probably swapped a working alternator just like scotty339 said.

[M302_imola]

This is concerning to me as within the past 2 weeks my HUD has starting working only intermittently. No slow starts though. Honestly, other than the HUD not working properly there's no indication of weak battery. I certainly don't want to go down the road you have.

[RossBMWZseries]

Originally Posted by RED_Y_

So far it sounds like you have a faulty IBS which doesn't charge your battery properly and drains it fast, the fact that you can't register new battery confirms it so you probably swapped a working alternator just like scotty339 said.

Maybe I spoke too soon: I was now able to register the battery. So now that it’s registered, I went for a drive. No “check engine” light on, but I do have “initialization of driving stabilization” on the cluster with the little traction control logo on. I read the voltage while driving and it averaged 13.8v. Now the real test is to leave the car off, locked and alarm activated, and see if it unlocks and starts in a few hours.

[RossBMWZseries]

Originally Posted by M302_imola

This is concerning to me as within the past 2 weeks my HUD has starting working only intermittently. No slow starts though. Honestly, other than the HUD not working properly there's no indication of weak battery. I certainly don't want to go down the road you have.

Well mine started just with the HUD intermittently not functioning, then the slow starts began towards the very end of the battery life. What’s supposed to be a simple battery replacement turned out into a nightmare and money spending. The bigger problem is I don’t think I’m done spending just yet 😭

[scotty339]

Originally Posted by RossBMWZseries

Maybe I spoke too soon: I was now able to register the battery. So now that it’s registered, I went for a drive. No “check engine” light on, but I do have “initialization of driving stabilization” on the cluster with the little traction control logo on. I read the voltage while driving and it averaged 13.8v. Now the real test is to leave the car off, locked and alarm activated, and see if it unlocks and starts in a few hours.

Take it for a long drive and try and keep your foot off both pedals when you can. If you have the 6WB cluster can you see when you are getting voltage from the alternator. You'll see when it kicks on and off if you can graph it out. The battery is not charged when on the gas, or during initial braking, only during the middle no throttle / no braking will the it send some voltage. Fuel efficiency took #1 here in design.

Take the vehicle out for a good drive if you can and try and get some voltage into the battery or hook it up to a trickle charger if you can. This will give your battery the best start.

I have the OEM battery and both are going into their 8th year (MFG 04/2014) I try and hit the with a charger as often as I can. My intermittent HUD issues were resolved by keeping the voltage high. Coming back overnight, the HUD would always work fine, but after a short drive or a quick restart or on off, where the vehicle never fully shut down (after the 15 min till sleep mode) the HUD would 50/50 be on or off. The dealership said a new 6WB cluster would fix it....

A short 5KM drive with heated steering wheel, heated front seats and rear defrost in -40C....wont be getting anything replaced into the battery from the alternator, I can see the battery discharged light if I do that.

Happy you got your issue sorted.

Keep driving, the light will go off eventually.

[RED_Y_]

Originally Posted by RossBMWZseries

Maybe I spoke too soon: I was now able to register the battery. So now that it’s registered, I went for a drive. No “check engine” light on, but I do have “initialization of driving stabilization” on the cluster with the little traction control logo on. I read the voltage while driving and it averaged 13.8v. Now the real test is to leave the car off, locked and alarm activated, and see if it unlocks and starts in a few hours.

You might need to do a calibration of the steering, I had same problem after battery disconnect and it did not go away
https://f15.bimmerpost.com/forums/sh....php?t=1683268

[RossBMWZseries]

My issue isn’t sorted yet. I went for a drive as you suggested and the message went away but now I have the logo for check engine. I went to oreillys and they checked the battery, they said it was good. They checked the alternator and stated that it was only pushing 12.6v so they said the alternator was the culprit but I just replaced it for a new one yesterday. I pointed out the IBS possibly being the issue and one of the guys asked me if I had done work on the pulleys or tensioner to be exact. A month ago I replaced the tensioner and idler pulley. He said that if I left the tensioner a bit loose it could be the reason for the lower voltage provided by the alternator.

At this point I’m not sure what to do.

[Tomcat_F15_STL]

A very bad idea listening to ANYTHING a local parts store has to say about a BMW. It is advanced alien technology compared to the Ford, Chevys & Toyotas they are used to. Seriously.

The voltage the alternator is outputting may be entirely appropriate based up what the vehicle is doing and the state it believes it is in.

I recommend you find a local Independent BMW specialist to help you. You will likely keep bleeding money as long as you listen to the unwashed and seek a quick fix.

Good Luck.

[MH20jy]

Originally Posted by RossBMWZseries

My issue isn’t sorted yet. I went for a drive as you suggested and the message went away but now I have the logo for check engine. I went to oreillys and they checked the battery, they said it was good. They checked the alternator and stated that it was only pushing 12.6v so they said the alternator was the culprit but I just replaced it for a new one yesterday. I pointed out the IBS possibly being the issue and one of the guys asked me if I had done work on the pulleys or tensioner to be exact. A month ago I replaced the tensioner and idler pulley. He said that if I left the tensioner a bit loose it could be the reason for the lower voltage provided by the alternator.

At this point I’m not sure what to do.

Did you get the check engine code? If not, buying one from amazon will save you a lot money.

[BMWdmk]

Originally Posted by RossBMWZseries

My issue isn’t sorted yet. I went for a drive as you suggested and the message went away but now I have the logo for check engine. I went to oreillys and they checked the battery, they said it was good. They checked the alternator and stated that it was only pushing 12.6v so they said the alternator was the culprit but I just replaced it for a new one yesterday. I pointed out the IBS possibly being the issue and one of the guys asked me if I had done work on the pulleys or tensioner to be exact. A month ago I replaced the tensioner and idler pulley. He said that if I left the tensioner a bit loose it could be the reason for the lower voltage provided by the alternator.

At this point I’m not sure what to do.

what was the code that triggered the recent check engine light?
Is the HUD and electronics working properly after battery registry?

[scotty339]

Picture posted. Relevant for OP. Credit to Qsilver7, as always, hahhaah.

Whats the fault code? Pull it with BimmerCode / ISTA and preferably not a generic code reader.
AutoZone are not BMW experts. Alternator trouble shooting could be done on older vehicles with a multi meter under the hood checking out the battery, and if you were extra keen, the alternator posts.

On these F and G series BMW's, you really need to go about it the computer way. BimmerLink can pull those data codes for you or a friend with ISTA can look at the readings to see if you Alternator is working accordingly.

[RossBMWZseries]

So the ultimate test was to let the X5 sleep (alarm activated) all night. This morning I hit the key fob to unlock it but no juice, totally dead again. I jumped it again from the engine bay and all back to normal, HUD up and running as well as all other electronics. I took my Foxwell scanner and got a few codes, most of which it pointed to under voltage going on and affecting a few systems. I cleared them all and the ones that don’t seem to go away are:

8040B1 (permanent): Wake up line to the IBS-short circuit to B+ or line disconnection
CD8E10 (permanent): LIN Bus - communications fault
B7F339 (intermittent): TCB Undervoltage detected

[Ascotgrun]

At this point it seems changing the IBS is the next move, unless you just trade the car in.

[scotty339]

Originally Posted by RossBMWZseries

So the ultimate test was to let the X5 sleep (alarm activated) all night. This morning I hit the key fob to unlock it but no juice, totally dead again. I jumped it again from the engine bay and all back to normal, HUD up and running as well as all other electronics. I took my Foxwell scanner and got a few codes, most of which it pointed to under voltage going on and affecting a few systems. I cleared them all and the ones that don’t seem to go away are:

8040B1 (permanent): Wake up line to the IBS-short circuit to B+ or line disconnection
CD8E10 (permanent): LIN Bus - communications fault
B7F339 (intermittent): TCB Undervoltage detected

Id be curious what the voltage was on the battery was before going to bed and what it was upon wake up causing a no start condition. You can either leave your trunk open and pull the battery cover and measure or use the hood posts as you only have one battery. Leave the hood / trunk open and after 15 minutes vehicle will go into sleep mode. Hazard triangle on the dash will dim out from its normal illuminated red.

Normally, from this "sleep state" is when you should pull the battery and swap out the connections. Did you do this or was it still "hot" when swapping? These weird little steps on these German cars with far too complicated electronics can help prevent some problems like you are experiencing.

Did you double check the connections upon reinstall? 8040B1 and CD8E10 both sound like you have a bad connection somewhere with the last code just showing the low voltage causing the no start condition.

Possible that something shorted when hooking up the battery?
Double check those connections.