Battery Charging Malfunction - Code 384A Generator

[houtan]

Was swapping my charge pipe, changing to the N20 tmap, and checking my spark plugs over the weekend. Also reflashed my MHD map to account for the change to an n20 tmap with a battery charger connected. One thing to note, I forgot to disconnect the negative terminal on my battery when I did the work on my car.

So everything went fine, car started right up. Went for a drive and of course it just so happens that a red battery symbol pops up on the dash ten minutes into my drive. (now i am really kicking myself for not disconnecting the battery because all i can think about is that is the cause of my issue!!) When i parked the car, i could hear something electric running under the hood, may have been the water pump. So I disconnected the negative terminal on the battery for a couple of minutes and reconnected it. Noise under hood stopped. Scanned the code - 384A Generator, cleared it. Code didn't come back for the remainder of my 15 minutes of driving. That was sunday.

On monday, drove the car for about twenty minutes to grab some logs, no malfunction light.

Today, tuesday, I drove my car into work, 30 min drive. As i exit the freeway, the same code pops up. Uhhhh, what is going on.

So i connect via MHD, volts with the car off is 11.96 (is this normal after a 30 min drive?), volts drop to 9 ish during cranking, then they go to 13.56 while the car is idling. So it looks like some sort of charge is being sent by the alternator, after some quick googling, it seems like I should be seeing anywhere from 13.5 - 14.4ish while the car is running?. Log of the battery volts is attached (here is a link to log: http://datazap.me/u/houtan/battery-v...log=0&data=3-4 ). You will see the starting volts is 12.53 in the log, but that is because i started and stopped the car just before. When I initially checked the volts prior to the first start, it was at 11.96.

The battery is probably about 2.5 years old, replaced by the dealer. Battery recall complete a few years ago. 50k miles on the car. I dont drive the car everyday, sometimes it sits for a week or two. I try to remember to connect my battery charger to it when i dont drive it for longer than 7 days, but i am not consistent. I also flash map updates, usually without a charger. Finally, the battery sat disconnected for a couple of months while i installed my turbo, back in April/May.

Would appreciate any tips on where to look/how to troubleshoot the issue. I am guessing it could be the battery, alternator, volt regulator (is that a thing), or something with the IBS. I am going to disconnect the battery for at least an hour today while at work to see if that helps? I will also log my drive home to see if anything odd pops up and post the log here as well. Thanks for your help.

[houtan]

So thinking about this some more, it seems the battery charge shouldve been higher after my 30min drive to work, right? Car may have sat for about 30 minutes before i went back and checked the volts via mhd, and that is when it showed 11.96. Does that mean bad battery?

The other thing i thought of if it isnt the battery is, maybe there is a loose connection somewhere? That would explain why it is happening at some point during my drive? Like today, after 30 min, exiting the freeway the malfunction popped up. Maybe a bump loosened a bad connection? Hopefully that will show up in the log on my next drive.

Anyway, hopefully someone else has experience with this that can share.

[houtan]

Ok, so while i was at work i disconnected the battery for about 15 minutes.

About 5 hours later i drove home. Grabbed about a 30 min log to the market. Then another 10 min log from the market to home. Both times the volts was between 14.x and 13.9ish. Starts out higher and then goes down as the drive gets longer. I am assuming that is because the charge on the battery is good?

The other thing is i can't tell if the batter indicator for the one cell is green or black. But if it was black, which means bad cell, would the battery still be able to get to 12.6 volts?

here are two additional logs, all three at the same link: http://www.datazap.me/u/houtan/batte...og=2&data=3-22

http://www.datazap.me/u/houtan/batte...og=1&data=4-22


Hopefully someone can shed some light.

[houtan]

Since I see this is such a hot topic I figured I would post an update lol.

No really, it seems like disconnecting the battery for 10 minutes yesterday did the trick. No more battery warning the last two 30 minute drives. Moral of the story, don't forget to disconnect your negative terminal anytime you work on your car because weird stuff will happen!

[Dackelone]

I think you should load test your battery. To me it sounds like its bad. How old is it?

You should have over +13v with the engine running. Also use a VOM for AC(yep AC)voltage across the battery with the engine running. IF you see more than 1AC volt across the battery... your alternator is bad.

It could also be something with the Intelligent Battery Charging System. Can your scan tool code your battery?

[houtan]

Originally Posted by Dackelone

I think you should load test your battery. To me it sounds like its bad. How old is it?

You should have over +13v with the engine running. Also use a VOM for AC(yep AC)voltage across the battery with the engine running. IF you see more than 1AC volt across the battery... your alternator is bad.

It could also be something with the Intelligent Battery Charging System. Can your scan tool code your battery?

Thanks Dack.

Battery is about 2.5 years old.

Per the logs, I am getting over 13v with the engine running, so I am assuming that is sufficient to determine the alternator is good. does that make sense?

I pulled the CAS.TRC file via ncsexpert last night, just to make sure the charge rate was correctly coded when the dealer replaced the battery 2.5 years ago. It is correct at 90AH since my is a 90AH lead acid battery.

What do you mean by code my battery? I can register via INPA or toolset32, but is that ok with an old battery?

I agree the battery may be bad, or maybe things were wonky because I didn't disconnect the negative terminal on the battery when I was working on the car.

[houtan]

Ok, so the code popped up again. This time i had MHD connected. 35 min drive home, volts via MHD were around 13.8ish. Then as I am getting close to my house cruising at 25mph, the red battery light comes on, i look at my tablet, and the battery volts is at 11.4!! Uhh, what the..

So i pull into the garage, leave the car running, set the voltmeter to DCV, and the volts at the battery is 13.8. I am not exactly sure what you meant by testing voltage across the battery, but i set the voltmeter to acv 750 and it read 28 with the car running.

Shut the car off, was about to go inside and i decided to check one more time. Battery read 13.58 with the car off, start the car and battery reads 15.35 at idle, looking at the app it is reading 13.8 again! Shut the car off, and the battery is at 14.2x and was dropping down real slow to when i took the picture at 14.18 (30 seconds after shut off) and MHD read the volts as 12.62.

Also got 384A - generator and 38A4 IBS missing, as well as a couple other codes but i think that is related to the battery faults.

Please let me know if i did the alternator check wrong. Doesn't it seem weird that the battery is charging the entire drive then all of the sudden 35 minutes into a drive the charging just stops? Stop and restart car and it is charging again?

[houtan]

So thinking about what happened earlier today, the mhd app said battery volts was at 11.4v when the red battery symbol showed up, but with the car still running, the voltmeter said volts at the battery was 13.8. So that would mean the alternator was charging the battery, right?

So I wonder where mhd is getting its battery volt reading from. Because the app said 11.2 and the battery said 13.8. Does that point to bad battery?

I just checked the volts on the battery. When I shut the car off at 4pm today, the battery was at 14.2ish. 7 hrs later it's at 13.37. So almost 1 volt lower than when is that normal?

[Dackelone]

Have your battery LOAD tested.

You said you have 28 ACvolts across the battery with the engine running? IF you have more than ONE ACvolt your alternator is bad.

When I said code your battery, yeah.... I meant register it. Maybe your ecu doesn't know what kind of battery you have when you flashed your car.

To me it sounds like your alternator or your IBS is not setup correctly. You might want to take the car to a pro.

[houtan]

I am the pro! lol jk. I will replace a few items to see if that works before taking it somewhere.

Yeah, I know the first thing I need to do is get the battery tested. I didn't a couple of days ago because the code didn't pop up after my commute home on Tuesday. Didn't show on the way to work Wednesday, then it pops up on the way home Wednesday.

Won't be able to get the battery tested until next week though.

I read that the alternator check you mention above can also mean the voltage regulator is bad and not the alternator. Not sure how I can test the VR separately though. I also just realized my black and decker battery charger has an alternator check function so I can try that as well. https://www.amazon.com/BLACK-DECKER-...ttery+chargers

I can re-register my battery and see if that helps. I confirmed it is coded correctly. What are the setup procedures for the alternator and IBS? If it has to do with coding, I can do it, I cant find any documentation on what needs to be done.

Also, does anyone know where the DME gets the Battery volt readout? I thought it was weird that it was seeing 11.4 volts via MHD app but at the battery I was seeing 13.8 volts via voltmeter.
I am also hoping something similar has happened to someone else and they can share what resolved the problem as well. What really worries me is the issue is not consistent, making it difficult to troubleshoot.

[tracer bullet]

Originally Posted by houtan

What really worries me is the issue is not consistent, making it difficult to troubleshoot.

No kidding!

I had some ideas, but you've already tried them or Dack mentioned them. FWIW I'm really interested in how this ends up. Good luck!

[02Pilot]

Probably not the case here, but in my experience inconsistent electrical problems are frequently caused by grounding problems. Check to be sure that the negative battery terminal is firmly secured and clean, and ensure that any other ground points you disturbed are as well.

[houtan]

Yeah I will check all the connections again, that's what I thought it was at first. They seemed good.

Anyone know any bmw techs that may be able to she share some knowledge?

[Dackelone]

Originally Posted by houtan

I am the pro! lol jk. I will replace a few items to see if that works before taking it somewhere.

Yeah, I know the first thing I need to do is get the battery tested. I didn't a couple of days ago because the code didn't pop up after my commute home on Tuesday. Didn't show on the way to work Wednesday, then it pops up on the way home Wednesday.

Won't be able to get the battery tested until next week though.

You could always just swing by an autoparts store(like Advanced or O'Reillys) and have them test your battery for free.

I bought this $45 tester last year when I was having some battery problems on my e39. The tester can be put in many languages(English, Spanish, French, German) too. It works great.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I read that the alternator check you mention above can also mean the voltage regulator is bad and not the alternator. Not sure how I can test the VR separately though. I also just realized my black and decker battery charger has an alternator check function so I can try that as well. https://www.amazon.com/BLACK-DECKER-...ttery+chargers

You test the Voltage Regulator by measuring stray AC volts across the battery terminals WITH the engine running. Anything more than 1AC volt and your VR is bad. At least that's the way it is on traditional alternators. Not sure about IBS charging.

I can re-register my battery and see if that helps. I confirmed it is coded correctly. What are the setup procedures for the alternator and IBS? If it has to do with coding, I can do it, I cant find any documentation on what needs to be done.

You just need to input what your battery CCA and load is. Look on top of your battery for this data. Then register your battery.

This might sound silly... but are you SURE your battery terminals are tight and free of corrosion ?

Also... did you ever have BMW do the battery cable recall ?

To test for a bad ground... Does your Volt/Ohm meter have a peak hold? Measure DCvolts and set it to "peak/hold", put one lead on the NEG battery post... and the other on the engine or engine bay main ground(s)... (there is one in each corner of the inner fender)... then go start the engine. IF you see more than ONE DC Volt... one of your engine ground straps is bad. Sometimes you can just use ONE jumper cable as a redundant ground and run the test again. (but I don't think this is your problem).


I really enjoy this guy on YT. He's very thorough in his testing to find out what is the failed part. This video might be of interest to you.

Also, does anyone know where the DME gets the Battery volt readout? I thought it was weird that it was seeing 11.4 volts via MHD app but at the battery I was seeing 13.8 volts via voltmeter.
I am also hoping something similar has happened to someone else and they can share what resolved the problem as well. What really worries me is the issue is not consistent, making it difficult to troubleshoot.

Sometimes you just have to wait until things fail totally before you can trouble shoot it.

Might be worth it to talk to a BMW tech and see what his thoughts are. Maybe bring a six pack or two late in the day. That always helps.

Perhaps these pdf's will help you...

.

[houtan]

Thanks for all the info. I plan to take a look later today.

Battery recall was done.

Yeah I agree, might just have to wait til the issue shows itself 100%.

I am a little strapped for time right now, but I did a quick check of the battery volts to see where they are at 24hrs later and it registers 12.06 volts. So yesterday same time it was 13.8 and today it's 12.06. Is that normal?

[02Pilot]

When you're checking the battery voltage, are you taking the surface charge into account? To remove that charge, IIRC (it's been a while since I checked) the BMW procedure is to turn on the high beams for five minutes with the engine off, then wait another five minutes, then test. If you don't do this before measuring, you'll end up with a false reading.

[juld0zer]

Sounds like you may have a BSD problem. That is the communications bus that the IBS, alternator, oil level sensor and water pump communicate on.

When you have multiple faults and all the faults relate to the same bus, that's where you should look first.

FYI when you drive with the IBS disconnected the DME will set the alternator output voltage at 13.7V approx. With a working IBS and healthy battery charged no more than 80% of capacity, idle and accelerating voltage can drop below 11.8-12.8V, but when braking and coasting downhill it will spike to 14.8V. This is all normal, on BMW cars with brake energy regeneration.

It usually takes an overnight rest period for the IBS to correctly and accurately measure the battery. Every time you disconnect the battery, it has to remeasure again. That's why you thought you fixed it when you disconnected the battery for a bit.

[houtan]

Originally Posted by 02Pilot

When you're checking the battery voltage, are you taking the surface charge into account? To remove that charge, IIRC (it's been a while since I checked) the BMW procedure is to turn on the high beams for five minutes with the engine off, then wait another five minutes, then test. If you don't do this before measuring, you'll end up with a false reading.

Thanks. No I wasn't doing that, will try it and post the results.

[houtan]

Originally Posted by juld0zer

Sounds like you may have a BSD problem. That is the communications bus that the IBS, alternator, oil level sensor and water pump communicate on.

When you have multiple faults and all the faults relate to the same bus, that's where you should look first.

FYI when you drive with the IBS disconnected the DME will set the alternator output voltage at 13.7V approx. With a working IBS and healthy battery charged no more than 80% of capacity, idle and accelerating voltage can drop below 11.8-12.8V, but when braking and coasting downhill it will spike to 14.8V. This is all normal, on BMW cars with brake energy regeneration.

It usually takes an overnight rest period for the IBS to correctly and accurately measure the battery. Every time you disconnect the battery, it has to remeasure again. That's why you thought you fixed it when you disconnected the battery for a bit.

Thanks. I read the PDF files dackel posted and that was my takeaway on how the system works.

So is the bsd replaceable? Couldn't find it on realoem. Do you know the location of the bsd? Lastly, any recommendations on how to test it to find out if it is functioning properly?

[juld0zer]

BSD is the communications bus that the items i listed communicate on. Usually people start diagnosis by disconnecting each item one by one and seeing if the fault or symptom disappears. But since you have multiple devices with a no comms issue, i would suggest looking at a global level rather than each device.

Can you tell me what was involved with the N20 TMAP swap? Did you repin anything?

The DME is very close to the TMAP sensor so it may be something simple like a snapped wire to the DME (this is the sort of thing to look for when i say look at a global level). It is either a broken circuit or a shorted wire somewhere. At worst, it could even be the DME but since you have done some software tweaks I'd suggest reverting it to stock before condemning the DME.

[houtan]

Thanks for the reply.

So the multiple faults happened he second time around. The first time the generator code popped up and the only other code was oil level sensor missing. The codes pictured above appeared about a day and half after I disconnected the battery.

The n20 tmap is connected via an adapter that goes from harness b to a. I sprayed everything with maf cleaner and the pins looked good. But I will recheck the wiring, and in the meantime reinstall my stock tmap and map 0 Mhd flash to see if that makes the issue go away. The one thing I did not do when installing the tmap is disconnect the negative terminal on the battery. Other things disconnected and reconnected during that time were the maf, and all six coilpacks.

I will get to look at my car tonight. Haven't driven it in four or five days, so I will check the battery voltage and also take it out to get tested. I hope this is all due to a bad battery!

[juld0zer]

Keep us updated.
Just a side note, the BSD lines for the devices i mentioned are almost all in the same harness cluster as the TMAP sensor. It is unusual for a plug and play adapter to cause something like this however