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avoiceoreason 10-04-2012 02:50 PM

A couple of battery questions
 
I am getting an "increased battery discharge" warning.

I have gotten this a couple of times in the past. Once it was something electrical not letting the car sleep properly, another time they told me not to use bluetooth, the last time they told me my driving patterns were the problem but then discovered some issue with the battery itself (can't remember what) and they replaced it under warranty.

So that was about a year ago. Had no problems until the other day. So a couple of questions.

1) I know the alternator doesn't engage (and therefore charge the battery) under a certain speed. What is that speed?

I have a short commute and touch maybe 45 for a few minutes at best. Of course I wasn't commuting at all prior to the last month and the car would go days at a time without being driven (which you would think would be the problem) - no problems - then when I start driving more regularly I get the error.

2) How far away from the car should the key fobs be? And is this a real issue or tilting at windmills? Mine are generally tossed in a bowl about 20 feet away.

3) After the issues the first time around, I have never again used the key to put the top down since this puts strain on the battery. But if the battery doesn't get charged even with the engine on unless it is travelling at a certain speed, is there any difference in battery strain putting the top down with the key vs. when the car is idling?

I have been charging the battery every other night since getting error, but the charge doesn't seem to hold for more than a day or so.

tampamark 10-04-2012 06:22 PM

Sounds like you have a weak battery or alternator. Hard to tell which at this point. The answer used to mostly be battery, but it seems the alternators are going out pretty often now. It is impossible to diagnose over the internet! They can tell if it is the alternator with an oscilloscope. Since you are going to the dealer for another top fix attempt have them check it out!

My wife drives the 6 daily and drives around 7 minutes to work, never more than 45, usually in stop and go traffic. The battery in my car was new when I bought it as a CPO car from the dealer. It failed in 2.5 years. I never had any issues with low battery until it simply failed.

Now, with this new battery, I make sure and put it on a trickle charger at least once a week overnight. This is to prevent failure.

In my case my "non-favorable driving profile" caused the battery to prematurely crap out. Maybe this is also true for you?

As far as keyfob, I have mine about 20 feet away also, never had a problem with that.

The alternator is always spinning, it is not like the a/c compressor with a clutch/brake. It is just at idle the alternator is only providing enough juice to power the car or just a bit under so the battery is being utilized. It isn't until higher rev's that it puts out increased voltage that can power the car's systems and charge the battery at the same time.

Yorgi 10-04-2012 06:53 PM

Quote:

Originally Posted by avoiceoreason (Post 7114049)
...1) I know the alternator doesn't engage (and therefore charge the battery) under a certain speed. What is that speed?

Not sure where you heard that but I am almost 100% certain this is not true. It would mean the car does not charge when at idle and I know it does charge at standstill.

Quote:

Originally Posted by avoiceoreason (Post 7114049)
I have a short commute and touch maybe 45 for a few minutes at best. Of course I wasn't commuting at all prior to the last month and the car would go days at a time without being driven (which you would think would be the problem) - no problems - then when I start driving more regularly I get the error.

The short trips are your big issue. The car stays awake for 30-45 minutes at the end of the trip and drains the battery. If you don't take 30 min trips on a regular basis the battery will eventually go flat. BMW calls it an "unfavorable driving profile" if you take short tips daily and try to blame it on you instead of admitting the majorly screwed up on the design of the electrical system on these cars.

If you battery is going flat in a few days after a charge you have an issue. Either:
1) you are not fully charging it (it will take at least overnight to charge with a trickle charger)
2) the battery is not holding a charge (battery is sulfated and needs replacing)
3) there is an issue with the cars charging system - alternator is on the way out/bad connection to alternator or battery/serpentine belt is slipping.
4) there is some system not shutting off and draining the battery

A good mechanic will be able to determine what is going on. You need someone to hook up the alternator to a oscilloscope to test it. Battery is easy to load test. Most mechanics are too lazy to test that connections are good.

No idea about the fob, I don't have comfort access.

avoiceoreason 10-05-2012 06:22 AM

Quote:

Originally Posted by Yorgi (Post 7114480)
Not sure where you heard that but I am almost 100% certain this is not true. It would mean the car does not charge when at idle and I know it does charge at standstill.

I could definitely be in the wrong here, but I seem to recall it having something to do with BMW trying to save an MPG or two by designing it this way.

Tampamark is likely more accurate in his description when he states that the alternator doesn't put out enough voltage to actually charge the battery at idle. Still curious as to what the trigger/tipping point is for the battery to actually receive charge while driving.


Quote:

Originally Posted by Yorgi (Post 7114480)
The short trips are your big issue. The car stays awake for 30-45 minutes at the end of the trip and drains the battery. If you don't take 30 min trips on a regular basis the battery will eventually go flat. BMW calls it an "unfavorable driving profile" if you take short tips daily and try to blame it on you instead of admitting the majorly screwed up on the design of the electrical system on these cars.

Amen to that! BMW doesn't like to take the blame for any poor design issue IMO unless they are worried they are going to get sued for the issue potentially hurting someone.

And the short trips could be the issue, and I'm sure that will be the response when I take it in. BTW, will they check the alternator proactively, or do I need to request it? Possbile they will just take the easy way out and point to the driving profile and leave it at that.

I am taking it in next week to have them look at it, along with another crack at the top not locked warning, and the battery cable recall. Sometimes I long for my old Honda Civic. :( (not sunny 75 degreee days like today though :thumbup:)

avoiceoreason 10-05-2012 06:27 AM

Quote:

Originally Posted by tampamark (Post 7114411)
Now, with this new battery, I make sure and put it on a trickle charger at least once a week overnight. This is to prevent failure.


The alternator is always spinning, it is not like the a/c compressor with a clutch/brake. It is just at idle the alternator is only providing enough juice to power the car or just a bit under so the battery is being utilized. It isn't until higher rev's that it puts out increased voltage that can power the car's systems and charge the battery at the same time.

So if I understand this correctly, then it would be a greater drain on the battery to drop the top via comfort access vs. while the car is idling. Correct?


Do you (or anyone) have a trickle charger that you recommend? If I have to get the battery replaced, I might try your method and see if that helps. How long has your battery lasted since using this weekly trickle charge approach? And for that matter, how long should the battery last in the first place?

roseng 10-05-2012 07:47 AM

Quote:

Originally Posted by tampamark (Post 7114411)
In my case my "non-favorable driving profile" caused the battery to prematurely crap out.

"non-favorable driving profile". I'm sorry but someone should get an award for this term. I would prefer to think of it as a "non-realsitic design criteria" issue. :rofl:

tampamark 10-05-2012 02:11 PM

Quote:

Originally Posted by avoiceoreason (Post 7115157)
So if I understand this correctly, then it would be a greater drain on the battery to drop the top via comfort access vs. while the car is idling. Correct?


Do you (or anyone) have a trickle charger that you recommend? If I have to get the battery replaced, I might try your method and see if that helps. How long has your battery lasted since using this weekly trickle charge approach? And for that matter, how long should the battery last in the first place?

It is absolutely a bigger drain when dropping the top with the car off as opposed to idle. At least at idle the system is partially able to supply the power. I only say that the car cannot sustain the system properly at idle since it is documented that short drives kill the battery. Obviously sustained driving is required to recharge the battery properly.

It is simple math, the car has so many electronic components that it just can't keep up without having the RPM at higher levels (and therefore the alternator spins faster to generate more voltage). Too much draw for not enough voltage! I know that the compressor will shut off on some cars under extreme load, but the V8 on the 6 wouldn't even acknowledge something as small as an alternator shutting off, hell I can't tell when the compressor kicks on and off. I used to have a 4 cylinder Celica in college that I would use the A/C button like it was a turbo boost. Turn it off and it felt like I had 40 more hp.

I have never checked the BMW, but on my motorcycle when applying a volt meter to it at idle it barely puts out above 12v, at 5,000 rpm (out of a max of 12,000 rpm) it is at peak output of close to 15v. Any higher RPM and the regulator is capping it from going too high.

Others have had the alternator fail in the other direction...the regulator fails which is in charge of capping the voltage that is output so that it doesn't drive the electronics wild or provide to high of voltage to the battery and killing it that way.

Yorgi has provided several recommendations for Battery Tenders, here is a thread that goes over different models in detail along with some recommendations:

http://www.bimmerfest.com/forums/sho...highlight=ctek

Quote:

Originally Posted by roseng (Post 7115344)
"non-favorable driving profile". I'm sorry but someone should get an award for this term. I would prefer to think of it as a "non-realsitic design criteria" issue. :rofl:

:rofl::rofl::rofl:

nupe009 10-05-2012 08:18 PM

I have the same problem. I purchased the BMW trickle charger from the service dept. I use it every now and then to keep the battery charged. My problem is that I don't drive it enough and I don't drive far enough when I drive.

avoiceoreason 10-09-2012 08:01 AM

I dropped it off last night, and my service rep happened to be there. I told him about the error and he immediately went to the unfavorable driver profile defense. In fact he said if that's what the diagnostic report tells them, BMW won't let them do anything else. How riduculous. This is what happened the first time around. They gave me the driver profile defense. Then when it failed again a month later they magically discovered that there was an electrical problem that was draining the battery. Then when it failed again they found the battery itself was faulty.

I should have asked them if their sales reps routinely offer a battery tender as an option. "By the way Ms. Jones, unless you commute via the interstate for greater than 30 minutes daily, you do realize your $100k car won't actually work unless you plug it into the wall with one of these handy devices!" German engineering indeed.

In other news, he also went into the discourse about heat being the issue behind my top not locked error to which I cut him off and said, "nope." I told him to go back and look at my service history and he will see it has popped up at all times/temperatures/seasons. This time - 70 degree, sitting in a garage. I told him not to bother with the TSB since that has been done at least five times and the sensors replaced twice. But given what he said about the battery, I doubt the techs will go beyond the, "well this is what BMW says to do for this error." I pleaded with him to ask his techs to think out of the box, but I am not hopeful.

houbmw-cm 10-09-2012 09:09 AM

Something to consider as well is to have them verify that the Battery you have is coded correctly to the car. When I went in and checked mine after the battery died, I discovered they had it coded incorrectly. They had it coded at 110Ah Lead Acid, instead of a 90Ah AGM. The 6 series is supposed to charge the battery in an "optimum" method, and you are supposed to tell the car when you chnaged the battery as well. My favorite comment by someone here about the "smart" system, was something along the lines of, "if it so smart, why can't it figure out when the battery was changed" GRIN. Come to think of it I had my system reset and software updated at BMW not too long ago. I will have to verify that they have my battery coded correctly too.

I use the C-tek Battery Tender, based on the information I found here on this forum. I have been putting her on the tender once a week as well. She typically responds well to that. I have had a wealth of other problems, of which I'm hoping I will have resolved this weekend. Fingers crossed, yes i am resorting to crossing my fingers, LOL.

tampamark 10-09-2012 09:54 AM

Quote:

Originally Posted by avoiceoreason (Post 7122612)

I should have asked them if their sales reps routinely offer a battery tender as an option. "By the way Ms. Jones, unless you commute via the interstate for greater than 30 minutes daily, you do realize your $100k car won't actually work unless you plug it into the wall with one of these handy devices!" German engineering indeed.

Do you feel like you own a Chevy Volt at times? We should start a commercial about how we only have to plug in once or twice a week and how cool and environmental we are. Wait, our car isn't electric, it is just electrically challenged!

Quote:

Originally Posted by houbmw-cm (Post 7122785)
My favorite comment by someone here about the "smart" system, was something along the lines of, "if it so smart, why can't it figure out when the battery was changed" GRIN. Come to think of it I had my system reset and software updated at BMW not too long ago.

haha, that is my quote!!! During one of my "BMW over-engineering rant sessions"!

http://www.bimmerfest.com/forums/sho...9&postcount=14

avoiceoreason 10-09-2012 11:44 AM

Quote:

Originally Posted by tampamark (Post 7122889)
Do you feel like you own a Chevy Volt at times? We should start a commercial about how we only have to plug in once or twice a week and how cool and environmental we are. Wait, our car isn't electric, it is just electrically challenged!

I actually uttered this line when first presented with the "unfavorable driver profile" line: "If I wanted a plug-in I would have bought a Volt!"

So yes, I do feel that way ... and then find myself wondering why I don't get better gas mileage.

Thanks for the tips/links to battery tender info BTW.

Is it a bad sign that I found myself trolling Porsche and Audi websites yesterday???

tampamark 10-09-2012 12:04 PM

Quote:

Originally Posted by avoiceoreason (Post 7123120)
I actually uttered this line when first presented with the "unfavorable driver profile" line: "If I wanted a plug-in I would have bought a Volt!"

So yes, I do feel that way ... and then find myself wondering why I don't get better gas mileage.

Thanks for the tips/links to battery tender info BTW.

Is it a bad sign that I found myself trolling Porsche and Audi websites yesterday???

Not at all, I am less than impressed with BMW in general. Love the 6, best car I have ever owned or driven, but from a reliability standpoint a complete dud of a brand.

I had a Boxster before this, some will call out the RMS/IMS failure which leads to engine replacement on 911's and Boxsters. But that can be done with a repair if out of warranty. Porsche chooses to change out the engine to save on tearing down to the part, which doesn't seem terribly hairy. And they typically cut a great deal even out of warranty if the RMS/IMS fails. But it was a very reliable car, easy to work on, very nice experience in my 9 years of ownership.

I drove the Audi S5 Convertible and it was a great ride. Very comparable in my mind to the 6, only faster! Less HP but quicker car, go figure. It doesn't have quick the looks or curb appeal though. Anyway, not ready to send my 6 packing yet.

Do yourself a favor and top off the battery every once and a while. It is a nice feeling when I come out to the garage and see the little green light saying I am all charged up, takes the entire night to get there.

avoiceoreason 10-09-2012 12:32 PM

I am definitely going to take a look at the Audi. You're right about the curb appeal, but the upside would be (being in PA) I might actually be able to get to work when it snows.

And, miracle upon miracles! My service rep just called and said they didn't get the "unfavorable driver profile" when they ran the diagnostic. Woohoo! He said the "battery was bad" but couldn't remember exactly what the tech said. Though he did hedge on whether they would replace it under warranty or not, but said he would try.

He did pass along the boesman push and my "sensor wire flip" fix for the top to the tech who apparently said that it didn't make any sense why that would work. Hopefully that gets them thinking. Though after speaking with him it sounds like they are just going to replace the sensor (time #3), which will as always clear the error, so I expect I will be back to boesman/flip mode in another 3-4 months.

Off to Amazon to buy a tender now.

houbmw-cm 10-09-2012 12:37 PM

TampaMark, Glad you found your quote, I could not for life of me remember which discussion that was in. It was perfect though.
And yes it does fee like a damn electric car sometimes. When my last battery was going bad, I had my charger in the trucnk and every where I stopped I woudl plug her in, people would ask, is that electric? HAHA

Avoiceofreason, I seriously considered trading in my 6 for an A5 or S5. I realized that I love this car entirely too much, and wanted to give it another attempt to resolve the issues with her. I'm hoping my efforts this weekend resolve her issues.

avoiceoreason 10-09-2012 01:51 PM

Quote:

Originally Posted by houbmw-cm (Post 7123243)
TampaMark, Glad you found your quote, I could not for life of me remember which discussion that was in. It was perfect though.
And yes it does fee like a damn electric car sometimes. When my last battery was going bad, I had my charger in the trucnk and every where I stopped I woudl plug her in, people would ask, is that electric? HAHA

Avoiceofreason, I seriously considered trading in my 6 for an A5 or S5. I realized that I love this car entirely too much, and wanted to give it another attempt to resolve the issues with her. I'm hoping my efforts this weekend resolve her issues.

I was reading your comments/story in the other thread, and you my friend have far more patience (and technical/mechanical skill) than me.

As I approach the end of my warranty period, which was extended by BMW NA given all my issues, I grow increasingly weary. So far all the problems and trips to service have been an annoyance. Once I have to start paying for it each time I think it will cause me to literally hate the car.

That is why I am considering cutting my losses and moving on. I keep thinking each time that maybe it will finally be better, but then every three months like clockwork, that little red "top-locked" button starts blinking at me as if to remind me I am on borrowed time.

houbmw-cm 10-10-2012 07:26 PM

Quote:

Originally Posted by avoiceoreason (Post 7123362)
That is why I am considering cutting my losses and moving on. I keep thinking each time that maybe it will finally be better, but then every three months like clockwork, that little red "top-locked" button starts blinking at me as if to remind me I am on borrowed time.

That thought process is what has kept me with this car through all of this. I keep thinking this will be it. Truth is I know it will never be it, as I love driving the car, and I hope that this will be all that keeps her from failing on me on occasions. If this works out I'll be happy. I've considered trading her in several times, but I just can't beat the price I paid for her, and I woudl have to pay another $15K to get something newer and most likely turn around and do it all again, so I have opted to stick with it. I do love the car, and hopefully in two weeks I won't be chaniging my mind, GRIN.

avoiceoreason 10-11-2012 11:50 AM

So the good news is that they did replace the battery under warranty. However, the description provided in the paper work has me stumped.

They said the there was a "battery failure" due to an "aged battery". This battery was just put in ~20 months ago, so what would cause it to age? Also, it was noted that the "aged" battery was originally "replaced but not registered." Could not registering the battery have caused the premature aging? If so, I guess that would be why they were willing to replace under warranty (as the last replacement was done at a different dealer).

And finally it says the tech "registered on ISID" and performed a battery "retrofit in ISTA-P". Huh? What does that mean?

Yorgi 10-11-2012 06:55 PM

Not registering the battery can lead to a shortened life. The car starts using a higher voltage when charging an older battery, and if the battery is not "old" this higher voltage will shorten its life.

Exposure to very high or very low temps also shorten the life of a battery. So does letting the battery go completely flat - this really shortens the life.

I find it hard to believe the previous dealer did not register the battery when installing it since they make such a big deal about needing to register.

ISTA/P is BMWs programming software.

avoiceoreason 10-15-2012 07:27 AM

So I got my CTEK-7002 battery charger and was flipping through the manual. One question I had was the normal vs. "snowflake" mode. I had assumed that normal would be the way to go with a brand new battery, but then I read in the manual that the "snowflake" mode was better for AGM batteries.

So which mode should I use for trickle charging on the weekends?

And secondly, it didn't note on my paperwork what kind of battery they put in. I assume it is AGM. Is that the right assumption?

Yorgi 10-15-2012 11:04 PM

Quote:

Originally Posted by avoiceoreason (Post 7134978)
...And secondly, it didn't note on my paperwork what kind of battery they put in. I assume it is AGM. Is that the right assumption?

Great choice on the charger, I think it's the best one available on the market. I have the same model.

The BMW TIS (online workshop manual) mentions to never go over 12.8 volts when charging the AGM battery or you will quickly destroy the battery.

The difference between "normal mode" and "snowflake mode" on the CTEK is a charging voltage of 12.4V vs 12.7V. I think 12.7V is pushing it close to the limit so I would stick to normal mode to be safe.

avoiceoreason 10-16-2012 10:02 AM

Quote:

Originally Posted by Yorgi (Post 7136774)
Great choice on the charger, I think it's the best one available on the market. I have the same model.

The BMW TIS (online workshop manual) mentions to never go over 12.8 volts when charging the AGM battery or you will quickly destroy the battery.

The difference between "normal mode" and "snowflake mode" on the CTEK is a charging voltage of 12.4V vs 12.7V. I think 12.7V is pushing it close to the limit so I would stick to normal mode to be safe.

Thanks Yorgi. Your help and knowledge are always appreciated. :thumbup:


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