BMW Alsway has an excuse

[nra4.8is]

Oh and as for the retarded ups truck comparison. What electrical demand does a ups truck have! Really! Again un-educated.

And as far as the MSA cars w self start stop, completely new starter design requires less energy w higher output. Again un-educated. Put down the latte and grab a wrench

[JCL]

No reason to blame the alternator or the capacity of the alternator, it has plenty.

Batteries are generally not the issue (although they can precipitate a problem as they get older).

The issue, IMO, is the energy management system. That system decides how much charging is required, and when to charge the battery based on many inputs. It is overly complicated. It is that complexity that breeds problems.

BMW engineers decided that a straightforward voltage regulator wasn't enough. And their solution presumes certain operating profiles which North Americans, who often do drive very short distances, don't comply with.

Anyone doubting this should just read the training materials on the Energy Management System that have been linked previously, and which are posted on this site, and see if they can anticipate any potential problems with this system. It won't take long. Here is a link for those that haven't seen it:

http://www.bmwmotorsports.org/pdf/e7...Management.pdf

35 pages of description of when the alternator will be commanded to charge the battery, or not. Emphasis on the latter, particularly when you consider the impact of various failure modes in the sensors, subsystems, etc.

Compare that to a standard voltage regulator (AVR), which measures the battery voltage and decides whether to run the alternator or not.

The differences in the two scenarios above make comparisons with older vehicles with less sophisticated systems not relevant. Sure, from a user perspective, the battery should be charged. It is a reasonable expectation. But owners are also asking for (or BMW believes they are asking for) more power to the drivetrain, better fuel economy over the full drive cycle, and so on. We got their engineer's response based on their understanding of what we as consumers wanted. If they had also had a line in their design spec that said "Oh, and we want it to be simple, easy to repair, reliable, and repairable at the corner gas station" then we may have gotten an AVR instead of an Energy Management System.

We can't change what BMW designed. But we can accept that if the types of solutions BMW comes up with (and there are lots of similar over-engineered examples) aren't in line with what we as consumers want, then we shouldn't buy the cars. The solution doesn't fit our own requirements in those cases.

I'd wager that if we could look at the DFMEA for the E70 charging system, it wasn't considered that people would drive 3 miles per day with all the electrical accessories in the options book turned on. So when the vehicle was designed (in Europe) for a European audience, and then built in North America and handed over to BMWNA to deal with the fall out, all they could do (since they don't design vehicles in North America) was hand out plug in battery chargers when they had to. That must really suck, for that to be the main customer satisfaction tool in your toolkit when encountering this problem.

If BMW sold fewer cars, because owners declined this over-complexity, then perhaps they would design simpler systems. At least that is the way it should work.

[Penguin]

Originally Posted by nra4.8is

And as far as the MSA cars w self start stop, completely new starter design requires less energy w higher output.

Precisely the point. If BMW cannot design an electrical system which can keep the battery charged with short trips, then they should use a "completely new starter design requires less energy w higher output" to produce a vehicle that can cope with the use profile which a good portion of the buyers do with their vehicle.

[Penguin]

Originally Posted by nra4.8is

The power management control unit does all of this and keeps running records of all events/ closed circuit infringement violations.

It certainly is suppose to. But obviously, many of these system do not work as designed. And lazy technicians have become slaves to what ever the computer readout tells them.

Case in point. On the way to the dealer I got a red message on the i-drive screen which said something to the effect of "Major Electrical System failure. Continued operation not possible. Pull to side of road and contact service center." So I began to pull to the side of the road and within 10 seconds the message disappeared. A check of the "Check Control" section of the i-drive said, "All System OK." Had a check engine light, but as it was yellow, not red, I continued to the dealer and left the vehicle. Call later in the day had the technician saying that there was nothing stored in the memory about an electrical system failure.

So no, I do not believe the BMW computer is either perfect, or that it has a perfect memory.

And, I might add, if a lengthy parasitic drain test to look for modules not going to sleep is so unnecessary, since the power management computer notes everything, why does BMW have such a test procedure in their documentation?

Think.

[nra4.8is]

One if you had a parasitic draw and the control unit wasn't working properly you wouldn't be able to even start the car. The control unit is designed to cut consumers even while sleeping to ensure start capability. Have you ever been able to not start? Have u ever had to reset the clock? What year is the car? Five year is rule of thumb for routine batt replacement to ensure a stable electrical system.

[Penguin]

Originally Posted by JCL

But owners are also asking for (or BMW believes they are asking for) more power to the drivetrain, better fuel economy over the full drive cycle, and so on. We got their engineer's response based on their understanding of what we as consumers wanted.

That reminds of me a recent mobile phone commercial where a salesman asks a person, "Will you come back to our network if I give you this smartphone for free?" The person asks, "will it makes phone calls?" and the salesman replies, "Well, no, but it will tell you if any of your family members are a dog."(or something to that effect)

Of course people want in their vehicle all those things you mention, but that doesn't mean people don't still want it to start in cold weather, or are willing to give-up reliable transportation to get those secondary things. The key is to remember that those things are secondary.

I'm willing to bet that BMW knows they made a mistake, and the that 2014 redesign will address this problem and complaints of dying batteries in X5's will be drastically reduced.

[Penguin]

Originally Posted by nra4.8is

One if you had a parasitic draw and the control unit wasn't working properly you wouldn't be able to even start the car. The control unit is designed to cut consumers even while sleeping to ensure start capability. Have you ever been able to not start? Have u ever had to reset the clock? What year is the car? Five year is rule of thumb for routine batt replacement to ensure a stable electrical system.

Two times in the past month it has failed to start when the vehicle was in single digit temperatures. One time it cranked about 1 second, and that was the end. The second time it wouldn't even crank. The morning I took it to the dealer, it cranks a half second and stopped. Tried again, cranked very slowly for 1 second and started. In each case, it was placed onto a CTEK 7002 smart battery charger afterwards and would start normally after overnight charging (obviously did not put it on the charger the last "slow start," as it was the trip to the dealer).

Never had to reset the clock.

Vehicle is a 2010 that is 3 1/2 years old.

Never had a problem until last Fall, when I started getting frequent "excessive discharge messages." Took to dealer in November for oil change and said I was concerned about the frequent recent "excessive discharge" messages that I had not gotten in the prior three years of use. I expected the dealer would have at least done a load test on the battery. What did the tech do? Wrote on the service record "no codes found."

Apparently the BMW power management computer doesn't log "Excessive discharge messages."

P.S. I sometimes log data via the OBD-II port using a CarChip, which is later downloaded to my computer. System voltage is typically just below 15 volts for the minute of two after starting, and then it settles-in to a range between 14.6 v and 14.9 v.

[Penguin]

Originally Posted by nra4.8is

One if you had a parasitic draw and the control unit wasn't working properly you wouldn't be able to even start the car.

As I am sure you know, that would depend upon (a) the length of time between starts, (b) how large the parasitic drain is, and (c) the effective capacity of a three and a half year-old battery.

My understanding is that for the E70, the acceptable parasitic drain is 40 milliamps after 60-70 minutes with TCU (30 minutes without TCU)

Depending upon what is not going to sleep, the excessive parasitic current could easily be such that it starts and is "made-up" if driven every day, but if left 3-4 days, would drain the battery.

[nra4.8is]

Sounds to me like, the battery has had under voltage too long and needs a replacement. Was it a special order car? Or was it at the dealer for a while. If it was at the dealer for a while un maintained in the beginning if its life it may have been compromised from the get. I want to say that they recently updated a bulletin to include unfavorable driving profile as a covered cond, so check into that ASAP.

[Penguin]

Originally Posted by nra4.8is

Sounds to me like, the battery has had under voltage too long and needs a replacement. Was it a special order car? Or was it at the dealer for a while. If it was at the dealer for a while un maintained in the beginning if its life it may have been compromised from the get.

It was special ordered and I picked it up about two weeks after it exited the plant. It now has 35K miles on it.

Any explanation was to why the power management computer would have no record of showing a "Major electrical system fault, continued operation not possible, pull to side of road" 23 miles and less than 6 hours after it occurred? Or why the power management computer apparently does not record "Excessive Battery Discharge" incidents?