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      05-16-2009, 08:15 PM   #67
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Cleveland, the specs are important because if the product does not meet the specs, I can return it for a refund. Rather simple really. Also, they help us make sense of what we are observing (one way or another)...

It is interesting to hear some modules failed to shut down in your E36/E46 after the ignition was turned off.
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      05-16-2009, 08:45 PM   #68
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Originally Posted by lucid View Post
Cleveland, the specs are important because if the product does not meet the specs, I can return it for a refund. Rather simple really. Also, they help us make sense of what we are observing (one way or another)...

It is interesting to hear some modules failed to shut down in your E36/E46 after the ignition was turned off.
The specs on my old battery were as follows:

925 cranking amps for 5 seconds
870 cranking amps for 10 seconds
765 cranking amps for 20 seconds
Short circuit current over 2400A
28 amp hours
50 minute reserve capacity with 25amp load
Female brass terminal w/M6 SS bolt
Length 6 15/32"
Width 6 7/8"
Height 4 7/8"
Weighs 24 lbs

I want you to understand something...

What happened to me in regards to the slow continuous amp draw, happens in all BMW cars with this type of central CAN-BUS communication system. The commands are embeded in a central processor, and it engages a shutdown of several modules in sequence after the car is shutoff. (like windows shutting down) My service adviser told me there is random fault can occur at anytime when the software commands get jumbled or corrupted. Any module connected to this system could receive a bad signal, and it will hang...

There is nothing you can do about it...it's a random thing that happens from time-to-time.

The good news is, that if it doesn't shut off, it only pulls an amp load in the .3A to .8A range. Many times, we (the car owners) never know this has even occurred...because the draw does not kill the heavy-duty OEM lead acid battery we have in the car.

But when you downgrade to a smaller battery, this issue can begin to show it's head. Your generous safety margins basically evaporate. This was how I figured out I even had this issue. If not for the battery downgrade, I would have never known this was occurring right under my nose.

There is no doubt that Braille makes a good product...but those specs are well...I'll just leave that alone...

Even if you believe they are telling you the truth, you are still sacrificing 60Ah of your 90Ah capacity to fit this smaller battery. (2/3) You are also losing over 150+ CA, and 350 CCA as well. That's huge...

I really hope it all works out, but I've seen this movie before...

I guess I'll just wish you the best then...

Take care.

Last edited by Cleveland; 05-16-2009 at 10:55 PM.
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      05-17-2009, 12:56 AM   #69
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Here's a TSB from BMW regarding dead battery, perform energy diagnosis, anyone try #5 New battery registration?

"SI B 61 13 05
General Electrical Systems

May 2008
Technical Service

This Service Information bulletin supersedes SI B61 13 05 dated May 2008.

[NEW] designates changes to this revision

SUBJECT
Dead Battery - Energy Diagnosis Must Be Performed

MODEL
E82, E88 (1 Series)

E90, E91, E92, E93 (3 Series)

E60, E61 (5 Series)

E63, E64 (6 Series

E65, E66 (7 Series) from 3/2004 vehicle production

E70 (X5)

E71 (X6)

SITUATION
The electrical system of BMW vehicles has been subject to an ongoing development process over the last few years. This has led to increased demands being placed on the battery. This document covers important information for the dealer on how to handle "dead battery" complaints.

[NEW] A dead battery can have various causes, most of which do not concern the battery itself. A failed battery is often the symptom and not the cause. A fully serviceable battery fails because it becomes discharged. For more information, refer to www.batteryuniversity.com/parttwo-42B.htm. For this reason, replacing the battery is not usually a permanent repair. The cause of the dead battery must be analyzed in order to guarantee a proper repair.

Only use the latest diagnostic software when diagnosing dead battery complaints.

For this reason, "Energy Diagnosis" must be performed on all dead battery complaints. At the conclusion of the "Energy Diagnosis" test plan, a diagnostic code will be generated.

This code must be included in the "Comments" section when submitting the warranty claim.Failure to quote the diagnostic code in the comments of the warranty claim may result in a delay in processing or refusal of the warranty claim.

In some cases, the "Energy Diagnosis" test plan stops before the results screen can be displayed. This error is corrected with the release of DIS V53.

The two exceptions to the rule are:

^ Battery damage and leakage

^ Use of mobile service and battery replacement to restore customer drivability as soon as possible. In the case of a battery replacement during a roadside repair, a subsequent service appointment needs to be scheduled for the customer in order to perform an energy diagnosis to locate and address the cause of the battery failure, as well as to register the replacement battery.

CAUSE
Refer to the "Procedure" section of this service information for details.

PROCEDURE1. Fault analysis (Energy Diagnosis)


There are currently two paths to access the energy diagnosis test plan:

^ If a power management fault is stored, the DIS will select the energy diagnosis test plan automatically.

^ The test plan can also be selected manually: "Function selection > Complete vehicle > Body > Power supply > Energy diagnosis > Execute energy diagnosis > Test plan".

Note : The vehicle must have had a dead battery before Energy Diagnosis can be performed. Also, fault codes must not be deleted.

Once the test plan has finished, the "Most Likely Causes" are automatically displayed if any are calculated by the test plan (new with DIS V53). Finish the test plan by processing all the "Most Likely Causes" starting from [1]. If no "Most Likely Causes" are calculated, the results screen will be displayed: "Most Likely Cause (0)".

Possible causes are:

Vehicle fault

^ Battery fault/alternator fault

^ Vehicle is not entering sleep mode

^ Vehicle is constantly awoken from sleep mode

^ Closed-circuit current is too high

^ Exhaustive battery charge (for information only).

^ Terminal 30g-f shutdown due to start capability limit (for information only).

^ Undetermined


Operating fault

If one of the causes shown below is displayed in "Most Likely Cause", this is not considered a factory defect and a warranty claim should not be submitted, even though a diagnostic code is generated at the
end of the test plan.

^ Lights/hazard warning lamps left on for too long

^ Terminal R/15 left on for too long


Except for the vehicles listed below, the fault is set when the engine is off and terminal 15/R is left on for more than 30 minutes, and the power supply drops below 11.5 volts for at least 2 minutes.

The amount of time that terminal 15/R is left on is accurate.

For the following vehicles, this fault is not reliable and should not be considered a customer error:

^ E65 and E66 (7 Series)

^ E90, E91, and E92 (3 Series) prior to 3/07

^ E60 and E61 (5 Series), vehicle integration level prior to E060-07-09-500

^ E63 and E64 (6 Series), vehicle integration level prior to E060-07-09-500

^ E70 (X5) prior to 3/07

^ Unfavorable driving profile (e.g., extremely short distances)

^ Vehicle parked for too long


A functional description of Energy Diagnosis and terminal control, together with troubleshooting information, can be found in the Energy Diagnosis test module.

2. Closed circuit current measurement


Refer to SI B61 08 00, Closed Circuit Current Measurement, for the procedure and troubleshooting hints.

Refer to the DIS/GT1 functional description for further information. Use the following path to access this information:

All except E65 and E66: Complete vehicle > Drive>Voltage and current control > Voltage and current supply > Off-load current measurement.

E65 and E66: Complete vehicle>Body>Power supply > Closed-circuit current
performance > Closed-circuit current diagnosis.

3. Checking the charging system


Refer to SI B04 25 02 for information on how to test the charging system.

4. Checking the battery condition

Refer to SI B04 25 02 for information on how to test the battery.
Refer to the DIS/GT1 functional description for further information. Use the following path to access this information:

^ All except E65 and E66: Complete vehicle > Drive > Voltage and current control > Voltage and current generation

^ E65 and E66: Complete vehicle > Body > Power supply > Alternator

5. New battery registration


Registration of the new battery is necessary, using the DIS/GT1 service function. If the new battery is not registered, erroneous messages (check control) may appear.

Use the following path the register the new battery: "Function selection > Service functions > Body > Power supply>Battery > Register battery change > Test plan". Follow the test plan instructions.

If a new battery is installed, the "Energy Diagnosis" test plan should be completed prior to registering the new battery. When the battery is registered, the stored energy history is deleted.

This may cause the vehicle to return if the root cause of the dead battery is not determined.

6. Recharging the battery


Refer to SI B04 11 02 for information on how to recharge the battery.







WARRANTY INFORMATION
Covered under the terms of the BMW New Vehicle Limited Warranty."
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      05-17-2009, 01:09 AM   #70
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BMW E9x locked current draw spec. is: 40mA after 60-70min with TCU(30 min without the TCU).

Here's some more info that could inform some:

http://www.batteryuniversity.com/parttwo-42B.htm
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      05-17-2009, 04:35 AM   #71
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Cleveland: Useful and valuable anecdotes. You may be right that those of us trying to get the Braille battery to work may never get there. However, this may not be entirely apples to apples with your experience and efforts. It sounds like you were trying some really small batteries (motorcycle batteries).

Can you confirm:

1. Did you ever try this particular B3121 battery?
2. Ah rating of the OEM E36/E46 batteries?
3. Ah rating of all the batteries you tried?
4. Also do note: I do not have an alarm, neither does lucid and I don't have satellite radio.

No one here (well at least lucid and myself) believes they can outsmart BMW/BMW engineers. Well you clearly can with regards to performance... but that is another topic. What part of the design for worst case scenario principal don't you understand? Let me repeat for the 3rd time: The OEM battery needs to handle various combinations of very cold weather, lengthy use of accessories with the engine not running and weeks of idle time. Cold weather in particular is a huge tax on a battery both for starting (CCA) and reserve. It sounds as if you do not believe the OEM system has a tremendous amount of extra capacity for warm weather, no extended use of accessories with engine off, and a mere couple of days between uses. Can you tell us your thoughts on this particular point? You just can not argue that the OEM battery both has no significant extra reserve but at the same time it is the smallest that will work reliably when not heavily taxed.

Did you miss that member ButterzM has had this battery for 3 weeks with no issues? If it can work for 3 weeks it can work for years as I see it.

My problem in particular has nothing to do with being able to start the car. It is not and has never died completely, it is just chronically a few tenths of a volt low. Again, the voltage does not fluctuate much, after a short drive, after a long one, after one night or after several. The voltage is just about the same - and is just a hair too low. All of this tells me there is a problem not with the battery's capacity but with its ouput.

Can you also expand on this point, "Modern alternators are not designed to deal with charging AGM batteries."? Do you mean the voltage regulator or alternator? The charging voltage on the battery is from the voltage regulator and it maintains a fairly constant voltage well above the zero load battery voltage, hence charging it. Alternators today do what they have done for decades.

Do you have any idea why for you a 33 lb battery seemed to magically work when a 20 lb one wouldn't? 33 lb was surely significantly lighter than the OEM battery. Where do you draw the line?

808MGuy: The voltage you measure at the battery terminals when the car is running is the alternator voltage, not the battery voltage, and as I mentioned at idle this is something like 14.5-14.8.
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      05-17-2009, 04:42 AM   #72
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Quote:
Originally Posted by TheMadDutchman View Post
BMW E9x locked current draw spec. is: 40mA after 60-70min with TCU(30 min without the TCU).
Can you clarify? Where did you get this spec? What does after X minutes mean.? I'm guessing that the current drae value could be larger before that point. HPAuto seems to indicate that having comfort access would significantly change this spec.

Note to others: TCU = telematics control unit (BMW Assist, basically).
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      05-17-2009, 11:36 AM   #73
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Specs are from a BMW TSB regarding proper Closed-Circuit Current Measurement: SI B 61 08 00 General Electrical Systems.

"On vehicles equipped with BMW Assist, there are additional current fluctuations as high as 500ma that last for approximately 2 minutes. The fluctuations occur every 15 minutes for up to 14 hours after key off. This is considered normal operation of the TCU and should not be considered a fault. This also applies to 2005 TCUs that were installed into earlier production vehicles as replacement parts."

E9x; I grouped the 3 series chassis designation; E90, E91, E92, & E93.
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      05-17-2009, 11:57 AM   #74
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Quote:
Originally Posted by swamp2 View Post
Cleveland: Useful and valuable anecdotes. You may be right that those of us trying to get the Braille battery to work may never get there. However, this may not be entirely apples to apples with your experience and efforts. It sounds like you were trying some really small batteries (motorcycle batteries).

No one here (well at least lucid and myself) believes they can outsmart BMW/BMW engineers. Well you clearly can with regards to performance... but that is another topic. What part of the design for worst case scenario principal don't you understand? Let me repeat for the 3rd time: The OEM battery needs to handle various combinations of very cold weather, lengthy use of accessories with the engine not running and weeks of idle time. Cold weather in particular is a huge tax on a battery both for starting (CCA) and reserve. It sounds as if you do not believe the OEM system has a tremendous amount of extra capacity for warm weather, no extended use of accessories with engine off, and a mere couple of days between uses. Can you tell us your thoughts on this particular point? You just can not argue that the OEM battery both has no significant extra reserve but at the same time it is the smallest that will work reliably when not heavily taxed.

Do you have any idea why for you a 33 lb battery seemed to magically work when a 20 lb one wouldn't? 33 lb was surely significantly lighter than the OEM battery. Where do you draw the line?
Woah, too many questions at one time...

Ok, I need to get something out of the way right off the bat...

In regards to your motorcycle battery comment:

EVERY SINGLE ONE of the small "Lightweight Racing Batteries" on the market are simply re-branded, re-engineered, MOTORCYCLE batteries. (more or less)

All of them. It's important that you know this...

The internal lead plates have been redesigned to squeeze out a little more power...but that's about it. Go to any Suzuki or Harley-Davidson dealer if you need any confirmation. These batteries are essentially motorcycle/4-wheel atv/jet-ski/lawn tractor batteries. (not kidding)

These are not, and never will be, SAE-approved STARTING batteries for automotive duty.

Putting an aftermarket brass screw-on SAE battery terminal (with a tiny 3/8" threaded stud on the bottom) does not magically turn a motorcycle battery into a automotive battery.

Don't even get me started on the whole "Pulse Cranking Amps" (PCA) or "Hot cranking amps" (HCA) thing...

These terms were invented by small lightweight racing battery manufacturers to help market their products better. Those numbers are going to be higher because of the skewed testing conditions. They cannot be used as a direct comparison tool with a conventional full-sized SAE approved starting battery.

Conventional SAE approved battery manufacturers use this basic criteria on virtually every battery you will ever find in the marketplace:

a) Cranking Amps @ 32F

b) Cold Cranking Amps @ 0F

c) Amp Hour (Ah) Capacity: Measured using the C/20 standard

d) Reserve minutes BCI: Using a 25 amp discharge rate @ 80F (26.7C) down to a 10.5V cut-off point

These are solid battery performance parameters, and they are only ones that really matter at the end of the day. Any comparison should be made using these yardsticks. I admit it, I got sucked into the high artificially ginned up numbers these little batteries can produce under certain lab conditions. They don't fair quite as well, when you compare them 'straight up' to a full sized SAE starting battery using the specs listed above.

And sometimes, it sends up a red flag on how some of their numbers don't add up. (performance wise) After running several of these small batteries, I suspect there is a lot of 'rounding up' involved in their claims. (and that's being a bit generous)

So let's not go down that road...

Once again, battery power is primarily a result of SIZE & WEIGHT.

Technology can help you tweak this a little, but the overall footprint is the key.

Larger battery case (dimensionally) = More room for LEAD plates with a larger surface area + Larger AGM sandwich material that absorbs the acid = More powerful battery in every category. Period.

This is a fact, not my opinion. Power output (CA, CCA, Ah, Reserve min.) are directly proportional to size and weight.

It's a pretty simple formula. It's not rocket science...

You can't have a 1500 cranking amp AGM battery that is the size of a shoebox. That's ridiculous.

And this is coming from the biggest lightweight battery fanboy you could have ever known just a few years ago.

I have done a complete 180 degree flip-flop on this issue. That is not only due to my own personal experiences, but also many other owners who I've corresponded with who went down the same rabbit hole with me.

It "sounds" like a great idea...in the beginning.

Here are just a few of the issues that tripped me up:

1) SMG pump/accumulator cycling

2) OEM iPod adapter/charger not shutting down

3) Bluetooth phone module (ASSIST tcu) including random calls to assist after the car was shut off...

4) My Radar Detector

5) OEM Home Link garage door opener module

6) OEM DVD Nav drive constantly rebooting itself

7) OEM CD changer cycling through discs

8) OEM SIRIUS satellite radio tuner not shutting off

9) OEM factory alarm and clown nose beacon

10) Light control module

And on, and on, and on...

The above items are just a small sampling of the modules that are largely hidden inside the car.

All these things are controlled by BMW proprietary I-BUS (CAN-BUS) communication interface software through the cars ECU.

I wasn't aware of how many systems and subsystems are connected to this system.


I never factored this into my original plan, and I ended up paying the price.

You seem to fashion yourself a very clever person (as do I), well that can sometimes be a hindrance to your ability to see things in an objective manner. I'm sure you believe your theories about why this WILL work. They are probably as sound as my initial theories were so long ago.

You are making the exact same arguments now, that I did in the beginning. I was convinced that I had figured out exactly why the BMW electrical engineers had designed a 800 CA 70Ah battery for my car, and how I could successfully trim that down by a substantial margin with no ill-affects.

You are using the same defense arguments I did, and didn't matter. I was blindsided by several things, including the various electronic modules all over the car. (that were working against me)

Unless you drive the car everyday (keeping this battery fully charged), you will have some reliability issues with a battery that size going forward. I can promise you this will happen. It may not die on you completely like some of the smaller sized batteries I tried to use, but you will find the breaking point where the car will barely have enough power to start the V8 engine. I had a number of accessories in my car for the cell phone and iPod, so maybe your a little better off if you don't add any accessories to the car.

The E92 M3 has even more of these electronic control modules than the E46 did, and I'm sure the next M3 platform will have even more. You can't stop the advancement of more electronic based control systems. That is here to stay. These devices are tucked away in every corner of your car, and they are all controlled by a central 32-bit processor in the ECU by proprietary CAN BUS software.

Do I have to paint you a picture?

Sometimes computers don't shut down everything (properly) like they are supposed to...

And when they don't...the battery takes the brunt of it. The BMW Electrical Engineers must have factored this in the final battery size and power specifications of this car. Are you saying you know for a fact they did not?

I spoke at lenght about this very issue with a BMW Field Engineer who works for BMW North America. He travels all over the country diagnosing the toughest service related cases that BMW gets. When my car was in the service bay, we spoke about the electrical systems in late model BMW cars, and he would certainly disagree with your hypothesis on why the OEM battery is so large. Some portions of your theory are correct (climate), but the overriding theme that you don't seem to get, is that it's a forgone conclusion that the CAN BUS will not always shut everything down as it should. It's apparently so important, that BMW can actually refuse to honor any legitimate electrical warranty repair if you remove the OEM battery from the car. (and you don't replace it with a unit with the same specs)

Check this out with your service advisor if you think I'm kidding...

The 90Ah battery in the trunk was designed as much as a safeguard against total electrical failure in case the software program goes off the reservation, as it was for any concerns about cold climate conditions. (or someone playing the radio after the ignition is killed)

You need to throttle back just a bit here. It's clear to me that you are assuming you know the exact reasoning behind their decision making process.

That is is a bit presumptuous don't you think?


Forget the "theory" of what's supposed to happen. That's how I got burned...

I found out much later, that BMW has issued many bulletins on defective control modules or ECU software glitches that don't shut down things when they're supposed to.

There is no engineering workaround to this random fault. If you figure one out, please let me know...so we can patent the idea and get filthy rich.

You only have one battery. And you have to think of it more as an insurance policy (security) instead of a target (to dump weight). I use to think of my OEM battery in that way, and it turned out to be counter-productive for my non daily driven street car.

The safety margins with these racing batteries are smaller than you think...

As I said to Lucid, I wish you best, and I really hope things work out for you in the end.

I'm just relaying some of potential downsides of this mod (that I experienced in spades), because you rarely get the other side of this story.

Take Care.

Last edited by Cleveland; 05-17-2009 at 12:32 PM.
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      05-17-2009, 12:25 PM   #75
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Quote:
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808MGuy: The voltage you measure at the battery terminals when the car is running is the alternator voltage, not the battery voltage, and as I mentioned at idle this is something like 14.5-14.8.
Yes I already mentioned that but if the engine on voltage is not getting up to 14V it could point to other problems. It looks like your charge voltage is good though.
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      05-17-2009, 12:31 PM   #76
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Quote:
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You are making the exact same arguments now, that I did in the beginning. I was convinced that I had figured out exactly why the BMW electrical engineers had designed a 800 CA 70Ah battery for my car, and how I could successfully trim that down by a substantial margin with no ill-affects.
I don't think anyone here has ever assumed that reducing the reserve capacity of the battery would have no ill effects. BMW has made a design choice based on assumptions pertaining extreme usage patterns. If you are willing to be on the other end of the usage "distribution", you can reduce the reserve capacity and weight. However, you have to be cognizant of the fact that you have made that choice and indeed stay with the required usage pattern to make things work.

Now, this discussion is really about understanding how far that approach can be pushed. We have the stock battery at 90 amp/hr and we have the Braille battery at 31 amp/hr (I understand you are questioning the methodology for arriving at the latter spec, which is perfectly appropriate). As an outcome of this exploration, we will most likely find out where that line is, and if the Braille battery is pushing things too far or not. A workable solution might very well end up being another battery, say perhaps at 60 amp/hrs with less weight reduction. But, the point stands: one can reduce battery size and weight if one is willing to make certain compromises in usage behavior. By definition, the stock battery cannot be at the very limit of any kind of nominal operational range.

Thanks for providing the information on the issue of some modules not shutting down properly. That information not only informs but complicates this consideration.
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      05-17-2009, 01:51 PM   #77
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Quote:
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I don't think anyone here has ever assumed that reducing the reserve capacity of the battery would have no ill effects. BMW has made a design choice based on assumptions pertaining extreme usage patterns. If you are willing to be on the other end of the usage "distribution", you can reduce the reserve capacity and weight. However, you have to be cognizant of the fact that you have made that choice and indeed stay with the required usage pattern to make things work.

Now, this discussion is really about understanding how far that approach can be pushed. We have the stock battery at 90 amp/hr and we have the Braille battery at 31 amp/hr (I understand you are questioning the methodology for arriving at the latter spec, which is perfectly appropriate). As an outcome of this exploration, we will most likely find out where that line is, and if the Braille battery is pushing things too far or not. A workable solution might very well end up being another battery, say perhaps at 60 amp/hrs with less weight reduction. But, the point stands: one can reduce battery size and weight if one is willing to make certain compromises in usage behavior. By definition, the stock battery cannot be at the very limit of any kind of nominal operational range.

Thanks for providing the information on the issue of some modules not shutting down properly. That information not only informs but complicates this consideration.
Very well said.

As long as everyone fully understands there are certain inherent risks to this mod, then I am in complete agreement with your rationale.
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      05-17-2009, 02:20 PM   #78
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Quote:
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Woah, too many questions at one time...
Look I really do appreciate the anecdotes. It is valuable. But when challenged you foray in to pages and pages of not so useful information. As well you did not reply to any of my direct questions. It would be useful for the discussion if you would review my questions and try to answer them. What part of 0F gives a battery somewhere from 40-60% of its power don't you get?

No one said that a Braille battery and a much smaller motorcycle battery are not essentially the same thing in a different sized package.

No one said that a battery's ultimate specs are not very closely governed by its size/weight.

Have you noted that the Braille specs for this 3121 are:

CCA at 0 F
CA at 80F
CA at 32 F
Capacity with the C/20 standard

These appear to be right in line with you view of the key specs and key standards. I don't care much about PCA myself...

Your long laundry list of items is more or less irrelevant in light of the spec provided just above by TheMadDutchman. The car will drain, under long periods of "complete" shutdown, at 40 mA, with short fluctuations of 500 mA for the TCU. The Braille 3121 is more than capable of dealing with 40 mA with 500 mA fluctuations for days, period. Perhaps the "shutdown bugs" you mention drastically violate this BMW spec. I doubt it though and I doubt most service advisors "know" this either. Similarly many of those items are simply irrelevant.

-The SMG/DCT pumps are 100% inactive when the car is fully off
-All accessories such as the ipod and radar detector get exactly 0 power when the car is fully off

It is like you are grasping at straws to explain your own circumstance and failure to find a working solution. Again did you have direct experience with a ~30 Ah battery in your E36 or E46?

Don't get me wrong. I'll be the first to admit defeat if I can't get this sucker to work. But if I can't there are really only 2 possibilities. Braille is lying about their specs or BMW is.
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      05-17-2009, 07:29 PM   #79
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Originally Posted by swamp2 View Post
Look I really do appreciate the anecdotes. It is valuable. But when challenged you foray in to pages and pages of not so useful information. As well you did not reply to any of my direct questions. It would be useful for the discussion if you would review my questions and try to answer them. What part of 0F gives a battery somewhere from 40-60% of its power don't you get?

No one said that a Braille battery and a much smaller motorcycle battery are not essentially the same thing in a different sized package.

No one said that a battery's ultimate specs are not very closely governed by its size/weight.

Have you noted that the Braille specs for this 3121 are:

CCA at 0 F
CA at 80F
CA at 32 F
Capacity with the C/20 standard

These appear to be right in line with you view of the key specs and key standards. I don't care much about PCA myself...

Your long laundry list of items is more or less irrelevant in light of the spec provided just above by TheMadDutchman. The car will drain, under long periods of "complete" shutdown, at 40 mA, with short fluctuations of 500 mA for the TCU. The Braille 3121 is more than capable of dealing with 40 mA with 500 mA fluctuations for days, period. Perhaps the "shutdown bugs" you mention drastically violate this BMW spec. I doubt it though and I doubt most service advisors "know" this either. Similarly many of those items are simply irrelevant.

-The SMG/DCT pumps are 100% inactive when the car is fully off
-All accessories such as the ipod and radar detector get exactly 0 power when the car is fully off

It is like you are grasping at straws to explain your own circumstance and failure to find a working solution. Again did you have direct experience with a ~30 Ah battery in your E36 or E46?

Don't get me wrong. I'll be the first to admit defeat if I can't get this sucker to work. But if I can't there are really only 2 possibilities. Braille is lying about their specs or BMW is.
There is no need to get testy...

You asked a lot of questions, and I was trying to explain what happened in detail. That's all.

You have to understand that I'm attempting to cram 4+ years of experiences into a few posts here. That's not exactly easy. There is a lot of information to go over, so please be a little more patient. There is no need to be so aggressive or confrontational. I will get to your questions in due time. Demanding answers in a very rude and forceful manner (on your timetable) isn't very nice.

I responded to this thread in order to help people like you, and anyone else who is thinking of doing this mod. As I have said repeatedly throughout this thread...no one ever tells you the other side of this story. (living with these batteries over the long haul)

Please allow me the courtesy of explaining myself in my own way.

I can't answer everything you want at the same time. It's important to lay the ground work of what I was trying to accomplish, and the issues I ran into before I get into the specific battery models and sizes I used. Slow down and take a deep breath...

I was under the impression, that you were trying to say these smaller batteries should work fine under 'normal' circumstances. I thought that statement was a little misguided because software glitches in our cars are normal. That scenario is a little unrealistic considering how many software driven devices are running in these late model BMW's. Only 1 of them needs to start acting up, and your safety margin is completely gone. That's why I responded with a long post detailing the many items in my car that didn't exactly follow the game plan.

I (like you) would assume the car wouldn't draw squat after the ignition was shutoff. It never dawned on me how this could eventually become a problem. Not that it's inevitable or anything, but that the possibility does exist, and it must be factored in somewhere.

Simply stating that it won't ever happen (to you)...is not going to make it so.

Failing to Plan = Planning to Fail

You cannot devise a successful long term game plan, without at least preparing for the remote possibility of an unforeseen deviation. I think you would agree that's a smart exit strategy right?

I also cannot have a constructive conversation with you, if you continue to argue that my SMG pump could not have possibly drained my battery down after the car was shutoff.

SMG pump cycling after the key is removed does happen. (it's a common fault) SMG pump/relay failures on the E46 M3 are also common. Having to use the key fob to lock and unlock the doors (enabling and disabling the CAN BUS processor) to get the SMG tranny out of neutral (so you can start the car) is also an anomaly that occurs from time to time.

Again, software commands are not always received and processed correctly.

I have to tell you, it's very difficult to have a constructive exchange of ideas when you take such a hardline position like that...

There is no room for debate at that point. You are just right...and everyone else is just wrong. Where exactly can we go from there?

I can see that you are a really bright guy, but you seem to see things as clearly black or white with absolutely no grey area. I'm not sure how conducive that is to a healthy exchange of information IMHO.

If you have specific questions, please ask them one at a time (in a respectable manner), and I will try to explain the results that I found throughout this long process. (including specs)

I think we could be friends, so let's try this again.

Okay?
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      05-17-2009, 07:58 PM   #80
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Dont take it the wrong way, Swamp2 treats everyone with similiar ignorance

Good info Cleveland
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      05-17-2009, 09:40 PM   #81
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Out of curiosity, any of the guys having problems with the Braille battery also have underdrive pulleys? This would compound the problem even more.
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      05-18-2009, 12:23 AM   #82
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Quote:
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Dont take it the wrong way, Swamp2 treats everyone with similiar ignorance

Good info Cleveland
Arrogance or ignornace? It is supremely ironic that you screwed up your word choice using a word that very much seems to be describing yourself.
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      05-18-2009, 12:43 AM   #83
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Quote:
Originally Posted by Cleveland View Post
There is no need to get testy...
...
Look I am not saying you did not have the experiences you did, you obviously did. I have also clearly stated that I may be having or will have a very similar one. I also am not sticking to my thoughts that my particular selection must/will pan out...

What I am saying is that many of your criticisms are unfounded. I am saying that you tend to write an awful lot of text without a tremendous amount of useful information. I like facts infinitely more than flowery anecdotes. I am also saying that you continue to refuse to address some key questions. If you can't parse my posts and see the direct questions I've posed I don't think I am going to bother to try to do that for you.

As far as the SMG issues it sounds like I was wrong, but it also sounds like the use is not a constant thing, that will continually drain a battery, but a small extra thing right after shutdown or right before start up (I do know it does right before start up). However, on the flip side, radar detectors and a no brainer - when they are wired so they they only get power when the ignition is on - they simply can not be a drain on your battery and you were wrong about this.

As far as outlook, attitude, philosophy, etc., yes, most issues to me are black and white. If they are simple matters of science, engineering, etc. then they are either black or white. I'm certainly not saying all science is nothing but black and white but also simple questions such as to a batteries suitability for a particular application - that question can be absolutely answered in an a priori fashion without experimentation. The grey area comes only from a few possibilities: 1. A misunderstanding or underestimate of real operating conditions. 2. Incorrect or misleading battery specs or vehicle operating conditions. To me it sounds like you had some very small capacity batteries and experienced #1.

Continue to participate in this topic as you like. I've not been mean nor unfair to you and I've thanked you for your valuable input.
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      05-18-2009, 12:44 AM   #84
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Quote:
Originally Posted by 808MGuy View Post
Out of curiosity, any of the guys having problems with the Braille battery also have underdrive pulleys? This would compound the problem even more.
No pulleys here. Good point though.
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      05-18-2009, 03:04 AM   #85
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If anyone has a current meter that can record over say a 1 hour time frame it would be helpful to meter the current draw while the car is off. Then you could see the fluctuations in current draw and get a better idea of what the actual demands are on the battery.
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      05-18-2009, 07:08 AM   #86
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Originally Posted by 808MGuy View Post
If anyone has a current meter that can record over say a 1 hour time frame it would be helpful to meter the current draw while the car is off. Then you could see the fluctuations in current draw and get a better idea of what the actual demands are on the battery.
Yes, I suggested this earlier, but it might be necessary to monitor for more than an hour unless we are sure that the systems don't go through sleep/wake up cycles that are longer than an hour.
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      05-18-2009, 07:45 PM   #87
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Despite some prior evidence that my battery does not drain slowly over time I can share some information on that. I did take prior measurements indicating no to a very small nominal drain. It seems consistent with Clevelands information that the while off drain may be inconsistent. Just after finishing a 45 minute drive, with some good high rpm use battery voltage, car turned off = 12.5 VDC. Next reading the morning after 12.1 VDC, today, the second day after sitting "idle" 12.0 VDC. Again it is unclear whether this is being caused by the steady and intermittent while off power requirements or by a problem with the battery. Either way the 12.5 number is definitely below spec. as it has been for some time. I was promised my new battery would ship last week but Braille remains completely out of stock and are not communicating well with me on the ETA.
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      05-24-2009, 01:22 PM   #88
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Lucid: Get your battery in and let us know. It is a simple mod to undo if you have any of the small glitches I've identified here. I'm still waiting for my replacement unit from Braille. They keep making promises on when it will be in stock and also when it will arrive here to me and they keep getting broken.
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