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      05-17-2009, 08:29 PM   #79

Drives: M3 coupe
Join Date: Apr 2009
Location: Louisiana

iTrader: (0)

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 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) 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.