Originally Posted by Cleveland
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 0°F 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 80°F
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.