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      06-04-2009, 02:44 PM   #115
tom @ eas
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Drives: BMW
Join Date: Nov 2005
Location: Anaheim, CA

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Garage List
2010 BMW M3  [5.00]
2015 BMW M4  [3.50]
Originally Posted by swamp2 View Post
Thanks for your reply. Can you clarify - what does the stored reading of battery capacity at 80% mean exactly?
It's essentially a registration mark reported to the Power Module, similar to cabin air filters, brake pads, oil, etc. Data can be stored (OD readings) for the last 7 battery replacements.

80% is simply the number BMW chose and used as a reference point.

Originally Posted by swamp2 View Post
Maybe you haven't read the whole thread. Do you have comfort access, Bluetooth? It was suggested (perhaps speculated) prior in this thread the comfort access may create a higher drain on the batter during the time the car is not used. My 21 lb B3121 simply can not handle two days in a row without driving, let alone simply being started once a week. Sure the car will start but the clock and trip odometer get reset and CA starts to not allow the one touch open. Something must be different, either our cars or our batteries.
I've been watching this thread from the beginning.

Our MY08 M3 is fully loaded w/ sunroof, including Sirius, Bluetooth, Comfort Access and other devices (for datalogging and other testing which communicate via CAN). If there is a potential issue - I want it happening to our car first since its rare that cars break down in driveways. I'm also using the B2131.

Our 135i project uses the Braille B2317 unit and is a daily driver, but the B2015 would give occasional "low battery" lights from time to time with no issues on cold start up, possibly related to battery registration.

2 days is a suspect, I have no issues as long as the vehicle is driven at least one a week. However, it should be known that a race battery cannot simply be held up to the same expectations as OEM on CCA/reserve capacity.

My situation is not saying one or the other is wrong or right - just simple reference. Hope this helps.
Tom G. | european auto source (eas)
email: web: tel 866.669.0705 ca: 714.369.8524 x22