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      06-03-2009, 04:34 PM   #111

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

iTrader: (0)

Originally Posted by swamp2 View Post
After many days of fairly trouble free use my new B3121 is back to the same old shortcomings. To be fair I do often let my car sit for 2 nights in a row without use. After doing this today my trip odometer reset to 0 and the clock once again "forgot" the time. It is my opinion that this battery will be an OK solution only if 2 criteria are met:

1. The car is used everyday.
2. You are in a warm weather climate.

The math still does not add up to me as to why this unit doesn't work better with a longer reserve time but it clearly isn't. I am going to pursue something in the range of 40-60 Ah.
Smart move.

That's the same conclusion I eventually came to after four years of trial and error. Given my infrequent use of the M, I should have conceded this a long before I did. Just being hard-headed I guess. The 'math' you mentioned is what got me too. It was 'supposed to work', but at the end of the day...they all underperformed.

It certainly would have saved me a lot of time, money, and aggravation...

...if I had stopped looking at the specs, and solely concentrated on the real world performance limitations for my application.

I ended up buying a somewhat larger automotive STARTING battery that had a 44Ah rating. It was a godsend, compared to all the headaches I had with the small lightweight batteries I was constantly trying to use.

There are a few batteries that I found, which might be perfect for you. Given your infrequent driving pattern, a slightly larger battery will work out much better than the Braille battery did. You were on or slightly under the breaking point for the M3. (for a non-daily driver)

Let me know if you're interested, so I can point you in the right direction as to the best available options in this new (more realistic) Ah range.