I bought my 49-DL in January 07, and a few months later, it was dead. I drive my car twice a week (wed/sun) so I figured that it died due to the fact I don't use the car much. I brought it back in to Autozone and they charged and tested it and they said it's fine, even though I demanded a replacement. The battery was fine for a while after that.

Now, 10 months later, it happened again. They attempted to charge it but it wouldn't hold a charge, so they replaced it finally. My brother had a 99 740i with the same issues, he said that he went through 2 of these batteries.

Now the interesting thing is that my bro told me that he read somewhere in a forum that to prevent this, you need to turn off all the accessories, radio, climate control, etc. upon shutting your car off. The V8 models have the "auto-crank" feature that is hard on the battery, and during a cold start, if the radio, A/C, etc is on, it eventually kills the battery.

I'm not sure if that's correct, but I've been shutting off my accessories when I shut the car off now.

Hmmm, have you ever noticed the illuminated "P" on your gear shift lever...and how it comes on as soon as you initiate the keyless entry button on your key fob...or raise the door handle? And that it remains on a few minutes after you turn the car off. Also, have you ever left a light on (on purpose or by accident) then after 15 minutes it autuomatically shuts off?

If you noticed any of those things above, then it should be enough evidence to debunk what your brother read "somewhere on a forum". Because if your car is operating normally, it shuts off "NON ESSENTIAL" items after 15 minutes except for small draws like the clock etc. when the car is not running :)

As far as the Duralast...good thing that AutoZone honored their warranty. :thumbup: Hopefully, you have the battery hooked up to the vent tube correctly.

And starting your car twice a week is more than enough to keep the battery charged under normal conditions. BMW only recommends that you supplement what you're doing if the car sits for more than 4weeks...

http://www.bimmerboard.com/members/q/original/Battery%20Storage.jpg

Yes, I'm not arguing that it shuts everything down when you shut the car off, but during a cold start, when you turn the key to the "on" position right before you start it, the accessories that were left on such as the radio, climate control, etc. will turn on will draw power from the battery simultaneously with the "auto-crank" feature, which "eventually" will kill the battery. Again, I'm not saying that this is true, but this is what I was told.

I never shut my accessories off and it's a habit of mine to just leave everything on and never believed that until now.

Oh and yes, I installed the previous battery myself and made sure that the vent hose is plugged in just like I did with this replacement.

Have you checked the alternator? I have an autozone, no problems, but there are bad batteries out there. Never heard about shutting down everything, but I am in 90 degree CA

... during a cold start, when you turn the key to the "on" position right before you start it, the accessories that were left on such as the radio, climate control, etc. will turn on will draw power from the battery simultaneously with the "auto-crank" feature, which "eventually" will kill the battery. Again, I'm not saying that this is true, but this is what I was told.


Ahhhh, now I get the gist of what you were saying. :) Still not sure if this actually "kills" the battery...but it probably does increase the load on it.

But there is another interesting thing that occurs when a BMW battery is starting to fail...the car will sometimes go thru something similar to a rolling "brown-out" in that small electrical gremlins can appear, then go away (as components come on then go off)...and the most common occurance is that the owner thinks something is wrong with the car because all the interior lights still come on , the radio, etc...but when the ignition is turned to start...nothing happens. And it takes lots of convincing to get them to check the battery because they assume that it's okay since the lights and radio work. :rolleyes

Still, it probably is a very good idea to turn stuff off before shutting down. :)

Yeah, my whole family routinely turns everything off before shutting the car down for a very long time now, except for me. I'm going to start sticking to that habit as well and see how it goes, at least on this car but not the 325is.