I have a 2005 545I with 76000 mi. I recently replaced the battery. The BC button stopped working and now I get high battery drain. Please tell me what can I check.

 

Is the original alternator in the car? When you replaced the battery recently did you get the car coded if you switched battery types?

 

What battery did you use?
Why did you feel the need to change it? I assume because you having issues with a weak battery. So....check the alternator. Probably not putting out correct voltage and your car is sucking life from the battery.

 

I used a Duralast Gold 95R DLG with same characteristics of BMW battery. It's the same battery. I did not get the battery registered. The only negative thing that's is the BC button does not work and high battery drain warning has come on intermittently. Thanks in advance for your help.

 

After verifying your alternator is producing at least 13VDC at idle (14+ VDC is better is better) check to see if your '05 is equipped with the IBS (intelligent battery sensor) - if that has failed, the charge will not be directed properly to the battery - as a result, it will die a slow death! You may need a qualified indy to verify the operation of the IBS or as I did when I replaced the original battery on my old e60 just spent the $100 to have it replaced and added it to the cost of ownership of a BMW :-(