I have a 05 X5 4.4,a couple of weeks ago,I was driving home from a road trip with the AC on when my service engine soon light came on.First thing Monday I took it to my mechanic to have checked out;the code was due to low voltage.He checked the voltage and erased the code.A few days later,after not driving for 2 days,would not start.Had towed to the shop;again,checked codes replaced battery.Few days later,car would not start,same problem.After doing some research and leaving hooked up to a computer,we determined the culprit to be a bad blower motor relay;replaced,let sit for 3 days,no voltage draws and started right up!