Battery Repl.
 

What sort of things should one look for if the oem battery needs to be replaced?

what should you look for as in what other brands you should look for?

I guess what i mean is...how do you know if its time to replace the battery? I don't wanna get stuck on the road with a dead battery......i have a 2003 x5 with 62,000 miles

You are probably ok for another year, but batteries can go at any time. Just have some jumper cables in the car. If you are really worried about it, you could just replace it.
Another thing you could do would take it to a shop that can check the status of the battery. Such as: how much juice it can hold, does it need a charge, how much life let, get their opinion, and what not.

I have 115K miles on my '01 and still have the original battery, so you should be fine.

I run my radio with amp all the time without the car on and have had no problems. I also keep a jump starter with me just in case ;)

I got a 'like' new (practically brand new) factory battery for sale - less then a month old from the dealer.

$80 picked up.

http://www.xoutpost.com/bmw-sav-items...e-battery.html