When your BMW X5 vehicle won't start, the battery is probably dead. You can jump-start the vehicle with jump leads or you can just replace the battery. If you want to change the battery you won't find it under the hood as in many vehicles; rather, it is in the boot. Changing the battery yourself will save you the price of the battery and the cost of installation charged by mechanics.
Pop the boot on your BMW X5.
Locate the battery. Pull up the floor cover in the boot that contains the spare tire. The battery is located in a case just above the spare tire on the left side.
Unlatch the strap holding the battery into the case. Unscrew the black negative cable first with the correct sized wrench (12mm or 13mm). Unscrew the red, positive cable.
Pull out the old battery. Set in the new battery. Screw the red, positive cable on tightly. Screw the black negative cable on tightly.
Latch the strap over the battery to securely hold it in the battery case. Set the floor cover back over the spare tire area. Shut the boot door.