BMW began manufacturing the X5, its first sports utility vehicle, in 1999 (on its website, BMW refers to the X5 as a "sport activity vehicle"). The company produces the X5 line in a variety of models and engine options, all of which feature all-wheel drive. While BMW has included a set of battery terminals -- for jump-starting a spent battery -- underneath the hood of the car, the battery itself lies in the rear. If the battery in your X5 dies and you cannot restart the car via a jump-start, you'll need to replace it by first removing the old battery.
Turn the car off.
Pop the rear hatch of the vehicle by either using your key to unlock the hatch or by pressing the "rear hatch" open button on the electronic key fob.
Remove the floor cover. The battery for the X5 sits underneath the spare tire compartment, which you can access by pulling up and sliding out the floor cover. Take out the spare tire and set it aside.
Unscrew the bolts holding the battery cover in place. The battery cover consists of a metal dome mounted atop a triangular frame. Use the wrench to unscrew the four bolts holding the dome to the triangular frame and then unscrew the four bolts that fasten the frame. Set the bolts aside.
Unscrew the black, negative wire from the negative terminal. Set the adjustable wrench to the diameter of the bolt holding the wire to the terminal. Then loosen it enough so that you can slide the wire from the terminal post.
Slide back the cover from the positive terminal and then unscrew the red, positive wire from the positive terminal. Unlike the negative wire, the positive wire contains a small plastic cover that sits over the terminal. After you lift it up and away from the terminal post, unscrew the bolt holding the red wire in place enough so that you can lift it away from the terminal post.
Pull the battery up and out of the battery compartment. Place the new battery in the compartment with the same alignment as the old one. If you've put it in correctly, the terminal posts should sit closer to the front end of the car.
Connect the red wire to the positive terminal and then tighten the bolt to secure it to the post. Connect the black wire to the negative terminal in the same manner.
Replace the battery cover, spare tire and floor cover, in that order.
In the manual for the X5, BMW points out that leaving the parking lights on for extended periods of time will drain the battery.
After a battery outage, you will need to reset a number of systems on the X5. These include the presets for the power seats, mirrors and steering wheel, radio and time and date display. You will also need to recalibrate the car's digital compass.