How to Change the Battery in Bmw Cars

by Contributing Writer; Updated June 12, 2017

Their first car was dubbed the Dixi. The Bmw car has come a long way since the Dixi. Today's Bmw car is a complex vehicle with a myriad of high-tech computers and automated systems, not to mention security devices. Most of these systems have memories programmed into them. The memory is kept alive with a very small amount of power when the vehicle is not running. Removing the battery without a back up system to keep the memories alive will erase the programming. The battery for a Bmw car is of a specific group because of its location. It is a sealed battery and possesses a vent nipple on the top side. A vent hose from this nipple passes through a hole in the floor below the battery. For this reason, use no other battery, as the lack of venting can cause an explosion or excessive corrosion in the battery well.

Under The Hood:

 How to Change the Battery in a BMW Key

Purchase the correct battery for your car model. Because of the variety of BMW keys and car models, the table is not recreated here. The E39 takes a CR2016, for example. The 325CI takes a VL2020. A dealership should be able to tell you what battery size you need.

Alternatively, open the circular cover over the battery to read the size number off the back of the battery. Have the battery ready for the switch before you open the key, since you have to accomplish this task within 60 seconds to avoid having to reprogram the key.

Unscrew the two screws at one end of the fob, if your BMW is a 2001 model or older. Then, pull open the fob and replace the battery. Accomplish this in less than one minute to avoid losing the encryption.

Pry open the circular cover over the battery. Undo the two screws with a Phillips screwdriver. Swap out the battery and then replace the screws. Accomplish this step in 60 seconds on working keys to avoid losing remote-entry programming.

Use a pocketknife on other keys. Stand the key with the metal part pointed up and drive a pocketknife down into the seam between two plastic parts. A penknife won’t give you enough leverage to do this. Make the separation in the seam carefully. Pull out the battery. Put in the new battery. Seal the seam closed with glue for plastic. Perform this step in 60 seconds to avoid having to reprogram a working remote.

Items you will need

  • Rechargable replacement battery

  • Glue for plastic

  • Pocketknife

 How to Change the Battery in a BMW E36 Key Fob

Pry the top cover of the remote from the bottom with a flathead screwdriver, needle-nose pliers or another flat object. This may require some leverage but should be done as gently as possible. You may have to work the flat object around the edges of the remote or find a small indented spot.

Notice which direction the battery is turned and which side is facing up.

Lift the small latch holding the battery in place and gently remove the battery from the remote.

Place your new battery in the same spot and position as the old battery and replace the latch over the battery.

Snap the covers back together on the top and bottom to return the remote to its proper position.

Items you will need

  • Flathead screwdriver or needle-nose pliers

 How to Change the Battery on a BMW 3 Series

Park your BMW, turn it off completely, and engage the parking brake.

Open the hood of the car using the release switch by the steering wheel, or with the latch on the hood itself.

Remove the brackets holding the battery in place using the screwdriver.

Remove the terminals from the old battery. You may need to use the wrench to get them off. Remove the negative ("-") terminal first, then the positive ("+") terminal.

Take out the old battery, and dispose of it safely.

Install the new battery, and replace the terminals, first the positive, then the negative.

Turn the car on to check the battery works.

Replace the brackets, and close the hood.

Items you will need

  • Wrench

  • Screwdriver

 Can I Change My Own Battery on My 1999 BMW 328I?

Plug the battery backup tool into the cigarette lighter (auxiliary power outlet). This is just a small 9-volt battery attached to a plug suitable to plug into this outlet. It will supply just enough power to keep the circuits and memories alive.

Open the trunk and remove the battery cover on the right side of the trunk floor. Remove the battery negative terminal connector with the use of a wrench. Remove the battery positive terminal connector. Loosen and remove the battery hold-down clamp using a wrench. Disconnect the battery vent tube. Lift the battery out of the car.

Install the new battery and tighten the hold down clamp using a wrench. Install the vent tube to the nipple on the top side of the battery and make sure the hose passes through the hole in the floor. Install the positive battery cable connector on the positive terminal on the battery and tighten it with a wrench.

Install the battery negative cable to the negative terminal on the battery and tighten it with a wrench. Re-install the battery cover on the trunk floor. Unplug the battery backup.

Items you will need

  • Set of wrenches

  • Battery backup tool (can be purchased at most auto parts stores)

 How to Change the Battery on a BMW X5

Pop the trunk on your BMW X5.

Locate the battery. Pull up the floor cover in the trunk 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 trunk door.

Items you will need

  • Metric wrench set

  • 12V battery

 How to Change the Battery on a BMW R1200C

Unscrew the three bolts holding your BMW's gas tank in place. The bolts are located on both sides and at the front of the gas tank. Use an Allen key wrench to remove the bolts.

Prop the gas tank up to give you access to the battery compartment or have an assistant hold the gas tank as you work with the battery.

Pull the battery from the compartment underneath the gas tank to access the battery's terminal access points. The terminals point towards the ground.

Remove the wires connected to the terminal access points by hand, starting with the negative (black) terminal wire.

Attach the wires to the terminal access points of the new battery by hand, starting with the positive (red) terminal wire.

Install the new battery into the battery compartment with the terminals facing towards the ground.

Reattach your BMW's gas tank by first installing the front screw and then the side screws.

Items you will need

  • Allen key wrench

  • Gloves

  • Goggles

 How to Replace the Battery in a BMW 325xi

Open your BMW 325xi's trunk.

Turn the knob holding the panel over the battery on the right side of the trunk. Remove the panel.

Loosen and remove the clamp holding the black cable to the battery's negative post. Loosen and remove the clamp holding the red cable to the battery's positive post.

Twist off the knob holding the center bracket over the battery. Pull up the bracket and remove the old battery. Put the new battery in place and tighten the bracket over it.

Tighten the clamp on the red cable over the positive post on the 12 volt battery. Tighten the clamp on the black cable over the negative post on the 12 volt battery.

Screw the panel back on over the battery. Close the trunk.

Items you will need

  • Crescent wrench

  • Replacement battery

 How to Replace a Battery in a BMW Z4

Place the Z4 in park and turn the engine off. Allow it to cool for a half hour.

Open the trunk. Pull up the removable carpet and flooring. You will now have access to the battery, on the right side seated in a bracket.

Remove the bracket with a screwdriver. There are a total of three screws, two on the bracket and one securing it.

Remove the positive cable from the battery using a socket. Place the cable to the side. Remove the negative cable in the same manner. Pull the wall out.

Lift the battery out of the vehicle. Batteries can weigh up to 70 pounds, so get some help.

Place the replacement into the bracket. Replace the three screws to secure the bracket to the battery. Connect the positive battery cable and tighten it. Repeat the same process for the negative.

Items you will need

  • 10 mm socket wrench

  • Phillips screwdriver

 How to Replace the Battery in a 745Li

Open the trunk of the vehicle. Pull back the carpeting on the right side of the trunk.

Locate the plastic battery cover. Remove the screws that are used to secure the battery cover with the Phillips-head screwdriver.

Pull the plastic covers off of the positive and negative terminals.

Remove the negative battery cable from the battery terminal with the wrench.

Remove the positive battery cable form the battery terminal with the wrench.

Locate the bolt that is used to secure the battery in the compartment. Remove the bolt with the wrench or a socket wrench.

Pull the battery out of the compartment and out of the trunk. Set the old battery aside.

Insert the new battery into the compartment. Replace the bolt that is used to secure the battery in the compartment.

Attach the negative and positive battery cables. Tighten the cables with the wrench. Place the plastic covers over the battery terminals.

Set the plastic battery cover back in place and tighten the screws. Fold over the carpet in the trunk.

Items you will need

  • Phillips-head screwdriver

  • Wrench

  • Socket wrench

 How to Replace a Battery in a BMW Trunk

Check your owner's manual or contact your dealer to determine what type of battery you need. Different BMW models, such as the 3-Series or 5-Series, require different types of batteries.

Open your trunk and remove the trunk liner and carpeting. Depending on your model, you may also have to remove the spare tire and cross brace (BMW X5 only).

Locate the battery compartment (passenger side on most models). Use the screwdriver or pliers to remove the battery access cover.

Lift the protective covering away from the negative (-) battery cable (usually black). Use the pliers to loosen the nut securing the cable to the battery terminal. Carefully lift the cable from the terminal, and then move on to the positive (+) battery cable (usually red).

Use the socket wrench to remove the bolts securing the battery to the battery compartment. Some BMW batteries are attached by a mounting bolt on top, others are attached by bolts on the bottom. You may need an extension to reach it.

Lift the old battery from the compartment using the battery handle. The handle is usually folded down onto one side when installed. Wear gloves to protect your hands.

Mount the new battery and replace the mounting bolts. Attach the positive (+) battery cable first and tighten the nut. Once the positive cable is attached, reattach the negative battery cable.

Replace the battery cover and the trunk liner. Start your BMW to make sure everything is working correctly.

Items you will need

  • Socket wrench

  • Pliers

  • Replacement battery

About the Author

This article was written by the It Still Runs team, copy edited and fact checked through a multi-point auditing system, in efforts to ensure our readers only receive the best information. To submit your questions or ideas, or to simply learn more about It Still Runs, contact us.