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Battery Connection Notes and Replacement
 
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Pelican Technical Article:

Battery Connection Notes and Replacement

Nick Czerula

Time:

1 hour1 hr

Tab:

$150

Talent:

**

Tools:

Set of sockets (10mm), trim panel tool

Applicable Models:

BMW Z4 Convertible (2003-06)
BMW Z4 Coupe (2006)

Parts Required:

Battery, battery vent hose

Hot Tip:

Wear eye and hand protection

Performance Gain:

Car will start well

Complementary Modification:

Replace battery vent hose

Your BMW Z4 is equipped with a six-cell 12-volt lead acid battery. Each cell consists of lead plates in a lattice and completely covered with sulphuric acid (the electrolyte). The chemical reaction between lead and sulphuric acid produces a nominal two volts per cell; the six-cells together provide the approximately 12 volts required to operate electrical and electronic components in the vehicle. After the battery is used to start the engine, the alternator (powered via the engine accessory belt) takes over electrical generation and also replenishes the charge that the battery used in starting the engine.

During operation and also during recharging, the chemical reactions in the battery produce heat, which causes the electrolyte (sulphuric acid) to evaporate. The cells in many older batteries are equipped with plastic caps, which allow the evaporated electrolyte to escape. If the level of electrolyte drops below the tops of the lead plates the plates can become damaged; also the heat in the battery begins to build excessively at that point. If your battery has removable cell caps, be sure to remove them periodically and inspect the electrolyte level. If the electrolyte is at the same level as the tops of the lead plates, add clean distilled water to the battery.

Most modern lead-acid batteries are sealed so that the evaporated electrolyte cannot escape. However, a charging battery also produces hydrogen. This is discharged from the top of the battery using a small vent tube. Make sure the vent tube is not blocked or damaged, and keep in mind that open flames or sparks around a charging battery are a potential source of battery explosion.

Heat, chemical reactions and electrical charges can cause battery connections to become covered with corrosive and insulating deposits. Any time you remove the battery terminals from the battery, be prepared to clean the metal surfaces with a metal brush. A solution of baking soda and water will neutralize acid deposits and clean the top of the battery and the battery compartment.

Keep in mind that when your car was serviced before, parts may have been replaced with different size fasteners used in the replacement. The sizes of the nuts and bolts we give may be different from what you have, so be prepared with different size sockets and wrenches.

Protect your eyes, hands and body from fluids, dust and debris while working on your vehicle. If you're working with the electrical system, disconnect the battery before beginning. Always catch fluids in appropriate containers and properly dispose of any fluid waste. Recycle parts, packaging and fluids when possible. Do not work on your vehicle if you feel the task is beyond your ability.

Vehicle models change and evolve, as they grow older, so the vehicle shown in our illustrations may vary slightly from yours. If something seems different, let us know and share your info to help other users. Do you have questions or want to add to the article? Leave a comment below. When leaving a comment, please leave your vehicle information.

The battery in BMW Z4 models is located in the right side of the trunk, under the carpet trim (red arrow).
Figure 1

The battery in BMW Z4 models is located in the right side of the trunk, under the carpet trim (red arrow). When replacing your battery be sure to use a high quality unit. Replacing the battery can be done in a short amount of time. Read the battery connection notes before disconnecting the battery. Before disconnecting your battery, remove the key from the vehicle and store it in a safe place while also noting the radio presets. When the battery is reconnected or loses its charge the following items may need attention (depending on vehicle equipment): You may have to reset your clock, enter radio presets, initialize the power windows and initialize the sunroof.

Charging battery: You can connect a battery charger directly to the battery or under the hood at the positive (+) and negative (-) grounding point junction.
Figure 2

Charging battery: You can connect a battery charger directly to the battery or under the hood at the positive (+) and negative (-) grounding point junction. The battery junctions are located at the right front strut tower. The red arrow points to the battery positive (+). The blue arrow points to battery negative (-). However, I suggest removing the battery from the vehicle when charging. This will avoid filling your trunk with gases the battery emits during charging. Follow the manufacturer's instructions on setting and using the battery charger.

Jump Starting vehicle:

A vehicle with a discharged battery can be jump-started using a good battery or a good battery in another vehicle. When jump-starting: Be sure to work in a well-ventilated area. Batteries can produce an explosive gas. Wear gloves and eye protection. If battery acid comes in contact with your skin, immediately flush with water and seek medical assistance. Move both vehicles close together but do not allow them to touch. Turn the ignition OFF in both vehicles. 
Unclip and remove the positive (+) terminal cover (cover on my vehicle subject vehicle was missing).
Figure 3

Unclip and remove the positive (+) terminal cover (cover on my vehicle subject vehicle was missing). Connect one end of the positive jumper cable to the positive (+) battery terminal of the vehicle with the good battery. Connect the other end of the positive jumper cable to the positive (+) junction terminal (red arrow) of the vehicle with the discharged battery. You will have to flip open the lid on the positive (+) junction connection. Connect one end of the negative (-) cable to the negative (-) battery terminal of the vehicle with the good battery. Connect the other end of the negative (-) jumper cable to the negative (-) junction terminal (blue arrow) of the vehicle with the discharged battery. Start the engine on the vehicle with the good battery. Allow it to idle. Then raise the engine to 2000 RPM. Next, start the engine of the vehicle with the discharged battery. Once the vehicle with the discharged battery starts, shut OFF any electrical accessories, radio, HVAC blower, etc. Carefully disconnect the jumper cable in the reverse order you connected them. Allow the vehicle with the dead battery to idle to recharge the battery.

Replacing battery: Working in the trunk, lever out the two plastic trim clips (red arrows) using a trim panel tool.
Figure 4

Replacing battery: Working in the trunk, lever out the two plastic trim clips (red arrows) using a trim panel tool.

Lift the carpet trim and remove from the trunk by sliding it straight out toward the left side of the vehicle.
Figure 5

Lift the carpet trim and remove from the trunk by sliding it straight out toward the left side of the vehicle.

Loosen the 10mm nut on the negative (-) battery cable (yellow arrow).
Figure 6

Loosen the 10mm nut on the negative (-) battery cable (yellow arrow). Remove the negative cable and place it out of the way in a place where it cannot come in contact with the negative terminal while replacing the battery.

Flip the positive terminal protective cover up (green arrow).
Figure 7

Flip the positive terminal protective cover up (green arrow).

Then loosen the 10mm nut on the positive (+) battery cable (yellow arrow).
Figure 8

Then loosen the 10mm nut on the positive (+) battery cable (yellow arrow). Remove the positive cable and place it out of the way in a place where it cannot come in contact with the battery terminal while replacing the battery. Disconnect the battery vent hose and lay it aside.

Loosen the 10mm battery hold down fastener (green arrow).
Figure 9

Loosen the 10mm battery hold down fastener (green arrow). Then remove the battery hold down.

Slide the battery out of the tray toward the rear bumper (red arrow).
Figure 10

Slide the battery out of the tray toward the rear bumper (red arrow). Lift the battery up and remove it from the trunk. Be careful and make sure you have a good grip. The battery is quite heavy. Clean the battery compartment thoroughly. Clean corrosion from the battery cable ends if present.

Before installing a new battery, check that the battery vent line (red arrow) is not pinched, in good condition and properly routed.
Figure 11

Before installing a new battery, check that the battery vent line (red arrow) is not pinched, in good condition and properly routed. Install the battery in the compartment. Attach the vent line (green arrow). Connect the positive (+) cable and install the cover. Next connect the negative (-) cable. Install the battery hold down bracket. Then reinstall the trunk carpet trim.










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Page last updated: Sun 12/11/2016 02:54:28 AM