Where to Find the Battery on a 2010 Audi S4

The main battery on a 2010 Audi S4 is located in the trunk, on the right-hand (passenger) side, beneath the trim panel. A separate positive jump-start terminal is located under the hood for convenience. This layout reflects Audi’s design to improve weight distribution and protect the battery from engine heat.

Understanding the Battery Layout in the 2010 Audi S4

The 2010 Audi S4 (B8 generation) does not place its primary 12-volt battery in the engine bay as many older cars do. Instead, Audi positions the main battery in the rear of the vehicle, while providing dedicated jump-start points under the hood. Knowing both locations is crucial for owners who need to replace the battery, perform maintenance, or safely jump-start the vehicle.

Main Battery Location: Trunk, Right-Hand Side

On the 2010 Audi S4 sedan, the battery is mounted in the trunk, below the carpeting and trim on the right (passenger) side. It is held in place by a metal or plastic bracket and connected to the vehicle’s electrical system via thick cables routed forward.

Step-by-Step: How to Access the Trunk-Mounted Battery

The following steps explain how to quickly and safely reach the battery in the trunk of a 2010 Audi S4, which is necessary for inspection, replacement, or disconnecting power for certain repair jobs.

• Open the trunk: Use the remote key fob, interior release, or trunk handle to open the trunk lid fully.
• Remove or fold back the trunk floor: Lift the carpeting or the removable floor panel to expose the lower trunk compartment.
• Locate the right-side trim panel: Look to the right-hand (passenger) side of the trunk; you’ll see a trim panel or cover that conceals the battery area.
• Remove the side trim panel: Gently pull back or unclip this panel. In some cars, there may be plastic fasteners or a small access door that swings open.
• Identify the battery and bracket: The battery will be visible in a recessed well, secured by a hold-down bracket and connected with large positive (red) and negative (black or brown) cables.
• Check for vent tube: On many S4s, the battery includes a small vent tube that routes gases outside the vehicle; note its position if you are planning to replace the battery.

After exposing the battery, owners can check connections, clean terminals, or proceed with a replacement. Returning all carpeting and panels to their original position afterward helps preserve noise insulation and protect the battery area.

Why Audi Puts the Battery in the Trunk

Audi’s decision to mount the battery in the rear is not just cosmetic. It is tied to vehicle dynamics, packaging, and reliability in a performance sedan like the S4.

The points below outline the key reasons for this trunk-mounted configuration and how it benefits owners in everyday use and long-term durability.

• Improved weight distribution: Moving a heavy component like the battery to the rear helps balance the car’s front-heavy layout, especially with a supercharged V6 up front.
• Reduced heat exposure: Keeping the battery away from the engine bay protects it from sustained high temperatures, which can shorten battery life.
• More space in the engine compartment: Relocating the battery frees space for other components, cooling hardware, and intake plumbing.
• Better protection from the elements: A trunk-mounted battery is less exposed to road spray, salt, and dirt, which can corrode terminals and connections.
• Noise and vibration control: The rear compartment is more isolated, helping limit vibration and potential rattles associated with battery hardware.

This design, though slightly less intuitive for owners used to under-hood batteries, contributes to the S4’s overall performance and durability when properly maintained.

Jump-Starting and Charging: Under-Hood Terminals

Even though the main battery is in the trunk, Audi provides a dedicated positive terminal under the hood and a recommended grounding point for jump-starting and charging. This means you do not need to access the trunk battery every time you use jumper cables or a charger, unless you are replacing or disconnecting it.

Finding the Under-Hood Jump Terminals

The steps below explain how to locate the engine-bay terminals on a 2010 Audi S4 that are designed for jump-starting or connecting a battery charger.

1. Open the hood: Pull the interior hood release, then lift the hood and secure it with the prop rod (if equipped) or rely on the gas struts.
2. Locate the positive terminal cover: On the S4, a red plastic cap or marked cover on the right side (from the driver’s seat perspective) of the engine bay typically indicates the positive jump-start terminal.
3. Flip open the red cover: Lift or slide back the cover to expose the metal stud or post used for the positive jumper cable connection.
4. Identify the ground point: Look for a solid, unpainted metal point nearby (often a dedicated stud or a heavy bolt on the chassis) identified in the owner’s manual as the recommended ground connection.
5. Attach jumper or charger cables correctly: Connect the positive cable to the under-hood positive terminal, and the negative cable to the recommended ground point, not directly to the battery in the trunk.

Using the designed under-hood terminals helps avoid damage to trim in the trunk and follows Audi’s intended procedure for charging and jump-starting, which is important for the vehicle’s electronics.

Replacing the Battery: Key Considerations

Swapping the battery on a 2010 Audi S4 is more involved than on basic economy cars due to its location and the car’s electrical architecture. While many owners can handle the physical replacement, some steps—such as “registering” the new battery in the control module—are best done with proper diagnostic tools.

Physical Replacement Steps (General Overview)

The following points outline the general procedure for physically replacing the trunk-mounted battery on a 2010 Audi S4. Exact steps may vary slightly, so cross-check with the official owner’s manual or a repair manual.

1. Prepare the vehicle: Park on a flat surface, set the parking brake, switch off the ignition, and remove the key. Open the trunk and access the battery area as described earlier.
2. Record settings: Save radio presets or note that some settings (clock, one-touch windows) may reset when power is disconnected.
3. Disconnect the negative terminal first: Using the appropriate socket or wrench, loosen the clamp on the negative (usually brown or black) cable and remove it from the battery post.
4. Disconnect the positive terminal: Loosen and remove the positive (red) cable clamp, taking care not to let tools bridge positive to metal bodywork.
5. Remove the hold-down bracket: Unscrew the bolt(s) securing the battery clamp or bracket at the base of the battery, then lift the bracket away.
6. Lift out the battery: Carefully lift the battery straight up and out. It is heavy, so use proper lifting technique and ensure you have enough clearance.
7. Install the new battery: Place a compatible AGM or lead-acid battery (matching the original spec) into the tray, ensuring it is seated flat and oriented correctly.
8. Reinstall the hold-down bracket: Secure the new battery firmly so it cannot shift while driving.
9. Reconnect cables in reverse order: Connect the positive cable first and tighten, then connect the negative cable and tighten, ensuring solid, clean contact.

After the physical installation, the car will usually start, but some comfort features may need resetting. For optimal battery life and accurate charging, many technicians also perform electronic battery registration with a diagnostic tool that communicates with the car’s control modules.

Battery Coding and Registration

On many modern Audis, including the B8-generation S4, the vehicle’s energy management system tracks battery condition and charging strategy. When the battery is replaced, updating this information—often referred to as coding or registering the new battery—helps prevent under- or over-charging.

The points below summarize why this registration matters and how it’s typically done.

• Energy management calibration: The car adjusts charging voltage and strategy based on battery age, type, and capacity. A new battery without reset data can be charged incorrectly.
• Extended battery life: Proper registration helps the new battery last longer by preventing chronic overcharging or insufficient charging.
• Diagnostic accuracy: Fault codes and battery status readings are more accurate when the system knows a new battery has been installed.
• How it’s done: A shop or experienced owner uses a compatible diagnostic tool (such as VCDS or manufacturer-level equipment) to enter the new battery’s specifications (capacity, type, sometimes serial number).
• Not always mandatory to start the car: The S4 will usually run without coding, but registration is recommended to avoid long-term issues and warning messages.

If you are not equipped with diagnostic tools, a dealership or independent Audi specialist can complete this process after you physically install the battery, or they can handle the entire job from start to finish.

Safety Tips When Working Around the Battery

Whether accessing the battery in the trunk or using the under-hood terminals, safety is critical. Modern cars contain sensitive electronics, and improper handling can cause damage or personal injury.

Key Safety Practices

The list below outlines basic safety guidelines that owners should follow whenever they work with the electrical system on a 2010 Audi S4.

• Wear eye protection and gloves: Batteries contain acid and can emit gas; safety glasses and gloves offer important protection.
• Avoid sparks and open flames: Never smoke or use open flames near the battery; hydrogen gas can ignite.
• Disconnect negative first, reconnect last: This reduces the risk of short circuits if a tool touches the body while on the positive terminal.
• Use correct polarity: Always match positive to positive and negative to ground; reversed connections can damage electronics.
• Secure the battery properly: A loose battery can move in a crash or over bumps, stressing cables and potentially causing shorts.
• Consult the owner’s manual: Audi’s manual for the 2010 S4 provides model-specific diagrams and precautions that should not be ignored.

By observing these precautions, S4 owners can safely manage basic battery tasks while minimizing the risk of costly electrical damage or injury.

Summary

The primary battery on a 2010 Audi S4 is located in the trunk on the right-hand (passenger) side, mounted beneath the side trim and trunk floor. For everyday jump-starting or charging, Audi provides designated terminals under the hood, meaning you rarely need to expose the trunk battery unless you are inspecting or replacing it. This rear-mounted layout improves weight distribution, reduces heat exposure, and protects the battery, but it also means replacement and maintenance should be approached carefully, ideally with proper tools and attention to safety and battery registration procedures.

Where is the battery located on an Audi?

The Audi battery is most commonly located in the trunk under the spare tire, accessed by lifting the carpeted floor, removing the spare tire, and then taking out a plastic cover. For some models, like the Q7, the battery is under the front driver’s seat. On very rare occasions, it could be under the hood in an older model. If the battery is dead and won’t open the trunk, use the designated jump start terminals in the engine bay.
 
This video shows the Audi A4 battery location in the trunk: 42sIrixGuy’s Adventure ChannelYouTube · Dec 2, 2021
For most Audis (A4, A5, A8, S5, etc.)

1. Open the trunk: Use the key fob or the button on the driver’s door panel to open the trunk. If the battery is completely dead, you will need to use the jump-start points in the engine bay to open the trunk first (see below). 
2. Access the spare tire: Lift the trunk’s carpeted floor mat to reveal the spare tire. 
3. Remove the spare tire: Unscrew the central nut holding the spare tire in place and lift it out of the trunk. 
4. Locate the battery: The battery will now be visible underneath where the spare tire was. There may be a plastic cover or other components to remove before you can get to the battery itself. 

For Audi Q7

• The battery is located under the front driver’s seat. 
• You may need to open a compartment or lift a panel to access it. 

If the battery is dead and the trunk won’t open

• You can use the jump-start terminals under the hood.
• Open the hood and locate the positive (+) terminal, which is often under a red cover marked with a ‘+’ symbol.
• Find a good ground point on the engine or body (an unpainted metal surface).
• Follow proper jump-starting procedures, connecting the positive and negative terminals correctly, to give the battery enough power to open the trunk. 

This video explains how to jump-start an Audi with a dead battery: 46sXcelerateYouTube · Aug 17, 2024

Is the Audi battery in the trunk?

So what we do lift this up. This little store storage bin. And then under here. And by the way this is where the jack is if you wanted to know that. Come on my hands are like Oh here we go.

Where is the battery in a 2010 Audi?

And that’s because it’s right here in the trunk. It’s right in the center of the trunk. I pretty much had to remove my spare tire. And this little plastic shield that was on top of the battery.

Where is the battery on an Audi S4?

That. And remove next carefully lift the spare wheel grab it from the center. Pull him up and out of the car. So you’ll see we have this plastic.