The main 12-volt battery in a 2015 Audi A5 is located in the trunk on the left-hand side (passenger side), not in the engine bay. This placement is standard for most A5 models from this era and helps shield the battery from heat and engine vibration.
Location and layout in the trunk
In the luggage area, the 12-volt battery sits behind a protective cover on the left side and is secured with a mounting bracket. Access is gained by removing the cover and bracket, then lifting the battery out if replacement is necessary. Some trims also provide a dedicated jump-start terminal accessible from the trunk side panel for emergencies.
What you’ll typically find around the battery area
Before listing the key components, note that some trims may vary slightly in layout. The following items are commonly located near the trunk-side battery or within the adjacent side panel:
- 12-volt lead-acid battery with a protective cover
- Battery mounting bracket and retaining bolt
- Jump-start terminal or post accessible from the trunk
- Nearby fuse/relay blocks or connections associated with the battery circuit
- Trunk side panel or trim piece that conceals the battery and prevents accidental contact
Understanding this layout helps with routine maintenance and jump-start scenarios, and it aligns with Audi’s design to isolate the 12-volt system from engine heat.
Step-by-step guide to access or replace the battery
To safely access or replace the battery, follow these steps. They provide a clear sequence so you can work without removing unrelated components.
- Park the car on a level surface, engage the parking brake, and turn off the ignition. Remove the key and wait a moment for all systems to power down.
- Open the trunk and locate the left-side interior panel. Remove the panel trim or carpet to expose the battery area.
- Remove the battery cover if present and locate the mounting bracket. Use the appropriate tool (often an 8–10 mm socket) to unbolt and lift the bracket away.
- Disconnect the negative (-) battery terminal first, then the positive (+) terminal. Use insulated tools and avoid touching metal parts with bare hands.
- Carefully lift the battery out of its tray. If you’re replacing it, install the new battery in the reverse order and reconnect the terminals (positive first, then negative).
- Reinstall the mounting bracket, replace the battery cover, and reattach the side panel. Close the trunk and test the electrical system by starting the car.
Always consult the owner’s manual for torque specs on the mounting bolt and for any specific model variations. If you’re unsure, have a professional perform the replacement to avoid damage to the electrical system.
Safety notes
Battery work can pose hazards, including acid exposure and short circuits. Wear eye protection and gloves, ensure the engine is fully off, and avoid metal jewelry that could bridge terminals. Dispose of or recycle a removed battery according to local regulations.
Additional context: jump-starting and maintenance tips
Because the 12-volt battery is tucked away in the trunk, many owners use the dedicated jump-start terminal inside the trunk for emergency starts, rather than reaching under the hood. Regular checks for corrosion on terminals and keeping the battery and tray clean can extend the battery’s life. If you notice slow cranking or dim lights, a professional test can confirm whether the battery or alternator needs replacement.
Summary
In a 2015 Audi A5, the 12-volt battery is housed in the trunk on the left side, not in the engine bay. Access is gained by removing the trunk-side panel and battery cover, and replacement follows a standard sequence of disconnecting terminals in the correct order. For routine starts and maintenance, use the trunk jump-start terminal and follow safety guidelines. When in doubt, consult the owner’s manual or a qualified technician.