How to test & replace battery on Porsche 911, Cayman, & Boxster (2005-2012)

Maintenance Interval 1 Year
Estimated Dealer Cost $500
Estimated Independent Mechanic Cost $400
Estimated DIY Cost $300
Repair Time 0.3 hours
DIY Difficulty Easy

A car battery has several simple, yet important tasks. It accumulates electrical energy created by the alternator while the engine is running. When the car is turned off, electricity stored in the battery powers all systems that still need to run and provides power for starting the engine. Because modern batteries are very reliable, we often don’t think about our car battery until we experience an issue. In most cases, car batteries last anywhere from 2 to 4 years. However, factors like your driving habits and the environment you’re in will impact the lifespan.

Porsche recommends testing your battery every 2 years. To replace your battery, check out this helpful tutorial above from the YouTube channel, CarFanatic. While the video is for a Porsche 911, the same exact procedure also applies to the 987 Boxster and Cayman. Detailed battery testing and replacement instructions can be found below.

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Step-by-Step Instructions:

Step 1: Test your battery.

  • Start by testing your battery. You can do this by taking your car to your nearest auto parts store.
  • To test the battery yourself, purchase a simple battery tester such as this one.
  • Open vehicle’s hood, then locate the remote battery terminals on the driver’s side under a plastic cover.
  • Remove the plastic battery terminal cover and attached the battery tester.
  • Run through the battery tester’s battery and crank tests. Here is a helpful video from Scotty Kilmer.

Step 2: If your battery is bad, remove the old battery.

  • Open the front compartment area on your vehicle.
  • Remove the plastic battery compartment cover by twisting the two plastic clips.
  • Remove the battery tie down clamp using a 13mm socket and an extension.
  • Loosen the battery terminals using a 10mm socket or wrench.
  • Carefully wiggle out your old battery and lift it out.

Step 3: Insert your new battery and reinstall everything.

  • Re-attach the battery tie down clamp and hand tighten it.
  • Place the battery terminals onto your new battery and hand tighten the 10mm bolts.
  • Replace the plastic battery compartment cover.
  • Clean up your work area and put away all your tools. You’re all done!

6 comments on “How to test & replace battery on Porsche 911, Cayman, & Boxster (2005-2012)

  1. I have a 2006 911S and even when I fully charge by battery it goes completely dead within 2 days just setting in the garage. Why is this happening? Thanks


    • I just had the exact experience with the battery in my wife’s 2011 Carrera S with a PDK. It took a couple of months to get to that point, but looking back I should have just replaced it the first time it died. I thought that something like the front trunk lamp might be staying on and draining it but it was just a dying battery. I have a new size Interstate MTX-94R/H7 from a Porsche dealer in it now. Haven’t gotten the ECU updated as of yet. Have driven 25 miles with no issues other than warning lamps when I first started the engine. Lamps and warnings went away after a very short distance.

  2. After you install a new battery…. do you have to reset the computer, so that the radio and other security software properly works?

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