Porsche 997: Why Does My Battery Keep Dying?

This article applies to the Porsche 997 (2005-2012).

For many owners, their Porsche 997 is a second or third (or fourth) car that doesn't get daily duty. Some end up sitting in a garage for weeks at a time between uses, and this can wreak havoc inside the car's battery. Lead/acid batteries, found in 99.9% of cars including the 997, are very picky about how much charge they have. If they are ever discharged fully, a chemical reaction known as sulfation occurs, and the capacity of the battery is reduced and cannot be brought back.

If you are having battery drain issues in your 997, read on to find out why and what you can do about it.

Step 1 – Verify the battery is good

The first thing to do is check your old battery's health and verify that it's the proper part for the 997. If it has been changed by someone who didn't do their research, it might not have the capacity or CCA (cold cranking amps) required for the car. If it is the correct battery, bring it to an auto parts store to have it tested. Finally, consider if it has ever been discharged before. If it has, it's a good idea to replace it.

(Related Article: How to Replace Porsche 997 Battery - Rennlist.com)

Step 2 – Prevent excessive draining

All modern cars have a lot of electronics built in that can and do function even when the engine is turned off. Adding on more accessories can increase the drain even further, so unplug the radar detector and iPod when parking the car. Inside the car's computer is a function known as "sleep mode," which shuts everything off. To activate it, simply lock the car with the remote. Without doing this, some systems remain on for several days, draining the battery.

Step 3 – Increase battery charge

The best way to ensure the life of your battery is to keep it topped up all the time. The obvious solution is to get out and drive the car! Once a week is a good rule of thumb to keep the battery (and the rest of the car) happy. A full warm up cycle will provide plenty of juice for the battery.

If you can't drive the car that often, the next best thing is to buy a battery tender. Many owners like the Porsche branded unit, and many opt for the CTEK. These both plug into the cigarette lighter, so it's extremely easy to install. The style that clips directly onto the battery also works just fine. These small chargers provide a low-amp current to the battery, to keep it at 100% even when the car isn't being used for extended periods of time.

Using a multimeter, touch the red probe to the red wire connected to the alternator, and touch the black one to the frame of the car. If you're not getting any power from it, then it's broken. Places like Autozone offer free tests in case you don't have a multimeter. The multimeter should read 14 volts; if it's reading anything significantly less than that, then it's not working properly to charge the battery.

Step 4 – Check the alternator

If the alternator is not working, the battery won't re-charge.

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