You can test it with a voltmeter (instead of taking it to Autozone or Pepboys). It should read between 12.4-12.7 volts (with the car off). If less, then most likely you will need a new battery.

 

PM sent.

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+1 on the Ctek. Have the same unit and the lighter plug. Same unit Porsche sells but at about half the price. Cords flat and I close the door on it at the bottom with no issues. Also agree it's time to replace the battery. They don't last forever and you're pushing the limit on the OEM that came with it.

 

I also have the CTEK 3300 from the source you listed, they have the cigarette lighter end available as well. It's the same unit Porsche puts their name on at a much better price.

 

Mine is a CTEK 3300, too. Why pay twice as much (for the Porsche model) for the same thing, right?

 

Yes and no. If you get a lower (below 12) reading on a fully charged battery you probably have a problem. However, you may get the 12.4+ static reading on an older/weaker battery but it drops immediately under load, indicating that your best days are over. This is why the load test rather than just a voltmeter is used.

 

Any recommendations on what to get if the garage I park in has no power plugs nearby? I'm thinking a portable thing I can lug down and leave next to or inside the car every couple of weeks or so?

 

$90,000 car....$100 battery replacement..$75 for a Porsche battery maintainer.
Cost of being stranded on a 4 yr old battery..priceless. Get the new battery and maintainer. Everyone spends big $$$ on everything for their car but the question remains about a battery?? I realize it isn't a "fun" upgrade but necessary like brake flushes and oil changes. Batteries usually let go at the worst of times

I say spring for the new battery, drive a couple times a week with some time behind the wheel.

 

Thanks for the link. I just purchased the battery maintainer & cig adapter.

 

+1, mine still works after 14 years of use.