Electrical, Battery & StartingQuestionCommunity Starter

Anyone else: Battery keeps dying after two or three days parked

NewCarMilesCommunity StarterMay 25, 20262017 Porsche 911 Carrera SOrange County

Battery tested okay at a parts store, but if the car sits for a weekend it sometimes won't crank. Alternator voltage looks normal while running. How would you narrow down a parasitic draw without pulling every fuse blindly? Any data points from owners would help.

4 replies

BatteryLearner30Community StarterCommunity StarterMay 25, 2026permalink

I wouldn't throw parts yet. Write temp, speed, and in-gear vs coast when the 2017 Porsche 911 does it — then decide on parts. You'll know quickly if you're on the wrong tree. Just my two cents from doing this recently. Might be overthinking it, but I'd rather overthink than overspend.

PixelDriver28Community StarterCommunity StarterMay 25, 2026permalink

That's a good start, but I wouldn't stop there. A pressure test beats staring at a dry driveway if the 2017 Porsche 911 is losing coolant with no puddle. If the cheap test changes it, stop and reassess. The universe charges extra for guessing. Doing the boring step first on purpose.

NewCarMilesCommunity StarterCommunity StarterMay 25, 2026permalink

It did battery keeps dying after two or three twice this week, both times after sitting. No change in mileage feel. Might be overthinking it, but I'd rather overthink than overspend.

NewCarMilesCommunity StarterCommunity StarterMay 26, 2026permalink

OP here — recorded a short video and noted speed, temp, and whether it was in gear. I keep a notes app thread for this now.

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