Hi everyone,

Hoping for some guidance here.

I’ve owned my 991 for four years and it’s been great, except for one issue. In the last six months or so the battery is out of charge when I try to start the car, and it’s been happening more frequently. I had the battery replaced a few months ago, and things were okay for a while, but now it’s happening again.

i took it to my local Porsche dealer who claimed that everything is fine and his response was:

”the vehicle started up immediately without a prolonged crank, afterwards we did a Draw test on monday and the car passed, tuesday the vehicle sat for majority of the day, Today we performed anoth parasitic draw test and the car passed as again, everytime we would let the car sit for a long duration of time the car would start with no issue at all.
”

This is now about the fourth or fifth time that the battery has died a day after being fully charged. I make sure the doors are always locked, lights are off and no accessories are plugged in. Haven’t hooked it up to a trickle charger, but don’t think I need to since I’m daily driving it.

Just at a loss of what to do now. If the car still has this problem when I get it back I’m going to take it to a good independent shop in my area for a second opinion.

Wondering if anyone else has had similar experiences and what may be causing this?

Thanks in advance for any help…

 

Hey there, electrical issues are the worst! I resorted to trickle chargers on each of my cars, the two late models especially need them for the lack of distance driving. I have experienced faults especially in the 992 due to low battery as the cars systems draw soo much. My Wife daily drives the 992 but just not long or far enough. I don't profess to know all, but can say that this has stemmed my issues. My 991 was having issues turning over until I put a similar T-charger on it. no more issues.
Hope this helps

 

The dealer’s tests passing might mean an intermittent issue, like a software glitch or a module not sleeping properly. Since you’re daily driving, the new battery might not be holding up due to short trips—try a voltage check (should be 14.2-14.5V when running) to test the alternator. Ask the dealer to update the ECU/PCM software, as that’s fixed similar drains for some. If it keeps dying, an independent shop might catch a hidden draw with a longer test.

 

It definitely sounds like you’re dealing with an intermittent parasitic drain that the dealer’s test isn’t catching. Since you’ve already replaced the battery and confirmed your usage habits are fine, I’d suggest checking common culprits like the front trunk light, glovebox light, or any module (PCM, comfort access, etc.) that might not be going to sleep properly. These issues can be tricky because the draw doesn’t always happen during short dealer tests. An independent Porsche specialist with experience in electrical diagnostics might be your best bet — they can monitor the system over a longer period to pinpoint the drain.