Low Battery oddity
01-06-2019, 03:20 PM
#1
Racer
Thread Starter
Low Battery oddity
My 2009 (until yesterday) had the original battery. The voltage finally dropped to ~11.5 V a couple of days ago. It started like it had a low battery, but did start (and I drove to the local library). The odd thing is that the computer display was showing the FM radio station. I couldn't figure out how to get it to show miles remaining, average speed or mpg, but it would show tire pressures. I could actually select radio stations for the lower left side (computer) stalk.
On the return trip, it started the same way (slowly turning, but eventually starting). This time, the computer display did (correctly) show the standard 4 options (miles remaining, average speed. mpg, tire pressures). At a traffic light, I stalled it and restarted it (again with difficulty). The gas gauge which had previously indicated about 1/2 tank and the computer display showing ~180 miles left, dropped to completely empty (orange indicator on), and the ! warning indicator now on. Drove home (obviously, I was not out of gas) and checked the OBD. It passed with no OBD alerts. Yesterday, I had to have AAA start the car, then drove it to Black Forest (local service independent where it sits now awaiting an ew battery and a 60,000 mile service), with the gas gauge still showing totally empty. All other gauges were acting normally.
Has anyone seen this behavior?
On the return trip, it started the same way (slowly turning, but eventually starting). This time, the computer display did (correctly) show the standard 4 options (miles remaining, average speed. mpg, tire pressures). At a traffic light, I stalled it and restarted it (again with difficulty). The gas gauge which had previously indicated about 1/2 tank and the computer display showing ~180 miles left, dropped to completely empty (orange indicator on), and the ! warning indicator now on. Drove home (obviously, I was not out of gas) and checked the OBD. It passed with no OBD alerts. Yesterday, I had to have AAA start the car, then drove it to Black Forest (local service independent where it sits now awaiting an ew battery and a 60,000 mile service), with the gas gauge still showing totally empty. All other gauges were acting normally.
Has anyone seen this behavior?
01-06-2019, 09:43 PM
#3
Nordschleife Master
01-06-2019, 11:27 PM
#4
Three Wheelin'
Not to be contraire, but I experienced almost the identical gremlins when my battery went south. A fresh battery should solve all of the problems you are seeing. Also, have your tech clear any codes that may have been triggered. I had several but nothing that could not be reset with a Durametric. Interestingly, however, when jumped the battery to get home (with one of the kits that you plug in to the wall to keep charged) the car started fine and all of the funny readings (gas gauge, clock, etc.) were not manifest.
01-06-2019, 11:31 PM
#5
Nordschleife Master
Not to be contraire, but I experienced almost the identical gremlins when my battery went south. A fresh battery should solve all of the problems you are seeing. Also, have your tech clear any codes that may have been triggered. I had several but nothing that could not be reset with a Durametric. Interestingly, however, when jumped the battery to get home (with one of the kits that you plug in to the wall to keep charged) the car started fine and all of the funny readings (gas gauge, clock, etc.) were not manifest.
01-07-2019, 01:17 AM
#7
Nordschleife Master
Yup. Based on a number of battery failures on my three 997's, I consider the OP lucky. None of my failures gave me any warning of any sort. Would have been thrilled with a fuel gauge rolling over all of a sudden and a tired crank as opposed to the car going from cranking strong to not cranking at all which describes all my failures.
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01-09-2019, 07:13 AM
#8
Just changed the battery in my 2009 997.2 and it was an OEM Porsche battery in there from before so quite impressed how long it had lasted (75'000 km since new) - or maybe the previous owner had swapped it with an original I don't know...
This said, for me the "dead" battery just didn't have enough juice for the engine to crank over. The lights in the car where as bright as always and the PCM worked fine without any issues.
Swapped the battery, and I got all sorts of strange error messages - even for options that are not installed - such as Lane Assistant Error (or something like that) and PSM Error, PASM Error etc etc.
Got a new battery the following day, swapped the old one, did a window reset (up - 10 secs, down - 10 secs) staying still turning the steering wheel left then right and drow off. Errors cleared after a while but the first few kilometers were a bit "rough" meaning the idling of the engine was not smooth but stabilized quickly there-after.
This said, for me the "dead" battery just didn't have enough juice for the engine to crank over. The lights in the car where as bright as always and the PCM worked fine without any issues.
Swapped the battery, and I got all sorts of strange error messages - even for options that are not installed - such as Lane Assistant Error (or something like that) and PSM Error, PASM Error etc etc.
Got a new battery the following day, swapped the old one, did a window reset (up - 10 secs, down - 10 secs) staying still turning the steering wheel left then right and drow off. Errors cleared after a while but the first few kilometers were a bit "rough" meaning the idling of the engine was not smooth but stabilized quickly there-after.
01-09-2019, 02:42 PM
#9
Nordschleife Master
Just changed the battery in my 2009 997.2 and it was an OEM Porsche battery in there from before so quite impressed how long it had lasted (75'000 km since new) - or maybe the previous owner had swapped it with an original I don't know...
This said, for me the "dead" battery just didn't have enough juice for the engine to crank over. The lights in the car where as bright as always and the PCM worked fine without any issues.
Swapped the battery, and I got all sorts of strange error messages - even for options that are not installed - such as Lane Assistant Error (or something like that) and PSM Error, PASM Error etc etc.
Got a new battery the following day, swapped the old one, did a window reset (up - 10 secs, down - 10 secs) staying still turning the steering wheel left then right and drow off. Errors cleared after a while but the first few kilometers were a bit "rough" meaning the idling of the engine was not smooth but stabilized quickly there-after.
This said, for me the "dead" battery just didn't have enough juice for the engine to crank over. The lights in the car where as bright as always and the PCM worked fine without any issues.
Swapped the battery, and I got all sorts of strange error messages - even for options that are not installed - such as Lane Assistant Error (or something like that) and PSM Error, PASM Error etc etc.
Got a new battery the following day, swapped the old one, did a window reset (up - 10 secs, down - 10 secs) staying still turning the steering wheel left then right and drow off. Errors cleared after a while but the first few kilometers were a bit "rough" meaning the idling of the engine was not smooth but stabilized quickly there-after.
01-09-2019, 11:57 PM
#11
Most owners don't drive these cars to keep them charged properly. A battery will eventually lose a cell or two and never be able to charge back. Recommend you use a ctek or noco charger.. But for you to get about 10 years on an oem battery is pretty good!
01-10-2019, 04:32 AM
#12
Nordschleife Master
All three of my 997's have been daily drivers and all battery failures have gone from cranking strong as new to not cranking at all.... in hours literally. Same with all of them.
01-10-2019, 05:25 PM
#14
Nordschleife Master
The trunk latch can be opened by attaching 12V to two terminals in the fuse panel by the driver's footwell using the FOB - instructions in the Owners Manual.
