23 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCHBattery drained
Leading reported evidence
Install optima
Performed · outcome unconfirmed
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
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Discussions that performed work without a confirmed outcome
1
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Leading evidence: 'Install optima' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, The most frequently discussed action is 'Install optima' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
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Discussions that performed work without a confirmed outcome
1
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Performed · outcome unconfirmed
I bought an 04 CPO, and 7 days after the sale they replaced the battery.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Performed · outcome unconfirmed
Replaced the stock battery yesterday with a Bosch.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
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Suggestion
I left my car with a full battery change for just a week and it was nearly dead when I fired her up.
Run battery tender if you're going 3 weeks between
Suggestion or failed attempt
No successful repair reported for this finding.
0
Reported fixes
0
Unsuccessful attempts
1
Discussions
Read evidence and context
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
Discussions that contain suggestions
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0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
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Suggestion
You might want to run a battery tender if you're going 3 weeks between uses.
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Suggestion · Original poster
I measured the current over each of the fuses in the fuse box and found out that the fuse for "instrument cluster, tiptronic, diagnosis, ASR/PSM button, convertible top control unit" uses about 0.2 A when the car is parked and all the doors are closed.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
23 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
1 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
I also bought an Interstate battery 2 years ago and it has worked great and quite a bit cheaper than any dealer quoted battery.
Hello
I have noticed for a while now that my battery gets drained so I can not start my 996 C2 2002 after it has been parked for about 3 weeks.
I measured the current over each of the fuses in the fuse box and found out that the fuse for "instrument cluster, tiptronic, diagnosis, ASR/PSM button, convertible top control unit" uses about 0.2 A when the car is parked and all the doors are closed. I do not have any tiptronic or convertible top so I guess it is the instrument cluster that is the culprit.
Are there any DIY things to do to fix the drain?
Robert
Do you lock your Porsche and remove the keys? I believe our cars drain more when unlocked and sitting. Others can verify and explain why. How old is the present battery?
Battery is less than 2 years old
When I measured the current I was sitting in the car with the doors closed and I waited until the interior light went off before starting to measure. 0.2 A is a lot, isn't it?
When I leave the car it I lock it with the key button and the alarm is then on.
Robert
Yes, in theory. To save power, after 5 days (ish) the car disables the remote receiver (perhaps other things). And you must use the key in the door to unlock.
With all the sub-systems running in the background your battery will drain down after any lengthy period of isolation! Take her out for a spin once and a while that will show her that you still care...
I heard the same but forget from where. I lock my car even though it is in a closed attached garage because of this reason. I use the car most days however so there is no likelyhood that the battery would go down anyway. One thing I will say is when the car was having a reconditioned transmission in it, it was in Porsche Lancaster PA for 3 weeks. More than likely unlocked inside thier work place. They told me that I should get a new battery as mine was on the blink. I went to pep boys and they tested it and said it was 18 months old and nothing wrong with it saving me over $100. That was last June. I have the same battery in the car and it starts first time, every time. So just maybe being unlocked does drain the battery more than being locked.
I think the stock Mahle battery suck. I bought an 04 CPO, and 7 days after the sale they replaced the battery. It started up very slow, but I never owned a Porsche before so I wasn't sure if the slow start-up was normal. The dealership covered the cost of the battery since I just bought the car 7 days ago.
That replacement Mahle battery lasted about a year or so. There were some periods of several snow storms in a row, and it was in my garage (without power for a battery tender) not being driven for about 4-5 weeks. I jumped it and it was back to the weak slow startups again. I replaced it with an aftermarket Interstate battery, and it has been prefect - even with a few 3 week stints. My 04 Hyundai beater/work car will start up after 2 months.
Interesting about the chug-chug-start example. Mine has done that since I purchased it six months ago. Being new to Porsche's as well, I thought it was normal until I rode in a friends Boxter. It cranked with so much more zest I asked him to listen to my 04 C2 start. He immediately told me to get a new battery! So I installed an Optima. Made a huge difference! Now even the sunroof and windows seem to operate a bit faster.
These cars don't like to go to sleep and be left very long. Apparently, the C4 cab is the biggest offender in the power drain department. I left my car with a full battery change for just a week and it was nearly dead when I fired her up. My indy told me that with so many computers and systems, battery drain is prevalent in the 996, particularly the 996 C4 cab...
When I leave for an extended time, I always leave the drivers down partway, so if the battery dies, I don't have to damage my door seals opening it up. I will get a tender one of these days!
Got mine about 6 months ago as well and thought it was normal because it passed the PPI inspection (battery test included). Just assumed that's how the 996 started.
That hasn't been my experience with the C4 Cab. I recently went on a 3 week vacation and when I returned, the car fired up fine. I had the top up and the doors locked.
Mine is a bosche also.. With an air breather on the left side venting via a rubber tube to atmosphere. Starts up fast every time. Mind you I hardly ever go out in the dark. I only use the radio now and then when I am in 6th gear on the tunpike. I like to hear the revs of the porsche.
Care to explain how leaving a key on the seat draws more power from the car? I'm not saying I don't believe you. I'm just curious about how it happens.
-Eric
I don't know the exact details but understand that certain systems shut down when the key is removed. Also as logray mentioned if you lock the car more systems will shut down after 5 days and you will have to put the key in the door to unlock it. I confirmed this on my car.
This is a source reference. Confirm exact model applicability in the original material.
