991.1 C2S Battery Drain - Close to Giving Up
02-12-2023, 01:33 PM
#1
991.1 C2S Battery Drain - Close to Giving Up
Hello everyone,
This is my first post here after lurking for a couple of years. Thank you to all those who have contributed to the discussion boards; they have been very helpful when buying and looking after my car.
I have read through the various posts around battery drainage, but I haven't found a solution that works for me so I wanted to ask you all for your opinion before I decide whether to give up on my car.
In short, I own a 2012 991.1 C2S purchased ~20 months ago from an OPC with less than 50,000 miles on the clock. Love the car, love driving it. Unfortunately, I live in London and can only drive on the weekends, and I also travel frequently so the car can easily go 2 weeks without being driven (sometimes a bit longer). When I do drive it, it's usually for return journeys of 30 mins each way - but these being primarily in London, it's typically low RPM driving.
About 8 months into my ownership, the battery started draining and at times wouldn't start. Usually if it didn't start on the first try, I could leave it a few hours and then I could get it to start. About 10 months ago it was clear that the battery was too drained and in bad shape, so I had it replaced at an OPC (because of the extended warranty). At the time, I asked the OPC to check the car to see if there is anything that might cause the battery to drain quicker than it should - they said they couldn't find anything. After about 3 months, the new battery started being drained again so I took it to the OPC - again, they said that there's nothing particularly wrong with it, but that these cars tend to drain the battery when the owners can't drive them regularly. Given that my car is parked on the street and I cannot use a plugged-in battery maintainer, the OPC suggested I get a solar-powered maintainer. I did that, which seemed to help in the 6 months that followed, until winter came and I was away for 2.5 weeks - sure enough, the car didn't start when I returned.
I will likely have to replace the battery again, but more importantly, I don't see how I can keep the car any longer. Constantly wondering whether the car will even start takes away all of the convenience and joy of having it.
The car is still under its extended warranty, so I could ask the OPC to take another look at this issue, but I'm not sure they will come up with a different answer this time. Equally, I don't love the idea of a kill switch / battery removal -type solution, and I'm not sure it would be compatible with the extended warranty anyway.
Given that the car is parked on the street and I cannot use a trickle charger, does this mean that I am pretty much out of options?
Thank you all for your help!
This is my first post here after lurking for a couple of years. Thank you to all those who have contributed to the discussion boards; they have been very helpful when buying and looking after my car.
I have read through the various posts around battery drainage, but I haven't found a solution that works for me so I wanted to ask you all for your opinion before I decide whether to give up on my car.
In short, I own a 2012 991.1 C2S purchased ~20 months ago from an OPC with less than 50,000 miles on the clock. Love the car, love driving it. Unfortunately, I live in London and can only drive on the weekends, and I also travel frequently so the car can easily go 2 weeks without being driven (sometimes a bit longer). When I do drive it, it's usually for return journeys of 30 mins each way - but these being primarily in London, it's typically low RPM driving.
About 8 months into my ownership, the battery started draining and at times wouldn't start. Usually if it didn't start on the first try, I could leave it a few hours and then I could get it to start. About 10 months ago it was clear that the battery was too drained and in bad shape, so I had it replaced at an OPC (because of the extended warranty). At the time, I asked the OPC to check the car to see if there is anything that might cause the battery to drain quicker than it should - they said they couldn't find anything. After about 3 months, the new battery started being drained again so I took it to the OPC - again, they said that there's nothing particularly wrong with it, but that these cars tend to drain the battery when the owners can't drive them regularly. Given that my car is parked on the street and I cannot use a plugged-in battery maintainer, the OPC suggested I get a solar-powered maintainer. I did that, which seemed to help in the 6 months that followed, until winter came and I was away for 2.5 weeks - sure enough, the car didn't start when I returned.
I will likely have to replace the battery again, but more importantly, I don't see how I can keep the car any longer. Constantly wondering whether the car will even start takes away all of the convenience and joy of having it.
The car is still under its extended warranty, so I could ask the OPC to take another look at this issue, but I'm not sure they will come up with a different answer this time. Equally, I don't love the idea of a kill switch / battery removal -type solution, and I'm not sure it would be compatible with the extended warranty anyway.
Given that the car is parked on the street and I cannot use a trickle charger, does this mean that I am pretty much out of options?
Thank you all for your help!
Last edited by Pdriver101; 02-12-2023 at 01:35 PM.
02-12-2023, 01:46 PM
#2
RL Community Team
Rennlist Member
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The car should have a low voltage disconnect from the factory. You'll be notified on the MFD, something like "battery saver triggered" when you first turn on the ignition. That's your final line of defense, if you see this then you need to charge the battery, either manually with an external charger or with a long, freeway speed trip.
You should also have an AGM battery in there. For USDM, this is the factory configuration. FLA batteries are cheaper, but they have a remarkably high self-discharge rate. AGMs are practically shelf stable. Lithium batteries are like AGM batteries, but extremely expensive and lower capacity. I wouldn't recommend one.
The driving habits you've mentioned will definitely lead to poor charging over time, as you've observed, so if you can't plug in and you can't take a longer highway-speed trip (~30 min or more) every week or two, you'll want to take other more drastic measures like a manual disconnect or your solar charger... which you've already mentioned, and don't want to do. I don't blame you, that sounds like an enormous pain in the ***.
The 991 shouldn't have that much parasitic drain when it's all locked up and asleep, the idea that "these cars have high drain" is an odd one and, frankly, untrue if the car is free of electrical issues. Aside from a 2.5 week kill, which I suspect was started with a nearly dead battery in the first place, the timelines you've mentioned are pretty decently in line with a semi-driven, outdoor stored car that sees mostly city style driving that has a very reasonable (read: not broken nor "high") parasitic drain.
If you don't already, try keeping the revs up when you drive around town. I've never, ever had battery issues in any of my cars, but I also actively avoid having the engine run under 2k RPM. Putting around town I'll shift around 3k, and downshift if I get below about 1600rpm if I'm not stopping.
You should also have an AGM battery in there. For USDM, this is the factory configuration. FLA batteries are cheaper, but they have a remarkably high self-discharge rate. AGMs are practically shelf stable. Lithium batteries are like AGM batteries, but extremely expensive and lower capacity. I wouldn't recommend one.
The driving habits you've mentioned will definitely lead to poor charging over time, as you've observed, so if you can't plug in and you can't take a longer highway-speed trip (~30 min or more) every week or two, you'll want to take other more drastic measures like a manual disconnect or your solar charger... which you've already mentioned, and don't want to do. I don't blame you, that sounds like an enormous pain in the ***.
The 991 shouldn't have that much parasitic drain when it's all locked up and asleep, the idea that "these cars have high drain" is an odd one and, frankly, untrue if the car is free of electrical issues. Aside from a 2.5 week kill, which I suspect was started with a nearly dead battery in the first place, the timelines you've mentioned are pretty decently in line with a semi-driven, outdoor stored car that sees mostly city style driving that has a very reasonable (read: not broken nor "high") parasitic drain.
If you don't already, try keeping the revs up when you drive around town. I've never, ever had battery issues in any of my cars, but I also actively avoid having the engine run under 2k RPM. Putting around town I'll shift around 3k, and downshift if I get below about 1600rpm if I'm not stopping.
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Pdriver101 (02-12-2023)
02-12-2023, 09:26 PM
#3
As noted above, the battery protection mode triggers after extended parking periods (a message displays). This will happen even with a battery tender connected. These cars do stress batteries. Further, this mode is apparently knocking my battery tender off its charge mode.
Long parked periods and short drives will kill batteries.
Those conditions also lead to moisture buildup in the engine fluids that don’t have the heat and time to evaporate. Something else to consider.
Long parked periods and short drives will kill batteries.
Those conditions also lead to moisture buildup in the engine fluids that don’t have the heat and time to evaporate. Something else to consider.
Last edited by BSO; 02-12-2023 at 09:32 PM.
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Pdriver101 (02-14-2023)
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Pdriver101 (02-14-2023)
02-12-2023, 10:51 PM
#5
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A couple issues to clarify in the event you don't know this.
If you have one or two deep over-discharges of a Lead/Acid Battery it damages the Lead/Acid cells within the battery. This is the number one cause of battery damage/failure and the signs of that are what you express. Inability to hold a charge well, but there definately could be other factors also.
If you have not already done so you should look up video on Youtube on how to track Parasitic drains. These are small, but significant drains caused by anything from a bad connection to sticking switches. I put a link to a fairly informative one below. The Porsche dealer will not really test this well for you. You can test for Parasitic drain with a Multimeter inline on the Negative Terminal just to see if you have a higher than normal Parasitic Drain. It should usually be around 50 to 80 miiliamps in general, but you have to wait until your car goes to sleep in about 15 mins to get a jist of what it really is... but again Youtube is your friend.
As far as Lithium, definately more expensive, but its a very viable option if you are super tired of what you are experiening... that is because a Lithium Battery has a Circuit Board inside that monitors the voltage and won't let the battery go to a point of damaging itself, so you completely eliminate the problem of damaging your Battery if you left the lights on, or were away to long as happens with Lead/Acid. Additionally some Lithium Battery have WIRELESS built-In Jump STarting so you won't be stranded by a dead battery again. Thats pretty cool, and yes I'm tooting our own horn, but its a great feature. Secondly to correct what Asselus said about having less Amp Hours and not recommending it... that is not actually accurate in the practicle use of the Battery. For example a Litium battery has a much higher USEABLE energy density than a lead acid battery. In fact you can have a lower Amp Hour Lithium Battery that will sit longer in the Car, and start the Car better due to the ability to use more of its available energy, and by having so much power available it can start the Car easily at a much lower voltage than Lead/Acid is able to. So effectively you can have a 60amp Hour Lithium battery that has more useable energy than a 90 Amp Hours Lead Acid Battery. Plus you will have built-in WIRELESS Jump Starting and weighs about 40% less than Lead/Acid Batteries, and has a much longer lifespan..... but the fact is the price point is not worth it for some, and that is also a fine reason to pass on them. Just wanted to point out all the options.
But the main thing is just to make sure you don't have any parasitic drains, or inherant problem FIRSTLY. So if you're handy, you can do it yourself, or take it to an independant dealr to ask them to check for some parasitic drains. Dealers are never gong to tell you the problem unless they can charge your for them.
If you have one or two deep over-discharges of a Lead/Acid Battery it damages the Lead/Acid cells within the battery. This is the number one cause of battery damage/failure and the signs of that are what you express. Inability to hold a charge well, but there definately could be other factors also.
If you have not already done so you should look up video on Youtube on how to track Parasitic drains. These are small, but significant drains caused by anything from a bad connection to sticking switches. I put a link to a fairly informative one below. The Porsche dealer will not really test this well for you. You can test for Parasitic drain with a Multimeter inline on the Negative Terminal just to see if you have a higher than normal Parasitic Drain. It should usually be around 50 to 80 miiliamps in general, but you have to wait until your car goes to sleep in about 15 mins to get a jist of what it really is... but again Youtube is your friend.
As far as Lithium, definately more expensive, but its a very viable option if you are super tired of what you are experiening... that is because a Lithium Battery has a Circuit Board inside that monitors the voltage and won't let the battery go to a point of damaging itself, so you completely eliminate the problem of damaging your Battery if you left the lights on, or were away to long as happens with Lead/Acid. Additionally some Lithium Battery have WIRELESS built-In Jump STarting so you won't be stranded by a dead battery again. Thats pretty cool, and yes I'm tooting our own horn, but its a great feature. Secondly to correct what Asselus said about having less Amp Hours and not recommending it... that is not actually accurate in the practicle use of the Battery. For example a Litium battery has a much higher USEABLE energy density than a lead acid battery. In fact you can have a lower Amp Hour Lithium Battery that will sit longer in the Car, and start the Car better due to the ability to use more of its available energy, and by having so much power available it can start the Car easily at a much lower voltage than Lead/Acid is able to. So effectively you can have a 60amp Hour Lithium battery that has more useable energy than a 90 Amp Hours Lead Acid Battery. Plus you will have built-in WIRELESS Jump Starting and weighs about 40% less than Lead/Acid Batteries, and has a much longer lifespan..... but the fact is the price point is not worth it for some, and that is also a fine reason to pass on them. Just wanted to point out all the options.
But the main thing is just to make sure you don't have any parasitic drains, or inherant problem FIRSTLY. So if you're handy, you can do it yourself, or take it to an independant dealr to ask them to check for some parasitic drains. Dealers are never gong to tell you the problem unless they can charge your for them.
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02-13-2023, 10:25 AM
#6
Rennlist Member
A few comments.
1. For a battery disconnect, consider something like this. It is not invasive.
2. batteries when they are drained below 12 V are damaged. The first time this happens, a little bit of life is pulled out of the battery and usually it doesn’t survive much longer. So I am sure you’re going to need yet another battery. Like above, I hope you are only installing batteries that are meant for the Porsche (AGM) at the sufficient capacity.
3. You mentioned that the inspection service checked the car. Did they check the charging system? One would think that without an idiot light coming on the charging would be sufficient, but not necessarily. On my 991.2, I can display voltage and usually that voltage is north of 14. Can you do the same and see what you were you were charging at? 4. Even with charging, a battery maintainer like a CTEK will charge the battery further even after driving for a long time. It seems to me that the Porsche charging system doesn’t fully charge the battery. This is conjecture but based on observation of my car.
4. The time and situations you described should not result in a discharge battery. One time I shipped my car and could not charge it for over three weeks and I had absolutely no problem getting it started afterwards. So after you verify that you’re putting the exact correct battery in that car, you have encoded the battery to the charging system (This is important to tell the car charging system how to regulate top voltage for charging), take the car to a Porsche service center and explain the issue. More than likely, the dealership in conjunction with Porsche, UK, or Porsche, Germany, have experience with this issue on your particular model year.
5. One last thing, if you have, or know of an individual with a shunt, install it and monitor the amperage at rest, discharging from the battery. That is in my opinion the only way to understand if there is a parasitic drain. And drive the car - have some fun. It’s hey you bought it.
Good luck
1. For a battery disconnect, consider something like this. It is not invasive.
2. batteries when they are drained below 12 V are damaged. The first time this happens, a little bit of life is pulled out of the battery and usually it doesn’t survive much longer. So I am sure you’re going to need yet another battery. Like above, I hope you are only installing batteries that are meant for the Porsche (AGM) at the sufficient capacity.
3. You mentioned that the inspection service checked the car. Did they check the charging system? One would think that without an idiot light coming on the charging would be sufficient, but not necessarily. On my 991.2, I can display voltage and usually that voltage is north of 14. Can you do the same and see what you were you were charging at? 4. Even with charging, a battery maintainer like a CTEK will charge the battery further even after driving for a long time. It seems to me that the Porsche charging system doesn’t fully charge the battery. This is conjecture but based on observation of my car.
4. The time and situations you described should not result in a discharge battery. One time I shipped my car and could not charge it for over three weeks and I had absolutely no problem getting it started afterwards. So after you verify that you’re putting the exact correct battery in that car, you have encoded the battery to the charging system (This is important to tell the car charging system how to regulate top voltage for charging), take the car to a Porsche service center and explain the issue. More than likely, the dealership in conjunction with Porsche, UK, or Porsche, Germany, have experience with this issue on your particular model year.
5. One last thing, if you have, or know of an individual with a shunt, install it and monitor the amperage at rest, discharging from the battery. That is in my opinion the only way to understand if there is a parasitic drain. And drive the car - have some fun. It’s hey you bought it.
Good luck
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Pdriver101 (02-14-2023)
02-13-2023, 10:46 AM
#7
Nordschleife Master
You may have a short or loose wire somewhere.
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02-13-2023, 08:52 PM
#8
I have been having something similar and found out my camera was slowly draining the battery, why it doesn't turn off when I lock the car, I have no idea as it's using the cigarette lighter socket. Do you have anything plugged into the car while it's parked ?
02-14-2023, 09:27 AM
#11
Instructor
Don't over analyze this by looking for parasitic current draws. Cranking the engine for irregular short trips may not recharge the battery properly and each time you crank you may take out more than you put back in your short drive.
I drive my car 3+ times a week, sometimes for more than 1 hour. Every few months I connect a CTEK MXS10 charger and it is 6-8 hours before the green light shows fully charged.
Find a safe place with a power point to park for 8 hours and charge the battery with a decent smart charger every few months, or more frequently in your case.
I drive my car 3+ times a week, sometimes for more than 1 hour. Every few months I connect a CTEK MXS10 charger and it is 6-8 hours before the green light shows fully charged.
Find a safe place with a power point to park for 8 hours and charge the battery with a decent smart charger every few months, or more frequently in your case.
02-14-2023, 09:31 AM
#12
Rennlist Member
Fully charge the battery and perform a capacity test.
Pulling fuses to find the parasitic draw is not the way to go about it in modern cars. This video explains it well.
And there is nothing wrong with the factiry fitted batteries from Porsche. My battery is rarely on a battery maintainer and it is 8 years old and going into its 9th year soon.
Last edited by IXLR8; 02-14-2023 at 09:33 AM.
02-14-2023, 06:30 PM
#13
RL Community Team
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the video above is pretty good, but the one thing that sticks out to me is that he's shrugging off 60+mA of passive draw as "not a problem" which I very, very much disagree with. A car fully asleep should be under 10mA.
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PathfinderGTS (02-15-2023)
02-14-2023, 11:02 PM
#14
Rennlist Member
Should and can be for the newer vehicles, but the 993 for example is 40 mA or less. I took the measurement over a decade ago, going on memory.
There is another YT video, or maybe it is that one where it shows how techs can get fooled by attempting to find a current leak.
There is another YT video, or maybe it is that one where it shows how techs can get fooled by attempting to find a current leak.
02-14-2023, 11:16 PM
#15
RL Community Team
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Ah yeah I remember we had this conversation a while ago. Something to do with the 993's rudimentary alarm system? Still bonkers to me.