Trickle Charger/Battery Tender for 2024 Taycan GTS

[Gino]

I didn't use the car for 9 days and it had 78% SOC but a sufficiently dead 12V battery for even the central locking not to work.
The life of the 12V is supposed to be the life of the car, totally different to the poor life of lead acid batteries.

Well that sucks. When Lithium ion batteries fail they really do just fall off a cliff. I hope it lasts at least the 8 years of the main battery warranty & my extended warranty which ends in January of 2030.
If I have to replace it every 8-10 years then that’s not too bad.

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[JohnPM]

This old thread has a lot about the 12V battery. In the US a replacement is around $1200 per another thread.

The Porsche info warns against using the app if the car is going to be dormant for a while as that can flatten the 12V battery.

 

[Gino]

This old thread has a lot about the 12V battery. In the US a replacement is around $1200 per another thread.

The Porsche info warns against using the app if the car is going to be dormant for a while as that can flatten the 12V battery.

As long as you are above 50% SOC then there will be no issue with the 12v battery but if you are too close to 50% SOC, constantly checking the app will wake up the electronics and potentially drain the main battery below 50% which would mean from that point until you return it could drain the 12V battery.
The worst battery drain can happen if your key fobs are too close to where the car is parked which would keep the electronics awake all the time. The key fobs will keep pinging as long as the vehicle responds and maintains readiness to drive. If you have climate controls set to prewarm or precool the cabin then this will burn down the the SOC every time the car sees either key fob. We keep our key fobs in faraday pouches whenever we aren’t using the car so that there is no chance the key fobs can communicate with the car as well as prevent thieves from stealing the car by using the signal from the key fob to turn the car on and drive away.

 

[Emokeff88]

I posted in the past that I went on a deployment and my car sat untouched for almost 5-6 months. It turned on and drove as if I left yesterday.

 

[f1eng]

As long as you are above 50% SOC then there will be no issue with the 12v battery but if you are too close to 50% SOC, constantly checking the app will wake up the electronics and potentially drain the main battery below 50% which would mean from that point until you return it could drain the 12V battery.
The worst battery drain can happen if your key fobs are too close to where the car is parked which would keep the electronics awake all the time. The key fobs will keep pinging as long as the vehicle responds and maintains readiness to drive. If you have climate controls set to prewarm or precool the cabin then this will burn down the the SOC every time the car sees either key fob. We keep our key fobs in faraday pouches whenever we aren’t using the car so that there is no chance the key fobs can communicate with the car as well as prevent thieves from stealing the car by using the signal from the key fob to turn the car on and drive away.

None of this explains what happened to mine, unfortunately.

Charge 78%

Keys in house about 60m from the car. I don't have comfort access anyway to make theft less easy.

Probably checked the app 3 or 4 times over the 9 days.

Hopefully the garage will replace the 12V battery if faulty. They have retained the car because they can not download some of the data, perhaps because the 12V drained and scrambled some memory though this is less likely to happen than 30 years ago I would imagine.

 

[Gino]

None of this explains what happened to mine, unfortunately.

Charge 78%

Keys in house about 60m from the car. I don't have comfort access anyway to make theft less easy.

Probably checked the app 3 or 4 times over the 9 days.

Hopefully the garage will replace the 12V battery if faulty. They have retained the car because they can not download some of the data, perhaps because the 12V drained and scrambled some memory though this is less likely to happen than 30 years ago I would imagine.

Unfortunately there are one of two reasons your 12v battery died. The first is straight forward. The battery itself failed prematurely. This is possible depending on how old the battery is and how many cycles it has been charged. I doubt it’s as simple as just a battery failure which leads me to the next reason your 12v battery died. Something in the car put an inordinate drain on the 12v battery. This is where it’s not straight forward. A component could have failed or the software could have become corrupted and even worse there could be an intermittent failure in the electronics induced by thermal expansion or contraction.
Intermittent failures can have the dealer chasing their tails.
All they can do is test the battery to see if it passes the charge discharge cycles properly and doesn’t have too much drain when not connected to the vehicle. Once that is done and determined that the battery is good or must be replaced you still have the underlying problem in either software or hardware which led to the battery draining so fast in a little over a week.
My vote is it is an intermittent hardware issue which will come back again and again until it stops being intermittent & fails permanently. The last thing the dealer wants to do it keep replacing components in the system which can impact the 12V system. This gets very expensive but does not address the wiring & interconnections between systems in the vehicle.
Hopefully you’ll get lucky and the act of removing the 12V battery for testing/verification that it’s good or confirming it must be replaced ends up clearing an unstable connection issue on the battery connections themselves. Usually the culprit is an improper ground somewhere in the system which leads to improper charging of the battery a well as causing high frequency electrical spikes which can degrade all the electronics induced the vehicle or at a minimum corrupt software/firmware in numerous vehicle control modules.
I hope for your sake they find the 12V battery just failed prematurely but I fear there is something lurking in your electrical system which is causing it to fail but is not obvious.
The only way you’ll know is if they do replace the battery and this high drain event never comes back for the next year or two and everyone is happy they found the battery was the sole source of failure. If the same high drain event comes back again out of the blue then it tells you it wasn’t the battery and instead it’s an intermittent component/module or connection failure. Intermittent failures are usually on their way to becoming more frequent failures on the way to becoming hard failures which is actually a good thing since hard failures are easy to diagnose.
The one question I have going down this path… Do you live near the ocean or anywhere salts are used on the roads for ice control? These corrosive environments can degrade grounds in a vehicle along with increase resistance in low voltage signal connections from module to module.
I had this happen with my 1991 Ford Explorer which had the battery, alternator, AM/FM radio/CD player as well as the main computer module 2-3 times in less than 3 years.
I didn’t find out the root cause of all these failures were connected by a bad ground connection on the battery itself which had a defective battery connector which made poor contact to the battery post. Over a timeframe of about a year after replacing the battery the connector would very slowly increase in resistance due to oxidation of the lead connector to the battery as well as on the battery post itself. Every time they replaced the battery they cleaned the connector but never found the defect I the $10 battery ground cable which was not making full contact. I finally got the answer from a 70 year old mechanic who saw the problem and knew exactly what it was and told me it was my negative battery connector. He said there is a ridge or bump inside the connector keeping the connector from making full contact with the post.
He then removed the post and magically there it was, a ridge on the inside of the connector with obvious oxidation on the post and more than 50% of the connector. He used a ridge reamer for lead battery connectors to scrape away the ridge as well as all the oxidation built up over time along with cleaning the battery post and all my problems went away. No more battery failures, no more alternators, no more electronics module failures. All because of the simplest component on the vehicle… a ground.
I hope to god they find something definitive because I absolutely hate troubleshooting intermittent failures…
Good luck my friend!

 

[eddieterry]

I doubt it is a failed 12 Volt as this problem has occurred although not often to quite a few Taycans if the recovery chaps can be believed. I am guessing that it is likely to just be a software failure which might never happen again. I think if it was anything else then it would have been solved in previous updates. Most owners do not seem to have experienced this and it has only happened to me once in one and half years which points to an obscure glitch. I just keep a jump starter Power Pack in glove compartment in case it happens when I am away - touch wood not had to use it since original prob.

 

[f1eng]

I doubt it is a failed 12 Volt as this problem has occurred although not often to quite a few Taycans if the recovery chaps can be believed. I am guessing that it is likely to just be a software failure which might never happen again. I think if it was anything else then it would have been solved in previous updates. Most owners do not seem to have experienced this and it has only happened to me once in one and half years which points to an obscure glitch. I just keep a jump starter Power Pack in glove compartment in case it happens when I am away - touch wood not had to use it since original prob.

I had a jump starter but could not unlock the door with the emergency key. Probably just frozen but fed my resentment about too much pointless gadgetry in modern cars.

I first felt that way when the electric seats failed on our car after my wife had driven it and I couldn't even get into the car to drive it. It was the first time I had a non functioning car due to failure of an unnecessary gadget, made even more annoying by the fact I hate electric seats because of the weight anyway..

 

[Gino]

I doubt it is a failed 12 Volt as this problem has occurred although not often to quite a few Taycans if the recovery chaps can be believed. I am guessing that it is likely to just be a software failure which might never happen again. I think if it was anything else then it would have been solved in previous updates. Most owners do not seem to have experienced this and it has only happened to me once in one and half years which points to an obscure glitch. I just keep a jump starter Power Pack in glove compartment in case it happens when I am away - touch wood not had to use it since original prob.

Good luck. Good point to keep jump starter power pack in the glove box but if the 12V battery dies then which is easier to get into? The interior/glovebox, the frunk or the trunk?
At least if you can get into the cabin then you can attach a charger to the OBDII port but if you can’t then the next best thing would be to leave the jump starter in the frunk since you’ll need to get it open to access the 12V battery.
What is your experience?

 

[eddieterry]

Good luck. Good point to keep jump starter power pack in the glove box but if the 12V battery dies then which is easier to get into? The interior/glovebox, the frunk or the trunk?
At least if you can get into the cabin then you can attach a charger to the OBDII port but if you can’t then the next best thing would be to leave the jump starter in the frunk since you’ll need to get it open to access the 12V battery.
What is your experience?

The idea is to use the emergency key to open drivers door then use the power pack / jump starter to connect to Fuse emergency pull out and to door catch to open frunk as per user manual then jump the 12 Volt which will allow the big battery to charge the 12 Volt. You can’t get into the trunk or frunk so this method of keeping jump starter in glove compartment is pretty much the only option.

 

[Tooney]

None of this explains what happened to mine, unfortunately.

Charge 78%

Keys in house about 60m from the car. I don't have comfort access anyway to make theft less easy.

Probably checked the app 3 or 4 times over the 9 days.

Hopefully the garage will replace the 12V battery if faulty. They have retained the car because they can not download some of the data, perhaps because the 12V drained and scrambled some memory though this is less likely to happen than 30 years ago I would imagine.

Is it possible that checking the app periodically over 9 days meant that the data connection between car and Porsche servers stayed active throughout the 9 days even when you were not checking it, resulting in power drain in vehicle?

 

[Gino]

The idea is to use the emergency key to open drivers door then use the power pack / jump starter to connect to Fuse emergency pull out and to door catch to open frunk as per user manual then jump the 12 Volt which will allow the big battery to charge the 12 Volt. You can’t get into the trunk or frunk so this method of keeping jump starter in glove compartment is pretty much the only option.

Perfect! Thanks. It would do my wife no good to look for the answer in the manual on how to get in the cabin if the manual is in the glovebox…

 

[simcity]

Good luck. Good point to keep jump starter power pack in the glove box but if the 12V battery dies then which is easier to get into? The interior/glovebox, the frunk or the trunk?
At least if you can get into the cabin then you can attach a charger to the OBDII port but if you can’t then the next best thing would be to leave the jump starter in the frunk since you’ll need to get it open to access the 12V battery.
What is your experience?

You need a 12V source to get into the frunk area for starters. Once in the frunk, you need a power source that has enough voltage and amperage to wake up the snoozing 12V battery. I tried unsuccessfully first with a CTEK lithium battery charger using "dead battery" mode - no dice.

Had to use a NOCO jump start pack on "dumb" setting to get the 12V battery back into life (it goes into a protective state and opens its safety contactor inside the top of the battery), which then woke up the rest of the car, most importantly the 800V-to-12V converter and charging system, to then carry on and recharge the 12V battery.

You don't use the OBD port!! For either access or trickle charging. You have to use the emergency pull out 12V in the drivers side fuse box - for access - as that is used to energise the adjacent relay which sends power to the convenience system control unit in the boot. By temporarily powering this module you can pop open the bonnet to get to the battery.

For any wake-up or trickle charging you go directly onto the battery access terminals in the scuttle area, in front of the 12v battery.

Have you ever had to do this?

 

[eddieterry]

No the AA chap did it for me while I watched and he then recommended I get the JUMP STARTER GREPRO Power Pack - Car Battery Booster 3000A that I obtained. I keep it in the glove compartment and if needed I will follow exactly what he did. The Noco was the other option but not quite as compact. I have tried the emergency key a couple of times to make sure I can get in - very stiff and has to be turned clockwise. Hopefully I won’t ever need it !

 

[simcity]

No the AA chap did it for me while I watched and he then recommended I get the JUMP STARTER GREPRO Power Pack - Car Battery Booster 3000A that I obtained. I keep it in the glove compartment and if needed I will follow exactly what he did. The Noco was the other option but not quite as compact. I have tried the emergency key a couple of times to make sure I can get in - very stiff and has to be turned clockwise. Hopefully I won’t ever need it !

Sorry I mis-quoted you insisted of @Gino above. Have updated and corrected my post to quote Gino. ?

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