Avoiding dreaded 12 volt battery issue during prolonged absence?

[Dave T]

I think I've seen this discussed here, but forget what people said. I'm going to be away from my car for a month. I want to avoid the dreaded 12 volt battery issue. How should I leave the car, does it matter? Locked? Unlocked? On the charger or off? Inside a hermetically sealed Faraday cage?

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[REIL]

I think I've seen this discussed here, but forget what people said. I'm going to be away from my car for a month. I want to avoid the dreaded 12 volt battery issue. How should I leave the car, does it matter? Locked? Unlocked? On the charger or off? Inside a hermetically sealed Faraday cage?

Posted originally by @louv Nov 16, 2020 credit to him.
https://www.taycanforum.com/forum/attachments/mc-10182251-0001-pdf.10661/

 

[Dave T]

Thanks! So plug it in and set charging to 85%. I’m not going to bother with over-inflating the tires.

 

[chrisk]

It is funny that the TSB about long term storage says leave it plugged in while the most recent TSB for the 12v drain says unplug as soon as charging is complete. The two TSB have conflicting info.
https://www.taycanforum.com/forum/threads/taycan-12v-drain-issues-caught-in-the-act.3729/post-51293

 

[feye]

I think I've seen this discussed here, but forget what people said. I'm going to be away from my car for a month. I want to avoid the dreaded 12 volt battery issue. How should I leave the car, does it matter? Locked? Unlocked? On the charger or off? Inside a hermetically sealed Faraday cage?

Considering the non-existing drain

https://www.taycanforum.com/forum/threads/long-term-storage.2404/post-49394

and the 12V battery bug

https://www.taycanforum.com/forum/threads/taycan-12v-drain-issues-caught-in-the-act.3729/post-51293

one must conclude that you park the car without charging, lock it and leave it until you get back.

 

[Pozuelo]

If parking at a private garage, I would charge to 85%, over-inflate tires if left for over a month, leave the hood popped open and the charger disconnected.

 

[wemct]

Before the pandemic I was going back and forth between two homes every week. Because of the pandemic I have left my car for 3-4 weeks at a time without driving it at my house in Georgia for 6 of the last 9 months. (Recently, I completed a road trip to drive the car from Georgia to Connecticut to enjoy it while I'm in Connecticut)

My routine when it sits for long periods of time is to:

1. keep it plugged to the Porsche Mobile Charger Connect
2. set the profile to 85%
3. reduce the charging amperage from 40Amps to 24Amps
4. I also use an 800mA Lithium Battery Tender trickle charger connected through the OBD port to the 12V battery
5. keep the car unlocked
6. you should probably add some air to the tires, but I didn't and have not had any flat spots on the all season tires
7. I have a security camera set up in the garage so that I can remotely see the colors on the PMCC display and the trickle charger to check status (or problems)

Against common practice on the forum, I use the Porsche Connect app (via my Android phone, my iPad, and my MacBook) on a regular basis while the car is in storage, and have changed profiles and monitored other car settings without triggering the 12V battery problem. I keep a NOCO GB40 jump starter in the glove box but have not had to use it.

I realize there are many different opinions and conflicting instructions even from Porsche. I just wanted to share what I have done very often over the past 6 months that has worked for me.

 

[Dave T]

Thanks everyone, but what the heck! Somehow someone decided to change the title of this thread. I suspect our mysterious moderator.

 

[epirali]

I have now left my car multiple times for 6 to 8 weeks or longer. I have not had the 12 V battery issue while idle, but in the spirit of full disclosure I’ve never had the 12 V battery issue. I leave mine plugged in, set a minimum charge profile at 40% (I would not leave the car at higher charges for long periods of time), and because it’s in a conditioned garage it’s usually unlocked. I am using it with the provided Porsche charger.

how is one data point. I have left the card this way at least four times in the past year.

 

[feye]

If parking at a private garage, I would charge to 85%, over-inflate tires if left for over a month, leave the hood popped open and the charger disconnected.

Exactly. And stop playing with the app, if you don't need it.

How much can you over-inflate the tires?

 

[rquinton]

Before the pandemic I was going back and forth between two homes every week. Because of the pandemic I have left my car for 3-4 weeks at a time without driving it at my house in Georgia for 6 of the last 9 months. (Recently, I completed a road trip to drive the car from Georgia to Connecticut to enjoy it while I'm in Connecticut)

My routine when it sits for long periods of time is to:

1. keep it plugged to the Porsche Mobile Charger Connect
2. set the profile to 85%
3. reduce the charging amperage from 40Amps to 24Amps
4. I also use an 800mA Lithium Battery Tender trickle charger connected through the OBD port to the 12V battery
5. keep the car unlocked
6. you should probably add some air to the tires, but I didn't and have not had any flat spots on the all season tires
7. I have a security camera set up in the garage so that I can remotely see the colors on the PMCC display and the trickle charger to check status (or problems)

Against common practice on the forum, I use the Porsche Connect app (via my Android phone, my iPad, and my MacBook) on a regular basis while the car is in storage, and have changed profiles and monitored other car settings without triggering the 12V battery problem. I keep a NOCO GB40 jump starter in the glove box but have not had to use it.

I realize there are many different opinions and conflicting instructions even from Porsche. I just wanted to share what I have done very often over the past 6 months that has worked for me.

Which battery tender are you using? Is the OBD connection on the left side panel near your left foot?

 

[wemct]

Which battery tender are you using? Is the OBD connection on the left side panel near your left foot?

Robert, see post #2 in the following thread. It is a low amp battery maintainer with different settings for lithium and non lithium batteries. Do not use a high amp charger through the OBD port.

The OBD port is on the underside of the dashboard (left side).

https://www.taycanforum.com/forum/threads/long-term-storage.2404/#post-32784

 

[wemct]

Exactly. And stop playing with the app, if you don't need it.

How much can you over-inflate the tires?

In the past both my Porsche and Aston dealers have recommended between 50-55 psi when I have stored my fair weather cars during the Connecticut winters. They said it is how the tires are inflated during transport of the cars on the ships to the dealerships.

 

[chrisk]

How much can you over-inflate the tires?

Copying from the Porsche TSB for long term storage:
"Inflate tires to minimize flat spots during storage: 51 to 58 psi (3.5 to 4.0 bar) at 68 °F (20 °C)"

 

[Mike in CA]

I'm hoping someone can indulge me with answers to a couple of questions about the 12V battery since I don't actually own a Taycan yet (I'm working on it).

1. Is the 12V battery readily accessible? In our e-tron it's located beneath a cover under the hood and can be easily reached. This makes it simple to connect a battery maintainer, if desired, which I do when the car has been sitting for a while. In the Audi, my understanding is that the 12V battery does not charge when the main vehicle battery is connected to the wall charger; it only charges when the car is actually being driven. Is it the same with the Taycan?

2. Is the 12V battery a normal AGM type automobile battery (like in the e-tron) or is it some sort of specialized unit? Lithium maybe?

Thanks.

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