If I don’t drive the car for six months, will the 12V battery run out of power?

[Chiu]

I'd like to ask if anyone has experience leaving their Taycan parked for up to 6 months without use.
I’ll be on an overseas assignment in the U.S. for a while (about 6 months), and before I leave, I plan to charge the high-voltage battery to at least 85%.

What I’d like to ask is:
Will the 12V auxiliary battery gradually lose charge due to the extended period of non-use?
I recall that after a certain software update, the main battery can charge the 12V battery. Sometimes, I even see the 12V battery voltage on the dashboard reading over 13.5V.

Do I need to manually charge the 12V battery?

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[SteveDC]

I'd like to ask if anyone has experience leaving their Taycan parked for up to 6 months without use.
I’ll be on an overseas assignment in the U.S. for a while (about 6 months), and before I leave, I plan to charge the high-voltage battery to at least 85%.

What I’d like to ask is:
Will the 12V auxiliary battery gradually lose charge due to the extended period of non-use?
I recall that after a certain software update, the main battery can charge the 12V battery. Sometimes, I even see the 12V battery voltage on the dashboard reading over 13.5V.

Do I need to manually charge the 12V battery?

If you will check the owner’s manual, I believe you are advised to have the HV SOC at about 50%, *not* 85% for long term storage. I understand the lower state of charge allows for rebalancing of cells. As to the 12 volt battery, I have had mine completely discharged in about 3 weeks. The HV battery will recharge the 12 volt while in storage, but I think the limit is about 6 recharges. After that you are SOL. You might get a trickle charger *specifically designed for* 12 volt batteries, generic ones can damage the 12 volt. THE Taycan lithium 12 volt includes some type of computer assembly, and the battery costs several thousand dollars to replace, inclusive of labor. So I would store @ 50% and get a trickle charger.

 

[Dee]

You can manually wake up the car (and get the charging of the 12V started) by starting pre-conditioning every two or three weeks.
Normally the car charges the 12V battery when it gets below a certain value.
My longest period was three weeks, no problem whatsoever.
Pre-conditioning is just a way to ensure the proces is triggered, no trickle charger required.

 

[Tooney]

Porsche has issued two TSBs about storing Taycans:
For Taycans delivered to owners: https://static.nhtsa.gov/odi/tsbs/2022/MC-10209809-0001.pdf
For new Taycans not yet delivered: https://static.nhtsa.gov/odi/tsbs/2022/MC-10209808-0001.pdf

 

[Chiu]

If you will check the owner’s manual, I believe you are advised to have the HV SOC at about 50%, *not* 85% for long term storage. I understand the lower state of charge allows for rebalancing of cells. As to the 12 volt battery, I have had mine completely discharged in about 3 weeks. The HV battery will recharge the 12 volt while in storage, but I think the limit is about 6 recharges. After that you are SOL. You might get a trickle charger *specifically designed for* 12 volt batteries, generic ones can damage the 12 volt. THE Taycan lithium 12 volt includes some type of computer assembly, and the battery costs several thousand dollars to replace, inclusive of labor. So I would store @ 50% and get a trickle charger.

Thanks Steve, so charging the main battery to around 50%, and if possible, starting the car once a week or every two weeks should help keep the 12V battery charged.

 

[Flying ace]

this sounds complicated (for the 12v) is there an actually lithium trickle charger approved for the car?

I know for the ICE cars with lithium, you can use the Porsche branded charger and it somehow knows. https://shop.porsche.com/us/en-US/p/-95804490171-B/95804490171

Taycan is not on the list of approved vehicles.

 

[SteveDC]

Thanks Steve, so charging the main battery to around 50%, and if possible, starting the car once a week or every two weeks should help keep the 12V battery charged.

That’s what I do if it’s been sitting more than about two weeks. It seems to work. Strictly, though, I would follow the TSB advice that Tooney referenced. If the 12 volt does die, learn how to use your emergency key to physically get into the car, using a portable electric source to pop open the hood (“bonnet”) to get at the 12 volt. (This was the same procedure on my 911.) When inserting the physical key, lift the handle slightly at the same time, otherwise it’s very difficult to get the key in. This is such fun, as you are in near panic state. Then recharge the 12 volt until the car turns on, so the HV can take it from there. I have the CTEK “CS Free” model which gradually brings your battery back. When I turn the car on to recharge the 12 volt, I generally leave it running for about 30 minutes.

 

[Dee]

I'd rather not interfere with the electrical system of the Taycan with a trickle charger...
What if the car starts to charge and the trickle charger as well?
Will it blow the charger?
Will the car shut down with all kinds of error codes?
Will it hurt the 12V battery's BMS?
All kinds of things...
The car should charge itself, period.

 

[Gino]

I'd like to ask if anyone has experience leaving their Taycan parked for up to 6 months without use.
I’ll be on an overseas assignment in the U.S. for a while (about 6 months), and before I leave, I plan to charge the high-voltage battery to at least 85%.

What I’d like to ask is:
Will the 12V auxiliary battery gradually lose charge due to the extended period of non-use?
I recall that after a certain software update, the main battery can charge the 12V battery. Sometimes, I even see the 12V battery voltage on the dashboard reading over 13.5V.

Do I need to manually charge the 12V battery?

The 12v battery is maintained by the main battery as long as it is above 50%.
Don’t charge it above 80% per Porsche recommended SOC. I plug in my 120V charger set to 80% when I’m away and the 12v battery has never dropped below 13.3v ever in the last 2 years.

 

[anonymouse]

The 12v battery is maintained by the main battery as long as it is above 50%.
[...] and the 12v battery has never dropped below 13.3v ever in the last 2 years.

You have been lucky. Technical information is hard to come by, but if you search the forum you will find postings that show the algorithm many think the Porsche has -- and it is not what you say: it has a limited number of times that it will recharge the 12V.

Quite a lot of us had flat 12V batteries last Christmas - in my case after just 9 days.

The manual simply says that if you are laying up the vehicle for a "longer" period of time (it doesn't say longer than what ) then you should talk to your Porsche partner for advice.

 

[Kev946]

I've had my 12v battery die so don't take chances now. I have a Lithium CTEK charger. I didn't know about the preconditioning and above 50% at the time but do this now also. It's a pain if it dies. There is a procedure on the forums on how to get the bonnet open and jump start the 12v battery which is what I had to do.

 

[Gino]

this sounds complicated (for the 12v) is there an actually lithium trickle charger approved for the car?

I know for the ICE cars with lithium, you can use the Porsche branded charger and it somehow knows. https://shop.porsche.com/us/en-US/p/-95804490171-B/95804490171

Taycan is not on the list of approved vehicles.

Porsche does not recommend any trickle charger which I badgered them on back in early 2024. In the end they alerted me to a software update which would keep the 12v batterY charged as long as the main battery is above 50%.
I was directed to keep my 120V charger plugged in when I am away so the main battery never drops below 50%.
As long as you don’t leave anything plugged in or allow your key fobs to communicate with the vehicle keeping it awake then the 12V battery will always stay charged.
I have not had my battery ever drop below 13.3V since I’ve owned my Taycan.

 

[Gino]

Porsche does not recommend any trickle charger which I badgered them on back in early 2024. In the end they alerted me to a software update which would keep the 12v batterY charged as long as the main battery is above 50%.
I was directed to keep my 120V charger plugged in when I am away so the main battery never drops below 50%.
As long as you don’t leave anything plugged in or allow your key fobs to communicate with the vehicle keeping it awake then the 12V battery will always stay charged.
I have not had my battery ever drop below 13.3V since I’ve owned my Taycan.

If any Taycan owner has had their 12V batterY go dead when their main battery is above 50% then it’s a Porsche battery charging software or hardware issue.
I put a meter in my 12V battery over a 6 month period to verify when it was being charged. Anytime the 12V battery dropped below 13.3V the battery began charging from the main HV battery. It worked like clockwork just as my Porsche dealer stated it was supposed to work to maintain the 12V battery.
I would keep a record of your SOC during the entire time it is parked so if the 12V battery dies you can prove to Porsche the 12V battery charging circuit &/or software is not functioning properly.
If you want to put a meter on the 12V battery as well just to be sure it is being properly charged as I did, you can but I stopped monitoring it after 6 months when I realized it was working as the new software update stated it should even if I left it for as long as 4-6 weeks.
You must also make sure the vehicle is not preconditioning the vehicle to warm up or to cool down the interior and make sure nothing is plugged in which could drain the 12V battery.

 

[Horizontally Opposed]

At the risk of taking this sideways, a friend just spent 6 mos away, and hooked the 12v on his EV6 to a smart charger. That charger was plugged into a WiFi outlet, and he had it programmed to come on for 3 hours once per week. When he got home car was ready to go, no problems.

 

[ct14garage]

If you don’t drive the car for 6 months disconnect the negative wire from the battery. Else you have very good chances of having to purchase an expensive Lithium battery once you come back.

conversion to AGM works very well and is very much prefered!

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