How to avoid 12v battery anxiety

[jdzions]

you can refer to this post. There is TSB with new SW update to address the issue. Porsche finally has came up with solution supposedly. I doubt you had that installed as just came out

https://www.taycanforum.com/forum/t...ing-parked-for-long-period-jan-12-2026.33336/

That's really good news.

Also, much more recent than the post I quoted (from Feb 2025) which made the "it's been fixed" claim.

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[Tooney]

you can refer to this post. There is TSB with new SW update to address the issue. Porsche finally has came up with solution supposedly. I doubt you had that installed as just came out

https://www.taycanforum.com/forum/t...ing-parked-for-long-period-jan-12-2026.33336/

And that software fix applies to the last 8 model years of 3 different Porsche models. . .
So, not a new problem, I guess.

 

[davidh]

Will be interesting to hear your experience with this battery indicator.

I thought these were designed for Lead acid batteries and have a green indication at full Lead acid battery, ie 12.7 volt.

Since the Taycan is equipped with a LFP battery with a very narrow difference between 20 to approx 80% SoC at 13.x volt, I wonder how it will work. LFP batteries are not easy to measure SoC from.

Or is this unit as described designed for Lithium batteries?

I think that it is only for 12V lead acid batteries1

 

[jdzions]

(tl;dr - got the 12v system to reset itself by plugging it in, and it's now at the dealer to get the required fix.)

Closing the loop (for me, anyway) - I called Porsche Roadside Assistance and they dispatched a tow truck. When I explained the problem to the operator, he said "let's give that forum solution a shot before I try to get your car out of the driveway."

Sure enough, he was able to get his 12v jumpstart box connected to the red tab in the fuse box and a ground in the doorjamb, so I popped the frunk. Then we lifted the cover over the battery enough for him to snake his positive clamp to the hot terminal. Once he connected to ground, I was able to get the car to open the charging port. Once I plugged into 240v/50A, the car claimed to be charging and his jumpbox also claimed to be charging.

He disconnected everything. When I tried to turn the car on, it complained about low 12v voltage (duh), "Service required" (also duh), and "No key" (huh?). I did a full power cycle (i.e. I turned it all the way off and then back on) and everything seemed okay-ish. After 15 minutes of level 2 charging, I disconnected and, with the frunk not latched ('cause I wasn't gonna go through *that* again), I was able to get the car to drive. Closed it all up and immediately drove to the dealer.

Service manager did a quick lookup to see what service campaigns had been tagged to my vehicle, and the "12v battery management" fix was in the list. (As was ASB2, backup camera shenanigans, for which I actually got a paper recall letter last week.)

I should have it back Monday. Hooray.

 

[Apple-J]

(tl;dr - got the 12v system to reset itself by plugging it in, and it's now at the dealer to get the required fix.)

Closing the loop (for me, anyway) - I called Porsche Roadside Assistance and they dispatched a tow truck. When I explained the problem to the operator, he said "let's give that forum solution a shot before I try to get your car out of the driveway."

Sure enough, he was able to get his 12v jumpstart box connected to the red tab in the fuse box and a ground in the doorjamb, so I popped the frunk. Then we lifted the cover over the battery enough for him to snake his positive clamp to the hot terminal. Once he connected to ground, I was able to get the car to open the charging port. Once I plugged into 240v/50A, the car claimed to be charging and his jumpbox also claimed to be charging.

He disconnected everything. When I tried to turn the car on, it complained about low 12v voltage (duh), "Service required" (also duh), and "No key" (huh?). I did a full power cycle (i.e. I turned it all the way off and then back on) and everything seemed okay-ish. After 15 minutes of level 2 charging, I disconnected and, with the frunk not latched ('cause I wasn't gonna go through *that* again), I was able to get the car to drive. Closed it all up and immediately drove to the dealer.

Service manager did a quick lookup to see what service campaigns had been tagged to my vehicle, and the "12v battery management" fix was in the list. (As was ASB2, backup camera shenanigans, for which I actually got a paper recall letter last week.)

I should have it back Monday. Hooray.

 

[Apple-J]

Left my 2023 Taycan 4S in heated garage for 2 weeks. Suddenly all locked out; dead 12v battery. Called Porsche roadside assistance waited 3 hrs after many false dispatches before a tow service arrived; bu garage too tight to remove car; struggled and finally tech was able to open door manually with key and jump start battery. Frustrating experience; car towed to dealership and after 3 days was told 12v battery sensor needed replacing. Weird since Porsche allegedly says one can leave car for up to 6 weeks. HV was 35% charged at time. I am now anxious as I travel quite a bit. IMy experience makes me doubt Porsche has fixed the issue despite what some claim. Will try leaving charger on at 60% charge as some recommed but still disaapointed and especially with Porsche roadside service.

 

[CrazyINP]

Left my 2023 Taycan 4S in heated garage for 2 weeks. Suddenly all locked out; dead 12v battery. Called Porsche roadside assistance waited 3 hrs after many false dispatches before a tow service arrived; bu garage too tight to remove car; struggled and finally tech was able to open door manually with key and jump start battery. Frustrating experience; car towed to dealership and after 3 days was told 12v battery sensor needed replacing. Weird since Porsche allegedly says one can leave car for up to 6 weeks. HV was 35% charged at time. I am now anxious as I travel quite a bit. IMy experience makes me doubt Porsche has fixed the issue despite what some claim. Will try leaving charger on at 60% charge as some recommed but still disaapointed and especially with Porsche roadside service.

did you car have the latest software update that supposedly address that issue?

 

[Apple-J]

did you car have the latest software update that supposedly address that issue?

Yes it did but according to the dealer there was a sensor that malfunctioned.

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