Don Breaks His Taycan - The Saga of the 12v Battery

[struther]

When I get my car back, I shall hug my 12v battery, love my 12v battery, and call it George.

If memory serves me correct from my distant childhood, that is a Bugs Bunny reference on the abominable snowman episode. I think. Love it.

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[louv]

If memory serves me correct from my distant childhood, that is a Bugs Bunny reference on the abominable snowman episode. I think. Love it.

Yes. Yes, it is.

 

[EVOG]

I would some how expect the Taycan to keep the 12 V battery topped off when plugged in. Apparently this is not the case. I've used CTEK trickle chargers on my recent Porsche cars and see CTEK has a trickle charger for Lithium Ion batteries: https://smile.amazon.com/CTEK-56-926-LITHIUM-Automatic-Phosphate/dp/B00EUF6UM8/ref=sr_1_10?crid=WFM30H3M2I6B&dchild=1&keywords=lithium+ion+car+battery+charger&qid=1587169647&sprefix=lithium+ion+car+battery+cha,aps,165&sr=8-10

Hopefully we will get some feedback from louv's dealer.

I saw this in the owners manual under long term storage:

Avoid using the Porsche Connect smartphone
app. Establishing a connection between the app
and the vehicle activates the high-voltage system,
thereby discharging the high-voltage and
12-volt battery.

Were either of you using Porsche Connect at the time the 12 V battery went flat? It is only a 40 AH battery.

I was actually using the app a lot a day or two before the battery died. I was trying to fix charging profiles and monitoring the state of charge since that was the first time I charged the car at home.

 

[louv]

I was actually using the app a lot a day or two before the battery died. I was trying to fix charging profiles and monitoring the state of charge since that was the first time I charged the car at home.

Yes, I was using it as well.

Sure, I understand that waking the car to talk to the cellular network is going to use some battery. But surely they can draw from the big battery pack to feed the little battery while the car is “off”.

maybe

 

[Cpoarchy]

Yes, I was using it as well.

Sure, I understand that waking the car to talk to the cellular network is going to use some battery. But surely they can draw from the big battery pack to feed the little battery while the car is “off”.

maybe

Crazy, but that makes so much sense.

 

[louv]

In the early years of Tesla Model S, the car would keep the whole computer network up and running if the car was parked. This allowed it to wake up very quickly when the driver got in. But.., it consumed about 1% of the high-voltage battery every day it was parked. (At some very low battery SoC it would finally go into hibernation). They later changed to shut down most of the car’s computers when it was parked.

It’s a learning process.

 

[Brassfactory]

Yes, I was using it as well.

Sure, I understand that waking the car to talk to the cellular network is going to use some battery. But surely they can draw from the big battery pack to feed the little battery while the car is “off”.

maybe

God guess. I debug human systems, not electronic ones, but that word ‘surely’ is often sitting on top of something worth looking at.

I really hope Porsche monitors your musings.

 

[r553]

Per Porsche info:

The 12 V LiFePO4 is supplied by the DC/DC converter at its 12 V output. A separate
50 mm² aluminium line (terminal 30 positive) leads to the terminal clamp of the positive
terminal, from there to the battery and across a metal bridge to the main fuse box (MFB).
The positive stud terminal for the jump-start point (12 V vehicle electrical system supply)
is attached to the MFB and protected against unwanted short circuit by a red plastic cover
with a black flap over it.

So either the DC/DC converter 12V output is bad ( it worked fine on your 10000 mile trip ) or the software was not paying attention to the state of the 12 V battery.

 

[Chuck J]

The 12V battery on my first Volt died and the car wouldn't start. 12-v-12v bad.

Chuck J

 

[SFEVER]

This is very common in EVs I've had this issue in 4 out of my 6 EVs and it was always due to a drain on the 12V battery when the car was parked for a few days and 100% or 90% charged. Using the connection app to connect to the car too much was one (although this was mainly years ago on the Tesla) having a camera system added was another and two cars just lost charge of the 12v attire for no reason that we could find. The last time it happened was with the Etron which I no longer have. Have not has the issue with he BMW or Kona but have read on forums where owners have had the same thing happen. Perhaps I'll buy a spare battery on keep in the garage on a trickle charger with the motorbikes so I have a spare!

 

[Chuck J]

Good points@

Chuck J

 

[KensingtonPark]

Perhaps I'll buy a spare battery on keep in the garage on a trickle charger with the motorbikes so I have a spare!

Is the battery accessible at all? The plugin cars that I have had gave me posts that were connected to the battery somewhere, but the battery itself was only accessible by lifting the car.

 

[louv]

Is the battery accessible at all? The plugin cars that I have had gave me posts that were connected to the battery somewhere, but the battery itself was only accessible by lifting the car.

The 12v battery is under a panel above and behind the Frunk. Passenger side (US car).

Here are the jumper cables connected to the (+) on the battery, and a (-) post on the body of the car.

Photo taken from in front of the car. The Frunk is lower right. Panel is removed.

 

[Scandinavian]

Since the battery is a Lithium kind I guess you will need a special charger for it as well? A standard charger will not be suitable?

 

[louv]

Since the battery is a Lithium kind I guess you will need a special charger for it as well? A standard charger will not be suitable?

Correct. If you are going to directly charge the 12v battery you want a charger designed for LiFePO4 chemistry batteries.

That being said, if the car is working correctly, you shouldn’t ever need to charge the 12v directly. Just plug in your j1772 charger and the car will take care of the rest.

If...

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