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

[felixtb]

This was and is a real issue on the old Tesla roadster. And to some extent on the early model Ss..... on the newer cars they have a tighter DC-DC converter/charger system which has mostly eliminated this problem to a pure service item at the annual service.... but sometimes there are bad 12V batteries that do fail..... if this is any “consolation” in your search for a possible reason.......

Sponsored

 

[louv]

This was and is a real issue on the old Tesla roadster. And to some extent on the early model Ss..... on the newer cars they have a tighter DC-DC converter/charger system which has mostly eliminated this problem to a pure service item at the annual service.... but sometimes there are bad 12V batteries that do fail..... if this is any “consolation” in your search for a possible reason.......

I’ll leave the hard work of this search (and a fix) to Porsche.

 

[JC Mann]

Yup. My ex-wife’s Model S went through three 12v batteries in two years.

Guess I’ve been very lucky. I replaced the 12-volt in my Model S about 3 months ago, but I had had it for just over 4 years. A month after that, I had to replace the 12-volt battery in my 2014 Cayman S. My service rep said he had never seen one last 6 years before.

 

[GRUNIQ]

You know your Taycan has a 12v battery, right? Do you know where it is? Do you what to do if it goes completely dead?

I do. Now. I didn’t pay much attention to it until yesterday morning. I mean, I knew it was there... somewhere. Probably.

Go grab a cup of coffee... aw, hell, you are probably stuck at home, Sheltered in Place, so go grab a beer... and come along for a new (but hopefully NOT epic) adventure.

Two days ago I finally had a crew out to the house to install a new Charging Station in my driveway. I started that process last November, but by the time the electricians could schedule it, the ground had frozen (remember: Maine) and the couldn't trench my driveway. "We'll come do it after the spring thaw." Well, now I have a ChargePoint Flex, capable of charging at 50A (the Taycan can only handle 40A, or 9.6kW), I fired it up, connected it to my WiFi, name it, set it to know that it was connected to a 50A breaker, and therefore limit itself to 40A.

I connected up to the car, and set up my Profiles and Timers. My location-aware Profile creatively named "Home" was set to have a minimum charge of 50%, and preferred charging times of 10PM to 5AM. I set up a Timer, Target charge of 90%, 7 days a week, departure time of 3AM, no climate control. All went as expected. The car was at 40% when first plugged in at 4PM. It immediately charged it self to 50%, then stopped charging, as expected. Then at 10PM it started charging... slowed down a couple hours later, and then picked up again and finished charging at 3AM at the requested 90%. Odd that it charged and stopped and charged again... but whatever, the end result was As Requested.

That's the setup. Most of that is PROBABLY all coincidental to what comes next. I am not implying any connection, just setting the stage.

The next morning, yesterday, I wake up and check the iPhone app at about 7:30am: the car is nicely charged as requested.

At 9:51am, my phone rings from an unknown number. I answer, and it's the Porsche Connect Security Team. "There's a problem with your car." "What's the problem?" "First you need to answer your two security questions..." <redacted> "<laughter> Yup, that's right. OK, either your car was broken into or there a problem with the battery." "Uh... those are really different things. OK, I'm out at the car now. No problems. No windows broken, no damage." "OK, well, have a good day, Call us back if you have any questions."

At this point I notice the car hasn't automatically unlocked. Odd. I grab the remote from my pocket and press the unlock button. No joy. I think maybe it's the remote. I read in the "Good To Know" Manual, to place the key near the upper right corner of the rear window and press unlock. Nope. Nothing.

I look at the Porsche Connect App now... It looks like this:

OK, let's try the Emergency key.
1) Pull it out of the remote.
2) Lift the driver's door handle, look underneath
3) Insert key, and turn.
Door unlocks and opens.

Car is still dead. No dash lights. Nothing. Press Start button. Nothing.

OK. This is all I know how to do. Time to call Roadside Assistance. And get my car towed.

Before the car can be towed, I have to unplug from my Charging Station. Hmmm. The car is locked. The car won't let go of the charger plug. There *must* be an emergency release somewhere. Back to the "Good To Know" app, to read the manual.

To Remove the Charging Stations' plug from the car:
1) Open the front door, on the side where you are plugged in.
2) Look for a round button at the top of the front body panel.
3) Pull on that knob, which is connected to a cord, which will release the lock on the charging station plug.

Tow truck arrives 20 minutes later. But, since the car is completely powerless, it can't be put into neutral. And he says, "I don't have dollies in this truck, and there's no way I'm going to drag that beautiful car up onto the truck." So, he goes away.

I call my local dealership's service department. They send out their head technician to my house.

Since the Tech is coming from his house, where he'd been sheltering in place, he had to go to the shop, get some tools, and then drive to my house, I know I have some time. So I read further into "Good To Know".

I discover instructions for applying power to the 12v system, so that the Frunk can be opened (and then the 12v Battery can be accessed directly). I go in the house, grab a spare 12v battery, and some charger clips and go back outside.

To Apply 12v Power to the car, when the car's 12v Battery is dead:
1) Open the fuse panel (to the left of the driver's side footwell)
2) Find the Red 12v Positive Terminal, and pull it out about 1/2 inch.
3) From your spare 12v Battery, Attach 12v Positive to that terminal.
4) From your spare 12v battery, attach negative to the hinge of the car. (bare metal)

At this point, I hear relays switching on and off... kinda like it was trying to connect, something was failing, and then it would try again. After 10 seconds of that, I disconnected. Never mind. I don't know what's really wrong, so I'm just going to stop.

Soon after, the technician arrives.

He connects a bigger batter to the same places. And tries to turn on the car. No joy. We wait a few minutes. Still nothing.

Then he says he needs their Lithium Ion Battery Charger. So a quick, 10 minute run back to the shop, he grabs the big charger. Meanwhile, I run a 100 foot extension cord so he can plug in the charger.

When he returns, and attaches the big charger, the car wakes up enough that we can pop the hood. Now we have access to the actual 12v Lithium battery, so the charger can do a better (read: faster) jobber-charging the 12v Battery.

After charging for about 5 minutes, the valiant Technician attached their diagnostic computer to the ODB-II connector, and collects some diagnostic data from the car.

We let it charge, and download data for another 10 minutes or so, and now everything seems fine.

We remove the brick from under the front wheel. (in case we needed to put it in neutral... I didn't want the car rolling downhill into the street). And he drives the car back to the Dealership, leaving me with a nice silver Cayenne loaner.

Später an diesem Tag fragten sie nach weiteren Details zu den Ladesitzungen, um zu analysieren, was wann passiert war. Ich konnte Ladungssitzungsprotokolle von ChargePoint senden und mithilfe von Überwachungskameras genau feststellen, wann der Akku leer war. (Das Blinklicht des Ladeanschlusses wurde rot und ging aus)

Hier endet dieses Kapitel.
Freut euch auf weitere Abenteuer in "Don Breaks His Taycan" (wieder).

[/ZITAT]
Auf der Suche nach einem neuen Abenteuer? Kaufen Sie einen Taycan!

 

[Dave T]

Don - sorry to hear about your problems! But great job documenting them. Hopefully they figure out a way to prevent this, and benefit all of us.

Gruniq - I’ve noticed that all your posts are in German. Any way you could stop doing that? Nothing against Germany or German, but most of us can’t read it. It’s a German car, but this is an English language forum.

 

[Brassfactory]

Google says he made a joke: Looking for an adventure? Buy a Taycan!

I for one appreciate a little European flavor to go with a European car. But then I’m watching Un Village Fraincais to get me through the quarantine.

 

[louv]

“Looking for a new adventure? Buy a Taycan!”

or...

Looking for someone to take your car beyond the normal? And Probably break it? Give it to Don.

 

[r553]

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.

 

[ron_b]

@r553 all EVs that I know of have a DC-DC converter from the high voltage pack to charge the 12v battery. They will only stop charging when the high voltage pack becomes very low. The @louv problem is some electrical or software issue in my opinion.
The Taycan by default shows the 12v battery voltage on the display by default. Not sure if Don had changed that display or noticed how it tracks?

 

[louv]

Update: The car is still at the dealer, and will be over the weekend (not like I was going anywhere, anyway). It seems they were able understand and maybe even reproduce the problem. They are waiting for feedback from Germany.

I guess I’m just helping all of you who still await your cars have a better experience! Don’t worry, we’ll get all the bugs worked out soon.

 

[louv]

@r553 all EVs that I know of have a DC-DC converter from the high voltage pack to charge the 12v battery. They will only stop charging when the high voltage pack becomes very low. The @louv problem is some electrical or software issue in my opinion.
The Taycan by default shows the 12v battery voltage on the display by default. Not sure if Don had changed that display or noticed how it tracks?

I changed the default displays. I thought, “12v battery?!? Why should I care about that?!? It’s the big battery that I care about!”

See? Again, I was shortsighted and wrong. I should have cared more. When I get my car back, I shall hug my 12v battery, love my 12v battery, and call it George.

 

[ron_b]

I changed the default displays. I thought, “12v battery?!? Why should I care about that?!? It’s the big battery that I care about!”

See? Again, I was shortsighted and wrong. I should have cared more. When I get my car back, I shall hug my 12v battery, love my 12v battery, and call it George.

Yes, I was thinking I would replace the 12v battery voltage with the high voltage battery temp first thing. Now I am rethinking.

 

[louv]

Yes, I was thinking I would replace the 12v battery voltage with the high voltage battery temp first thing. Now I am rethinking.

In hindsight, I don’t think it would have mattered. I *think* the problem isn’t when the car is on and running (and you would be looking at that display), I think the problem is happening when it is plugged in, but not charging. Maybe. That’s my Speculation. Not science.

 

[ron_b]

In hindsight, I don’t think it would have mattered. I *think* the problem isn’t when the car is on and running (and you would be looking at that display), I think the problem is happening when it is plugged in, but not charging. Maybe. That’s my Speculation. Not science.

I would totally agree as both you and @EVOG had the same issue while charging, just may have been interesting to see how the battery has been keeping up. I.e how much variance day to day.
Not that I would try telling a ex-QA manager anything.
I do thank you Don for finding the early issues and reporting them is such detail to aid their resolution.

 

[louv]

I would totally agree as both you and @EVOG had the same issue while charging, just may have been interesting to see how the battery has been keeping up. I.e how much variance day to day.
Not that I would try telling a ex-QA manager anything.
I do thank you Don for finding the early issues and reporting them is such detail to aid their resolution.

The trouble with Lithium Ion batteries... (ok, just one trouble... or really just a difference) is that you can’t easily determine their charge state by just looking at voltage.

Old school lead acid batteries had a pretty linear curve of voltage as it related to State of Charge.

The 12v battery in all modern Porsches is a lithium ion (LiFePO4) battery. TheIr voltage curve isn’t linear. It drops sharply in the first 10-15% of usage from full, and then is very, very flat until the last 10-15% where it drops very quickly again.

So, watching the 12v Voltage on the cluster wouldn’t really tell you anything interesting until it was near dead. Not much warning.

Sponsored