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

[louv]

I know this isn't what you want to hear but at this point aren't you entitled to a new replacement vehicle under the "Lemon law"?

I have zero interest in Lemon Law for this car, or this situation. I’m 99.99% sure this is a software issue.

I’m 100% sure Porsche will (eventually) fix the problem.

I adore this car. You can’t pry it out of my hands. (Well, unless you handed me a free upgraded car built to my spec!)

Also, I now have the tools (and knowledge) to “recover” from a dead 12v battery. No more house calls necessary from my local Service Technician.

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[r553]

The Taycan 12 V battery is relatively small at 60 AH. It is enough to boot up the car and then it is to be kept topped off from the 800 V battery.

 

[wemct]

Eleven days ago I left my Taycan 4S in a garage about 1000 miles away from where I am currently staying. When I parked the car, I set up the Porsche Mobile Charger Connect (wifi, linked it to my Porsche Connect account, plugged in as a Level 1 charger using a standard US wall plug – 6A setting on PMCC). I installed a Blink security camera in the garage to see/monitor the status lights on the PMCC. When I left the car I did not set up a Timer profile. The only active profile was the one set by the factory to ensure 25% minimum state of charge. To address the potential problem experienced by @louv with the 12v battery, I also installed a trickle charger made by Battery Tender for lithium batteries. Since the accessory outlets in the Taycan are off when the car is off, I used a connector made by Battery Tender to plug in the trickle charger to the OBDII port under the dashboard.

Five days after I left the car, I decided to discontinue the AC charging before it reached 100% SOC. Following the instructions provided by @louv in a different thread, I used the Porsche Connect app to stop the direct charging at 70%. I successfully created a Timer profile to charge up to 85% SOC every day. This was all done remotely. It worked. I have been monitoring the trickle charger and the PMCC status lights via the security camera.

Four days ago, I noticed that the SOC dropped from 85% to 83% and the solid green LEDs on the PMCC switched to flashing blue lights and the charging status changed to Paused. According to the owner’s manual no cause for alarm for the blue lights. Two days later, I noticed via my security camera that the blue lights changed to the slow flashing green LEDs indicating the PMCC was charging the high voltage battery. The next day the status lights on the PMCC were solid green again indicating that the SOC was back to 85% in accordance with the Timer profile.

However, a few days ago the Porsche Server stopped communicating with the car. The Porsche Connect app still indicates that the PMCC is in the Pause status and the Porsche Connect app shows red dots in the network diagram between the Porsche Server and the car. The SOC and charging status have not updated in the Porsche Connect app since the communication with the Porsche server was lost. I know the current status of the PMCC via my security camera in the garage. The 12v trickle charger has been solid green for the last ten days. I will be flying down next Wednesday to check on the house and car. Fingers crossed the SOC is 85% and the 12v battery is not flat.

I don’t know if the drop in the SOC of the high voltage battery from 83% to 85% while the car was parked and the change in status to the blinking blue lights and Paused status were related to the car waking up and draining the 12v battery that @louv experienced.

If you are planning to leave your Taycan parked/stored for an extended period of time, I recommend using a trickle charger made for 12v lithium batteries (not just for lead acid batteries). The OBDII connector makes it very easy to connect and disconnect the trickle charger.

 

[KerbMonster]

The Taycan 12 V battery is relatively small at 60 AH. It is enough to boot up the car and then it is to be kept topped off from the 800 V battery.

For a car requiring and engine to crank, yes pretty small but for a 12v system
Assuming it’s fully charged (and not faulty) that 60AH battery should easily last 12 hours with a 3 amp load with a decent safety margin. That’s a reasonable load.
It’s not doing something stupid like tripping the interior lights?
(I had one car where the passenger sun visor was dropping enough under its own weight it tripped the mirror light... oh that was such fun tracking that one down...
Another one I had was the brake pedal return spring giving out and it resting on the brake light switch...)

 

[r553]

Don,
Were you able document your DIY the dead Taycan recovery steps?

Thanks,

Rob

 

[louv]

For a car requiring and engine to crank, yes pretty small but for a 12v system
Assuming it’s fully charged (and not faulty) that 60AH battery should easily last 12 hours with a 3 amp load with a decent safety margin. That’s a reasonable load.
It’s not doing something stupid like tripping the interior lights?
(I had one car where the passenger sun visor was dropping enough under its own weight it tripped the mirror light... oh that was such fun tracking that one down...
Another one I had was the brake pedal return spring giving out and it resting on the brake light switch...)

I haven’t tried monitoring each fuse to see what is being left on. That is an excellent diagnostic step, but is bordering on “work”. I know it isn’t keeping the interior lights on because I’ve watched it with a camera.

And two things about “work”: Porsche isn’t paying me for this “work”. In fact Porsche USA has NEVER contacted me directly about this issue.

Secondly, I fully believe they can now recreate the bug and probably don’t need my help!

 

[Poluski]

Don...which charger dedicated for LiFePO4 batteries did you purchase? I scanned previous posts but did not find a reference. Anyone else with some good recommendations feel free to chime in. I'm thinking of having one in the garage or trunk just in case.

thx.

 

[louv]

Don...which charger dedicated for LiFePO4 batteries did you purchase? I scanned previous posts but did not find a reference. Anyone else with some good recommendations feel free to chime in. I'm thinking of having one in the garage or trunk just in case.

thx.

This is the 10A charger I use. It’s not fancy, but it works. There a 20A version too, for more money.

https://www.bioennopower.com/collec...dc-10a-ac-to-dc-charger-for-lifepo4-batteries

 

[louv]

Don,
Were you able document your DIY the dead Taycan recovery steps?

Thanks,

Rob

It’s actually in the “Good To Know” App manual!

In the Section
12-volt battery

Emergency unlatching of the hood
And
Charging the 12 V battery using the charger

I’ll try to write it up in a simplified form.

 

[GDHazy]

Any news on this? I was due to pick my new Taycan up today and I now can't do to a 12v battery issues. So pissed off

 

[louv]

Any news on this? I was due to pick my new Taycan up today and I now can't do to a 12v battery issues. So pissed off

No. No progress. No news from Porsche.

Does this go away if they recharge the 12v battery and reset the fault?

Or does it still stay? Which means the 12v battery is damaged. Replacement will take a few days (order a new one, wait, then the installation takes a day because the 800v system has to be disconnected which is a huge safety process)

Anyway, sorry to hear your car is delayed.

 

[GDHazy]

No. No progress. No news from Porsche.

Does this go away if they recharge the 12v battery and reset the fault?

Or does it still stay? Which means the 12v battery is damaged. Replacement will take a few days (order a new one, wait, then the installation takes a day because the 800v system has to be disconnected which is a huge safety process)

Anyway, sorry to hear your car is delayed.

No idea, this was sent from Porsche as I was due to collect today. Based on this they can not release the vehicle until a fix is found

 

[Gogs]

No idea, this was sent from Porsche as I was due to collect today. Based on this they can not release the vehicle until a fix is found

That delay in delivery is crazy. If that were me I’d tell them to invoice it now, but tell them not to register till September. Pay in September obviously.

 

[Chuck J]

Not cool!!!

Don: I thought this was just when you were using your Chargepoint charger. Not true?

Chuck J

 

[louv]

That delay in delivery is crazy. If that were me I’d tell them to invoice it now, but tell them not to register till September. Pay in September obviously.

It's not crazy. They obviously can't deliver a vehicle to a customer if they can't get a warning message to go away.

I'll wager it is no more than a week delay (assuming the 12v battery is dead).

Of course, it might be a different problem.

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