Car is Dead

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Gogs

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Car is now at the dealer for a recall. High voltage software. The guy said it MIGHT fix the problem. I doubt it. I’m going to ask them if not 100% fixed to register that fault properly with Porsche. I can’t live with a car that is unreliable. I’m unfortunately at a stage in my life where I need to be at customer meetings etc. Can’t have a car that might not work! That all said, the dealer have given me a 991 loaner, now that’s a nice car, but honestly I think it’s atrocious! Loud, hard ride etc, never could go back to that now...
 

Matt8442

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Car is now at the dealer for a recall. High voltage software. The guy said it MIGHT fix the problem. I doubt it. I’m going to ask them if not 100% fixed to register that fault properly with Porsche. I can’t live with a car that is unreliable. I’m unfortunately at a stage in my life where I need to be at customer meetings etc. Can’t have a car that might not work! That all said, the dealer have given me a 991 loaner, now that’s a nice car, but honestly I think it’s atrocious! Loud, hard ride etc, never could go back to that now...

Hi Gogs, been following this thread intently as we are soon to be picking up our Taycan 4s and I want to be as ready as I can be if this happens to us. Read on another thread here a great idea of perhaps connecting a 12v battery charge cable ( like what you get on a motorbike trickle charger) to the battery terminals of the car then having them routed and hidden to somewhere discreet and out of sight. Then have the battery boost pack in the car. That could then alleviate having to open the trunk first before trying to get 12v to the car. Not sure how much time this would save or if the effort would be worth the reward though. If you had had access to a battery booster would you have needed to call recovery?
I know though also that it’s important that Porsche get informed of every instance of this happening, so would still tell them even if I fixed the issue as they need to find the fault.
Anyway just some thoughts and would like to know yours...
 
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Yeah, I had a think about this and looked to see how you could route a positive & negative feed to behind the wiper blades. I couldn’t do that myself, so would need a auto electrician to take a look.

Opening the car with the key was tough, you really need to put pressure on the key to open. Then attach a booster to open the trunk, then move the booster to the 12 volt battery. That allies the car to turn on, then it starts recharging the 12 volt. I was told s full recharge takes 20 minutes and it charges from the high voltage battery.

@jetbox has a battery thing that I believe can be kept in the glove box, I think the first step is quite easy. @jetbox what battery did you buy?
 

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Yeah, I had a think about this and looked to see how you could route a positive & negative feed to behind the wiper blades. I couldn’t do that myself, so would need a auto electrician to take a look.

Opening the car with the key was tough, you really need to put pressure on the key to open. Then attach a booster to open the trunk, then move the booster to the 12 volt battery. That allies the car to turn on, then it starts recharging the 12 volt. I was told s full recharge takes 20 minutes and it charges from the high voltage battery.

@jetbox has a battery thing that I believe can be kept in the glove box, I think the first step is quite easy. @jetbox what battery did you buy?
I have one of these in my glove box, had it a few years for other things and as a power bank for the kids. I think it’s a good insurance policy that I never have to use to jump the Taycan.

0AF17D16-22DE-49A5-9E11-D79FA892A67F.png
 
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I have one of these in my glove box, had it a few years for other things and as a power bank for the kids. I think it’s a good insurance policy that I never have to use to jump the Taycan.

0AF17D16-22DE-49A5-9E11-D79FA892A67F.png
Perfect. Just ordered something similar, like you I’ll keep in the glove box charged up.

F594F3B8-D4EF-4B09-B610-E90D92315598.jpeg
 

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That is perfect. Glovebox it is!
 
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At least if it happens again, I’ll be mobile within ~10 minutes. Pissed off. but moving!
 

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Give the dealer the bill for the charger tomorrow! ;-)
that looks like it should do the job, I’ll be getting one as well. Thanks everyone for sharing the info on here.
 

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that looks like it should do the job, I’ll be getting one as well. Thanks everyone for sharing the info on here.
Give the dealer the bill for the charger tomorrow! ;-)
Gogs,

could you connect to the OBD2 socket to charge the 12v battery
1602192981204.jpeg

there is a permanent 12v connection.
It will handle enoogh current to get the 13v up and running
 
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Not sure, I think I saw on a US thread that it wouldn’t work. I’ll try and get the senior tech when I pick up the car. He’s a good guy at my dealership, see what he thinks & Ill post back.
 

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Gogs,

could you connect to the OBD2 socket to charge the 12v battery
a few things:
  1. when the 12V dies it's not from a gradual load - it's a large load such that the vehicle needs the 800V battery to charge the 12V and it still goes dead when the big battery gives up it's retry counter - and it drains quickly from there
    1. in my case Porsche indicated the vehicle stepped into to charge the car with the 800V battery no less than 7 times in a 6 hour period - but that system has a maximum retry count and when it's the maximum it will no longer try - the 12V in my case still died!
    2. 7 times in 6 hours (at least 7 times - porsche was unable to unwilling to tell me the exact number of times) is more than once an hour - that's a pretty big load on a 12V battery that started the evening fully charged.
  2. it is my SWAG (scientific wild ass guess) that an ODBII charger and it's power limits on electrical current will NOT be able to keep up with the sort of 12V load that has been demonstrated to kill the 12V in the Taycan - and keep in mind the 800V battery does try and charge the 12V - but due the the continuous 12V load it eventually gives up and let's the 12V die.
  3. once the 12V battery is allowed to die - it is off line (behind a tripped relay) until you reboot the vehicle via the 12V jumper posts in the frunk - once your vehicle is in this state you can _NOT_ charge the 12V by any means (other than disassembling the vehicle and directly accessing the battery -not recommended).
it is therefore my informed SWAG that 12V trickle charging via ODBII port will NOT avoid this issue, and once the car is in this state it certainly will _NOT_ charge the 12V battery because the whole car Is dead and various systems are isolated behind relay's that have "opened" and therefore you can not electrically reach the 12V to charge it due to the tripped safety relay.

also keep in mind when you are attaching to the 12V posts - you are _NOT_ charging the 12V battery - you are providing an external 12V power source to reboot the Taycan's and it's computer systems - once the computer systems are back online the Taycan's computer will open/close relays as it sees fit to bring the vehicle back to life…

I don't believe a 12V trickle charger can avoid this problem.

post #42 on this thread contains the details as to why I believe this to be true - I welcome factual corrections - but will bristle at speculation with out a source.

https://www.taycanforum.com/forum/threads/car-died-over-night….2525/page-3#post-35628

post #11 from the thread below also contains more of my speculation on this topic - but I will stress I'm doing my best to make it "informed speculation" - factual and evidence based corrections are welcome.

https://www.taycanforum.com/forum/threads/car-is-dead.2616/#post-35700
 
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daveo4EV

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this picture is conceptually accurate - but technically simplified and may lack exact details…

Screen Shot 2020-09-30 at 10.49.44 AM.png


once the car is dead - _ALL_ the red-boxes are computer controlled relay's that have "tripped" - meaning they have disconnected their components from the electrical bus - they will _NOT_ receive any power from the main 12V bus until the main computer "resets" the relay and reconnects those components to power…

the jumping posts are the only documented method to "power" the main computer to reboot the taycan - and it's not clear/documented that you can provide enough power via the ODBII port to reboot/power the main computer…

so far the _ONLY_ documented method to recover the taycan (Porsche's own documented process) is to provide a 12V external power source via the jumping posts in the frunk…after that gives power to the car it recover's itself…

again I stress jump starting a Taycan is NOT charging or jumpstarting the 12V battery - it's providing power to the Taycan's computer which reboots the car and reinitializes everything and which point the vehicle recover's itself, and will charge the 12V battery if it deems it necessary with power from the 800V main battery.

ICE thinking and techniques will do you no good here - the 12V battery in the case of most EV's serves a few rolls:
  • it provides 12V compatible power to the 12V supply chain components that all automobiles are based on
  • it provides continuous power to the vehicle's computers that are running when he car is "off/idle"
  • it provides 12V power source so that the main 800V DC battery can be safely offline when not in use - it's bad juju to have 800V DC on tap if it's not being used - and just safer to have it behind a computer controlled relay such that the main battery is online/connected only when the vehicle is in use
  • it is "in essence" a starter battery like an ICE 12V battery - but only indirectly - it provides power to the main computer, and the main computer controls the DC power relay's to bring the main 800V battery online - if you have no 12V power - you have no computer, and therefore you have no way to engage the 800V relay's to bring the big battery online…so your vehicle is dead…
and it is confirmed the 12V battery in the Taycan is a 12V battery with it's own computer, firmware, and one of the roles of the firmware is to trip a relay switch in the positive terminal of the battery when it's low voltage for safety -apparrently this style of battery is common across Porsche's line of automobiles these days and shares that behavior with at least the 992 911 12V battery.
 

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Perfect. Just ordered something similar, like you I’ll keep in the glove box charged up.

F594F3B8-D4EF-4B09-B610-E90D92315598.jpeg
Wow, that's a lot cheaper than the NOCO ones I was looking at as emergency backup options. Mine doesn't arrive until Dec with a Nov build so hoping progress has been made by then. That said, for £37 it's a good plan.
 

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a few things:
  1. ..
  2. it is my SWAG (scientific wild ass guess) that an ODBII charger and it's power limits on electrical current will NOT be able to keep up with the sort of 12V load that has been demonstrated to kill the 12V in the Taycan - and keep in mind the 800V battery does try and charge the 12V - but due the the continuous 12V load it eventually gives up and let's the 12V die.
it is therefore my informed SWAG that 12V trickle charging via ODBII port will NOT avoid this issue, and once the car is in this state it certainly will _NOT_ charge the 12V battery because the whole car Is dead and various systems are isolated behind relay's that have "opened" and therefore you can not electrically reach the 12V to charge it due to the tripped safety relay.
A fairly decent car charger will provide 5A or more, the car would really have to be going some to deplete the battery with that much charging going on.

Bear in mind that even with a smallish 500mA draw, a 50AH battery will be dead in a couple of days.

Based on that, I suspect a mid range trickle charger (even via the OBD port, apparently fused around 5-15A) would keep the battery going. Doesn't solve the underlying problem though!


edit: Jump pack wise I've got a NOCO, would recommend.
 
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