Theft alarm = low 12v battery!

[Scandinavian]

Understood but in the real world most people would not leave their car unused for a very long period to encounter the above scenario. Layups as long as this would require other arrangements to be made as you would with an ICE vehicle.

I left mine for about 6 weeks and it died. Same procedure to revive it as the AA guy did. And that is not difficult to do.

But not fun to do in the parking garage at the airport in the early evening.

1. Unlock the car with the physical key.
2. Down on your knees with your phone shining at the footwell to take off the fuse cover.
3. Fumble around with the NOCO booster to unlock the bonnet. = ALARM set off ?
4. Quickly press the key to open car and bonnet = ALARM stops.
5. Open bonnet and take out plastic cover for battery.
6. Get booster connected and car lights up alive.

All watched by the parking security guy who appears and starts asking questions. ?? Wants to check if it really is my car! That is the service that you pay for when parking at the secure more expensive airport parking of course. Pleased that aspect of the secure parking worked as promised, but wifey not so impressed with the experience!

Six weeks at the airport is not unusual for us and there is no way of connecting to a charger there.

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[kl98cwg]

I left mine for about 6 weeks and it died. Same procedure to revive it as the AA guy did. And that is not difficult to do.

I was away for over 3 weeks, but because the problem triggered as a theft alarm I know it occurred when the car hadn’t been used for just 12 days. It really shouldn’t be necessary to have to use a trickle charger or go through the “AA rigmarole” for such a short period of time.

In the two previous years I’d left the car for 4-5 weeks several times and it was fine, so either the 12V battery is degrading or there is a software issue. I suspect the latter … also this was the first time I’d left it after getting the uPdate, so it would be interesting to know if anyone had this issue pre-uPdate.

(also thanks to Simcity for the info from the e-tron GT - really interesting read)

 

[ciaranob]

I finally arrived back home last night and, as expected, the car was dead. It went exactly as TAYC4S described and Porsche Assistance/AA had the car up and running again in no time at all.
The AA chap said he‘d dealt with a number of calls like this and he also suspected a software issue.

The app was still showing ‘theft detected’ today, but I called the Security Operations Centre and they resolved that straight away.

The car is in for a service soon so I’ll get it investigated.

Agree this is not typical I.e. there is likely some sort of sw issue or possibly even a 12v battery defect?
I have left my car for 3-4 weeks garaged 3 separate times this year alone (my first year of ownership of car), once in spring, once in summer and the other through Dec 2022 and NOT hooked up to my home EVSE and not once experienced any issues with 12v drain. I also have a FitCamX installed all this time and of course theft alarm std. On two addl occasions I’ve had the car in a custom shop for weeks and 2 other trips away for nearly 2 weeks (again car garaged and not hooked up, all in the same year) same result.
PS: also same results pre and post uPdste.

 

[timc3]

Agree this is not typical I.e. there is likely some sort of sw issue or possibly even a 12v battery defect?
I have left my car for 3-4 weeks garaged 3 separate times this year alone (my first year of ownership of car), once in spring, once in summer and the other through Dec 2022 and NOT hooked up to my home EVSE and not once experienced any issues with 12v drain. I also have a FitCamX installed all this time and of course theft alarm std. On two addl occasions I’ve had the car in a custom shop for weeks and 2 other trips away for nearly 2 weeks (again car garaged and not hooked up, all in the same year) same result.
PS: also same results pre and post uPdste.

Do you use the App during that time (or anything other integration that would be talking to the car often)?

 

[ciaranob]

Do you use the App during that time (or anything other integration that would be talking to the car often)?

Yep - not super frequently but def pinged the car many times when on vacation and when in shop - also, for ref, generally lost only 1-3% of total HV battery charge over these periods too (exception was one shop stay but they had workers all over it constantly so lost something like 10% HV charge on that occasion but never any issues with the 12v battery).

 

[Speuk]

What is the max current the 12v battery needs to deliver? I just thinking about what size battery booster is sensible for emergency starts on dead 12v.

 

[tchavei]

What is the max current the 12v battery needs to deliver? I just thinking about what size battery booster is sensible for emergency starts on dead 12v.

As far of what I've gotten by reading this forum, it's not really "jump starting" at all. In case of a "dead" battery, you're required to

a) power up the frunk circuit to be able to unlock it with the key (should be a few miliamps at most)

b) power up the central computer through the frunk that will, after about 30 seconds and a dozen of health checks, re enable all relays (12v battery, computer, hv battery communication) after which the car should start to charge the 12v by itself

That being said, I ordered a noco gbx45. Don't have the car yet but I'm doing preventive, psychologically rewarding purchases in antecipation ?

I ordered a gbx instead of a gb because gbx is the most recent model and is usbc compliant. I deeply hate micro USB.

 

[simcity]

What is the max current the 12v battery needs to deliver? I just thinking about what size battery booster is sensible for emergency starts on dead 12v.

It’s a 40 Ah size battery. This is the spec from the supplier:
http://www.a123systems.com/wp-content/uploads/12V-Starter-Battery-Flier_2017_40Ah.pdf

Use a lithium chemistry specific charger if you can. Not a (traditional) lead acid chemistry booster pack.

 

[Speuk]

As far of what I've gotten by reading this forum, it's not really "jump starting" at all. In case of a "dead" battery, you're required to







a) power up the frunk circuit to be able to unlock it with the key (should be a few miliamps at most)







b) power up the central computer through the frunk that will, after about 30 seconds and a dozen of health checks, re enable all relays (12v battery, computer, hv battery communication) after which the car should start to charge the 12v by itself







That being said, I ordered a noco gbx45. Don't have the car yet but I'm doing preventive, psychologically rewarding purchases in antecipation 







I ordered a gbx instead of a gb because gbx is the most recent model and is usbc compliant. I deeply hate micro USB.

Thanks, I was thinking that the load is probably not that high as you say it is not like turning a starter motor on an ICE... I'll do some more research on the battery to to try and see what it is rated at.

 

[Speuk]

It’s a 40 Ah size battery. This is the spec from the supplier:

http://www.a123systems.com/wp-content/uploads/12V-Starter-Battery-Flier_2017_40Ah.pdf

Use a lithium chemistry specific charger if you can. Not a (traditional) l acid chemistry booster pack.

[/QUOTE

Perfect! Yes I was reading an article about the voltage required to wake up the BMS and it recommended a 3 lithium cell booster rather than 4 cell so it was not exposed to a too high voltage

 

[simcity]

In the UK these are the chargers I would use:

1. CTEK Lithium XS
2. Optimate Lithium
3. Porsche Charge-o-mat Pro

 

[simcity]

Perfect! Yes I was reading an article about the voltage required to wake up the BMS and it recommended a 3 lithium cell booster rather than 4 cell so it was not exposed to a too high voltage

Yep. The chargers I linked above all have tried and tested dedicated mode/function to “kick to life” an otherwise dead or sleeping lithium battery, so that it can then accept a charge.

The BMS in these things is usually clever enough to cut the supply to the cells if the incoming voltage goes too high. But honestly you don’t want to risk it with anything lithium. Personally I’d use only a dedicated lithium charger and nothing else.

 

[Scandinavian]

What is the max current the 12v battery needs to deliver? I just thinking about what size battery booster is sensible for emergency starts on dead 12v.

It is not a very high current, nothing like an ICE to start. It needs to just energise the relay and be connected for a short time to get the HV battery to start charging.

There was not much energy drawn from my booster during the exercise.

The CTEK Lithium battery charger also has a boost function to close that relay, but then you need access to mains power.

 

[Speuk]

It is not a very high current, nothing like an ICE to start. It needs to just energise the relay and be connected for a short time to get the HV battery to start charging.

There was not much energy drawn from my booster during the exercise.

The CTEK Lithium battery charger also has a boost function to close that relay, but then you need access to mains power.

Excellent, I have looked at the chargers but as you say you need mains to use them. Despite the manual saying do not use a booster I will get one for emergency use after a spell of airport parking etc. I want something reasonably small as Ideally it needs to be stored in the glove box or cabin so that it is accessible without power.

 

[satchurator]

I finally arrived back home last night and, as expected, the car was dead. It went exactly as TAYC4S described and Porsche Assistance/AA had the car up and running again in no time at all.
The AA chap said he‘d dealt with a number of calls like this and he also suspected a software issue.

The app was still showing ‘theft detected’ today, but I called the Security Operations Centre and they resolved that straight away.

The car is in for a service soon so I’ll get it investigated.

Is your Taycan an MY21? I wonder is your car subject to the WNB4 (interior sensor replacement) recall? IIRC some people affected by that where experiencing LV battery issues as a side effect.

If your car was in regular use, generally connected to the EVSE in your garage in the period leading up to this issue, it sounds like something is defective. I would suggest you press for replacement of the LV battery under warranty if you still have coverage.

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