Theft alarm = low 12v battery!

[MTGBUK]

Yeah, so it seems having it plugged into an EV charger still won’t help for prolonged periods.

I agree. A while ago the car was charged to 100% the night before. I hadn't driven the car for a few days. Washed the car which usually takes between 1-2 hours and towards the end got a low 12v warning on the dash and to plug in the car. The car was open but not 'On'. This has only happened post software update. Thankfully turning the car 'On' seems to initiate charging of the 12v battery. I'm guessing the 12v is relatively small in the Taycan. They recommend driving at least 20 minutes to fully recharge the battery in an ICE car. In the Taycan the voltmeter on the dash shows the battery ramp to 14V+ only for a few mins before returning to 13.4V - 13.6V.

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[tchavei]

Yep. Don’t boost it. Charge it with the correct device which has a wake up function.

Long term you’re potentially fudging your 12V battery and short term it’s potentially quite dangerous.

"IF" (and that's a big "IF") I'll ever need it (like stranded in a tight parking lot at some shady airport at 3 am after a 12h flight), I won't be "charging" anything. I will simply unlock a frunk and momentarily boot a computer to get me home. In any other scenario, I'll call assistance because a) I'm too old to be on the ground trying to unlock a 100k+ car, b) I pay insurance for a reason and c) Porsche also needs to "feel" that this is an issue.

I think people are confusing some concepts around here. I never said one should "charge" or "boost" the battery. If you want to "charge" (trickle or not) a LifePO4 battery, please use an adequate charger. Anything else is a serious risk.

Peace

 

[MrBlueSky]

Thanks to all for the input on this thread which has made a very interesting read as it's something I've been wondering about for a while.

I work a rotation of 6 weeks on and 6 weeks off. The car will be at home while I'm away and connected to the EVSE. It seems on balance, from reading all of this, it would be sensible to invest in a suitable lithium trickle charger for the 12V and connect that up just before I depart. So, that's what I'll do.

I live in the countryside and would prefer to just have the car working when I need it? To be honest, I have to admit I'm not getting a warm fuzzy feeling that the HV looking after it's wee brother while I'm away is actually guaranteed and, I'd rather not test it.

I take onboard the comment about Porsche being informed of the issue and using Porsche Assistance higlights things but, I'll do that through my dealership if required.

 

[W1NGE]

Thanks to all for the input on this thread which has made a very interesting read as it's something I've been wondering about for a while.

I work a rotation of 6 weeks on and 6 weeks off. The car will be at home while I'm away and connected to the EVSE. It seems on balance, from reading all of this, it would be sensible to invest in a suitable lithium trickle charger for the 12V and connect that up just before I depart. So, that's what I'll do.

I live in the countryside and would prefer to just have the car working when I need it? To be honest, I have to admit I'm not getting a warm fuzzy feeling that the HV looking after it's wee brother while I'm away is actually guaranteed and, I'd rather not test it.

I take onboard the comment about Porsche being informed of the issue and using Porsche Assistance higlights things but, I'll do that through my dealership if required.

I don't think this is necessary particularly if you leave your car connected to your EVSE (it will trickle charge the 12v as needed (as per owner's manual).

The 12v drain issues have been addressed with several updates since launch. It may be there is a new one lurking but this would be the subject of a recall if so.

Appreciate the risk but I'm assuming also that you'd need to leave your car unlocked and / or frunk open (will lead to the trunk light being on for a period). Normally you'd connect to an internal 12v socket rather than the battery direct.

 

[MrBlueSky]

Hi Adrian. Yep, I appreciate that's how it's supposed to work but there does appear to be a concern that this isn't happening? Whether this indicates a bit of bad luck with individual 12V batteries or another software bug lurking in the system, time will tell.

On reflection, I might test it out after my first rotation with the car by going with the manual's advice just to see what happens. If nothing else, it might provide additional evidence in support (or otherwise) of a new issue. I'll look to report back how it goes.

 

[Scandinavian]

TE="Raphie, post: 218029, member: 8831"]
Yeah, so it seems having it plugged into an EV charger still won’t help for prolonged per

It is in the manual.

It is stated for the main HV battery I thought. It is under the 12 volt battery section, but it refers to the HV battery.

If you look at the document I attached and look further down on the manual, it again states that the 12 volt battery should be charged after 6 weeks.

The manual states the for the 12 volt battery!

With that extra advice I still believe that you actually will have to proper start the car and drive it for some time, in order for the 12 volt battery to start a new sequence of cycles.

This is a major flaw with the design, if you can not leave the car at an airport or marina when away for a longer period.

 

[simcity]

This is a major flaw with the design, if you can not leave the car at an airport or marina when away for a longer period.

Presumably this is all in software - so quite ‘fixable’ if there is a real long term issue as the cars and battery ages naturally and becomes more susceptible to a low SoC during extended non-use.

 

[W1NGE]

TE="Raphie, post: 218029, member: 8831"]
Yeah, so it seems having it plugged into an EV charger still won’t help for prolonged per

It is stated for the main HV battery I thought. It is under the 12 volt battery section, but it refers to the HV battery.

If you look at the document I attached and look further down on the manual, it again states that the 12 volt battery should be charged after 6 weeks.

The manual states the for the 12 volt battery!

With that extra advice I still believe that you actually will have to proper start the car and drive it for some time, in order for the 12 volt battery to start a new sequence of cycles.

This is a major flaw with the design, if you can not leave the car at an airport or marina when away for a longer period.

It is a right muddle with incomplete / conflicting advice in various Porsche documents.

My logic is that the HV masters the 12v and so when needed tops up the 12v automatically at a certain threshold. HV maintains this when left connected to an EVSE and so a trickle to the HV to keep say at 85% and should the 12v drop then the HV tops it off without the car being powered on by the owner.

Fortunately I never leave my car at an airport nor have a boat and therefore hopefully never have this level of stress to contend with.

Clarification is needed from Porsche and documentation amended as appropriate. Dealerships need to up their game in terms of education as there is a wave coming in the shape of a Macan EV where Joe Public likely won't be on this forum and left high and dry with a product they're I'll equipment to run and maintain.

Suspect this isn't unique to Porsche.

 

[rb33gl]

My 12v won't last more than 2 weeks with not driving it. I cannot understand why, when it's sitting on a battery with up to 93Kw.

The advicce from my OPC so far is to put it on a trickle charger. Given the dangers outlined in this and other threads of not doing this correctly, I'm not forking out £100+ for the wrong charger. If it's so sensitive and needs doing, Porsche should give me one.

Having come form an air cooled 911 which was always on a trickle charger when I wasn't using it, I thought I'd left all this behind!

 

[W1NGE]

My 12v won't last more than 2 weeks with not driving it. I cannot understand why, when it's sitting on a battery with up to 93Kw.

The advicce from my OPC so far is to put it on a trickle charger. Given the dangers outlined in this and other threads of not doing this correctly, I'm not forking out £100+ for the wrong charger. If it's so sensitive and needs doing, Porsche should give me one.

Having come form an air cooled 911 which was always on a trickle charger when I wasn't using it, I thought I'd left all this behind!

93.4 is your gross and actual usable 83.7 - but your point still applies.

 

[simcity]

My 12v won't last more than 2 weeks with not driving it. I cannot understand why, when it's sitting on a battery with up to 93Kw.

Thats simply not right.

Do you have any aftermarket devices fitted - dash cams etc.?

I would say, if not, then either your car needs the 'big' software update everyone got last year or the 12V battery is simply knackered.

The 12V battery typically charges once per week, when the car is fully powered off - this was verified by a member who put a CTEK Battery Sense unit on it and could see the HV system kickoff the charges fairly regularly to the 12V battery. If your battery cant last 2 weeks something is either draining it or as said its fudge.

 

[rb33gl]

Thats simply not right.

Do you have any aftermarket devices fitted - dash cams etc.?

I would say, if not, then either your car needs the 'big' software update everyone got last year or the 12V battery is simply knackered.

The 12V battery typically charges once per week, when the car is fully powered off - this was verified by a member who put a CTEK Battery Sense unit on it and could see the HV system kickoff the charges fairly regularly to the 12V battery. If your battery cant last 2 weeks something is either draining it or as said its fudge.

No, nothing after market. No dash cam. Also had the big update (that was supposed to be a remedy) last year.

I reported it to my OPC and they had 'no concerns about my battery'. They thought it was due to:

a) the car's low mileage
b) it being 'fairly normal to lose charge' over 2 weeks
c) keyless entry (which I don't have) discharging the battery
d) the need to use a trickle charger

I'm waiting for a further response from them as this isn't good enough. I'm not going to grovel around the fuse box with a spare battery to get the frunk open to reboot the 12v... Or hang about for Porsche Assist.

I believe it's software related. The HV battery should always ensure the 12v is charged (as long as there's more than say, 10% charge left) becuase it is so central to the operation of the car.

 

[rb33gl]

Incidentally, I read somewhere the 12v battery costs about £1,000.

 

[Speuk]

Incidentally, I read somewhere the 12v battery costs about £1,000.

Yep, but crazy to use a unique battery which costs that much.

 

[simcity]

Incidentally, I read somewhere the 12v battery costs about £1,000.

Probably from me. I had a search online during the infamous battery-gate shortage.

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