PSA: 12V Battery - Warning to New Owners/Shops

[Mbgt72]

So I certainly know the 12V lithium battery has been discussed ad nauseam here between ongoing shortages causing shipment delays, and the uPdate working on better management of the 12V system. But I felt it like it would be prudent to post my experience given new owners taking deliveries.

As posted I just picked up a '21 CT4S and my very first priority was a full ceramic coating (inside & out) as well as PPF on the front clip. We have a phenomenal installer in the area who commonly works on high end cars and has done amazing work in the past. I was fortunate to get an appointment quickly and dropped off the car for what I planned on 3-5 days.

Well the owner was out sick, but his assistant started with the interior ceramic coating, and for whatever reason when he left that night left, he left all the doors open. By unfortunate chance, no one came into the shop the following day, so all my doors were open for ~36-48 hours. By the time someone did come in the 12V system was completely dead. They borrowed a specialized charger from the Porsche dealer, but the 12V battery would not take a charge. The car can be "jumped" by connecting a battery to the 12V system and the car will remain on as the high voltage battery tries to charge the 12v system. But once the car is "off" again, and the protection relay for the 12v system closes, and the 12v battery is fully dead again.

The car is set to be towed on Monday to the dealer for the 12V battery to be ordered and installed, but currently the parts department is estimating 3-4 weeks as it has to be shipped from Germany. I am really really hoping that timeline does not get worse.

Long story short, for new owners getting detail work done, tint work, or general outside services completed, please make sure explicit instructions are given. Additionally, a lot of outside shops are not aware newer Porsches are being shipped with Lithium 12V batteries that need special battery tenders etc. I have ordered the following CTEK charger to have for my personal use as I always keep CTEK chargers for my other vehicles if needed.

I do not intend to name the shop and am appreciative of my local dealer trying to assist as best they can. But to say I am disappointed less than a week into ownership is beyond an understatement.

Sponsored

 

[800v]

Thanks for sharing -- interesting that the battery ran out in 48hrs; I wonder if there is some defect though. I have a post here that details how the 12V battery recharges from the HV battery and I don't think it should discharge this quickly (even with the doors open? well maybe if the door and interior lights were on?)

(As an aside, I bought that ctek charger a few months ago, but when I tried using it, it ran super hot -- very very hot; too hot to touch; and this was at 4.5A only. I ended up buying another LiFePO4 charger that works much better, has variable amp setting, and has a fan to keep it cool.)

Almost all LiFePO4 chargers have a mode that will "unlock" a locked LiFePO4 battery by giving an extra boost -- I wonder if the shop has tried that? May save you from towing the car. (I think on the CTEK you have to hold the button for 10s or so -- but also, there is this review where someone notes that the CTEK was unable to wakeup his Porsche (while another brand charger worked)).
(Also, if you happen to have this "Tecmate Optimate DC-to-DC battery connector" you can try to jump start from any regular car battery)

 

[Mbgt72]

Thanks for sharing -- interesting that the battery ran out in 48hrs; I wonder if there is some defect though. I have a post here that details how the 12V battery recharges from the HV battery and I don't think it should discharge this quickly (even with the doors open? well maybe if the door and interior lights were on?)

(As an aside, I bought that ctek charger a few months ago, but when I tried using it, it ran super hot -- very very hot; too hot to touch; and this was at 10A only. I ended up buying another LiFePO4 charger that works much better, has variable amp setting, and has a fan to keep it cool.)

Almost all LiFePO4 chargers have a mode that will "unlock" a locked LiFePO4 battery by giving an extra boost -- I wonder if the shop has tried that? May save you from towing the car. (I think on the CTEK you have to hold the button for 10s or so -- but also, there is this review where someone notes that the CTEK was unable to wakeup his Porsche (while another brand charger worked)).
(Also, if you happen to have this "Tecmate Optimate DC-to-DC battery connector" you can try to jump start from any regular car battery)

Thanks for the reply and all of the info (both in your previous post and this one). I did come across your older post through some searches and appreciated seeing that info.

That is interesting about the CTEK not being able to trip the safety relay to charge a low battery. As you mentioned, it is specifically part of the user manual which I've attached below. A buddy with a McLaren had the McLaren branded charger, but it is just the same CTEK variant. Obviously I don't have a car to test it on currently, but surprising if it doesn't have enough juice to do what is needed. I kind of question if the Amazon review had connections made appropriately or used the charger correctly. The Shop actually borrowed the Porsche specific 12v charger from the dealership to try to jump & charge the battery with no luck.

Either way, thanks for posting the second (and cheaper) charger option. That is the first charger I've seen list a separate mode button for Lithium battery and LiFePO4 battery. Do you have any input on that mode difference?

 

[simcity]

I've got several of the CTEK Lithium XS chargers as I use them on my bikes, out of season, that have Lithium batteries fitted.

Never had a problem with the charger - although a 'dead' LiFePo battery often needs a voltage bump to get it out of failsafe mode.

Porsche also offer a 5A battery charger, the Charge-o-Mat Pro (Part no. 95804490176) made for them by CTEK, which is both a lead acid and a Lithium specific charger. Cost around £120 here. I've got one sitting here in the box waiting for my Taycan to arrive (hopefully this week).

Photo of both below.

 

[800v]

Never had a problem with the charger - although a 'dead' LiFePo battery often needs a voltage bump to get it out of failsafe mode.
...
Photo of both below.

Yes, I had that one as well -- good to hear you have positive experiences but mine was super hot; felt like about to melt. So I turned it off and threw it away as it seemed unsafe. Maybe I was just unlucky and I might have had a faulty unit (but even then, at that price point I expect it to work safely).

 

[simcity]

Yes, I had that one as well -- good to hear you have positive experiences but mine was super hot; felt like about to melt. So I turned it off and threw it away as it seemed unsafe. Maybe I was just unlucky and I might have had a faulty unit (but even then, at that price point I expect it to work safely).

They come with a 5 year warranty here. Not sure about the states. I would have sent it back, rather than binned it, but each to their own.

 

[Mbgt72]

Whelp, my local dealer tried two batteries they had in inventory that were the old part number sitting on their shelf past their "expiration date" and neither worked. Then in the last 2 weeks they have had 2 more batteries shipped in from other dealers, and none have been viable as they wouldn't take a charge from the Porsche LiFePO4 charger.

Apparently they ship from Germany at 30% charge for them to be more stable in transport. But I guess dealerships just put them on a shelf when received and if they sit for long enough that charge drops low enough for them to be donezo.

So now I'm told that Porsche NA is expecting a new battery to be stateside by the 3rd week of January. Quite a sour way to start ownership, and hasn't been fun watching all the new car goodies I've bought get delivered over the past couple of weeks.

 

[Mbgt72]

Just wanted to update that I did get the car back yesterday ahead of the most recent schedule. Great to have the car back though and I have already been putting the miles on!

 

[SergeyIndy]

I had the same issue but with a 2020 Cayenne. The shop that was working on replacing a door stopper left the door open for a long period of time that drained its 12V to the point it could not be recharged. They called me and said it is giving electrical system error and needs to be taken to the dealer asap. It could be jumped but when turn off, it cannot be started, and needed to be jumped again. The dealer gave me the quote for replacement as $3,520 plus tax and shop supplies and I was shocked at how this could be possible, but they explained that some relay closes, and the battery is toast with the following diagnostics message:


Battery Replacement: VEHICLE
ELECTRICAL SYSTEM BATTERY STATE
OF HEALTH IS TOO LOW. VEHICLE
WAS LEFT IN READINESS RESULTING
IN BATTERY BECOMING TOO LOW TO
CHARGE. MUST BE REPLACED.
FAULTS P1D6C00, U141100

Sponsored