One of the advantages of many EV’s is that the 12v battery, used to basically run all the electronics in the car (just like with an ICE car), is that the HV traction battery is used to automatically re-charge the 12v battery when it drops below a specified voltage. So, in theory, unless one has a defective 12v battery, and can’t be re-charged, the traction battery will be used to insure that the 12v battery is always charged up.

As far as why don’t EV manufacturers eliminate the 12v battery:

”High voltage inside the passenger compartment would require many layers of safety protection. That’s why instead of eliminating the 12 V battery altogether, some recent EV designs opted to replace the lead-acid battery with a much smaller and lighter lithium-based battery with lower available output current.

To completely eliminate the 12 V battery requires a rugged power supply that can safely draw from the high-voltage battery packs. It needs to have a wide input voltage range, ideally 30 VDC to 1000 VDC, to cover both 400 V and 800 V nominal battery voltages, as well as 30 V operation for functional safety critical applications. It needs to be highly efficient to reduce operating temperature and minimize discharge of the traction battery. It also needs to have a low component count, which saves space and increases reliability.”

So, in a nutshell, it;’s safety and cost. Much cheaper to keep the 12v battery.

 

Is this true for all EVs?

For example, older model Teslas, still have lead acid 12v batteries that need to be replaced every 3-4 years (now the newer Teslas use lithium-ion low voltage batteries)

 

Can’t speak to “all”,

 

This is the most logical. That would make a nice lineup of Carreras with a bit more definition than the 992.1 Carrera lineup. I'll add one more speculation into the mix (speculated by me!):

-Base Carrera. 394BHP (388HP SAE), PDK only.
-Carrera T: 420-450BHP (some where in the 991.2-992.1 Carrera S range), manual or PDK, many of the sporty chassis options standard, a couple optional as with previous T's (PLEASE bring back PCCB!).
-Carrera S 480BHP (473HP SAE), manual or PDK.

 

From an EE point of view, it's hard to explain what a facepalm of an excuse that is. The 'safety' ship sailed when they added the HV battery pack in the first place. All of the relevant regulations came into play at that point, and are not the least bit affected by the decision to step the HV down to 12V and/or 48V. HV is never routed anywhere near the passenger compartment.

As for efficiency, there are a few ways to address that. High-current transient loads on the 12V battery are encountered only during engine cranking, so they can simply be driven from a subset of the HV battery. Low- and medium-current accessories should be running on 48V anyway by now, but even at 12V the series-parallel configuration of the HV battery provides plenty of load balancing options that can operate at near 100% efficiency.

Cost? The lithium 12V batteries cost, what, $2000 to replace? I can build you a very efficient buck converter for $2000. In any event, weight is more important than price to 911 buyers, and I think the company understands that. At some point before removing the back seats (which may have costly insurance implications by itself in some markets), yanking the 12V battery should have been on somebody's list.

Reliability? Let's not go there. No shortage of horror stories about people whose hybrids left them stranded because the 12V battery was dead while the traction battery was at 80% SOC.

Anyway, OT, but the TL,DR is that the arguments in favor of lugging around a heavy lead-acid 12V battery or an expensive lithium 12V battery are all completely invalid.

 

Not gonna debate the issue because, as you stated, that ship has already sailed.

But the fact remains that ALL EV manufacturers use the 12v battery. All of them. That said, I assume they do so for an assortment of reasons, including regulatory and financial reasons.

 

The S outsold the base and the GTS. It isn’t going anywhere, it just hasn’t been announced yet.

 

I think the real answer is that while the 12V lithium battery costs us $2000 to replace, it costs the manufacturer about 1/10 as much. If they can't derive 12V from the traction battery for less than that, which they probably can't, then that's the correct explanation.

 

Just for my own curiosity, i checked Amazon for 12v Li car batteries. I found quite a few ranging in price between $300-$600. I’m sure in quantity, a manufacturer of EV’s can get them for far less. But, whatever the price is, I’m sure the manufacturers have looked at the pro’s and cons of keeping the 12v battery…and decided it makes sense.

Porsche charges $2k-$3K for their Li battery on the 992 because, well, they can. Everything Porsche has an inflated price.

 

This last statement is very important. Just look how much Porsche charges for a simple oil change.

 

A high quality H6 Lithium 12 V Battery (antigravity) costs $1000 direct sale to consumer. Not sure what you are finding for $300

 

Said nothing about “high quality”. Just a 12v Li car battery. To get back on topic…the 12v batteries on EV’s are notoriously low quality, and they don’t have to have the “cranking power” of a battery found on an ICE car. They are only needed to power the electronics in the car….and when the level drops, they automatically get topped off to ~ 14v by the traction battery.

That said, I can buy a H6 Li car battery from AntiGravity for $583.

A replacement for the Li battery in my 992 is between $2k-$3k. Can’t go 3rd party. There are several threads on this topic, if interested.

 

Everyone except for Porsche. “Hybrid” implies full hybrid. The 992.2 is a mild hybrid by definition. Nobody else is marketing their mild hybrid vehicles as “hybrid” except for Porsche with the 992.2.

And nobody else is marketing their non-turbocharged vehicles as “Turbo” except for Porsche.

 

Yes i agree, but there have also been people that buy a lower trim and add leather and other options, which is what i was referring to, our Carrera S MSRP was $165, we got it CPO recently, so i consider it a luxury spec,.. so i think there might well be room for a sub $200k buyer that is looking for a nice interior and some extra amenities but doesn't care about having Turbo type HP. I picked the 992.1 C2s over a 991.2 Turbo i guess i'm that guy.

 

We have a 2023 X5 and on its window sticker in small print it said MIld Hybrid, so they didnt advertise as a selling point but it was on the build spec.