“and claims a charging rate of up to 11 kW and with an efficiency of about 90% for easy overnight charging.”

That’s a some 9kW lost on a 80kW battery. I get the convenience, but I think the best use for those would be when standardized and installed in public parking spots, for a brief charge bump, not to charge fully at home, e.g overnight, which is what Porsche aims for.

> That’s a some 9kW lost on a 80kW battery

It's about the same as wired AC charging. There are always charging losses:

https://insideevs.com/features/711659/ev-charger-efficiency-...

The 90% efficiency of the wireless transmission would be on top of the efficiency of typical charging (which is mostly losses after the power reaches the vehicle).

It's 90% from grid to battery.

It is not.

It is "up to 90%"

We all know what this means in reality.

Do we? Because if you're invoking scare quotes, I don't think you have a good grasp on what's actually happening here.

90% is pretty good efficiency at this level of power. One cannot give an exact figure because it depends heavily on environmental factors, primarily temperature. 90% is pretty much exactly what I'd expect to see in the real world under same conditions.

>One cannot give an exact figure because it depends heavily on environmental factors

Right there. You've restated the problem. "up to 90%" is nothing guaranteed. If the suspension does not lower, you're not getting 90%. If the charger is covered in dirt, you're not getting 90%. If nothing is guaranteed, I'm scared to volunteer.

Question. Is it guaranteed efficiency with wired?

Well at least doesn’t have to worry about “suspension does not lower” and “charger covered in dirt “ or “cat hides under there for warmth” problems. Those are on top of the existing charging losses.

Poor cat...

Now I'm wondering how this thing would affect a cat sitting on it while the car is parked above.

The charger includes motion sensors and “foreign object detection”.

If a pet, person, or metal object gets between the pads, the system supposedly stops working so nothing overheats.

So, it might get a cat yelled at ^_^

Heh. I didn't mean it in a gruesome way :-) just saw that someone mentioned it has a sensor to shut it off. So assuming it works as designed a cat might like the nice warm pad to hang out on in the winter. Owner parks hoping to charge their car by morning, the pad charges for 10 min, stray cat notices car is back and hides in there for warmth, charger stop charging immediately, cat moves on, and next day the car is not charged and the owner can't leave for work. It's just not a failure mode a cable has to worry about.

The efficiency of a wired connection tends to be well-known and rather stable over time, yes.

> I don't think you have a good grasp on what’s actually happening here

Then you don’t, unfortunately.

> 90% is pretty good efficiency at this level of power

Too good. That’s what they’re saying.

Porsche is famous for underpromising and overdelivering.

For instance they claim a 0-60 time of 2.4s for this car. Car & Driver independently tested it and achieved 2.1s. They also claim 298 miles of EPA range (mixed highway & city driving). Car & Driver worked out 300 miles at a constant 75 mph (which is harder on an EV than city driving.) On the base model, which claims 303 miles range, MotorTrend achieved 350 miles of pure highway driving.

Pick any Porsche and you'll see that they lie to make things sound worse than they really are.

Yeah, the difference between "reported and delivered" in the range of 350-298=62miles is actually that one special thing, that makes Porsches worth the price :-D

German brands in general tend to do that - BMW is notorious for under-reporting power, for example. They'd rather understate than have customers be mad at them for underdelivering.

> That’s a some 9kW lost on a 80kW battery.

*kWh

Using the right units is important.

"This may sound like one of those overly pedantic fixations... but it's not. Power and energy are very different concepts." -Technology Connections

https://www.youtube.com/watch?v=OOK5xkFijPc

52 minute video to explain a high school integral.

High-schools probably also spend about 52 mins explaining integrals...

> not to charge fully at home, e.g overnight, which is what Porsche aims for.

Wouldn't an overnight (usually cheaper) 10+ hour charge be a great use for (slow) 11 kW charging?

Yes, and you typically don't have to charge your battery at 100%. More likely you top up whatever you consume for your daily commute.

It will still be 90% efficient regardless of who uses it. In fact if it is used more, the total losses will be higher.

(Some of this becomes clearer when you have a feeling for the units: kW is a measurement of power, not energy)

Charging rate of 11 kW, with efficiency of about 90%, means that the charger sucks around 12.2 kW of power from the grid, of which 1.2 kW is continually lost*, and only 11 kW is effectively being stored in the battery at any point in time.

I don't understand the mention about battery capacity (80 kWh, which would translate to around 7½ hours of charging at 11 kW, if a battery could charge at a uniform rate) or where the "9 kW lost" figure comes from.

*Which is probably useful to melt snow above the device, when installed outdoors on cold climates.

unit confusion

The average person is spending about $1.50 to $2.00 in electricity per day to drive a car.

This would cost $0.15 to $0.20 per average trip to NOT plug in.

Average person spending $100k on a car would likely pay that without a second thought.

The Cayenne seems to need about 315Wh / mile. I assume a substantial number of them are sold in California, where rates are often above $0.50/kw. I think $1.50 would get you about 9 miles.

I drive a more efficient PHEV and spend much more than $1.50/day.

Average cost of electricity is around 18¢/kWh. $2 of electricity at 18¢/kWh is about 11kWh. 11000 / 315 = 34.9. The average US driver does about 40 miles of driving a day. Its a pretty close gut-estimate figure to a median US driver paying an average price per kWh with this particular car.

> I drive a more efficient PHEV and spend much more than $1.50/day.

Cool story bro. I drive a more efficient EV and spend less than $1.50/day. Isn't it fun to share anecdotes?

you think Porsche owners give a shit about efficiency? Laughable at best.

Based on what it takes to change the oil?

Seemingly not.

I keep wondering why a robot-vacuum-charging-dock style solution hasn't materialized. We've seen to robotic arm demos but those aren't around because they are overkill for the task. But something that the car autonomously and accurately docks into and attaches from either the front fascia or underneath. Same charging standard but with a more forgiving connector design that guides and locks in.

Probably because it requires working connectors and humans driving into the exact centimeter correct parking position each and every day, no matter if in a hurry or at night or in snow with impaired vision.

Flip the problem? The base station is the car, and the cord is on the roomba

Start by using wet Roomba tech to clean the port prior to opening the seal/door and doing the plugging? Assuming it's accessed from below.

2015 called: https://www.greencarreports.com/news/1099489_tesla-releases-...

...obviously never productionized.

There were rumors flying that WiTricity had a deal to provide wireless charging for Kia and Hyundai’s joint EV power train project.

They were claiming that they’d gotten the losses down to 2x the wall to battery losses of wired chargers, by removing the transformer in the charger and handling the voltage conversion in the coils.

Also you’re prematurely optimizing. By comparing wireless charging to wired instead wireless to internal combustion. If we did things your way it would reduce the rate of electrification of the market. So calm down.

The way my house is set up I can only get power from the passenger side of my car and almost twenty feet away. There’s no EV I’m interested in that can b charged from that side. They tend to put them on the driver’s side to keep you from driving off while still plugged in. Wireless has no plugin. Which would also simplify public charging stations.

Those public chargers are likely to see much higher utilization than in-home ones. If your concern is wasted energy, time an individual vehicle spends charging seems like the wrong metric.

Charging at home is already more convenient and quicker (in human time) than driving to a gas station, and now they're optimizing the 30 seconds it takes to plug the car in.

I agree in so far that plug-in charging shouldn't be an issue for most people.

Yet I can see the advantages for someone with a disability.

And what a lot don't seem to understand: at 11kW we aren't talking about high charging efficiency anyway. Meaning, you cannot assume close to 100% for cable based charging and talk about how much 90% loose on a full battery (like others here do).

It's not just that; there's a new capability unlocked. You can now have self driving cars charge at remote places and come back without human interaction. Imagine you live in a place with no grid power

How does wireless charging unlock this usecase? Robot arms exist?

I guess if you see the video on the linked post, you'll see what the usecase is unlocked. A neighboor city with a wireless charger station or a road wireless charger station can receive a self driving car above it, charge the car and with some kind of NFC do the payment and goes back.

> the video on the linked post

The 3D rendered video of a car driving over the pad doesn’t really show anything unlocked. There are a lot of possible ways to build automated charging stations. This is not necessary tech for that scenario.

This is a lot better maintainable than a robot arm.

I have a robot vacuum that manages to do automated direct contact charging just fine. I don’t understand why wireless would be any easier. It seems more complex and less safe than a direct wired connection.

I also have a lot of trouble believing in the scenario of a neighborhood that has an automated charging station for EVs but no grid. That seems like very misplaced priorities.

Robo vacuum charging is almost inherently safe. They probably charge at something like 12V/2A. Voltage too low to penetrate skin, wattage too low to cause serious injury unless you’re really trying.

You can kind of just leave them exposed and live.

None of that applies to a 220V, 50A (or whatever amperage) charging. That can absolutely kill somebody; jet fuel may not melt steel beams, but 11,000W sure will.

You’d end up needing some kind of recess probably, and then getting cars to connect to it like planes refueling mid-flight is a nightmare. You could try some sort of USB-C like signaling before power is sent, but people are never going to enjoy “exposed 220V contacts that may or may not be live depending on if things malfunctioned”.

The point wasn’t that my robot vacuum is handling large current but that “moving device connects to power” is a solved problem. A car capable of driving itself onto this pad could as easily drive itself to a spot to plug in. Extendo-arm from the car could easily slot into an outlet in the floor. Or vice versa. Or a wall or pole.

Planes refueling mid flight is hardly an apt metaphor given the charging station isn’t moving at all and the car can move as slowly as needed.

This seems like one of those “reality has a surprising amount of detail” situations.

Surely getting something to autonomously without fail extend an arm and plug in for the lifespan of these vehicles vs just park in this allocated spot you would park in anyway is an obvious tradeoff.

It’s definitely a trade off but both options have a lot of real world concerns. If safeguards on the wireless pad fail you could easily cook an animal or start a fire. The bottom of the car now needs to be metal free to allow this to work. Distance matters which means if it charges your Porsche it might not be able to charge a Rivian and certainly not with the same efficiency.

I also frankly do not believe the 90% efficiency claim because it seems so much higher than any other wireless charging I’ve heard of.

This seems like one of those things that seems cool but is not generally practical. As a convenience for wealthy Porsche EV owners, sure. As a general purpose charging solution? I doubt it.

> you could easily cook an animal or start a fire

Starting a fire, maybe, cooking an animal, extremely not likely.

Turn on an induction stove to max. Put your hand on it. Did it burn your hand? No. Put a ferrous pan on it. Suddenly, really hot.

Same concept happening here. A 36" induction stove top is likely putting out about the same inductive power. If the risk of being over the pad while it operated was enough to burn someone, so would cooking food on an induction stove.

Maybe? I’m definitely not an expert in inductive charging. I would think a cat laying between the charging pad and the receiver would be getting a big hit of radio waves. Maybe not.

Inductive current generation isn't utilizing radio waves. This isn't like a microwave oven.

If you put a chicken breast in a microwave oven and turn it on, it will rapidly cook. If you stand next to a radio antenna emitting hundreds of watts you can potentially get burns. These things use electromagnetic radio fields (E + H) to blast energy out, and those fields can stably radiate out on their own.

Inductive cooking and charging is radically different. If you put a chicken breast directly on an induction cooktop and turn the cooktop on, nothing happens. The unit doesn't even really increase its energy usage, because there is no load. This is because this energy transfer is relying on just the magnetic fields (H). It relies a lot on the target being harmonically in tune, and the other side needs to actually be conductive and at least somewhat magnetic. Non-magnetic materials don't couple with these magnetic fields. This is why some pans (like aluminum and copper) "don't work" with induction cooktops.

So if a cat did climb on the charging pad, maybe some parts of the collar would energize and heat up.

If animals were significantly affected by things like wireless charging pads or inductive cooktops we wouldn't be able to survive MRIs.

I did not mean that the inductive pad was blasting microwaves but that the transfer is via electromagnetic waves.

Regardless, your MRI comparison is very apt. MRIs use similar amounts of energy for scanning and do sometimes cause burns. But no one seems to be getting cooked.

https://pmc.ncbi.nlm.nih.gov/articles/PMC9849420/

My MRI one isn't really that apt, and you're showing the reasons why. An MRI does bombard the imaging target with RF and watches those waves using inductive fields. My point was that if you were reactive to pulsing magnetic waves you'd instantly be cooked in an active MRI. The magnetic fields are intensely powerful, but they don't affect your body at all.

> that the transfer is via electromagnetic waves.

An induction charger doesn't transmit it's energy through electromagnetic waves. That's what I'm saying. It's inducing a current through magnetic fields. Its a very different process. If the material isn't magnetic it doesn't react. Which is why a steel pan heats up very rapidly while your hand is cool, why an induction stove doesn't use much electricity at all when there isn't a pan on it to heat. If it worked by emitting RF, it would have the same power output regardless of the pan type. Which is like your microwave, if the magnetron is energized it's putting out 1,000W regardless of what you have in there.

I am well outside my area of expertise, having underinvested in electrical engineering fundamentals. I trust that you are generally correct but I can’t reconcile that with the fact that Porsche specifically calls out that the system detects living creatures and halts charging. Clearly Porsche believes this is a necessary feature. So does the SAE standard (SAE J2954) apparently.

So while I buy the distinction between magnetic coupling and propagating EM waves, it seems that there is some risk.

I will acknowledge, some parts of your body are weakly ferromagnetic or can react to magnetic fields, especially things like nerves (see: https://www.mayoclinic.org/tests-procedures/transcranial-mag... ). For these reasons there are regulations, especially in Europe, about how strong of magnetic fields people can be exposed to for products sold there.

Maybe at 11kW+ of effective power delivery these fields are enough to actually make eddy currents in your blood enough to cause damage. There's a decent chance it could cause neurological disruptions while in the field. But once again, its really not the same kind of thing as RF radiation emissions, and how these things will affect you is pretty different in the end.

> A car capable of driving itself onto this pad could as easily drive itself to a spot to plug in. Extendo-arm from the car could easily slot into an outlet in the floor.

Those two things really aren't comparably difficult. Eg in the dumbest case for pads, you could make the pads slightly smaller than axle diameter (to prevent dead shorts) and have the car randomly jostle around the space until it detects current flow. I've seen some amateur systems that work vaguely like this. Some signal that charging is nearby, and then a semi-random search to find exposed contacts.

That's not going to cut it on a recessed outlet. Your odds of hitting it randomly are tiny, and it will probably the damage the port with enough repetitions of ramming it into the floor.

> Planes refueling mid flight is hardly an apt metaphor given the charging station isn’t moving at all and the car can move as slowly as needed.

Change your reference point to the plane carrying the fuel and they get an awful lot closer. The planes are moving a lot relative to the ground, they're moving very little relative to each other. I'm not sure if you've watched them doing it, but relative to each other it's actually a very slow process.

> Your odds of hitting it randomly are tiny, and it will probably the damage the port with enough repetitions of ramming it into the floor.

Why would it be random? The scenario here is self driving cars. Suddenly we are talking about random jostling instead of actually targeting.

> Change your reference point to the plane carrying the fuel and they get an awful lot closer. The planes are moving a lot relative to the ground, they're moving very little relative to each other. I'm not sure if you've watched them doing it, but relative to each other it's actually a very slow process.

What is your point here? I’m totally lost. You seem to be trying to hand-wave away the difficulty of refueling mid flight. The specific difficulty there is the fact that it’s happening at high velocity, not the difficulty of plugging a hose into a port. (Traditional mid air refueling is manually directed anyway.)

You are probably fully capable of fueling your car at a self serve gas station. Try doing the same at highway speed. Just reach out the window of the vehicle you are in and fill up your friend’s car from a gas can. Should be easy since the cars are “moving very little relative to each other”, right?

> Imagine you live in a place with no grid power

This thread is full of people trying to invent problem to a solution.

And the funny thing is China's already picked up the dropped torches elsewhere; Xiaomi's going to be launching a robotic arm for your garage by the end of this year to plug in for you. Tesla gave up on their charging tentacle, but, wellp.

https://carnewschina.com/2026/06/13/xiaomi-unveils-home-char...

Wall-E future here we come. Soon the people loader that lifts you from your sofa and plops you into the seat!

I think of this / feel this way when I ride my onewheel instead of walking

We are talking about a car. Something already designed for convenience

Porsche’s induction charging strategy seems a lot smarter and much more reliable than a robot arm.

I don’t know. I’ve stopped using my wireless phone charger because it’s spotty. Sometimes it charges. Sometimes it doesn’t (or barely charges). Sometimes it wakes me up at night because it’s glitching in between charging and noncharging states and my phone feels the need to beep and wake me up.

I’ve seen similar issues with multiple watch chargers. “Oh, it didn’t charge overnight again.”

I’m not as sold on wireless charging as I once was.

It's also more energy-wasteful. Yes, it's efficient enough to be useful, but you will pay for the convenience.

It's all in the execution. Tesla's been working on them for awhile, but apparently they haven't found tech they think is ready yet. There's actually a chunk of empty space on cybertrucks where the induction receiver was designed to go, but it didn't make it in time. Tesla bought a german wireless charging company a couple years ago (then sold it off, keeping some employees/tech).

They're optimizing the cable you can trip over/have to walk around/remember both at home and at, eventually, parking lots.

guys, guys. They're optimizing: people with a lot of money being nagged.

Welcome to capitalism.

We’re talking about a particularly inconvenient 30 seconds coming out of an expensive machine built entirely for convenience. Some people will want it and pay for it. If I was in the market, I probably would.

Home charging us a reasonably thick cable. It’s not bad by any stretch but it’s more than an appliance cord.

Plus you just got home. You probably want to go inside and may be carrying packages or such, which you might have to juggle or put down to get the cable and plug in.

When it’s time to leave you have to unplug and then store the cable, leave it on the floor (trip hazard for others), or have installed an overhead cable system.

With wireless it’s all gone. Pull into you’re garage? You’re done. You were doing that anyway, so it’s no different. Ready to leave? Just back out. Again, same thing. Nothing extra.

Yeah it’s convenience. But it’s not a small win, it’s big. And it’s every time you use your car. Twice.

Your car can always charge. It can always precondition. You used to have to go to gas stations, now you don’t even have to plug in. It’s fully automatic and taken care of for you.

“You don’t need a remote. You can just get up to change the volume”. How well did that argument go over? Every TV has remotes. Buttons are hidden and effectively dead.

Let’s waste precious energy to save 30 seconds twice a day. A remote control is apples to oranges here.

Maybe your remotes run on fairy dust but the rest of ours run on alkaline batteries.

The losses from this charger are nearly the same as the losses from a wired charger.

It’s a 10% loss in addition to the normal losses

That's not what's written in the article.

The article is very much not clear if that 90% is talking about round trip or just the efficiency of the wireless charging in addition to the usual charging losses.

Applying a little common sense with experiences of other wireless chargers, its most likely just the losses of the wireless charging solution.

Time is more precious then energy for a great number of people. Which includes a lot of Porsche drivers I'm guessing.

Well they’re paying for their extra time with the destruction of our planet we rely on to survive so fuck em

Still a hell of a lot better than the twin turbo V8 that's in the high-end gas Cayenne

thanks Claude

AI;DR

The convenience factor is nice because most people (like me) don't bother to actually charge the EV every night.

Just laziness / not necessary for my commute. However, my understanding is that keeping the battery around 80% is better for lifespan. So, the convenience will actually result in longer lasting batteries?

It’s the time that matters the most to users imho. You arrive home, you want to just be done and not think about your car one bit

It does seem a little silly, especially given the inherent losses.

Yet, the five seconds you save by not plugging in a USB cable have led to charging coils being added to nearly every phone to the market these days.

It's a flashy convenience feature, but this is Porsche we're talking about. People interested in buying these cars are all about flashy features without any practical use, because if they wanted a practical car, they wouldn't be buying a Porsche.

I prefer to wirelessly charge my phone because the charging port is the part that typically wears out before the rest of the phone. My first EV's charging cable also wore about after around seven years of use, so I had to replace the entire charger. Charging port doors on some EVs also also known to develop faults in the locking motor, and the ports and/or its cover tends to fall of, which is is costly to repair as you need to repaint the new part. And then come the issues with having to choose EV models to suit the layout of your garage, as well as issues with the cable getting in the way when trying to pass the charging car with your bike, etc.

I cannot afford the Cayenne, but once this gets to cheaper models this will be an option I would be willing to pay for.

They’re optimizing for unplugging the car, which is your first interaction every time you get into the damned thing.

Damaged equipment >> time savings

Step reduction >> time savings

You clearly don't have a partner that refuses to plug in the car. Sigh.

the imaculate lifestyle aproaches, but then in the way of reality, will then prove to be just out of reach, with some new more minor and tedious 'inconvienience' taking on the roll of 'proof' in bieng a victim.

This is something that isn't going to work for two practical reasons:

1. Losses remain very high for daily use.

2. Nobody is going to spend to install these propriety chargers except for millionaires that don't care about the costs.

This isn't a luxury charger; it is an exotic charger.

> Losses remain very high for daily use.

It's about the same as wired AC charging:

https://insideevs.com/features/711659/ev-charger-efficiency-...

A Porsche owner is not likely to be concerned about these items.

Tesla still has their patents open for anyone to use, I'll bet it'd work out like the NACS chargers.

1. No, losses similar to cable charging, ie cents per charge impact. People lose more by leaving their roof rack/bike rack on year round, I suspect.

2. Nobody is going to buy these cars except for millionaires (and delusional credit-hounds), so that's not a problem either.

It might not work for you, and that's cool, but for someone spending that much on a car it's just a small percentage increase in lease payments. And on the Porsche they might have spent as much on a custom colour as on this item.

porsche owners routinely spend > $1k for leather dashboard stitching.

We already have several, see the Xiaomi SU7 lineup

I want to know what mechanisms the car provides to ensure you're lined up to the mat correctly. Seems like a small target to hit.

Plenty of modern cars have all-round cameras that track what you've driven over. Probably pretty easy if it has that.

As you approach, the dashboard starts showing the mat position on the ground relative to your car and helps you align perfectly. There's a longer youtube video explaining a lot of the tech in there: https://www.youtube.com/watch?v=aeMQfA45LN8

I’m waiting for the "needs a $100-200/mo subscription" to unlock wireless charging headline.

Dell did this on a laptop back in 2009 so why not in a car?https://phys.org/news/2009-09-dell-latitude-wireless-video.h...

Cats gonna disrupt these systems. And people gonna be angry when next morning the percentage sits around 11%, because the neighbor's cat was sleeping under the car :D

Unsure why you're downvoted:

> Charging is automatically paused if a person or animal enters the area, or if a metallic object is detected and begins to overheat.

https://dealer.porsche.com/gb/porschecentresouthlakes/en-GB/...

They should have spent money on auto-pluggin charger, some kind of snake robot. Much cooler and environment friendlier

McLaren had this with the Speedtail and all the owners hated it. Main problem being you need to park the car in a very specific spot.

This sounds like a great improvement actually, but Porsche should maybe first work on their own Porsche chargers at the Porsche dealerships to be working, make sure that their card / mobile app work with all chargers from all charger companies (I don't care if some contracts they have are more expensive, but I want to charge when I'm there), plugging in Porsche car should start charging automatically with any EV charger (Ionity always works better than Porsche chargers, so I go there).

Also adding in sentry mode and dashcam support to all Porsches would be some basic security need when it already contains great cameras.

Charging at home is already supere easy, that's never the part when I advise other people against owning an EV when they are asking me about it.

I think the big market for this is self-parking.

Telsa's are capable of both self-park and summon, but neither of these can charge the car without manual intervention.

This is why you can't just let the car go in or come out of your garage at home, no charging.

I could see it for restaurants or malls.

(they have a solution for this for the cybercab, but it has a port in a different place and is not wireless)