Wireless Charging Standard To Reach 250 kW, Magnetic Field Alignment Now In The Works

FEB 26 2017 BY MARK KANE 35

Standardization of wireless charging is progressing with 3.7 and 7.7 kW power levels currently being testing on the front line, and the 11 kW power level is soon to enter its own stage of final testing.

Now, according to the latest reports, the power level of J2954 is to reach 250 kW, with applications in both the light duty and heavy duty vehicle fields in mind (50-250 kW).

The bus can be wirelessly charged at one of its stops via a charging station located under the road surface (1). A receiver, mounted in the bus floor, absorbs electric energy (2) and charges the battery

A new and interesting feature also now mentioned in the wireless charging segment is vehicle alignment over the station through magnetic field generation (which would be especially useful for autonomous charging). The question is (as always) what method to use for standard recommended practice?

“The Recommended Practice SAE J2954 will also contain guidance for vehicle alignment methods and determine a common location for the wireless charging ground assembly. Currently, magnetic field alignment through triangulation using the existing coils and alignment using an auxiliary antenna are being evaluated for this decision.

The goal is to provide one methodology to align in order to be able to charge with high efficiency all SAE J2954 stations. This is for both manual (self-parking) and autonomous (automated) alignment possibilities. It is important to know that the only way to charge an autonomous vehicle automatically is to use wireless charging and SAE J2954 Recommended Practice will standardize this.
—Jesse Schneider”

The final news is SAE International’s proposal to start pilot infrastructure projects with wireless charing from 2019 (California and ZEV states).

“The first stage, for light duty vehicles, creates an infrastructure based on J2954 (for example in malls, large workplaces, condominium complexes, etc). SAE also proposes 100 Heavy Duty Chargers in 2020 based on SAE J2954/2 (for example public transit agency, truck stops for anti-idling, etc.) in 2021 to create a wireless charging infrastructure with alignment communications for autonomous vehicles (for example, taxi fleets).”

source: Green Car Congress

Categories: Charging

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35 Comments on "Wireless Charging Standard To Reach 250 kW, Magnetic Field Alignment Now In The Works"

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“…to be able to charge at high efficiency.”

Seems to me this article should state what percentage loss is meant by “high efficiency” in this metaphor. Even with perfect, automated shaping of an induction field, what qualifies as “high efficiency” here? 2% loss? 8% loss? Oppcharging to overhead copper via a pantograph is pretty close to zero loss. I’d hate to see a national standard that says it’s okay to waste 10% of every charge, for example. What’s the number?

It’s ok to waste 70% of the energy in a diesel bus so 10% isn’t that bad.


It’s 10% loss with respect to conductive charging. Why not have 0% loss by using conductive charging? Implementation effort is about the same, unlike diesel to electric transition.

Also, where the hell do those losses go? Into the air? Into the bus? Around the metal frame of the bus, like a Faraday cage? What happens if a little old lady is sitting in the front seat of the bus, and her titanium knee replacement has stainless steel pins? Do those pins heat up from “lost” wireless charging waves when she sits atop the target of a quarter megawatt shaped beam? I honestly don’t know, but I’d like somebody to explain this stuff. In the back of my head I can hear the daytime TV ads in 2028, saying “Have you been injured by a radiation field? Call now, attorneys are standing by…”

BTW, I’m not a lone nut. The FDA has the same concerns about, just as one example, steel-toe work boots:


This sounds like high voltage cancer city.

I also think this would be deadly for someone with a pace maker.

I personally think that wireless would be good for under 11 kilowatts and even then if there are no people in or around the car when it’s charging.

Low frequency (< 1 kilo-Hz) radiation does NOT cause cancer. Even microwave radiation (Giga-Hz) damages cells due to heating but does not mutate cell DNA (mutation required for cancer).

There are lots of tinfoil hat wearing people who say otherwise. Even 60 Hz from powerline supposedly cause cancer, and there’s big hoopla about it.

Any little disturbance to status quo will cause lawyer headaches, especially with general public’s ignorance of the mysterious electromagnetic fields. Ghost hunters, anyone?

But tin foil hat is supposed to provide 100% protection from all these evil electromagnetic fields!

Yes, because tin foils magically become superconductors that have 0 ohm resistance once it’s placed over the head, thus protecting from EM waves.

I really dislike when the topic of effects of electromagnetic fields on the human organism is reduced to “cancer” or “tinfoil hats” There is so much in between, and using a dogma in this discussion is pretty useless. Throwing around the typical short sighted keywords does not provide any insight. Would anyone like to give their opinion on whether molecules exhibiting a dipole moment exist within the human body and argue why there should be no effect on those? Yes those molecules exist, and yes electromagnetic fields exhibit a force on them. This is the basic physics on which a discussion should start. Most likely those effects will not cause cancer (although there might still be the possibility because we are talking about a quite complex and not yet well understood system which is our body) I doubt that anyone here (explicitly including myself) has the appropriate background to elaborate the possible effects of an electromagnetic field of a given frequency on blood clotting, neurological processes or the myriad of other biochemical processes. In fact does anyone know of one of those processes which are not driven by electromagnetic forces? Come on people! Don’t be dogmatic. Be creative! Use the… Read more »

Sure it’s Physics that molecules are affected by EM. But considering a refrigerator, microwave oven, or even electric blanket would have far stronger field that’s many orders of magnitude larger, worrying about tiny fields just because they’re on big poles is ridiculous.

If you’re really worried about such tiny EM, you’d avoid going outside at all since sunlight would have even more radiation, including ionizing kind that really does cause cancer. In fact, you should cover all your windows; even scattered sunlight has far more energy and intensity than above EM.

If you don’t believe in the magic of tin foil hat, maybe you wrap yourself in tin foil suit. But then, how do you see out side since EM leaking into your eyes from daylight would be many times what you get from low energy RF? All of this is nonsense.

I am not worried at all… Well better let’s put it this way: I do not think that electromagnetic pollution is the most important thing to worry about. But I think that it would be wise to not just say it’s tiny but better to study which effects exist, which risk results and then use this information to make an informed decision. There is absolutely nothing one could do without taking a risk. We all wilfully decide to take those risks (unless we suffer from some special neurotic disease) What worries me is that people just throw out things like “it’s tiny”. All of the devices you mentioned produce electromagnetic pollution, but that says nothing about what effects are induced inside the human body. You are putting a microwave oven into the same category like an electric blanket? You know that those devices work at different frequencies? I usually enjoy reading your comments, but this time it disappoints me that you seem to think that you can qualify or quantify the risk of negative effects of a given em field of a given strength at a given frequency at a given distance. We all tend to blind out what we… Read more »
“If you’re really worried about such tiny EM, you’d avoid going outside at all since sunlight would have even more radiation, including ionizing kind that really does cause cancer.” I even wear my sunglasses at night because future is so damned bright! I’m not afraid of cancer. It’s a disease which mostly affects the lives of those who would already have been dead without healthcare 😉 I know that I am dying by a heart attack since I was 14, that was long before I took the decision to smoke… Now at 35 I finally had that stroke but still I’m alive. As I said before I am not scared. Everything comes with a negative and a positive side. This applies to technology as well as to the myriad of real and imaginary organic and psychic diseases. I like roots as I like imaginary numbers. There is not enough tin foil on earth to keep me protected. By now everyone in this comment section community should know that I see a lot of things as fun. Fun is what keeps us (humans) alive. That’s the dirty little secret which makes all intelligent species in the universe go crazy. All of… Read more »

Your tone and conservative approach is completely appropriate. Scientific testing – especially for a newly deployed application – is needed to ensure safety. There is an adage: ‘one experiment is worth more than a thousand expert opinions’. Arrogance and assumptions can lead to disastrous filter. Try Googling: Micronite filter.


It’s nice to hear that. I do suffer the “just a little bit too honest syndrome” and got used to negative feedback so I really appreciate positive feedback 😉

Regarding the filter: thanks for the tip. Nonetheless I am really disturbed that my tin foil hat failed to protect me from being identified as a smoker. I surely am a member of a species that is going to make ourselves extinct 😉

People that are too lazy to plug in, are now the ones that can accept their Health issues with magnetic field fluctuations. Just like power line pole climbers back in the day.

I do know a lot of Linemen and a lot of the Linemen have special gear that they have on when they work with these high levels of current.

current =/= magnetic field when it comes to protection gear

Current have well known harmful effects. Scaling of those effects with current level is also well known.

Magnetic fields harmful effects are a bit more difficult to study as they are (mostly) subtle – for the fields that are actually in use around us.

I don’t see many studies about the possible magnetic issues for health not only from wireless charging but also from EV in general. Engine, batteries. Are we really fully protected from magnetic fields when seated in an EV.

I know there is also magnetic field with ICE startup but potentially less than EV

Do you have any clue?

Low frequency (< 1 kilo-Hz) radiation does NOT cause cancer. Even microwave radiation (Giga-Hz) damages cells due to heating but does not mutate cell DNA (mutation required for cancer e.g. UV, X-rays and Gamma-rays are higher frequency than visible light).

Well, and then there’s this (https://www.ncbi.nlm.nih.gov/pubmed/10944614), this (https://www.ncbi.nlm.nih.gov/pubmed/11055621), and this (https://www.ncbi.nlm.nih.gov/pubmed/20877339).

TL;DR: a good number of studies suggest a potential 1.5-2x increase in childhood leukemia risk from exposure to low-frequency EMF at 0.4 micro-tesla or above. For reference, 0.4 uT is what a wire carrying 700A (250kW into a typical 350V EV battery) produces at 1 ft away. Now, of course, there are many ways to shield from it etc. but still 😉

BTW if you want to geek out with magnetic field calcs: http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/magcur.html#c2

I saw such study long ago. They didn’t control for other environmental factors. People who live near high power lines tend to have lower economics, which expose them to all sorts of other variables. For example, was it only the magnetic field or was it also corona discharge? Do they live near industrial areas?

There’s too many unaccounted variables in such study to draw a conclusion that it’s just the magnetic field.

Hmmm. So you “saw” a single study “long ago” and it didn’t account for other potential causal factors. Well – I guess that settles the safety question. No further tests required.

If they can control the variables, sure, test away. But how are you going to do that unless you kidnap a person and subject them to live like rats, controlling every aspect of his existence? That’s not going to happen unless you’re North Korea.

The best we can hope for is something slightly better than meta analysis. When it’s something as complex as this, drawing conclusion that it’s magnetic field and not something else from meta analysis is ridiculous.

Think of it this way; there’s a source of magnetic field that’s 100 times stronger, but you draw a conclusion that it’s the power lines causing the problem. What?!?!

It’s a subject raised from time to time. Electric vehicles do not have greater electromagnetic fields than other vehicles.

“It is important to know that the only way to charge an autonomous vehicle automatically is to use wireless charging”

It is also important to know that somebody will have to periodically clean out taxis and in the process can connect/disconnect a charging cable.

I’m sorry. I’m not ready to believe this is anything other than hogwash. Any good magic trick relies on half a truth embedded in a fantastic story, and it relies on a small misperception by the audience. This is a good magic trick. It’s a fantastic story. The half-truth is that it’s about city buses. This is about our perception, as the audience. But let’s talk reality. Even before the FDA’s concerns about human safety, this has virtually no application in municipal buses, and very little application in airport terminal/hotel shuttles or even theme parks (except as a gimmick, like a monorail). But that doesn’t mean the developers wouldn’t like public/political support and perhaps even some research dollars. Where this does make sense is in three places, IMHO: 1.) Warehousing, with autonomous forklifts rather than humans, conveyors, and picklights. Those forklifts can stop and go charge themselves. With smart telemetry to all the inbound trucks, they could even minimize the charge time (maximize the work time), and do cute things like picking frozen stuff quicker for reefers. 2.) Lawncare. You can pull, say, a meangreen turf mower into the purpose-built wireless charging trailer (maybe a trailer equipped with a PowerWall,… Read more »

Even more crap in the air…

If you’re going through all these alignment mumbo jumbo, why not just have a robotic arm with a brush that scrape off the dirt from contacts? That’d be just as much effort as alignment, yet far more efficient.

You can buy robotic arm for $50 at Amazon and coded by elementary school kids as class project.

The real tinfoil hat stuff is the assumption made that just because radiation is non-ionizing that it is perfectly safe.

The power levels of WI-FI repeaters in school classrooms are, on an absolute scale, low, but combined with all the other laptops, certain children have serious health issues from them and do not recover until placed in a radiation reduced environment.

The same as ‘Smart Meters’ were always advertised as being ‘Totally Safe’, but then more than a few non-UL-Listed (I wonder why) devices have set fire to their homes. And, of course, since they work on the Collision-Mesh principle, things really get GOOD when you have a cluster of 30 of them in one place. Since the majority of the communication THEN is useless collisions, and since they all ‘Repeat’ (i.e. the repeater function) for each other, anything biological in proximity of the ‘meter bank’ is in serious trouble – many reporting that the ‘new meter bank’ killed the Shrubs planted around it, or, people complaining of sickness whose Headboard was on the adjoining wall.

Now someone is sure to say that since these cordless car chargers are running at lower than microwave frequencies, there can be no danger.

As a ham radio operator, I run into 2 meter cavity resonators at repeaters all the time – these things are used so that the transmitter doesn’t SWAMP the receiver operating only at a 0.6 mhz different frequency – in other words almost on top of the receiver. Since it is essentially just a garbage can sized tuned-circuit trap – I’ve put hot dogs in the thing and used the resonator to cook them – which it did just fine even though the frequency was no where near what a microwave oven is.


“The real tinfoil hat stuff is the assumption made that just because radiation is non-ionizing that it is perfectly safe”


Sometimes I wonder if we would have a better life if we just took all “news” and just generally exchange the word “safe” with “dangerous” and vice versa.

it’s a fun thing to do and given the percentage of the “scary type ANGST!!!” news it results in less fear…

It’s strange but the more I think about what produces doubt in me it’s always those “Perfectly safe systems”

Anyone to discuss nuclear power once again 😉

Well, as you know, First things First, as we say in the States.

Many things that we were taught as children by the Authorities turn out to be not quite so.

And before taking a position on a subject it would be educational for each of us to research each topic a bit to the extent reasonable.

A criticism of Americans has been for Decades: “American People don’t Read” – therefore unscrupulous Politicians and Industry heads can take advantage of the more insouciant amoungst us.

Well, Some of us DO read. And we as a group will bring along others when they finally see things not quite going ‘according to Hoyle’.

“It is important to know that the only way to charge an autonomous vehicle automatically is to use wireless charging”

That is simply not true.
For example there is also the Tesla experimental snake charger, shown here several times.
There is also much simpler possibilities with pantographs like with buses. Nothing prevent two small pantographs from coming down from under the car on two small plastic bumps on the ground wearing inox contacts on top of them. Cheap efficient and 100 % efficient. A simple Bluetooth connection and a security control protocol would allow automated charging very well. The more, since the two small pantographs would be on the car, retracted behind a protection trap, the contacts on the ground would be so cheap that they could be afforded to equip virtually every parking place as well as allow dedicated megacharging stations ultra fast charging. Two in one, fast, 100% efficient, no MF, super cheap, what else to desire.
Magnechargers could still be useful to charge submarines or perhaps boats but not a car in your garage, on the street or at a supercharger.