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Tesla Would Be Proud: Wireless Charging For Electric Cars Gets Closer To Reality 176

Posted by timothy
from the get-amped dept.
curtwoodward writes "For some reason, we're still plugging in electric-powered devices like a bunch of savages. But technology developed at MIT could soon make that a thing of the past, at least for hybrid cars. A small Boston-area company, WiTricity, is a key part of Toyota's growing experiment with wireless charging tech---something the world's largest car maker says it will start seriously testing in the U.S., Japan and Europe next year. The system works by converting AC to a higher frequency and voltage and sending it to a receiver that resonates at the same frequency, making it possible to transfer the power safely via magnetic field. Intel and Foxconn are also investors, and you might see them license the tech soon as well."
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Tesla Would Be Proud: Wireless Charging For Electric Cars Gets Closer To Reality

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  • Efficient? (Score:5, Insightful)

    by Mr D from 63 (3395377) on Thursday December 05, 2013 @12:01PM (#45608359)
    Whether or not it catches on will depend mostly on efficiency. If the losses are minimal, it makes sense to eliminate mechanical connections.
    • by Ignacio (1465)
      Even if it isn't terribly efficient, it could still mean that your car could charge almost anywhere you park it. Traditional wired charging could be used at service stations where speed is more important than convenience.
      • Considering the price of energy and the whole economic crisis, a lot of people would probably rather plug in manually if the losses are any more than a couple of percent. Even 1% would probably put a lot of people off if they were aware of it.

        • Re:Efficient? (Score:4, Insightful)

          by Anonymous Coward on Thursday December 05, 2013 @12:51PM (#45608911)

          Considering the price of energy and the whole economic crisis, a lot of people would probably rather plug in manually if the losses are any more than a couple of percent. Even 1% would probably put a lot of people off if they were aware of it.

          Millions of people still insist on using incandescent light bulbs. Do you think the majority would give a damn about 1%?

          • Do you think the majority would give a damn about 1%?

            I was about to make a poorly thought out joke about the Occupy movement. Something along the lines of most people being powerless to do anything about the 1%.

          • by mordred99 (895063)

            Yes they would if A) they were totally educated on the issue. B) those non-incandescent lights didn't cost an arm and a leg just to buy one or two. C) people's experiences with the first generation of those bulbs were positive (ie. no warming up for a minute before the light got up to proper lumens)

            This is the same issue today with Americans and Diesel engines vs. traditional gasoline engines.

        • by Jeremi (14640)

          Considering the price of energy and the whole economic crisis, a lot of people would probably rather plug in manually if the losses are any more than a couple of percent. Even 1% would probably put a lot of people off if they were aware of it.

          Would they? I'm not so sure. According to Wikipedia, the cost of power to drive 25 miles in an electric car [wikipedia.org] is in the $1-$2 range. So even a 10% inefficiency would only cost drivers an additional 10 to 20 cents per commute. Would people spend that extra money to avoid the hassle of plugging and unplugging their car every day? Based on the number of dimes I see abandoned on the ground because nobody can be bothered to pick them up, I think many people would -- especially those who are wealthy enough to

          • Re:Efficient? (Score:4, Insightful)

            by cyberchondriac (456626) on Thursday December 05, 2013 @12:57PM (#45609001) Journal
            Considering that some people will drive an extra 3 miles to go to a gas station that's just 4 cents cheaper per gallon, yeah, a lot of people probably would.
          • You seriously looked at that list and described the prices as "in the $1-$2 range"? There's 8 cars under $1 and 4 cars between $1 and $1.32. Of those 4 listed over a dollar, only the Model S is still for sale.

            Plugging and unplugging my car is faster and far less of a hassle than plugging in my phone.

          • by tgd (2822)

            Would they? I'm not so sure. According to Wikipedia, the cost of power to drive 25 miles in an electric car [wikipedia.org] is in the $1-$2 range.

            Wikipedia is wrong. Most EVs get between 3-4 miles per kwh, there's about a 20% loss in charging the battery, so you're looking at 7.5-10 kwh of electricity from the mains to go 25 miles. Only in Alaska and Hawaii is electricity expensive enough to cost $2 to go 25 miles. The average kwh cost in the US is about twelve cents, or $0.90 to $1.20 to go 25 miles.

            So I agree with you -- very few people (even the environmentally conscious who tend to buy EVs) would care about the extra dime a day it costs, if it me

            • by tgd (2822)

              Okay, let me amend my statement, having looked at the Wikipedia page.

              Wikipedia isn't wrong. You just made up a number that doesn't appear anywhere in Wikipedia... for some bizarre reason. Did you make up a number to make the 10% figure worse than it is? The real numbers supported your case better.

            • by tftp (111690)

              The average kwh cost in the US is about twelve cents, or $0.90 to $1.20 to go 25 miles.

              PG&E has standard rate plans that vary from 11c/kWh (which is so little that you can't afford a refrigerator) to 30c/kWh. There are also special plans (time- and season-driven); one of them is specifically intended for charging EVs [pge.com]. In that plan, IIRC, the rate is about 5 c/kWh - but that is at night only. I do not recall what is the rate during the day. Utilities hide the actual rate tables. PG&E has a conveni [pge.com]

            • That said, I doubt its only 10% loss...

              According to the WiTricity FAQ [witricity.com] the efficiency can be quite high:

              Q: How efficient is WiTricity technology?
              A: The power transfer efficiency of a WiTricity solution depends on the relative sizes of the power source and capture devices, and on the distance between the devices. Maximum efficiency is achieved when the devices are relatively close to one another, and can exceed 95%.

              What "relatively close to one another" means, how big the marketing sauce on that is and if it still works with other conducting items with 1 km radius remains to be seen.
              My own limited knowledge of this stuff tells me this could work. High frequency usually helps with transmission efficiency and resonant coils help a lot too.
              The WiTricity site mentions near field transmission. I can't find the exact frequency, but I'll assume that it's the

        • I doubt that electric car consumers are different than gaosoline car consumers. They are more worried about what people think about their car purchase than the economic impact of the fuel (ie big shinny SUVs). Electric car owners cars say "I love the Earth more than you" and if they don't have to touch a dirty plug, all the better for them.
        • by Arker (91948)

          Those people dont buy electric cars to begin with man.

          These are expensive status-symbols for spoiled rich kids. The same people who voluntarily pay more for 'green' electricity. If they have to purchase twice as much juice because their fancy wireless charger is less efficient, I really dont think that will bother them. It might even be a plus.

          • Good point :p I was just thinking of my friends who are always concerned about a few pennies difference on groceries, but I guess they can't afford a new car in the first place. And electric cars aren't going to be great in the used market until battery tech/cost improves.

        • by LoRdTAW (99712)

          People who make a lot of money wouldn't care so much. They would rather eat a few dollars more per week if it meant they didn't have to get their hands dirty. However, people who are on a budget would probably stick to plug-in charging if it saves them a few bucks a week.

        • People rarely care about more than 10%-25% depending. Seriously, people have known for years about electricity vampires in their homes, and most people don't unplug their TVs so they don't sap power when not in use, because it's convenient to hit the power button on the remote.

          Personally, I would use it if at least 20% of the power was actually used (80% loss) for my electric car. I'd rather pay the $0.25 per day than have to plug it in. Just park in my garage every night, and let it charge. I might eve

      • Re:Efficient? (Score:4, Interesting)

        by timeOday (582209) on Thursday December 05, 2013 @01:44PM (#45609649)

        Even if it isn't terribly efficient, it could still mean that your car could charge almost anywhere you park it

        Why park? If our freeways could power electric cars wirelessly, you could drive forever without stopping to recharge. Line the freeway median with solar panels, and the loss of wireless transmission is offset by minimizing losses through power lines and battery storage.

        • I like that idea, but the problem becomes who's going to pay for the solar panels and their upkeep? Maybe charge people based on how far along the route they drive, but it'll most likely be a tax and everyone, with or without a car, will pay. It might fly up here in Canada, or in Europe, or in Japan, but no way Americans will do it.
          • by timeOday (582209)
            Well, that seems like asking who will pay for your data usage as you roll down the freeway streaming music to your cellphone. You will still buy the energy to power your car.
            • And that's true, but the cost is going to be significantly higher to maintain hundreds of thousands, maybe millions, of solar panels, along with the tech in the road to transmit to the car, than it would be to download a few hundred megs of data. Which I don't do by the way because in Canada, at least in Nova Scotia, it's too expensive to have that kind of data plan considering I've never used more than half a Gig. I definitely wouldn't trust NS Power to keep the price reasonable.

              I'd need to see actual fi
              • by timeOday (582209)
                I think I see your point now, which is that taking advantage of the immediate proximity to the power source removes your choice of providers. Whereas you can fill up your gas tank at your choice of gas stations, there would only be a single power infrastructure built into the road, so, no choice. It's a good point. Although, electricity transmission losses aren't THAT bad, so if the company operating the solar panels by the road got too greedy, it would be cheaper to use electricity piped in from somewhe
              • by Aighearach (97333)

                Where I live, in Oregon, USA, we have lots of local public utilities with elected boards, open books, and a history of low prices and efficient power generation. If my utility was running it, the rates would end up being at cost and spread over time. And that would also be true if any of the utilities from neighboring communities were running it.

                • We had a great public run utility, NS Power, back in the 80's. Then the 90's conservative government sold the utility to Emera. Politicians don't like having to explain why power rates need to go up, even if it's just by a half a percent. So they sold off the utility and spun it that the private sector would be able to provide better rates and service.

                  Unfortunately the opposite happened. We have monthly power outages because of "salt vapor" accumulating on power lines. In the last ten years rates have sho
      • why not line the freeway?
        charge while you drive it.

        Want a 300 mile range?
        put 100 miles of chargers for every 300 miles of road..

        Recreate the electric bus, powered externally.

    • Re:Efficient? (Score:4, Insightful)

      by Z_A_Commando (991404) on Thursday December 05, 2013 @12:23PM (#45608611)

      Whether or not it catches on will depend mostly on efficiency. If the losses are minimal, it makes sense to eliminate mechanical connections.

      Efficiency will definitely play a part, but I think more important will be Convenience, Cost, and Coverage.

      When you get an electric car, you need to plug it in every time you get home so that the charge is topped off and you never leave with a near empty battery. If all you have to do is drive over a special mat or the technology is embedded in the floor/pavement/whatever then that will be infinitely more convenient because it doesn't add any extra steps when you park your car.

      If the mats cost a fortune to install or require significant upgrades to a home's existing infrastructure (a la a 220V system) they'll be less likely to be deployed. If they're sold separate from the car purchase, that could cause another issue.

      Finally, if there are a bunch of competing standards or the technology doesn't catch on very widely the coverage for installations in semi-public areas like parking lots would likely never happen, leaving a large amount of city dwellers unable to get on the bandwagon.

      • Re:Efficient? (Score:5, Insightful)

        by internerdj (1319281) on Thursday December 05, 2013 @12:50PM (#45608895)
        Just don't plug it in at your kid's tennis match.
      • *If the mats cost a fortune to install or require significant upgrades to a home's existing infrastructure (a la a 220V system) they'll be less likely to be deployed.*

        Not really different than having another panel installed for a central A/C IMO. But the biggest point is the efficiency of wireless charging.

      • by Idbar (1034346)

        Some people keep thinking about the convenience of parking without plugging. I see it as the future possibility of charging while you're driving (Am I the only one thinking those could be used in some roads? Probably charge your car while in a traffic jam. And even reduce the anxiety that your battery is depleting while stuck in traffic).

    • Re:Efficient? (Score:4, Insightful)

      by jellomizer (103300) on Thursday December 05, 2013 @12:28PM (#45608661)

      There is a lot to say about convenience over efficiency. Now if the price to charge per mile is still less then gasoline then it will probably still work. If we could get off the grid for a lot of this stuff with say Solar Power Stations setup at stores parking and offer it for free it will be a big hit, even if it means you can add a few miles when you are parked for a half an hour.

    • by jythie (914043)
      That tends to be the main problem. Tesla assumed that power would be too cheap to meter and thus efficiency wouldn't be an issue, but that never really panned out
      Even if you direct it to try to reduce loss, it is still extremely wasteful and last time I checked keeping up with electricity demand is already a looming problem.

      I actually have seen wireless power used in some situations though, mainly places where the distances are small and it is cheaper to broadcast power then run a bunch of wires or traces
    • by es330td (964170)
      Given that an "efficient" diesel internal combustion engine is only about 40% efficient, if electricity can be generated by non-fossil fuel sources like wind or solar it doesn't have to be efficient, especially since most driving takes place in daylight hours when potential wind and solar energy are at their peaks. All we have to do is get the Green supporters to kick some NIMBY butts and this has promise.
      • The choice between mechanical and inductive field charging has nothing to do with electric vs fuel vehicles. It is about which choice makes sense for charging electric vehicles. Whether or not they achieve mass adoption is a completely different discussion.
    • Quoting a friend, "Magnetic fields have to follow Maxwell equations. Aperture is defined in wavelength, so higher frequency can be more directive. Presume power only applied to the pad when a car has been sensed. Radio effects and power levels to transfer limit frequency selection, so this is still going to be modest directivity. Drive-on charging pad can't couple efficiently if the car body is metal (conductive), so efficiency will be very low."

      • We're not talking about broadcasting here. This is more like a transformer with the primary on the floor and the secondary on the bottom of the car outside the metal body. The trick is making the gap from primary to secondary small enough to minimize stray magnetic fields, and finding a frequency range that makes the gap tolerable without requiring too expensive electronics for generating the high frequency.
        • That cannot work without a core to contain the magnetic field effectively. Without a core you'd need to rely on directivity of RF energy to find efficiencies and those are not really available. This sounds like "magic" to an RF engineer with 30 years experience.

    • Charging my car and my devices while driving down the road is extremely efficient. The cost of infrastructure required to support this gain in efficiency is another discussion.
  • The fundamental physical principles of electromechanics have always allowed this, but safety and efficiency concerns couldn't really be mitigated without good sensors.

  • by oodaloop (1229816) on Thursday December 05, 2013 @12:02PM (#45608369)
    When I read Tesla in the title, my first thought was the car manufacturer. It wasn't until a few minutes later I realized it was referring to the inventor. If someone would kindly give me the proper address, I will hand in my nerd card. I'm sorry, everyone.
  • Unless the efficiency is high, you're basically paying more to charge your car than if you just plugged it in.
    • by tlhIngan (30335)

      Unless the efficiency is high, you're basically paying more to charge your car than if you just plugged it in.

      True, but it can be like WiFi where the convenience trumps the inefficiency. Think public charging spaces - you park your car, pay the parking fee (which can include the cost of the charge) and walk away. You save yourself the hassle of bringing out your heavy charge cable and all that, saving it from potential theft (I haven't seen many that can lock to the car) and unplugging by activists (I haven

  • by wren337 (182018) on Thursday December 05, 2013 @12:17PM (#45608541) Homepage

    Italy has been using this for buses since 2003.
    http://www.wired.com/autopia/2013/08/induction-charged-buses/ [wired.com]

    • Good article with some believable numbers. But when transmitting 100 kW at 85% efficiency, you have to wonder what is happening to 15 kW of magnetic field. Where is it going, who is it affecting? Will my fillings heat up, or my cochlear implant overload if I am near by?
      • by Scorchmon (305172)

        Not all of the power is being converted into a magnetic field. Some of it is being lost due to resistances in the circuit from cables, copper traces, and other components where it is converted to heat.

  • All we need to do is put poles with flexible wire strips on top of the cars and then put a wire mesh over all the roads that can be electrified so the cars can be charged while driving.

    Works for bumper cars anyway!

    (I used to joke about this but I really foresee the day when we charge our cars using a USB x.0 cable to both charge the car and sync its data (stereo, playlists, etc) nightly like we do our phones and tablets...)

  • by mark_reh (2015546) on Thursday December 05, 2013 @12:20PM (#45608573) Journal

    because they are energy efficient, and we're going to use wireless charging because it isn't? A wireless system will NEVER match the efficiency of plugging the thing in with wires.

  • Not if you could get arrested just for parking [11alive.com] your EV in a local school parking lot.

  • by bobbied (2522392) on Thursday December 05, 2013 @01:03PM (#45609063)

    Gee folks, the laws of physics pretty much govern how "wireless" transmission of energy works. Using magnetic fields to transfer power from here to there is not new, we've been doing it long before Edison and Westinghouse where fighting it out over AC verses DC over 100 years ago. Westinghouse used "transformers" way back then so transferring power from one coil of wire to another though a magnetic field is not new.

    But they are using a different frequency! That's new right? Not so fast... Designers have been using higher frequencies in transformers for a long time now. Aircraft have routinely used 400 Cycle power systems so designers could use smaller (and lighter) transformers since before WWII. Further, we now routinely use frequencies in the Kilohertz in switching power supplies for the same reason. More efficiency, smaller size and weight by using higher frequencies.

    But they really haven't solved anything or come up with anything new. They will suffer efficiency losses because their magnetic flux coupling is weak due to the distances involved, they will suffer from limited ability to transfer power because the maximum flux density of air is pretty low, and they will have to add significant weight to the cars being charged by adding large coils of wire with many turns to them.

    Nothing new to see here..

    • Re: (Score:2, Informative)

      by Anonymous Coward

      YOU aren't familiar with the difference between power transfer by way of magnetic induction, and power transfer by way of *resonant* magnetic induction, so THEY haven't done anything new. :sigh:

      There's a TED Talk where the prototype-level version of this technology was demoed. It's a few years old at this stage. It doesn't require minute distances, it has lower power losses than your typical 'wall wart' AC/DC converter, and transfer efficiency doesn't drop off with the square of the range.

  • The static application of this, automatic charging while parked over a mat in a garage is not that interesting really. But what if sections of a similar technology was installed in interstates that could charge a car on the move? Cars with a receiving system, and a way to verify and bill the driver for the electricity while moving. We would then have electric cars with potentially infinite range.

    That application we could take a bit of inefficiency for the convenience added.

  • With all the hype about cell phone radiation, what do you think it would be for a car charger? Of course the idea of having a loop on my garage floor that begins to charge when I park the car is very interesting. It'll probably have to have some interlock to make sure no people are nearby.
    • by DeTech (2589785)
      You should look up the difference between ionizing and non-ionizing rad.
    • by Ksevio (865461)
      The creator did a TED talk where he demonstrated standing between the two loops while it powered a TV. Since he's not dying of cancer, you'll probably be ok without an interlock.
  • Jeez just have some sprung conductors in the floor of your garage that come up and touch corresponding contact points on the underside of the car whenever you park.
    For safety, Include some trivial electronics to only power the conductors after a data handshake happens with the car. This both ensures the car is in contact properly and that its not say, your kids bike.

  • Can you go to jail for parking in a public lot and then have the cops show up 11 days later to hull you to jail?
    http://yro.slashdot.org/story/13/12/04/1817227/ev-owner-arrested-over-5-cents-worth-of-electricity-from-schools-outlet [slashdot.org]

  • ...to my credit cards.

  • Is the cord really a big problem when charging an electric car? I mean, I've never felt the need to have a gas pump that would squirt fuel right into the filler neck without using a hose...

    I would have thought the biggest stumbling block to widespread charging infrastructure would be the truly ridiculous power feed that would be needed to charge a significant number of cars along long-haul routes.

  • by hendrikboom (1001110) on Thursday December 05, 2013 @01:59PM (#45609877)

    The bandwidth of a truck full of magnetic tapes goes to zero as everything is erased.

    -- hendrik

  • by Lumpy (12016) on Thursday December 05, 2013 @03:16PM (#45611033) Homepage

    They have had wireless charging for a decade for larger vehicles. the Golf carts at the local golf course have done this for at least 10 years. you drive on a rubber mat and the golf cart starts charging, Exact same thing for a car unless they claim they can charge the car from dead to full in 20 minutes, then I highly doubt it as inductive charging cant handle that much power in a wide air gap transformer (This is what "wireless" charging is)

  • Cmon, converting electric power to radio frequency AC is at best 80% efficient, and coupling it maybe 50% at best, and converting it back to DC 80% again. I get 32% best efficiency and those are for the most optimum situation. No way this will ever fly, economically. And since people are scared of their water meters e-field of a fraction of a watt, how are they going to feel about megawatts? Not gonna fly, or even crawl.

  • Just don't leave your wallet in your car, or the mag strips on your credit cards might stop working...
    Or your laptop with its old magnetic hard drive..

    Transferring kilowatts of power via magnetic fields is going to have some losses.

  • Conductive rubber tires.
    Park on metal plates and if two of the 4 tires are on different plates, you can pull power. Just don't walk over them in bare feet.

  • And they said all of those hours I spent practicing F-Zero were wasted!

  • That's what we need. A multi-thousand KWh device charging at pathetically low efficiency as a gimmick because people are too lazy to touch a cable to a socket. I'm going to take a wild guess that the entire neighborhood better not be using wifi or cell phones either because that level of EM can't possibly fail to affect things.

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