View source for Inductive charging

{{short description|Type of wireless power transfer}}
{{redirect|Wireless charging|other power transfer|conductive wireless charging}}
[[File:Inductive charging.svg|thumb|upright=1.3|The primary coil in the charger induces a current in the secondary coil in the device being charged.]]

'''Inductive charging''' (also known as '''wireless charging''' or '''cordless charging''') is a type of [[wireless power transfer]]. It uses [[electromagnetic induction]] to provide electricity to portable devices. Inductive charging is also used in vehicles, power tools, electric toothbrushes, and medical devices. The portable equipment can be placed near a [[charging station]] or inductive pad without needing to be precisely aligned or [[conductive charging|make electrical contact]] with a dock or plug.

Inductive charging is named so because it transfers energy through [[inductive coupling]]. First, [[alternating current]] passes through an [[induction coil]] in the charging station or pad. The moving electric charge [[Oersted's law|creates a magnetic field]], which fluctuates in strength because the electric current's amplitude is fluctuating. This changing magnetic field [[Faraday's law of induction|creates an alternating electric current]] in the portable device's induction coil, which in turn passes through a [[rectifier]] to convert it to [[direct current]]. Finally, the direct current charges a [[Battery (electricity)|battery]] or provides operating power.<ref name=":1">[https://www.edn.com/electronics-blogs/brians-brain/4461755/Wireless-charging--The-state-of-disunion Wireless charging: The state of disunion]</ref><ref name="Treffers" />

Greater distances between sender and receiver coils can be achieved when the inductive charging system uses [[resonant inductive coupling]], where a [[capacitor]] is added to each induction coil to create two [[LC circuit]]s with a specific resonance frequency. The frequency of the alternating current is matched with the resonance frequency, and the frequency is chosen depending on the distance desired for peak efficiency.<ref name=":1" /> Recent developments to resonant inductive coil systems as of 2024 include mounting one of the coils on a movable arm that brings one coil closer to the other,<ref>{{citation |url=https://www.youtube.com/watch?v=K20LV6YwLiQ |title=37 - The Future of Wireless EV Charging: Insights from Electreon's Charlie Levine |date=December 23, 2024 |website=YouTube |author=Insider's Guide to Energy podcast |at=3 minutes and 14 seconds}}</ref> and the use of other materials for the receiver coil such as [[Silver|silver-plated]] [[copper]] or sometimes [[Aluminium|aluminum]] to minimize weight and decrease [[Electrical resistance|resistance]] due to the [[skin effect]].{{cn|date=February 2025}}
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==History==
Induction power transfer was first used in 1894 when M. Hutin and M. Le-Blanc proposed an apparatus and method to power an electric vehicle.<ref name="HutinPatent" /> However, combustion engines proved more popular, and this technology was forgotten for a time.<ref name="Treffers" />

In 1972, Professor Don Otto of the [[University of Auckland]] proposed a vehicle powered by induction using transmitters in the road and a receiver on the vehicle.<ref name="Treffers" /> In 1977, John E. Trombly was awarded a patent for an "Electromagnetically coupled battery charger." The patent describes an application to charge headlamp batteries for miners (US 4031449). The first application of inductive charging used in the United States was performed by J.G. Bolger, F.A. Kirsten, and S. Ng in 1978. They made an electric vehicle powered with a system at 180&nbsp;Hz with 20&nbsp;kW.<ref name="Treffers" /> In California in the 1980s, a bus was produced, which was powered by inductive charging, and similar work was being done in France and Germany and Europe around this time.<ref name="Treffers" />

In 2006, a research group at [[MIT]] began using{{clarify|date=December 2019}} [[Resonant inductive coupling|resonant coupling]]. They were able to transmit a large amount of power without radiation over a few meters. This proved to be better for commercial needs, and it was a major step for inductive charging.<ref name="Treffers" />{{Failed verification|date=April 2022}}

The Wireless Power Consortium (WPC) was established in 2008, and in 2010 they established the [[Qi (standard)|Qi standard]]. In 2012, the Alliance for Wireless Power (A4WP) and the Power Matter Alliance (PMA) were founded. Japan established Broadband Wireless Forum (BWF) in 2009, and they established the Wireless Power Consortium for Practical Applications (WiPoT) in 2013. The Energy Harvesting Consortium (EHC) was also founded in Japan in 2010. Korea established the Korean Wireless Power Forum (KWPF) in 2011.<ref name="Treffers" /> The purpose of these organizations is to create standards for inductive charging. In 2018, the Qi Wireless Standard was adopted for use in military equipment in North Korea, Russia, and Germany.

==Application areas==
Applications of inductive charging can be divided into two broad categories: Low power and high power:
* Low power applications are generally supportive of small consumer electronic devices such as [[cell phones]], handheld devices, some computers, and similar devices which normally charge at power levels below 100 watts. The AC [[utility frequency]] of 50 or 60 [[hertz]] is often used, <ref>{{cite web |last1=Dipert |first1=Brian |title=Wireless charging: The state of disunion |date=28 March 2019 |url=https://www.edn.com/wireless-charging-the-state-of-disunion/ |access-date=12 September 2021}}</ref> or in the case of Qi-compliant devices, frequencies in the range of 87 to 205 kHz are typical. <ref>{{cite web |title=Qi Specification Introduction |page=11 |publisher=Wireless Power Consortium |url=https://www.wirelesspowerconsortium.com/knowledge-base/specifications/download-the-qi-specifications.html |archive-url=https://web.archive.org/web/20191105114155/https://www.wirelesspowerconsortium.com/knowledge-base/specifications/download-the-qi-specifications.html |url-status=dead |archive-date=November 5, 2019 |access-date=8 September 2023 |language=en}}</ref>
* High power inductive charging generally refers to inductive charging of batteries at power levels above 1 kilowatt. The most prominent application area for high power inductive charging is in support of [[electric vehicle]]s, where inductive charging provides an automated and cordless alternative to plug-in charging. Power levels of these devices can range from approximately 1 kilowatt to 300 kilowatts or higher. All high-power inductive charging systems use resonated primary and secondary coils. These systems work in the [[long wave]] range with frequencies up to 130&nbsp;kHz. The use of [[short wave]] frequencies can enhance the system's efficiency and size<ref>{{citation |last1=Regensburger |first1=Brandan |last2=Kumar |first2=Ashish |last3=Sreyam |first3=Sinhar |last4=Khurram |first4=Afridi |title=2018 IEEE 19th Workshop on Control and Modeling for Power Electronics (COMPEL) |chapter=High-Performance 13.56-MHz Large Air-Gap Capacitive Wireless Power Transfer System for Electric Vehicle Charging |chapter-url=https://ieeexplore.ieee.org/document/8460153 |publisher=IEEE |access-date=September 12, 2021 |doi=10.1109/COMPEL.2018.8460153 |year=2018|pages=1–4 |isbn=978-1-5386-5541-2 |s2cid=52285213 }}</ref> but would eventually transmit the signal worldwide. High powers raise the concern of [[electromagnetic compatibility]] and radio frequency [[interference (communication)|interference]].

===Advantages===
* Protected connections – No [[corrosion]] when the electronics are enclosed, away from water or oxygen in the atmosphere. Less risk of electrical faults such as short circuits due to insulation failure, especially where connections are made or broken frequently.<ref name="Madzharov et al, 2017" />
* Low infection risk – For embedded medical devices, the transmission of power via a magnetic field passing through the skin avoids the infection risks associated with wires penetrating the skin.<ref>“Wireless Power For Medical Devices.” MDDI Online, 7 Aug. 2017, www.mddionline.com/wireless-power-medical-devices.</ref>
* Durability – Without the need to constantly plug and unplug the device, there is significantly less wear and tear on the socket of the device and the attaching cable.<ref name="Madzharov et al, 2017" />
* Increased convenience and aesthetic quality.
* Automated high power inductive charging of electric vehicles allows for more frequent charging events and consequently an extension of driving range.
* Inductive charging systems can be operated automatically without dependence on people to plug and unplug. This can result in higher reliability.
* Automatic operation of inductive charging in roads theoretically allows vehicles to run indefinitely.<ref>{{Cite news|url=https://www.technologyreview.com/s/607902/the-case-for-building-roads-that-can-charge-electric-cars-on-the-go/|title=Do you really need wireless charging roads?|last=Condliffe|first=Jamie|work=MIT Technology Review|access-date=2018-10-04|language=en}}</ref>

===Disadvantages===
[[File:Inductive charging efficiency.jpg|thumb|upright=1.5|Charging with induction (left image) creates more waste heat than using a cable (right image).]]
The following disadvantages have been noted for low-power (i.e., less than 100 watts) inductive charging devices, and may not apply to high-power (i.e., greater than 5 kilowatts) electric vehicle inductive charging systems.{{Citation needed|date=April 2022}}
* Slower charging – Due to the lower efficiency, devices take 15 percent longer to charge when supplied power is the same amount.<ref>{{Cite news|url=https://www.nytimes.com/2018/10/03/technology/personaltech/wireless-charging-pros-cons.html|title=Wireless Charging Is Here. So What Is It Good For?|work=The New York Times |date=3 October 2018 |access-date=2018-10-04|language=en|last1=Chen |first1=Brian X. }}</ref>
* More expensive – Inductive charging also requires drive electronics and coils in both device and charger, increasing the complexity and cost of manufacturing.<ref name="hsw">{{Cite web|url=http://home.howstuffworks.com/question292.htm|title=How can an electric toothbrush recharge its batteries when there are no metal contacts between the toothbrush and the base?|website=[[HowStuffWorks]]|date=April 2000|publisher=[[Blucora]]|url-status=live|archive-url=https://web.archive.org/web/20070817180809/http://home.howstuffworks.com/question292.htm|archive-date=August 17, 2007|access-date=August 23, 2007}}</ref><ref name="pat6972543">{{patent|US|6972543|"Series resonant inductive charging circuit"}}</ref>
* Inconvenience – When a mobile device is connected to a cable, it can be moved around (albeit in a limited range) and operated while charging. In most implementations of inductive charging, the mobile device must be left on a pad to charge, and cannot be moved around or easily operated while charging. With some standards, charging can be maintained at a distance, but only with nothing present between the transmitter and receiver.<ref name="Madzharov et al, 2017" />
* Compatible standards – Not all devices are compatible with different inductive chargers.  However, some devices support multiple standards.<ref name="Android Authority, 2017" />

Inefficiency has other costs besides longer charge times. Inductive chargers produce more waste heat than wired chargers, which may negatively impact battery longevity.<ref>{{cite news|last1=Bradshaw|first1=Tim|title=Review: the joys of smartphone wireless chargers|work=Financial Times|archive-url=https://web.archive.org/web/20190919035555/https://www.ft.com/content/871843e8-aa78-11e7-93c5-648314d2c72c|url=http://www.ft.com/content/871843e8-aa78-11e7-93c5-648314d2c72c|archive-date=September 19, 2019}}</ref>{{Better source needed|reason=FT article only passingly mentions heat problem and provides neither specific numbers nor concrete examples|date=April 2022}} An amateur 2020 analysis of energy use conducted with a [[Pixel 4]] found that a wired charge from 0 to 100 percent consumed 14.26 Wh ([[Kilowatt-hour|watt-hours]]), while a wireless charging stand used 19.8 Wh, an increase of 39%. Using a generic wireless charging pad and mis-aligning the phone produced consumption up to 25.62 Wh, or an 80% increase. The analysis noted that while this is not likely to be noticeable to individuals, it has negative implications for greater adoption of smartphone wireless charging.<ref>{{cite news |last=Ravenscraft |first=Eric  |title=Wireless Charging Is a Disaster Waiting to Happen |work=onezero |publisher=[[Medium (website)|Medium]] |url=https://onezero.medium.com/wireless-charging-is-a-disaster-waiting-to-happen-48afdde70ed9 |date=August 5, 2020 |access-date=2020-08-27}}</ref>

Newer approaches reduce transfer losses through the use of ultra thin coils, higher frequencies, and optimized drive electronics. This results in more efficient and compact chargers and receivers, facilitating their integration into mobile devices or batteries with minimal changes required.<ref name="Pogue Pre, NYTimes" >{{cite news
 |url         = http://pogue.blogs.nytimes.com/2009/06/03/another-pre-innovation-the-touchstone-charging-stand/?ref=personaltech
 |title       = Another Pre Innovation: The Touchstone Charging Stand
 |first       = David
 |last        = Pogue
 |author-link  = David Pogue
 |newspaper   = [[The New York Times]]
 |date        = 2009-06-03
 |access-date  = 2009-10-15
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20110930022759/http://pogue.blogs.nytimes.com/2009/06/03/another-pre-innovation-the-touchstone-charging-stand/?ref=personaltech
 |archive-date = 2011-09-30
}}</ref><ref>{{cite news
  |url=http://techon.nikkeibp.co.jp/english/NEWS_EN/20081113/161182/ |last=Yomogita |first=Hiroki |title=Non-contact Charging System Simultaneously Charges Multiple Mobile Devices |work=Nikkey Technology |date=November 13, 2008 |url-status=live |archive-url=https://web.archive.org/web/20081205093209/http://techon.nikkeibp.co.jp/english/NEWS_EN/20081113/161182/ |archive-date=December 5, 2008 
}}</ref> These technologies provide charging times comparable to wired approaches, and they are rapidly finding their way into mobile devices.

==Safety==
An increase in high-power inductive charging devices has led to researchers looking into the safety factor of the electromagnetic fields (EMF) put off by larger inductor coils. With the recent interest in the expansion of high power inductive charging with electric cars, an increase in health and safety concerns has arisen. To provide a larger distance of coverage people would in return need a larger coil for the inductor. An electric car with this size conductor would need about 300 kW from a 400 V battery to emit enough charge in order to charge the vehicle. {{clarify|reason=Why is the power coming from the battery if we're charging it? Enough for what?|date=August 2022}} This much exposure of electromagnetic waves to the skin of a human could prove harmful if not met within the right conditions. Exposure limits can be satisfied even when the transmitter coil is very close to the body.<ref name="Bernard, IEEE">{{cite journal |last1= Bernard |first1= Laurent |last2= Pichon |first2= Lionel |last3= Razek |first3= Adel |title= Evaluation of Electromagnetic Fields in Human Body Exposed to Wireless Inductive Charging System |journal= IEEE Transactions on Magnetics |date=February 2014 |volume=50 |issue=2 |pages=1037–1040 |doi=10.1109/TMAG.2013.2284245 |bibcode= 2014ITM....50.1037D |s2cid= 22268995 |url=https://ieeexplore.ieee.org/document/6749191 |access-date=February 6, 2022 |ref= Bernard, IEEE |issn= 1941-0069|url-access= subscription }}</ref>

Testing has been done on how organs can be affected by these fields when put under low levels of frequency from these fields. When exposed to various levels of frequencies, dizziness, light flashes, or tingling through nerves can be experienced. At higher ranges, heating or even burning of the skin can be experienced as well. Most people experience low EMF in everyday life. The most common place to experience these frequencies is with a wireless charger, usually on a nightstand located near the head.<ref name="EMF, life">{{cite web |title=Electromagnetic fields in daily life|url=https://www.rivm.nl/en/electromagnetic-fields/emf-dailylife |website=www.rivm.nl |access-date=6 February 2022 |language=en}}</ref>{{clarification needed|date=June 2023}}

==Standards==
{{Multiple image|direction=vertical|align=right|image1=Electric car wireless parking charge.jpg|image2=Electric car wireless parking charge closeup.jpg|width=220|caption1=Wireless charging station|caption2=Detail of the wireless inductive charging device}}
There are two main standards that ensure compatibility between chargers and small electronic devices: Qi and PMA.<ref name="Android Authority, 2017" /> The two standards operate very similarly, but they use different transmission frequencies and connection protocols.<ref name="Android Authority, 2017" /> In January 2012, the [[IEEE]] announced the initiation of the [[Power Matters Alliance]] (PMA).<ref>{{cite web |url=http://standards.ieee.org/news/2012/pma.html |title=Global Industry Leaders Aim To Refine Power in 21st Century as Smart and Wireless with Formation of the Power Matters Alliance |publisher=IEEE newsroom |date=2012-01-09 |url-status=dead |archive-url=https://web.archive.org/web/20130713114044/http://standards.ieee.org/news/2012/pma.html |archive-date=2013-07-13 }}</ref> [[Rezence (wireless charging standard)|Rezence]] was an interface standard developed by the Alliance for Wireless Power (A4WP). It merged with PMA in 2015.<ref>{{cite web |url=https://www.airfuel.org/2015/11/03/verge-former-wireless-charging-rivals-join-forces-new-airfuel-alliance/ |title=Former wireless charging rivals join forces as new AirFuel Alliance |publisher=airfuel.org |date=2015-11-03 |access-date=2019-06-08 |archive-date=2019-06-08 |archive-url=https://web.archive.org/web/20190608175905/https://www.airfuel.org/2015/11/03/verge-former-wireless-charging-rivals-join-forces-new-airfuel-alliance/ |url-status=dead }}</ref>

The first standard for vehicle wireless charging was the [[SAE J2954]] standard. It allows inductive car charging over a pad, with power delivery up to 11&nbsp;kW.<ref>{{cite web |website=SAE International |url=https://www.sae.org/standards/content/j2954/ |title=Wireless Power Transfer for Light-Duty Plug-in/Electric Vehicles and Alignment Methodology |date=23 April 2019}}</ref> As of 2024, standards for higher-power wireless charging and for charging while driving are being developed.<ref name="SAE-DWPT-standards" /> [[Magne Charge]], a largely obsolete inductive charging system, also known as J1773, used to charge battery electric vehicles (BEV) formerly made by General Motors.

== Electronic devices ==
[[File:Smartwatch & Smartphone.jpg|thumb|[[Samsung Galaxy Z series|Samsung Galaxy Z]] foldable smartphones have "Wireless PowerShare" technology.]]
Many manufacturers of smartphones have started adding this technology into their devices, the majority adopting the [[Qi (standard)|Qi wireless charging standard]]. Major manufacturers such as [[Apple Inc.|Apple]] and [[Samsung]] produce many models of their phones in high volume with Qi capabilities. The popularity of the Qi standard has driven other manufacturers to adopt this as their own standard.<ref name=":0">{{Cite news|title=Apple buoys wireless charging industry with WPC membership|last=Alleven|first=M|date=2017|work=FierceWirelessTech|id = {{ProQuest|1880513128}}}}</ref> Smartphones have become the driving force of this technology entering consumers’ homes, where many household technologies have been developed to utilize this technology.

Samsung and other companies have begun exploring the idea of "surface charging", building an inductive charging station into an entire surface such as a desk or table.<ref name=":0" /> Contrarily, Apple and Anker are pushing a dock-based charging platform. This includes charging pads and disks that have a much smaller footprint. These are geared for consumers who wish to have smaller chargers that would be located in common areas and blend in with the current décor of their home.<ref name=":0" /> Due to the adoption of the Qi standard of wireless charging, any of these chargers will work with any phone as long as it is Qi capable.<ref name=":0" />

Another development is ''reverse wireless charging'', which allows a mobile phone to wirelessly discharge its own battery into another device.<ref>{{Cite web |last=Pocket-lint |date=2021-07-30 |title=What is reverse wireless charging? |url=https://www.pocket-lint.com/phones/news/146874-reverse-wireless-charging-explained-which-phones |access-date=2022-04-21 |website=www.pocket-lint.com |language=en-gb}}</ref>

===Examples===
{{example farm|section|date=April 2022}}
[[File:Phone wireless charge.jpg|thumb|upright|An [[iPhone X]] being charged by a wireless charger]]
[[File:Wireless power transfer from inductive charging pad to Deutsche Telekom T Phone Pro 5G.ogv|thumb|Wireless power transfer from inductive charging pad to Deutsche Telekom T Phone Pro 5G]]

* [[Oral-B]] rechargeable [[toothbrush]]es by the [[Braun (company)|Braun company]] have used inductive charging since the early 1990s.
* At the [[Consumer Electronics Show]] (CES) in January 2007, [[Visteon]] unveiled its inductive charging system for in-vehicle use that could charge only specially made cell phones to MP3 players with compatible receivers.<ref>{{cite web
 |url         = http://www.mobilemag.com/2007/01/03/visteon-to-unveil-wireless-charger-for-your-car-at-ces/
 |title       = Visteon to unveil wireless charger for your car at CES
 |date        = 2007-01-03
 |publisher   = mobilemag.com
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20130606095001/http://www.mobilemag.com/2007/01/03/visteon-to-unveil-wireless-charger-for-your-car-at-ces/
 |archive-date = 2013-06-06
}}</ref>
* April 2009: An Energizer inductive charging station for the Wii remote was reported on IGN.<ref>{{cite web
 |url         = http://gear.ign.com/articles/977/977418p1.html
 |title       = Energizer Induction Charger for Wii Preview
 |date        = 2009-04-28
 |publisher   = IGN.com
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20090502172350/http://gear.ign.com/articles/977/977418p1.html
 |archive-date = 2009-05-02
}}</ref>
* At CES in January 2009, [[Palm, Inc.]] announced its new [[Palm Pre|Pre]] smartphone would be available with an optional inductive charger accessory, the "Touchstone". The charger came with a required special backplate that became standard on the subsequent Pre Plus model announced at CES 2010. This was also featured on later Pixi, Pixi Plus, and Veer 4G smartphones. Upon launch in 2011, the ill-fated HP Touchpad tablet (after HP's acquisition of Palm Inc.) had a built in touchstone coil that doubled as an antenna for its NFC-like Touch to Share feature.<ref name="Pogue Pre, NYTimes"/><ref>{{cite web
 |first       = Paul
 |last        = Miller
 |url         = https://www.engadget.com/2009/01/08/palm-pres-wireless-charger
 |title       = Palm Pre's wireless charger, the Touchstone
 |date        = 2009-01-08
 |publisher   = Engadget
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20170912222440/https://www.engadget.com/2009/01/08/palm-pres-wireless-charger/
 |archive-date = 2017-09-12
}}</ref><ref name=digitaltrends100225>{{cite web
 |first       = Nick
 |last        = Mokey
 |url         = http://www.digitaltrends.com/product-reviews/cell-phone-reviews/cell-phone-smart-phone-reviews/palm-pre-plus-review/
 |title       = Palm Pre Plus Review
 |publisher   = Digital Trends
 |date        = February 25, 2010
 |access-date  = 2010-03-09
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20100324155310/http://www.digitaltrends.com/product-reviews/cell-phone-reviews/cell-phone-smart-phone-reviews/palm-pre-plus-review/
 |archive-date = March 24, 2010
}}</ref>
* March 2012: [[Samsung]] launched the [[Galaxy S3]], which supports an optionally retrofittable back cover accessory, included in their separate “Wireless Charging Kit”.
* [[Nokia]] announced in September 2012, the [[Nokia Lumia 920|Lumia 920]] and [[Nokia Lumia 820|Lumia 820]], which supports respectively integrate inductive charging and inductive charging with an accessory back. 
* March 2013: Samsung launched the [[Samsung Galaxy S4|Galaxy S4]], which supports inductive charging with an accessory back cover.
* July 2013: Google and ASUS launched the Nexus 7 2013 Edition with integrated inductive charging.
* September 2014: [[Apple Inc.|Apple]] announced [[Apple Watch]] (released in April 2015), which uses wireless inductive charging.
* August 2017: Wärtsilä claimed operation of a full scale pilot installation with 1.6MW and 500mm distance between landside and onboard coils for charging of an electric hybrid ferry in commercial operation, the pilot test was run for one year.<ref>{{cite web | url=https://www.wartsila.com/media/videos?wchannelid=s8uxmc66ya&wmediaid=yrl0nc9sww | title=Videos - Wärtsilä }}</ref>
* September 2017: Apple announced the [[AirPower (hardware)|AirPower]] wireless charging mat. It was meant to be capable of charging an [[iPhone]], an Apple Watch, and [[AirPods]] simultaneously; however, the product was never released. In September 2018, Apple removed most mentions of the AirPower from its website and in March 2019, it canceled the product completely.<ref>{{Cite web |date=29 March 2019 |title=Apple cancels AirPower product, citing inability to meet its high standards for hardware |url=https://techcrunch.com/2019/03/29/apple-cancels-airpower-product-citing-inability-to-meet-its-high-standards-for-hardware/ |url-status=live |archive-url=https://web.archive.org/web/20190602023325/https://techcrunch.com/2019/03/29/apple-cancels-airpower-product-citing-inability-to-meet-its-high-standards-for-hardware/ |archive-date=2019-06-02 |access-date=2019-03-29 |website=TechCrunch |language=en-US}}</ref>

====Qi devices====
[[File:Wireless Charging Pad 2018.jpg|thumb|upright|Wireless charging pad used to charge devices with the Qi standard]]
* [[Nokia]] launched two smartphones (the [[Lumia 820]] and [[Lumia 920]]) in September 2012, which feature Qi inductive charging.<ref name=engadget>{{cite web
 |first       = Terrence
 |last        = O'Brien
 |url         = https://www.engadget.com/2012/09/05/nokia-adds-qi-wireless-charging-tech-to-new-lumia-phones-we-go/
 |title       = Nokia launches smartphones with Qi Wireless charging and Pillow 'charging dock'
 |publisher   = Engadget
 |date        = September 5, 2012
 |access-date  = 2012-09-05
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20120907053540/http://www.engadget.com/2012/09/05/nokia-adds-qi-wireless-charging-tech-to-new-lumia-phones-we-go/
 |archive-date = September 7, 2012
}}</ref>
* [[Google]] and [[LG]] launched the [[Nexus 4]] in October 2012 which supports inductive charging using the Qi standard.
* [[Motorola Mobility]] launched its [[Droid 3]] and [[Droid 4]], both optionally support the Qi standard.
* In November 2012 [[HTC]] launched the [[Droid DNA]], which also supports the Qi standard.
* In October 2013 Google and LG launched the [[Nexus 5]], which supports inductive charging with Qi.
*April 2014 - Samsung launched the [[Samsung Galaxy S5|Galaxy S5]] that supports Qi wireless charging with either a wireless charging back or receiver.
*November 2015 - Microsoft launched the [[Lumia 950 XL]] and [[Lumia 950]] which support charging with the Qi standard.
*February 2016 - Samsung announced its new flagship [[Samsung Galaxy S7|Galaxy S7]] and S7 Edge which use an interface that is almost the same as Qi. The [[Samsung Galaxy S8]] and [[Samsung Galaxy Note 8]] released in 2017 also feature Qi wireless charging technology. 
* September 2017 - [[Apple Inc.|Apple]] announced that the [[iPhone 8]] and [[iPhone X]] would feature Qi wireless charging. 2020 models branded this capability [[MagSafe (wireless charger)|MagSafe]] with added magnets.

====Furniture====
*[[IKEA|Ikea]] has a series of wireless charging furniture that supports the Qi standard.

====Dual standard====

* March 2015: Samsung announced its new flagship [[Samsung Galaxy S6|Galaxy S6]] and [[S6 Edge]] with wireless inductive charging through both [[Qi (inductive power standard)|Qi]] and [[Power Matters Alliance|PMA]] compatible chargers. All phones in the Samsung Galaxy S and Note lines following the S6 have supported wireless charging. 
* November 2015 - [[BlackBerry]] released its new flagship [[BlackBerry Priv]], the first BlackBerry phone to support wireless inductive charging through both [[Qi (inductive power standard)|Qi]] and [[Power Matters Alliance|PMA]] compatible chargers.

====Research and other====

* [[Transcutaneous Energy Transfer]] (TET) systems in [[artificial heart]]s and other surgically implanted devices.
* In 2006, researchers at the [[Massachusetts Institute of Technology]] reported that they had discovered an efficient way to transfer power between coils separated by a few meters. The team, led by [[Marin Soljačić]], theorized that they could extend the distance between the coils by adding resonance to the equation. The MIT inductive power project, called [[WiTricity]], uses a curved coil and capacitive plates.<ref>{{cite web
 |last        = Hadley
 |first       = Franklin
 |url         = http://web.mit.edu/newsoffice/2007/wireless-0607.html
 |title       = Goodbye wires…
 |work        = MIT News
 |publisher   = [[Massachusetts Institute of Technology]]
 |date        = 2007-06-07
 |access-date  = 2007-08-23
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20070903142421/http://web.mit.edu/newsoffice/2007/wireless-0607.html
 |archive-date = 2007-09-03
}} MIT team experimentally demonstrates inductive power transfer, potentially useful for powering laptops, cell phones without cords.</ref><ref>{{cite journal | last = Castelvecchi | first = Davide | url = http://web.mit.edu/newsoffice/2006/techtalk51-9.pdf | title = Wireless energy may power electronics: Dead cell phone inspired research innovation | journal = TechTalk | publisher = Massachusetts Institute of Technology | volume = 51 | issue = 9 | date = November 15, 2006 | access-date = August 23, 2007 | url-status = live | archive-url = https://web.archive.org/web/20070302091819/http://web.mit.edu/newsoffice/2006/techtalk51-9.pdf | archive-date = March 2, 2007 }}</ref>
* In 2012 the Russian private museum [[Grand Maket Rossiya]] opened featuring inductive charging on its model car exhibits.
* As of 2017, [[Disney Research]] has been developing and researching room-scale inductive charging for multiple devices.

==Transportation==
[[File:Движущиеся автомобили на макете.jpg|thumb|A wirelessly powered model lorry at the [[Grand Maket Rossiya]] museum]]
Electric vehicle wireless power transfer or wireless charging is generally divided into three categories: stationary charging when the vehicle is parked for an extended period of time; dynamic charging when the vehicle is driven on roads or highways; and quasi-dynamic or semi-dynamic charging, when the vehicle moves at low speeds between stops,<ref name="Jang2018"/>{{Rp|847}} for example when a taxi slowly drives at a taxi rank.<ref>{{citation |url=https://www.autofutures.tv/2021/09/10/sprint-power-mobility-moments/ |title=Tomorrow's Wireless Charging Taxis – Mobility Moments With Sprint Power Director Ben Russell |author= Tom Fogden |date=September 10, 2021 |website=autofutures.tv}}</ref> Inductive charging is not considered a mature dynamic charging technology as it delivers the least power of the three [[Electric road#Technology|electric road technologies]], its receivers lose 20%-25% of the supplied power when installed on trucks, and its health effects have yet to be documented, according to a [[Transport in France#Electric roads|French government working group on electric roads]].<ref>{{citation |url=https://www.lemoniteur.fr/article/mobilite-electrique-2-5-une-fenetre-etroite-pour-brancher-les-autoroutes.2203237 |title=Sur les routes de la mobilité électrique |author=Laurent Miguet |date=April 28, 2022 |website=[[Le Moniteur des travaux publics et du bâtiment|Le Moniteur]]}}</ref> [[SAE International]] notes that wireless charging systems do not have well-established foreign object detection technologies, and proposes establishing safety tests for these technologies. Foreign objects pose a fire or burn risk if metals or organisms are between the ground pad and the receiver when the system is active.<ref name="SAE-DWPT-standards">{{citation|publisher=US Department of Transportation Federal Transit Administration|date=December 2024|title=Effectiveness of Wireless Charging for Electric Transit Buses|author=Katrina Sutton|url=https://www.transit.dot.gov/sites/fta.dot.gov/files/2024-12/FTA-Report-No-0270.pdf|website=FTA Reports and Publications |pages=10–13}}</ref> The German Ministry of Economy, [[BMWK]] tested infrastructure by Electreon in 2023 with a bus equipped with inductive coils that receive power from a 200-meter strip of transmitters under the road surface. The receivers were able to collect 64.3% of the energy emitted from the transmitters. Installation proved complex and costly, and finding suitable locations for the coils' roadside power cabinets proved difficult.<ref name="WPTCE-japan-2024">A. Wendt et al., "Wireless Electric Road Systems – Technology Readiness and Recent Developments," 2024 IEEE Wireless Power Technology Conference and Expo (WPTCE), Kyoto, Japan, 2024, pp. 177-182, doi: 10.1109/WPTCE59894.2024.10557264.</ref>

===Dynamic charging===
Wireless [[electric road|charging of an electric vehicle while driving]] is known as "dynamic wireless charging" or "dynamic wireless power transfer", DWPT. The first working full-scale DWPT prototype is generally regarded to have been developed at the [[University of California, Berkeley]] in the 1980s and 1990s. The first commercialized DWPT system, [[Online Electric Vehicle]] (OLEV), was developed as early as 2009 by researchers at the [[Korea Advanced Institute of Science and Technology]] (KAIST).<ref name="Jang2018">{{citation |url=https://koasas.kaist.ac.kr/handle/10203/246539 |title=Survey of the operation and system study on wireless charging electric vehicle systems |journal=Transportation Research Part C |year=2018 |issue=95 |author=Young Jae Jang|volume=95 |pages=844–866 |doi=10.1016/j.trc.2018.04.006 |bibcode=2018TRPC...95..844J |doi-access=free }}</ref>{{Rp|848}} Vehicles using the system draw power from a power source underneath the road surface, which is an array of inductive rails or coils.<ref>{{cite news |url=http://newatlas.com/kaist-olev-electric-vehicle/12557/ |last=Ridden |first=Paul |title=Korean electric vehicle solution |work=New Atlas |date=August 20, 2009 |url-status=live |archive-url=https://web.archive.org/web/20170405171420/http://newatlas.com/kaist-olev-electric-vehicle/12557/ |archive-date=April 5, 2017 }}</ref><ref>H. Feng, R. Tavakoli, O. C. Onar and Z. Pantic, "Advances in High-Power Wireless Charging Systems: Overview and Design Considerations," in IEEE Transactions on Transportation Electrification, vol. 6, no. 3, pp. 886-919, Sept. 2020, {{doi|10.1109/TTE.2020.3012543}}.</ref> Commercialization efforts of the technology have not been successful because of high costs,<ref>{{cite news|url=https://www.koreatimes.co.kr/www/tech/2019/04/325_265924.html|title=ICT minister nominee accused of wasting research money|author=Kwak Yeon-soo|date=March 24, 2019|newspaper=[[The Korea Times]]}}</ref> and its main technical challenge is low efficiency.<ref name="RISE2021" />{{Rp|57}}

In the 2020s, companies and organizations such as Vedecom,<ref>{{citation |url=https://www.vedecom.fr/inductive-charging-for-electric-vehicles-while-driving/?lang=en |title=Inductive charging for electric vehicles while driving: a major ecological challenge |date=April 19, 2022 |website=vedecom.fr}}</ref> [[Purdue University]], ENRX (formerly IPT),<ref name="Reilly2024">{{citation |url=https://www.youtube.com/watch?v=hnlukyi9qw0 |contribution=Dynamic Wireless Power Transfer Pilot Projects |author=Greg Reilly|title=Fall 2024 Kent Seminar Series |date=November 21, 2024}}</ref> [[Electreon]], and Magment continued developing dynamic inductive coil charging technologies.<ref>{{citation |url=https://www.concretepavements.org/2021/08/29/german-co-works-alongside-indot-to-create-concrete-roads-that-can-charge-evs-as-they-drive-along/ |title=German Co. Works Alongside INDOT to Create Concrete Roads that Can Charge EVs as they Drive Along |author=Amy M. Dean |work=International Society for Concrete Pavements |date=August 29, 2021 }}</ref> IPT develops a system that uses inductive cables instead of coils, as the existing standards which use coils are "extremely expensive" for dynamic charging, according to the CEO of IPT.<ref>{{citation |url=https://www.emobility-engineering.com/wireless-charging/ |title=Wireless Charging |date=September 6, 2021 |author=E-Mobility Engineering staff}}</ref>

[[SAE International]] has started developing standards for dynamic wireless power transfer in 2023.<ref name="SAE-DWPT-standards" /> The [[Michigan Department of Transportation]] (MDOT) has tested one wireless [[electric road]] technology from 2023 to 2025 on a quarter-mile stretch of public road. One of the project's goals is developing an interoperable system that will interact with the infrastructure regardless of manufacturer.<ref>{{citation |url=https://www.asce.org/publications-and-news/civil-engineering-source/article/2025/02/05/looking-for-anxiety-free-ev-driving-in-road-charging-holds-promise |title=Looking for anxiety-free EV driving? In-road charging holds promise |author=Robert L. Reid |date=February 5, 2025 |website=[[ASCE]]}}</ref>

====Effects on road surface====
Inductive charging infrastructure was found to increase the occurrence of [[reflective crack]]s in [[road surface]]s.<ref name="RISE2021">{{citation |url=http://ri.diva-portal.org/smash/get/diva2:1534916/FULLTEXT02.pdf |title=Research & Innovation Platform for Electric Road Systems |author=Martin G. H. Gustavsson |publisher=[[Research Institutes of Sweden (RISE)|RISE]] |isbn=978-91-89385-08-5 |date=March 5, 2021 }}</ref>{{Rp|64}}<ref>F. Chen, N. Taylor, R. Balieu, and N. Kringos, “Dynamic application of the Inductive Power Transfer (IPT) systems in an electrified road: Dielectric power loss due to pavement materials,” Construction and Building Materials, vol. 147, pp. 9–16, Aug. 2017, doi: 10.1016/j.conbuildmat.2017.04.149</ref> Testing of various [[binder (material)|bonding materials]] between the inductive coils and the asphalt showed that standard installation techniques of inductive coils under the asphalt were not satisfactory and resulted in critical strains. Performance was satisfactory with the use of specific bonding resins, with non-critical degradation in performance compared to reference pavements with no inductive coils. Despite satisfactory results, even the best-performing methods showed risk of debonding.<ref>{{citation |url=https://www.youtube.com/watch?v=QZtLOuZ0Xmk&t=42m50s |contribution=Advancing road-based charging for electric vehicles |author=Pierre Hornych|title=Fall 2024 Kent Seminar Series|date=October 11, 2024}}</ref><ref>{{Citation| last   =  Hornych | first  = Pierre| contribution = Design of a pavement solution for electric vehicle charging by induction| year   = 2023| title  = XXVIIe Congrès mondial de la Route| publisher = [[World Road Association|AIPCR]]| contribution-url = https://hal.science/hal-04420080}}</ref> [[INDOT]] has been testing in 2024 a DWPT installation with special polymer-concrete previously used for bridges.<ref name="Reilly2024"/>{{Rp|at=38m19s}}

===Stationary charging===
In one inductive charging system, one winding is attached to the underside of the car, and the other stays on the floor of the garage.<ref>{{citation
 |url         = http://link.aip.org/link/?JAPIAU/99/08R902/1
 |title       = A non-contact energy transferring system for an electric vehicle-charging system based on recycled products
 |journal     = [[Journal of Applied Physics]]
 |volume      = 99
 |issue       = 8
 |pages = 08R902
 |doi         = 10.1063/1.2164408
 |last1       = Matsuda
 |first1      = Y
 |last2       = Sakamoto
 |first2      = H
 |last3       = Shibuya
 |first3      = H
 |last4       = Murata
 |first4      = S
 |date        = April 18, 2006
 |access-date  = 2009-04-25
 |bibcode     = 2006JAP....99hR902M
 |url-status     = dead
 |archive-url  = https://archive.today/20130223094222/http://link.aip.org/link/?JAPIAU/99/08R902/1
 |archive-date = February 23, 2013
|url-access= subscription
 }}</ref> The major advantage of the inductive approach for vehicle charging is that there is no possibility of [[electric shock]], as there are no exposed conductors, although interlocks, special connectors and [[Residual-current device|RCD]]s (ground fault interruptors, or GFIs) can make conductive coupling nearly as safe. An inductive charging proponent from Toyota contended in 1998 that overall cost differences were minimal, while a conductive charging proponent from Ford contended that conductive charging was more cost efficient.<ref name="autochan98">{{citation
 |url         = http://www.theautochannel.com/news/press/date/19981123/press000865.html
 |title       = Car Companies' Head-on Competition In Electric Vehicle Charging
 |publisher   = The Auto Channel (website)
 |date        = November 24, 1998
 |access-date  = 2009-04-25
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20090602074351/http://www.theautochannel.com/news/press/date/19981123/press000865.html
 |archive-date = June 2, 2009
}}</ref>

From 2010 onwards car makers signaled interest in wireless charging as another piece of the digital cockpit. A group was launched in May 2010 by the [[Consumer Electronics Association]] to set a baseline for interoperability for chargers. In one sign of the road ahead a General Motors executive is chairing the standards, effort group. Toyota and Ford managers said they also are interested in the technology and the standards effort.<ref>{{cite web |url=http://www.eetimes.com/electronics-news/4209856/Car-makers-signal-interest-in-wireless-charging |last=Merritt |first=Rick |title=Car makers signal interest in wireless charging |work=EE Times |date=October 20, 2010 |url-status=live |archive-url=https://web.archive.org/web/20101028125931/http://www.eetimes.com/electronics-news/4209856/Car-makers-signal-interest-in-wireless-charging |archive-date=October 28, 2010 }}</ref>

Daimler's Head of Future Mobility, Professor Herbert Kohler, however, expressed caution and said the inductive charging for EVs was at least 15 years away (from 2011) and the safety aspects of inductive charging for EVs have yet to be looked into in greater detail. For example, what would happen if someone with a pacemaker is inside the vehicle? Another downside is that the technology requires a precise alignment between the inductive pick-up and the charging facility.<ref>{{cite journal |last=Davis |first=Matt |title=Mission Critical |journal=Electric & Hybrid, Vehicle Technology International |date=July 2011 |pages=68}}</ref>

In November 2011, the [[Mayor of London]], [[Boris Johnson]], and [[Qualcomm]] announced a trial of 13 wireless charging points and 50 EVs in the [[Shoreditch]] area of [[London]]'s [[East London Tech City|Tech City]], due to be rolled out in early 2012.<ref>{{cite web |url= https://www.sourcelondon.net/london-charges-ahead-wireless-electric-vehicle-technology |title=London charges ahead with wireless electric vehicle technology |publisher=Source London, Transport for London |date=November 10, 2011 |access-date=2011-11-11 |url-status=dead |archive-url= https://web.archive.org/web/20120424030306/https://www.sourcelondon.net/london-charges-ahead-wireless-electric-vehicle-technology |archive-date=24 April 2012 }}</ref><ref>{{cite web |url= http://www.qualcomm.com/news/releases/2011/11/10/first-electric-vehicle-wireless-charging-trial-announced-london |title=First Electric Vehicle Wireless Charging Trial Announced for London |publisher=Qualcomm Incorporated |date=November 10, 2011 |access-date=2011-11-11}}</ref> In October 2014, the [[University of Utah]] in [[Salt Lake City]], [[Utah]] added an electric bus to its mass transit fleet that uses an induction plate at the end of its route to recharge.<ref>{{cite news |last=Knox |first=Annie |title=University of Utah electric bus runs on a wireless charge |url=http://www.sltrib.com/home/1754251-155/bus-battery-wave-lake-salt-vehicles |newspaper=[[Salt Lake Tribune]] |access-date=December 17, 2016 |url-status=live |archive-url=https://web.archive.org/web/20161220170345/http://www.sltrib.com/home/1754251-155/bus-battery-wave-lake-salt-vehicles |archive-date=December 20, 2016 }}</ref> [[Utah Transit Authority|UTA]], the regional public transportation agency, planned to introduce similar buses in 2018.<ref>{{cite web |title=UTA Announces Plans to Add First All-Electric Buses to Fleet |url=https://www.rideuta.com/news/2016/04/UTA-Announces-Plans-for-All-Electric-Buses |website=Ride UTA |publisher=Utah Transit Authority |access-date=17 December 2016 |url-status=live |archive-url=https://web.archive.org/web/20161220130127/https://www.rideuta.com/news/2016/04/UTA-Announces-Plans-for-All-Electric-Buses |archive-date=20 December 2016 }}</ref> In November 2012 wireless charging was introduced with 3 buses in [[Utrecht]], The Netherlands. January 2015, eight electric buses were introduced to Milton Keynes, England, which uses inductive charging in the road with proov/ipt technology at either end of the journey to prolong overnight charges.,<ref>{{cite web |url=https://www.bbc.co.uk/news/technology-25621426 |title=Wirelessly charged electric buses set for Milton Keynes |publisher=BBC |date=January 9, 2015 |access-date=2015-01-08 |url-status=live |archive-url=https://web.archive.org/web/20150114052059/http://www.bbc.co.uk/news/technology-25621426 |archive-date=January 14, 2015 }}</ref> Later bus routes in Bristol, London and Madrid followed.

Work and experimentation is currently underway in designing this technology to be applied to electric vehicles. This could be implemented by using a predefined path or conductors that would transfer power across an air gap and charge the vehicle on a predefined path such as a wireless charging lane.<ref name=":02">{{Cite journal|last1=Lin |last2=Tsai |last3=Lin |last4=Chang |last5=Yeh |last6=Pei |last7=Wu|first1=Chang-Yu |first2=Chih-Hung |first3=Heng_Tien |first4=Li-Chi |first5=Yung-Hui |first6=Zingway |first7=Chung-Chih|year=2011|title=High-frequency polymer diode rectifiers for flexible wireless power-transmission sheets|journal=Organic Electronics|volume=12 |issue=11|pages=1777–1782|doi=10.1016/j.orgel.2011.07.006}}</ref> Vehicles that could take advantage of this type of wireless charging lane to extend the range of their onboard batteries are already on the road.<ref name=":02" /> Some of the issues that are currently preventing these lanes from becoming widespread is the initial cost associated with installing this infrastructure that would benefit only a small percentage of vehicles currently on the road. Another complication is tracking how much power each vehicle was consuming/pulling from the lane. Without a commercial way to monetize this technology, many cities have already turned down plans to include these lanes in their public works spending packages.<ref name=":02" /> However this does notmean that cars are unable to utilize large scale wireless charging. The first commercial steps are already being taken with wireless mats that allow electric vehicles to be charged without a corded connection while parked on a charging mat.<ref name=":02" /> These large scale projects have come with some issues which include the production of large amounts of heat between the two charging surfaces and may cause a safety issue.<ref name=":03" /> Currently companies are designing new heat dispersion methods to combat this excess heat. These companies include most major electric vehicle manufacturers, such as [[Tesla, Inc.|Tesla]], [[Toyota]], and [[BMW]].<ref>{{Cite book
  |title=Power Sources and Supplies World Class Designs |last=Brown  |first=Marty |year=2007 |publisher=Elsevier  |location=Boston |pages=290–300}}</ref>

====Examples====
{{example farm|section|date=April 2022}}
[[File:Primove Charging Pad1 Markuskirche Mannheim Germany.jpg|thumb|right|200kW Charging-Pad for Buses, 2020 [[Bombardier Transportation]].]]
* [[EPCOT]] Universe of Energy is equipped with moving theater "pews," which take passengers/viewers through the exhibit. They are self-propelled, and inductively recharged when at rest.<ref>{{Cite web |title=EPCOT's Universe of Energy Companion Site: Pavilion |url=https://progresscityusa.com/energy/tech_charging.htm |access-date=2022-04-22 |website=progresscityusa.com}}</ref> This exhibit with the recharging technology was in place ca. 2003.
* [[Hughes Electronics]] developed the [[Magne Charge]] interface for [[General Motors]]. The [[General Motors EV1]] [[electric car]] was charged by inserting an inductive charging paddle into a receptacle on the vehicle. General Motors and [[Toyota]] agreed on this interface and it was also used in the [[Chevrolet S-10 EV]] and [[Toyota RAV4 EV]] vehicles.
*September 2015 [[Audi]] Wireless Charging (AWC) presented a 3.6&nbsp;kW inductive charger<ref>{{cite web | url = https://www.audi-mediacenter.com/en/audi-future-performance-days-2015-5097/fast-charging-and-audi-wireless-charging-5102 | title = Fast charging and Audi wireless charging | publisher = AUDI | author = AUDI | date = 2015-09-17 | access-date = 2015-09-17 | url-status = live | archive-url = https://web.archive.org/web/20160405182713/https://audi-illustrated.com/en/future-performance-2015/Ladetechnologien | archive-date = 2016-04-05 }}</ref> during the 66th International Motor Show (IAA) 2015.
*September 2015 [[Bombardier Transportation|Bombardier-Transportation]] PRIMOVE presented a 3.6&nbsp;kW Charger for cars,<ref>{{cite web | url = http://primove.bombardier.com/media/news/news-detail-page/article////experts-convinced-by-primove-solution-for-cars.html | title = Experts convinced by PRIMOVE solution for cars | publisher = Bombardier | author = Bombardier Mannheim | date = 2015-09-17 | access-date = 2015-09-17 | url-status = dead | archive-url = https://web.archive.org/web/20160405182716/http://primove.bombardier.com/media/news/news-detail-page/article////experts-convinced-by-primove-solution-for-cars.html | archive-date = 2016-04-05 }}</ref> which was developed at Site in Mannheim, Germany.<ref>{{cite web | url = http://de.bombardier.com/content/dam/Websites/bombardiercom/Sites/supporting-documents/BT-SiteFactSheet-Mannheim-Germany-2014-DE.pdf | title = SITE FACT SHEET Mannheim Germany | publisher = Bombardier | author = Sybille Maas-Müller | date = 2015-03-12 | access-date = 2015-03-12 | url-status = dead | archive-url = https://web.archive.org/web/20160405182720/http://de.bombardier.com/content/dam/Websites/bombardiercom/Sites/supporting-documents/BT-SiteFactSheet-Mannheim-Germany-2014-DE.pdf | archive-date = 2016-04-05 }}</ref>
*[[Transport for London]] has introduced inductive charging in a trial for double-decker buses in London.<ref>{{cite web|title=New hybrid bus charging technology trial announced|url=https://tfl.gov.uk/info-for/media/press-releases/2014/august/new-hybrid-bus-charging-technology-trial-announced|website=Transport for London|access-date=2 December 2016|url-status=live|archive-url=https://web.archive.org/web/20160824211611/https://tfl.gov.uk/info-for/media/press-releases/2014/august/new-hybrid-bus-charging-technology-trial-announced|archive-date=24 August 2016}}</ref>
* [[Magne Charge]] inductive charging was employed by several types of [[electric vehicle]]s around 1998, but was discontinued<ref>{{cite web |url=http://www.eanet.com/ev1-club/ |title=EV1 Club Home Page |quote=GM Pulls the Plug on Inductive Charging: Letter from General Motors Advanced Technology Vehicles (Letter dated 2002-03-15) |publisher=EV1 Club |access-date=2007-08-23 |url-status=live |archive-url=https://web.archive.org/web/20080603161730/http://www.eanet.com/ev1-club/ |archive-date=2008-06-03 }}</ref> after the [[California Air Resources Board]] selected the [[SAE J1772]]-2001, or "[[Avcon]]", [[conductive coupling|conductive]] charging interface<ref>{{cite web |url=http://www.arb.ca.gov/regact/charger/uid.pdf |title=Rulemaking: 2001-06-26 Updated and Informative Digest ZEV Infrastructure and Standardization |date=2002-05-13 |work=title 13, California Code of Regulations |publisher=[[California Air Resources Board]] |access-date=2010-05-23 |quote=Standardization of Charging Systems |url-status=live |archive-url=https://web.archive.org/web/20100615234417/http://www.arb.ca.gov/regact/charger/uid.pdf |archive-date=2010-06-15 }}</ref> for electric vehicles in California in June 2001.<ref>{{cite press release |title=ARB Amends ZEV Rule: Standardizes Chargers & Addresses Automaker Mergers |url=http://www.arb.ca.gov/newsrel/nr062801.htm |publisher=[[California Air Resources Board]] |date=2001-06-28 |access-date=2010-05-23 |quote=the ARB approved the staff proposal to select the [[conductive charging]] system used by Ford, Honda and several other manufacturers |url-status=dead |archive-url=https://web.archive.org/web/20100616001956/http://www.arb.ca.gov/newsrel/nr062801.htm |archive-date=2010-06-16 }}</ref>
*In 1997 Conductix Wampler started with wireless charging in Germany, In 2002 20 buses started in operation In Turin with 60&nbsp;kW charging. In 2013 the IPT technology was bought by [http://www.proov.com Proov]. In 2008 the technology was already used in the house of the future in Berlin with Mercedes A Class. Later Evatran also began development of [[Plugless Power]], an inductive charging system it claims is the world's first hands-free, plugless, proximity charging system for [[Electric Vehicle]]s.<ref name=swvatoday090918>{{cite web |url = http://www.swvatoday.com/comments/electric_car_company/news/6018/ |title = Electric (Car) Company |publisher = Wytheville News |last = Hubbard |first = Nate |date = September 18, 2009 |access-date = 2009-09-19 |url-status = dead |archive-url = https://archive.today/20130111091735/http://www.swvatoday.com/comments/electric_car_company/news/6018/ |archive-date = January 11, 2013 }}</ref> With the participation of the local municipality and several businesses, field trials were begun in March 2010. The first system was sold to Google in 2011 for employee use at the Mountain View campus.<ref>{{cite web |last=Thibaut |first=Kyle |title=Google Is Hooking Up Their Employees With Plugless Power For Their Electric Cars (Video) |url=https://techcrunch.com/2011/03/22/google-is-trying-out-plugless-power-for-their-electric-cars-video/ |website=TechCrunch.com |date=22 March 2011 |publisher=Techcrunch |access-date=March 6, 2015 |url-status=live |archive-url=https://web.archive.org/web/20150402131414/http://techcrunch.com/2011/03/22/google-is-trying-out-plugless-power-for-their-electric-cars-video/ |archive-date=April 2, 2015 }}</ref>
*[[Evatran]] began selling the Plugless L2 Wireless charging system to the public in 2014.<ref>{{cite news |last=Bacque |first=Peter |title=Evatran to begin shipping its Plugless electric vehicle charging system |url= http://www.richmond.com/business/national-international/article_e92e9d29-28f4-523f-b782-22f137b2a540.html |access-date=March 6, 2015 |publisher=Richmond.com |date=January 6, 2014}}</ref>
* {{anchor|Momentum Dynamics}}[[Volvo Group]] invested in January 2019 in U.S.-based wireless charging specialist Momentum Dynamics.<ref>{{Cite web|url=https://insideevs.com/news/342225/volvo-group-invests-in-momentum-dynamics-for-wireless-charging/|title=Volvo Group Invests In Momentum Dynamics For Wireless Charging|website=InsideEVs}}</ref> Volvo and Momentum Dynamics will run a three-year pilot project, starting in 2022, for wireless charging of electric taxis in taxi ranks.<ref>{{citation |url=https://www.nyteknik.se/elbilar/volvos-nya-projekt-ladda-elbilar-utan-sladd-7029659 |title=Volvos nya projekt – ladda elbilar utan sladd |date=March 3, 2022 |website=TT / NyTeknik}}</ref>
*[[BRUSA Elektronik AG]], a specialist provider and development company for electric vehicles, offers a wireless charging module named ICS with 3.7&nbsp;kW power.<ref>{{Cite web|title=Das Induktivladesystem ICS115 von BRUSA basiert auf einer weltweit einzigartigen FRAME®-Technologie.|url=https://www.brusa.biz/entwicklung/induktives-laden.html|archive-url=https://web.archive.org/web/20170210210022/http://www.brusa.biz/entwicklung/induktives-laden.html|url-status=dead|archive-date=February 10, 2017|website=brusa.biz|access-date=2020-05-28}}</ref>
*A partnership between Cabonline, Jaguar, Momentum Dynamics, and Fortum Recharge is launching a wireless charging taxi fleet in Oslo, Norway. The fleet consists of 25 [[Jaguar I-Pace]] SUVs equipped with inductive charging pads rated at 50-75&nbsp;kW. The pads use [[resonant inductive coupling]] operating at 85&nbsp;Hz to improve wireless charging efficiency and range.<ref>{{Cite web|title=Wireless Charging Tech to Keep EVs on the Go|url=https://spectrum.ieee.org/wireless-charging-tech-to-keep-evs-on-the-go|access-date=2020-09-29|website=IEEE Spectrum: Technology, Engineering, and Science News|date=27 August 2020|language=en}}</ref>
*On February 3, 2022, [[Hyundai Motor Group]] developed a [[wireless charging]] system for electric vehicles using the principle of magnetic induction.<ref>{{cite web |title=The electric vehicle wireless charging system & automated valet parking system |url=https://tech.hyundaimotorgroup.com/video/the-electric-vehicle-wireless-charging-system-automated-valet-parking-system/ |website=Hyundai Motor Group TECH |access-date=2022-04-29}}</ref> Power is transmitted to the vehicle through resonance between the magnetic pad at the bottom of the charging space and the magnetic pad at the bottom of the vehicle. The transmitted power is stored in the battery through a converter in the vehicle system. It was applied on a trial basis at [[Genesis Motor]] EV charging station located in South Korea.<ref>{{cite news |last1=HALVORSON |first1=BENGT |title=Exclusive: Genesis GV60 will be first EV to include wireless battery charging |url=https://www.greencarreports.com/news/1133317_exclusive-genesis-gv60-will-be-first-ev-to-include-wireless-battery-charging |access-date=2022-04-29 |publisher=GREEN CAR REPORTS |date=2021-08-21}}</ref>

== Medical implications ==
Wireless charging is making an impact in the medical sector by means of being able to charge implants and sensors long-term that is located beneath the skin. Multiple companies offer rechargeable medical implant (e.g. implantable neurostimulators) which use inductive charging. Researchers have been able to print [[Wireless power transfer|wireless power transmitting]] antenna on flexible materials that could be placed under the skin of patients.<ref name=":03">{{Cite journal|last1=Yong Zhi|first1=Cheng|last2=Ji|first2=Jin|last3=Wen Long|first3=Li|last4=Jun Feng|first4=Chen|last5=Bin|first5=Wang|last6=Rong Zhou|first6=Gong|year=2017|title=Indefinite-permeability metamaterial lens with finite size for miniaturized wireless power transfer system |journal=AEU - International Journal of Electronics and Communications|volume=12|pages=1777–1782}}</ref> This could mean that under skin devices that could monitor the patient status could have a longer-term life and provide long observation or monitoring periods that could lead to better diagnosis from doctors. These devices may also make charging devices like pacemakers easier on the patient rather than having an exposed portion of the device pushing through the skin to allow corded charging. This technology would allow a completely implanted device making it safer for the patient. It is unclear if this technology will be approved for use – more research is needed on the safety of these devices.<ref name=":03" /> While these flexible polymers are safer than ridged sets of diodes they can be more susceptible to tearing during either placement or removal due to the fragile nature of the antenna that is printed on the plastic material. While these medical based applications seem very specific the high-speed power transfer that is achieved with these flexible antennas is being looked at for larger broader applications.<ref name=":03" />

==See also==
{{div col|colwidth=23em}}
* [[Charging station]]
* [[Conductive wireless charging]]
* [[Ground-level power supply]]
* [[Litz wire]]
* [[Wardenclyffe Tower]]
* [[Wireless power transfer]]
* [[Wireless Power Consortium]]
{{div col end}}

==References==
{{Reflist|refs=

<ref name="HutinPatent" >
{{cite patent
| country	=
| number	= US527857A
| status	=
| title		= TRANSFORMER SYSTEM FOR ELECTRIC RAILWAYS
| pubdate	= 1894-10-23
| gdate		= 
| fdate		= 
| pridate	= 
| inventor	= Maurice Hutin and Maurice Leblanc
| invent1	=
| invent2	= 
| assign1	= 
| assign2	= 
| class		= 
| url		= https://patents.google.com/patent/US527857A/en
}}</ref>

<ref name="Treffers" >{{Cite magazine
  |last=Treffers  |first=Menno
  |title=History, Current Status and Future of the Wireless Power Consortium and the Qi Interface Specification
  |magazine=[[IEEE Circuits and Systems Magazine]]
  |volume=15  |issue=2
  |year=2015
  |pages=28–31
  |doi=10.1109/mcas.2015.2418973
}}</ref>

<ref name="Madzharov et al, 2017" >{{Cite journal
  |last1=Madzharov  |first1=Nikolay D.
  |first2=Valentin S.  |last2=Nemkov
  |title=Technological inductive power transfer systems
  |journal=[[Journal of Electrical Engineering]]
  |publisher=The Journal of Slovak University of Technology
  |volume=68  |issue=3 
  |pages=235–244
  |date=January 2017
  |doi=10.1515/jee-2017-0035
|bibcode=2017JEE....68..235M|doi-access=free}}</ref>

<ref name="Android Authority, 2017" >{{Cite web
  |title=Wireless charging technology: what you need to know
  |website=Android Authority
  |date=16 January 2017
  |url=http://www.androidauthority.com/wireless-charging-qi-pad-technology-580015/
}}</ref>

}}

==External links==
* [http://electronics.howstuffworks.com/inductor.htm How Inductors Work]
* [http://home.howstuffworks.com/question292.htm How Electric Toothbrushes Recharge Using Inductors]
* [http://www.fastcompany.com/magazine/132/brilliant.html Wireless Electricity Is Here]
* [http://www.heraldsun.com.au/technology/electric-car-is-going-wireless/story-fn7celvh-1226210839878 Wireless charging]
* [https://www.wired.co.uk/news/archive/2012-12/05/electric-bus-charges-as-it-drives Electric Bus Rapidly Recharges Using Wireless Charge Plates at Stops] {{Webarchive|url=https://web.archive.org/web/20160307204940/http://www.wired.co.uk/news/archive/2012-12/05/electric-bus-charges-as-it-drives |date=2016-03-07 }} – ''[[Wired (magazine)|Wired]]''
* [http://www.teslasociety.com/teslatower.htm Tesla Tower] – Inductive charging in year 1900
* [https://www.youtube.com/watch?v=CEGlmQS692w Wireless Qi Charger], DiodeGoneWild on YouTube 16 August 2017
* [https://chargehere.de/ratgeber/induktives-laden-von-e-autos-kabellos-in-die-zukunft-der-elektromobilitaet/ Induktives Laden von E-Autos – Kabellos in die Zukunft der Elektromobilität], German Source, Ines Lemberger, 04.03.2025

{{DEFAULTSORT:Inductive Charging}}
[[Category:Wireless energy transfer]]