How Does Wireless Charging Work? The Science of Contactless Power Transfer
TL;DR
Wireless charging transfers electrical power through the air using electromagnetic induction — an alternating current in a transmitter coil creates a magnetic field that a receiver coil converts back to usable power. Standard inductive charging (Qi) requires precise coil alignment; magnetic resonance charging, used by Voltraware’s AirFuel Resonant platform, adds resonant tuning to enable power transfer across 2–20 cm without precise alignment, at greater than 90% coil-to-coil efficiency.
Wireless charging transfers electrical power between two coils using magnetic fields — no physical contact, no cable, no connector. The transmitter coil generates an alternating magnetic field; the receiver coil captures that energy and converts it to usable electrical power. The result is a sealed, contactless power link that eliminates connector wear, reduces manual intervention, and enables charging in environments where exposed electrical contacts are impractical.
There are two main methods in commercial use today: standard inductive charging, which dominates consumer smartphones, and magnetic resonance (MR) charging, which extends the effective range and enables multi-device support for industrial, fleet, and medical applications. This guide explains how each works, how they compare, and where each is deployed — with particular focus on magnetic resonance technology and its real-world industrial applications.
The Physics Behind Wireless Charging — Electromagnetic Induction
Electromagnetic induction is the process by which a changing magnetic field generates an electrical current in a nearby conductor. This principle, described by Faraday’s law of electromagnetic induction, is the foundation of all wireless power transfer technology in commercial use today.
In practical terms: when alternating current (AC) flows through a wire coil, it creates an oscillating magnetic field around that coil. If a second coil is placed within that magnetic field, the changing flux induces a voltage — and therefore a current — in the second coil. That induced current is then converted to direct current (DC) to charge a battery or power a device. The entire energy transfer happens across an air gap, with no physical connection between the two coils.
Why must the current be alternating? Because induction requires the magnetic field to be changing over time. A constant DC current produces a static magnetic field, which induces no current in a nearby coil. The oscillating AC field is what drives the energy transfer.
The Role of the Transmitter and Receiver Coils
Every wireless charging system has two core components: a transmitter coil and a receiver coil. The transmitter coil is connected to an AC power source and generates the alternating magnetic field. The receiver coil — embedded in the device, robot, or vehicle — captures that field and delivers power to the load.
The efficiency of energy transfer between the two coils depends on several factors: the distance between them, their relative alignment, the frequency of the AC signal, and whether the coils are resonantly tuned to each other. Standard inductive charging manages the first two factors by requiring the coils to be very close and well-aligned. Magnetic resonance charging manages all four — including resonant tuning — to achieve efficient transfer across a much wider range of positions. For more on the coupling mechanism specifically, see our guide on inductive coupling and wireless power transfer.
What Is the Difference Between Standard Inductive and Magnetic Resonance Charging?
Both standard inductive charging and magnetic resonance (MR) charging use electromagnetic induction as their underlying mechanism. The critical difference is that MR charging adds resonant tuning — both coils are tuned to oscillate at the same resonant frequency, which allows efficient energy transfer to be maintained across a significantly larger air gap and with greater tolerance for misalignment.
Standard inductive charging, governed by the Wireless Power Consortium’s Qi standard, requires coils to be closely coupled — typically within a few millimetres. Even small deviations in alignment cause efficiency to drop sharply. It supports one transmitter per receiver only. Magnetic resonance charging, governed by the AirFuel Alliance’s AirFuel Resonant specification (operating at 6.78 MHz), maintains strong coupling across distances of 2–20 cm and supports up to 8 receivers per transmitter simultaneously.
Feature
Standard Inductive (Qi)
Magnetic Resonance (AirFuel Resonant)
Alignment requirement
Precise — within a few millimetres
Flexible — 2–20 cm spatial freedom
Coil-to-coil efficiency
70–85% under ideal alignment; degrades with misalignment
>90% across the full operating range
Multi-device support
1:1 — one transmitter per receiver
1 transmitter : up to 8 receivers simultaneously
Operating frequency
~100–300 kHz
6.78 MHz (AirFuel Resonant)
Governed by
Wireless Power Consortium (Qi)
AirFuel Alliance (AirFuel Resonant)
Best suited for
Consumer smartphones, wearables, earbuds
Industrial robots, fleet vehicles, medical devices, e-micromobility
The table above uses published AirFuel Alliance benchmarks for the MR column and Wireless Power Consortium published data for the Qi column. Voltraware’s platform implements AirFuel Resonant, which is why spatial freedom and multi-device support are among its core design advantages.
How Does Magnetic Resonance Charging Work? Step by Step
Magnetic resonance charging follows the same fundamental induction principle as standard wireless charging, but adds a resonant frequency layer that dramatically extends the practical operating range. Here is how the process works from power input to device charging:
AC power is applied to the transmitter coil. The transmitter, typically a floor-mounted pad or embedded surface unit, receives AC power from the mains.
The transmitter oscillates at 6.78 MHz. The power electronics drive the transmitter coil to oscillate at the AirFuel Resonant frequency, generating an alternating magnetic field at that frequency.
The receiver coil couples resonantly. The receiver coil — mounted in the device, robot undercarriage, or vehicle — is tuned to the same 6.78 MHz resonant frequency. Because both coils resonate together, the magnetic coupling between them remains efficient even across a gap of 2–20 cm and without requiring precise positional alignment.
Energy is transferred across the air gap. The oscillating field induces an AC current in the receiver coil. The power transfer remains above 90% coil-to-coil efficiency because resonant coupling sustains strong magnetic linkage despite the distance.
The receiver converts AC to DC. A rectifier circuit on the receiver side converts the induced AC current to the DC voltage required to charge the battery or power the device directly.
The control IC manages the session in real time. Voltraware’s VW8000 IC handles resonance tuning, power regulation, communication between transmitter and receiver, and foreign object detection — continuously, throughout the charging session.
What Is Foreign Object Detection and Why Does It Matter?
Foreign Object Detection (FOD) is the mechanism by which a wireless charging system identifies metallic objects — other than the intended receiver — that have entered the charging field. A metallic object in an active magnetic field will heat up through eddy-current induction, in the same way a frying pan heats on an induction hob. Without FOD, a loose bolt, tool, or coin between transmitter and receiver could become dangerously hot.
In consumer charging, FOD is a regulatory requirement for Qi-certified devices. In industrial and medical applications, it is a safety-critical feature — particularly where metallic debris, swarf, or tools may be present in the vicinity of the charging pad. Voltraware’s VW8000 IC integrates FOD functionality as a core feature, continuously monitoring the charging field and halting power transfer if an unexpected metallic object is detected.
Why Does Wireless Charging Efficiency Matter?
Coil-to-coil efficiency measures how much of the electrical power consumed at the transmitter is actually delivered to the receiver. Voltraware’s VW8000 IC achieves greater than 90% coil-to-coil efficiency across its full 2–20 cm operating range. This is the efficiency figure relevant to the magnetic transfer process itself — it does not include losses in the wider power electronics (AC/DC conversion, cable losses, etc.), which is why total system efficiency will always be somewhat lower.
Why does this matter operationally? Because energy that is not transferred to the receiver is dissipated as heat — and heat management is an engineering cost. Higher coil-to-coil efficiency means lower thermal loads on both the transmitter and receiver, smaller heat sinks, reduced cooling requirements, and lower energy costs over the lifetime of the system.
At industrial scale, efficiency differences compound significantly. A fleet of 100 autonomous mobile robots (AMRs), each charging for several hours per day, will experience material differences in operating cost between a system running at 75% and one running at above 90% — across months and years of continuous operation. Explore how this translates to real-world outcomes in our guide to wireless charging for AMRs.
Where Is Wireless Charging Used Today?
Wireless charging is deployed across four primary application domains, each with different requirements for range, efficiency, and device count.
1. Consumer Electronics — Smartphones, Wearables, and Earbuds
The Qi standard dominates consumer wireless charging. Apple MagSafe, Android Qi charging, wireless earbuds cases, and smartwatches all use standard inductive charging at close range. This market is large and mature, but the 1:1, close-proximity constraint is by design — consumer devices are hand-placed on flat pads at consistent positions. This is not Voltraware’s primary market, but it provides the contrast that makes MR charging’s advantages clear in industrial contexts.
2. Industrial Robots and Autonomous Mobile Robots (AMRs)
Wireless charging is increasingly being adopted for AMRs in warehouse automation, logistics, and manufacturing. The key requirement here is spatial freedom — robots move dynamically and cannot be expected to dock with millimetre precision to a charging connector. Floor-mounted transmitter pads, combined with receiver coils on the robot undercarriage, allow AMRs to top up their state of charge (SoC) during brief operational pauses at pick stations, buffer zones, or staging areas.
This approach — known as opportunity charging — eliminates scheduled charging downtime and the manual intervention required by wired docking systems. Because the coils are sealed and require no physical contact, there is no connector wear, no maintenance of charging contacts, and no risk of connector damage in the physical environment of a warehouse or factory floor. Learn more at our wireless AMR charging solutions page.
3. E-Micromobility — Shared E-Scooters and E-Bikes
AirFuel Resonant wireless charging is being deployed for shared e-scooter and e-bike fleets in urban environments. Charging pads embedded in the pavement, dock bays, or parking bays allow vehicles to begin charging as soon as they are parked — without a rider or operator physically connecting a cable. The elimination of exposed electrical connectors also removes a significant vandalism and weathering risk that affects conventional charging infrastructure. For a detailed look at this application, see our guide on e-micromobility wireless charging.
4. Medical Devices — Implantables and Wearables
In medical applications, wireless power eliminates the need for percutaneous power leads — cables that pass through the skin to power an implanted device. This dramatically reduces infection risk and improves patient outcomes for devices such as left ventricular assist devices (LVADs), cochlear implants, and next-generation pacemakers. The sealed, contactless power transfer that magnetic resonance enables is uniquely suited to environments where conventional connectors are clinically unacceptable. Explore the full clinical implications in our article on the impact of MR technology on invasive medical devices.
What Are the Limitations of Wireless Charging?
A credible assessment of wireless charging technology must acknowledge its current constraints alongside its advantages. Understanding these limitations is essential for teams evaluating wireless charging for a specific application.
Range Is Not Unlimited
Magnetic resonance charging operates at 2–20 cm. This is a significant improvement over standard inductive charging (which requires millimetre-level proximity), but it is not long-range wireless power. Charging through walls, across rooms, or at distances measured in metres is not what this technology does. Applications requiring power transfer beyond 20 cm are outside the scope of current AirFuel Resonant deployments.
Efficiency vs. a Direct Cable Connection
Even at greater than 90% coil-to-coil efficiency, a direct cable connection to the same battery will be slightly more efficient — a copper conductor delivering DC power loses very little energy in the cable itself. The TCO argument for wireless charging is not that it is more efficient than cable in the abstract; it is that the operational benefits (no connector wear, no manual intervention, no scheduled downtime, no maintenance of contacts) justify the marginal efficiency difference at industrial scale. Total cost of ownership (TCO) consistently favours wireless over wired when those operational factors are accounted for across multi-year fleet deployments.
Upfront Infrastructure Cost
Wireless charging infrastructure — particularly embedded floor pads for industrial or micromobility applications — has a higher upfront capital cost than conventional cable chargers. The business case rests on the reduction in ongoing maintenance costs, connector replacement, downtime, and manual handling over the operational lifetime of the deployment. Teams evaluating the technology should model TCO over three to five years rather than comparing purchase price alone.
Frequently Asked Questions
How does wireless charging work?
Wireless charging transfers electrical power between two coils using electromagnetic induction. An alternating current in the transmitter coil creates an oscillating magnetic field, which induces a voltage and current in the nearby receiver coil. That induced current is then converted to DC power to charge a battery or power a device — all without any physical contact between the transmitter and receiver.
What is the difference between inductive and magnetic resonance wireless charging?
Both methods use electromagnetic induction, but magnetic resonance (MR) charging adds resonant tuning — both coils are tuned to the same frequency (6.78 MHz in the AirFuel Resonant standard), which allows efficient energy transfer across gaps of 2–20 cm and with significantly more positional tolerance than standard inductive charging. Standard inductive charging (Qi) requires coils within millimetres of each other and supports only one receiver per transmitter. MR charging supports up to 8 receivers per transmitter simultaneously.
How efficient is wireless charging compared to wired charging?
Voltraware’s magnetic resonance platform achieves greater than 90% coil-to-coil efficiency across its full 2–20 cm operating range, which is the efficiency of the magnetic transfer process itself. Standard inductive charging achieves approximately 70–85% under ideal alignment conditions, and degrades further with even minor misalignment. A direct cable connection is marginally more efficient than either wireless method, but the operational advantages of contactless charging — no connector wear, no manual intervention, sealed hardware — typically outweigh that difference in total cost of ownership calculations across industrial fleet deployments.
How far away can a device charge wirelessly?
With Voltraware’s magnetic resonance technology, wireless charging operates at distances of 2–20 cm between transmitter and receiver — without requiring precise alignment. Standard inductive charging (Qi) requires coils to be within a few millimetres and precisely aligned. Long-range wireless power transfer at distances of metres or more is a separate research field and is not yet commercially available at useful power levels for battery-charging applications.
What is the AirFuel Resonant standard and who governs it?
The AirFuel Resonant standard is the magnetic resonance wireless charging specification that defines how compliant transmitters and receivers communicate and transfer power at 6.78 MHz. It is governed by the AirFuel Alliance, an international standards body whose members include technology companies, automotive OEMs, and semiconductor manufacturers. Voltraware is an AirFuel Alliance member and its wireless charging platform complies with the AirFuel Resonant specification, ensuring interoperability and industry-standard safety and performance benchmarks. Learn more about AirFuel Alliance’s work on AirFuel Resonant in micromobility applications.
Key Takeaways
Wireless charging uses electromagnetic induction — an alternating current in a transmitter coil creates a magnetic field that induces a current in a nearby receiver coil.
Standard inductive charging (Qi) requires coils within millimetres and supports only 1:1 transfer; magnetic resonance charging enables transfer across 2–20 cm and supports up to 8 receivers per transmitter.
Voltraware’s AirFuel Resonant platform achieves greater than 90% coil-to-coil efficiency — higher than standard inductive and maintained across the full spatial freedom range.
Foreign Object Detection (FOD) is a safety-critical feature in any industrial or medical wireless charging deployment — Voltraware’s VW8000 IC integrates it as a core function.
The primary applications for magnetic resonance charging are industrial AMRs, e-micromobility fleets, and medical devices — contexts where precise alignment cannot be guaranteed and connector wear is operationally unacceptable.
Explore Voltraware’s Wireless Charging Solutions
Voltraware’s magnetic resonance platform delivers the spatial freedom, efficiency, and multi-device capability that industrial, fleet, and medical applications demand. Built around the VW8000 IC and compliant with the AirFuel Resonant standard, the platform is designed to integrate into your product or facility without requiring the precise mechanical alignment that limits traditional inductive approaches.
Whether you are evaluating wireless charging for an AMR fleet, an e-micromobility deployment, or a medical device programme, our team can walk you through the technical requirements and integration path. Explore our wireless power solutions or contact our team to discuss your application.
How Does Wireless Charging Work? The Science of Contactless Power Transfer
Wireless charging transfers electrical power through the air using electromagnetic induction — an alternating current in a transmitter coil creates a magnetic field that a receiver coil converts back to usable power. Standard inductive charging (Qi) requires precise coil alignment; magnetic resonance charging, used by Voltraware’s AirFuel Resonant platform, adds resonant tuning to enable power transfer across 2–20 cm without precise alignment, at greater than 90% coil-to-coil efficiency.
Wireless charging transfers electrical power between two coils using magnetic fields — no physical contact, no cable, no connector. The transmitter coil generates an alternating magnetic field; the receiver coil captures that energy and converts it to usable electrical power. The result is a sealed, contactless power link that eliminates connector wear, reduces manual intervention, and enables charging in environments where exposed electrical contacts are impractical.
There are two main methods in commercial use today: standard inductive charging, which dominates consumer smartphones, and magnetic resonance (MR) charging, which extends the effective range and enables multi-device support for industrial, fleet, and medical applications. This guide explains how each works, how they compare, and where each is deployed — with particular focus on magnetic resonance technology and its real-world industrial applications.
The Physics Behind Wireless Charging — Electromagnetic Induction
Electromagnetic induction is the process by which a changing magnetic field generates an electrical current in a nearby conductor. This principle, described by Faraday’s law of electromagnetic induction, is the foundation of all wireless power transfer technology in commercial use today.
In practical terms: when alternating current (AC) flows through a wire coil, it creates an oscillating magnetic field around that coil. If a second coil is placed within that magnetic field, the changing flux induces a voltage — and therefore a current — in the second coil. That induced current is then converted to direct current (DC) to charge a battery or power a device. The entire energy transfer happens across an air gap, with no physical connection between the two coils.
Why must the current be alternating? Because induction requires the magnetic field to be changing over time. A constant DC current produces a static magnetic field, which induces no current in a nearby coil. The oscillating AC field is what drives the energy transfer.
The Role of the Transmitter and Receiver Coils
Every wireless charging system has two core components: a transmitter coil and a receiver coil. The transmitter coil is connected to an AC power source and generates the alternating magnetic field. The receiver coil — embedded in the device, robot, or vehicle — captures that field and delivers power to the load.
The efficiency of energy transfer between the two coils depends on several factors: the distance between them, their relative alignment, the frequency of the AC signal, and whether the coils are resonantly tuned to each other. Standard inductive charging manages the first two factors by requiring the coils to be very close and well-aligned. Magnetic resonance charging manages all four — including resonant tuning — to achieve efficient transfer across a much wider range of positions. For more on the coupling mechanism specifically, see our guide on inductive coupling and wireless power transfer.
What Is the Difference Between Standard Inductive and Magnetic Resonance Charging?
Both standard inductive charging and magnetic resonance (MR) charging use electromagnetic induction as their underlying mechanism. The critical difference is that MR charging adds resonant tuning — both coils are tuned to oscillate at the same resonant frequency, which allows efficient energy transfer to be maintained across a significantly larger air gap and with greater tolerance for misalignment.
Standard inductive charging, governed by the Wireless Power Consortium’s Qi standard, requires coils to be closely coupled — typically within a few millimetres. Even small deviations in alignment cause efficiency to drop sharply. It supports one transmitter per receiver only. Magnetic resonance charging, governed by the AirFuel Alliance’s AirFuel Resonant specification (operating at 6.78 MHz), maintains strong coupling across distances of 2–20 cm and supports up to 8 receivers per transmitter simultaneously.
The table above uses published AirFuel Alliance benchmarks for the MR column and Wireless Power Consortium published data for the Qi column. Voltraware’s platform implements AirFuel Resonant, which is why spatial freedom and multi-device support are among its core design advantages.
How Does Magnetic Resonance Charging Work? Step by Step
Magnetic resonance charging follows the same fundamental induction principle as standard wireless charging, but adds a resonant frequency layer that dramatically extends the practical operating range. Here is how the process works from power input to device charging:
What Is Foreign Object Detection and Why Does It Matter?
Foreign Object Detection (FOD) is the mechanism by which a wireless charging system identifies metallic objects — other than the intended receiver — that have entered the charging field. A metallic object in an active magnetic field will heat up through eddy-current induction, in the same way a frying pan heats on an induction hob. Without FOD, a loose bolt, tool, or coin between transmitter and receiver could become dangerously hot.
In consumer charging, FOD is a regulatory requirement for Qi-certified devices. In industrial and medical applications, it is a safety-critical feature — particularly where metallic debris, swarf, or tools may be present in the vicinity of the charging pad. Voltraware’s VW8000 IC integrates FOD functionality as a core feature, continuously monitoring the charging field and halting power transfer if an unexpected metallic object is detected.
Why Does Wireless Charging Efficiency Matter?
Coil-to-coil efficiency measures how much of the electrical power consumed at the transmitter is actually delivered to the receiver. Voltraware’s VW8000 IC achieves greater than 90% coil-to-coil efficiency across its full 2–20 cm operating range. This is the efficiency figure relevant to the magnetic transfer process itself — it does not include losses in the wider power electronics (AC/DC conversion, cable losses, etc.), which is why total system efficiency will always be somewhat lower.
Why does this matter operationally? Because energy that is not transferred to the receiver is dissipated as heat — and heat management is an engineering cost. Higher coil-to-coil efficiency means lower thermal loads on both the transmitter and receiver, smaller heat sinks, reduced cooling requirements, and lower energy costs over the lifetime of the system.
At industrial scale, efficiency differences compound significantly. A fleet of 100 autonomous mobile robots (AMRs), each charging for several hours per day, will experience material differences in operating cost between a system running at 75% and one running at above 90% — across months and years of continuous operation. Explore how this translates to real-world outcomes in our guide to wireless charging for AMRs.
Where Is Wireless Charging Used Today?
Wireless charging is deployed across four primary application domains, each with different requirements for range, efficiency, and device count.
1. Consumer Electronics — Smartphones, Wearables, and Earbuds
The Qi standard dominates consumer wireless charging. Apple MagSafe, Android Qi charging, wireless earbuds cases, and smartwatches all use standard inductive charging at close range. This market is large and mature, but the 1:1, close-proximity constraint is by design — consumer devices are hand-placed on flat pads at consistent positions. This is not Voltraware’s primary market, but it provides the contrast that makes MR charging’s advantages clear in industrial contexts.
2. Industrial Robots and Autonomous Mobile Robots (AMRs)
Wireless charging is increasingly being adopted for AMRs in warehouse automation, logistics, and manufacturing. The key requirement here is spatial freedom — robots move dynamically and cannot be expected to dock with millimetre precision to a charging connector. Floor-mounted transmitter pads, combined with receiver coils on the robot undercarriage, allow AMRs to top up their state of charge (SoC) during brief operational pauses at pick stations, buffer zones, or staging areas.
This approach — known as opportunity charging — eliminates scheduled charging downtime and the manual intervention required by wired docking systems. Because the coils are sealed and require no physical contact, there is no connector wear, no maintenance of charging contacts, and no risk of connector damage in the physical environment of a warehouse or factory floor. Learn more at our wireless AMR charging solutions page.
3. E-Micromobility — Shared E-Scooters and E-Bikes
AirFuel Resonant wireless charging is being deployed for shared e-scooter and e-bike fleets in urban environments. Charging pads embedded in the pavement, dock bays, or parking bays allow vehicles to begin charging as soon as they are parked — without a rider or operator physically connecting a cable. The elimination of exposed electrical connectors also removes a significant vandalism and weathering risk that affects conventional charging infrastructure. For a detailed look at this application, see our guide on e-micromobility wireless charging.
4. Medical Devices — Implantables and Wearables
In medical applications, wireless power eliminates the need for percutaneous power leads — cables that pass through the skin to power an implanted device. This dramatically reduces infection risk and improves patient outcomes for devices such as left ventricular assist devices (LVADs), cochlear implants, and next-generation pacemakers. The sealed, contactless power transfer that magnetic resonance enables is uniquely suited to environments where conventional connectors are clinically unacceptable. Explore the full clinical implications in our article on the impact of MR technology on invasive medical devices.
What Are the Limitations of Wireless Charging?
A credible assessment of wireless charging technology must acknowledge its current constraints alongside its advantages. Understanding these limitations is essential for teams evaluating wireless charging for a specific application.
Range Is Not Unlimited
Magnetic resonance charging operates at 2–20 cm. This is a significant improvement over standard inductive charging (which requires millimetre-level proximity), but it is not long-range wireless power. Charging through walls, across rooms, or at distances measured in metres is not what this technology does. Applications requiring power transfer beyond 20 cm are outside the scope of current AirFuel Resonant deployments.
Efficiency vs. a Direct Cable Connection
Even at greater than 90% coil-to-coil efficiency, a direct cable connection to the same battery will be slightly more efficient — a copper conductor delivering DC power loses very little energy in the cable itself. The TCO argument for wireless charging is not that it is more efficient than cable in the abstract; it is that the operational benefits (no connector wear, no manual intervention, no scheduled downtime, no maintenance of contacts) justify the marginal efficiency difference at industrial scale. Total cost of ownership (TCO) consistently favours wireless over wired when those operational factors are accounted for across multi-year fleet deployments.
Upfront Infrastructure Cost
Wireless charging infrastructure — particularly embedded floor pads for industrial or micromobility applications — has a higher upfront capital cost than conventional cable chargers. The business case rests on the reduction in ongoing maintenance costs, connector replacement, downtime, and manual handling over the operational lifetime of the deployment. Teams evaluating the technology should model TCO over three to five years rather than comparing purchase price alone.
Frequently Asked Questions
How does wireless charging work?
Wireless charging transfers electrical power between two coils using electromagnetic induction. An alternating current in the transmitter coil creates an oscillating magnetic field, which induces a voltage and current in the nearby receiver coil. That induced current is then converted to DC power to charge a battery or power a device — all without any physical contact between the transmitter and receiver.
What is the difference between inductive and magnetic resonance wireless charging?
Both methods use electromagnetic induction, but magnetic resonance (MR) charging adds resonant tuning — both coils are tuned to the same frequency (6.78 MHz in the AirFuel Resonant standard), which allows efficient energy transfer across gaps of 2–20 cm and with significantly more positional tolerance than standard inductive charging. Standard inductive charging (Qi) requires coils within millimetres of each other and supports only one receiver per transmitter. MR charging supports up to 8 receivers per transmitter simultaneously.
How efficient is wireless charging compared to wired charging?
Voltraware’s magnetic resonance platform achieves greater than 90% coil-to-coil efficiency across its full 2–20 cm operating range, which is the efficiency of the magnetic transfer process itself. Standard inductive charging achieves approximately 70–85% under ideal alignment conditions, and degrades further with even minor misalignment. A direct cable connection is marginally more efficient than either wireless method, but the operational advantages of contactless charging — no connector wear, no manual intervention, sealed hardware — typically outweigh that difference in total cost of ownership calculations across industrial fleet deployments.
How far away can a device charge wirelessly?
With Voltraware’s magnetic resonance technology, wireless charging operates at distances of 2–20 cm between transmitter and receiver — without requiring precise alignment. Standard inductive charging (Qi) requires coils to be within a few millimetres and precisely aligned. Long-range wireless power transfer at distances of metres or more is a separate research field and is not yet commercially available at useful power levels for battery-charging applications.
What is the AirFuel Resonant standard and who governs it?
The AirFuel Resonant standard is the magnetic resonance wireless charging specification that defines how compliant transmitters and receivers communicate and transfer power at 6.78 MHz. It is governed by the AirFuel Alliance, an international standards body whose members include technology companies, automotive OEMs, and semiconductor manufacturers. Voltraware is an AirFuel Alliance member and its wireless charging platform complies with the AirFuel Resonant specification, ensuring interoperability and industry-standard safety and performance benchmarks. Learn more about AirFuel Alliance’s work on AirFuel Resonant in micromobility applications.
Key Takeaways
Explore Voltraware’s Wireless Charging Solutions
Voltraware’s magnetic resonance platform delivers the spatial freedom, efficiency, and multi-device capability that industrial, fleet, and medical applications demand. Built around the VW8000 IC and compliant with the AirFuel Resonant standard, the platform is designed to integrate into your product or facility without requiring the precise mechanical alignment that limits traditional inductive approaches.
Whether you are evaluating wireless charging for an AMR fleet, an e-micromobility deployment, or a medical device programme, our team can walk you through the technical requirements and integration path. Explore our wireless power solutions or contact our team to discuss your application.
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