For the Samsung Galaxy S7 and S7 Edge, the perfect fast wireless charger would be their own Samsung Fast Charge Qi Wireless Charger available in Samsung’s site here. Its price is at $59.99 but is currently on sale at $52.99, saving you $7. The wireless Fast Charge feature is compatible with ONLY Galaxy Note5, Galaxy S6 edge+ and later models of the Galaxy Note and Galaxy S series. The other Qi devices will charge at a regular speed. For iPhone charging, you need a wireless charging receiver which is not included.
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145 with 94 posters participatingWireless charging has a long way to go before it replaces wired charging, but the technology has advanced dramatically in the past few years. Everyone with the newest smartphones, wearables, and other gadgets can get behind the idea—simply place your device on a charging pad or stand and let it sit. Within a few minutes, you'll have more battery power than you did before, and you didn't have to fuss with wires or cables to get it.
But quite a bit of technology goes into making an accessory that makes your life that much easier. Most wireless chargers come in the form of circular or rectangular pads, some of which are propped up on legs to make stands that take up minimal space and work well as nightstand or desk accessories. But don't be fooled by their minimalist exteriors—there are a number of things you should know before investing in a wireless charging pad. To navigate this murky world, Ars tested out some of the most popular devices available now to see which are worth buying.
Note: Ars Technica may earn compensation for sales from links on this post through affiliate programs.
Table of Contents
How does wireless charging work?
Modern wireless chargers for smartphones use inductive charging to transfer energy between the charging pad and a mobile device. A loop of coiled wires sits inside the charging pad with a magnet in the center. As electric current passes through these wires, it creates an electromagnetic field around the magnet. That field can then transfer energy to a nearby receiver coil that's found in smartphones and other mobile devices that support wireless charging.
The amount of power that can be transferred from the inductor (the charging pad) to the receiver (the mobile device) is dependent on many things, including the number of wire coils in both devices, the strength of the magnet in the inductor, and the distance between the inductor and the receiver. The latter explains the design of most wireless chargers today: smartphones need to sit very close to (i.e., directly on top of) the wireless charger to receive the most amount of energy possible.
Qi standard and your smartphone
Within the past couple of years, the Qi (pronounced 'chee') wireless charging standard has emerged victorious over other competing standards. At the start of 2018, Powermat, which pushed the PMA charging standard, joined the Wireless Power Consortium, the organization that represents the Qi standard. Powermat's CEO stated at the time that Qi had become the 'dominant wireless charging standard on the market,' and it only continues to exert its dominance by pushing other standards out of the game.
Knowing that a wireless charging pad follows the Qi standard simply means knowing that it uses Qi's method of inductive power transfer and that it will power Qi-friendly smartphones. All Qi 'base stations' (charging pads, stands, etc.) derive energy from a power source (typically an outlet) and activate only when a Qi-compatible mobile device has been placed on it. The base sends test signals to the device to ensure that it's compatible, and once it has confirmed this, it starts inductively transmitting power to the receiving mobile device.
The underlying goal of Qi's wireless charging technique is to power the compatible mobile device only to 100 percent. The receiving device and the base constantly communicate through signals that tell the base how much more power is necessary to power the mobile device's battery in full. Once that's achieved, the base essentially goes into standby mode, automatically stopping its transfer of power.
All of the wireless charging pads we've tested in this guide are Qi-compatible, so you'll need a Qi-compatible smartphone to use them. Many recent flagship smartphones including the iPhone 8, iPhone X, iPhone XS, Galaxy S10, and Pixel 3 support Qi-wireless charging. If you have a smartphone that came out in the last two years, it probably supports wireless charging through the Qi standard.
But you can't just throw your smartphone onto the charging pad and expect it to be powered up when you return hours later. Most Qi chargers follow the 'guided positioning' principle, which means that the mobile device needs to be precisely placed on the pad so that its internal receiving hardware is lined up with the coiled wires and magnets that live in the charging pad.
So if your phone lands even just a few millimeters off of the intended placement, it may not charge while sitting on the base. Qi charging pads employ a few tricks to help users position their devices correctly, like visual and tactile design elements. Some bases even have internal coils that move to align with a user's mobile device.
Wired or wireless charging?
If your top priorities are speed and efficiency, you should stick with wired charging. Plugging your smartphone into a charging cable that's connected to a power outlet will almost always charge your device faster than a wireless charging pad. By its nature, wireless charging technology isn't as efficient as wired charging, so you will not see the same rate of energy transfer that you would when charging with a wire.
However, wireless charging can be more convenient. Whether you have a charging pad or a stand, it's easy to set your smartphone down and come back a little while later to a topped-up device. That's why wireless charging pads are popular accessories for bedroom nightstands and office desks—they leave the environment free from messy cables while still providing a convenient method of charging your mobile device.
But wireless charging has hardware and software limitations. Be sure to check the wattage of your wireless charger and the compatible wattage on your smartphone. For example, iPhones running the latest version of iOS support 7.5W wireless charging. Even if you have a 10W charger, the iPhone will max out at 7.5W of wireless charging. While Apple has vaguely described faster wireless charging capabilities (up to 10W) in the iPhone XS and XS Max, there's no official documentation or details to support this.
A note about Qualcomm Quick Charge
During our testing, Qualcomm announced it began working with the UL and Wireless Power Consortium to officially bring its Quick Charge technology to Qi-compatible wireless chargers. Not only does Qualcomm want to do this because the industry is slowly shifting away from wired charging, but it also wants to make it clear which devices support Quick Charge and which do not (some devices falsely claim to support the technology now).
These plans are still in the works, so we're eager to update this guide when more Qualcomm-approved, Quick Charge-capable devices become available. Some of the devices we tested for this guide claim 'fast charge' capabilities, but we mostly ran our tests (see below) to judge just how quickly each device could charge a smartphone.
How we tested
We tested some of the most popular wireless chargers on the market and judged them based on design, power, price, and charging efficiency. To benchmark each charger, we used a few smartphones: iPhone XS, iPhone XS Max, iPhone XR, Google Pixel 3, and the Samsung Galaxy Note 9. Before testing each charger, we powered up each smartphone from 0 percent battery life using its included charging cable to obtain standard charging reference points. We then ran the following tests three times per smartphone and averaged the data to get a final score.
- One-hour charge: Charge smartphone wirelessly for one hour, starting at 0 percent battery, and record the result in percentage-charged.
- Full battery charge: Charge smartphone wirelessly, starting at 0 percent battery, until battery level reaches 100 percent, and then record the result in minutes-charged.
If a wireless charging pad came with an AC adaptor, we used that adapter in our testing. If a pad didn't come with an AC adapter, we used the Anker Dual USB PowerPort II 24W Charger along with the cables provided with the device (every wireless charging pad we tested came with a cable). In addition to charging percentage and time, we also recorded the temperature of each smartphone after it was fully charged using the Etekcity Lasergrip 774 Digital Laser Infrared Thermometer.
Wireless charging has been around for a good while now, but it's only in the last couple of years that it's started to take off. More and more manufacturers have been getting on board with the ubiquitous Qi wireless charging standard and the tech is now inside virtually every flagship phone.
Samsung has supported wireless charging since the Galaxy S6 while Apple adopted wireless charging with the iPhone X and iPhone 8 and iPhone 8 Plus. It's coming to the Galaxy S10, too.
So what exactly is wireless charging, how does it work and does your phone even support it? Allow us to answer all these questions and more.
An increasing number of phones also support reverse wireless charging where you can charge other devices from the phone - for more information on this, check out What is reverse wireless charging and which phones have it?
What is wireless charging?
Wireless charging is the transfer of power from power outlet to device, without the need for a connecting cable. It involves a power transmitting pad and a receiver, sometimes in the form of a case attached to a mobile device or even built into the phone itself.
How does wireless charging work?
Wireless charging is based on inductive charging, whereby power is created by passing an electrical current through two coils to create an electromagnetic field.
When the receiving magnetic plate on the mobile device comes into contact with the transmitter - or at least within the specified range - the magnetic field generates an electrical current within the device.
This current is then converted into direct current (DC), which in turn charges the built-in battery.
What is the standard for wireless charging?
The main wireless standard is Qi (pronounced 'chee'). Qi is a standard that has been developed by the Wireless Power Consortium (WPC) for inductive charging over distances of up to 40mm.
Qi wireless charging has been adopted by many of the major smartphone manufacturers: Samsung, Apple, Sony, LG, HTC, Huawei, Nokia (HMD), Motorola and Blackberry.
Another wireless charging standard was Powermat. It was used by some retailers such as Starbucks to enable customers to charge their phones. But it wasn't cross-compatible with Qi and so it lost out. Indeed it lost the format war, if you like, so Powermat said in 2018 that it would develop commercial wireless charging technology compatible with Qi.
Qi has three separate power specifications, beginning with low power, which is primarily what we're talking about here, for charging mobile devices. At the moment there are several wattages that can be applied to this. 5W is a minimum, while some handsets support 7.5W, 10W and even up to 15W - this higher wattage is supported by some newer devices like the Huawei Mate 20 Pro.
There is a medium power spec which can deliver up to 120W and is used for monitors and laptops. And there is a high spec that can deliver up to 1kW to power devices such as kitchen utensils.
Can I get a wireless charging adapter for my phone?
While many phones actually have the technology built-in, other handsets require an adapter or case to be attached in order to support Qi charging - the iPhone 7 and 7 Plus (also 6 and 6 Plus) have a variety of cases available, for example. The downside is that these don't look great.
Who sells wireless charging mats and stands?
Many peripheral manufacturers now have their own wireless chargers including Anker, Belkin, Logitech and Mophie. Some of these look like mats or pads, others like desk stands.
Wireless charging is now appearing in a variety of places; Swedish flat-pack extraordinaire Ikea has a number of pieces of furniture, mainly side tables and lamps, that have Qi wireless charging built into them. The furniture chain sells standalone wireless charging pads too, as well as a range of cases for different phones.
Apple is releasing its own wireless charging mat, Apple AirPower, soon which will not only work with the latest iPhones, but the Apple Watch and even the new version of AirPods which will have a wireless charging case. As we said above, Apple's phones will also work with conventional Qi charging mats. The Apple Watch isn't Qi compatible but AirPods 2 might be - we just don't know yet.
Can I get wireless charging in my car?
Many car manufacturers have wireless charging in certain models, but even then it often isn't as standard. These include various models from Audi (and the rest of the WV group), BMW, Ford, Honda, Mercedes-Benz, Peugeot, Toyota, and Volvo.
What are the advantages of wireless charging?
- Safer way to transfer power to your phone.
- Simple to just drop your phone on the charging pad.
- Puts less strain on the charging port of your phone.
- Qi wireless charging pads being installed in various places around the world, if you run out of juice and don't have a cable you can still charge your phone.
What are the disadvantages of wireless charging?
- Wireless charging is slower, especially for phones with Quick Charge technology - plugging into a wall outlet will be much, much quicker for those devices.
- If you've got your phone charging via a cable, you can still hold it and use it as normal. If you take your phone off a wireless charging pad to use it, it stops charging.
- Not all phones have it.