The transition from plugging a cable into a smartphone to laying it on a wireless charging pad was a small but convenient one. No more damaging connections, and laying a phone on a compatible cafe table or in a cubbyhole of a car to share wire-free felt like living in the future.

But at home, where the wireless charger still needs plugging into a wall outlet and using your phone while resting on the charger is more difficult than when attached to a cable, it feels like we are still a long way from perfection.

Read More:

• How wireless charging will power your smartphone through the air
• Long-range wireless power is coming to smart home devices

This is where long-range wireless charging comes into play – a technology that safely broadcasts energy far enough to top up the battery of a smartphone or other device from across a room. The future could see our smartphones constantly having their batteries filled up as we sit in the bar or restaurant, nap on a plane, or stroll through a shopping mall, automatically connecting to charge stations the same as it does to Wi-Fi routers and 5G masts today.

We first wrote about the potential for such a future back in 2018, when a number of firms were researching ways to take the Qi (pronounced chee) wireless charging standard, and turn it truly wireless.

A year later, in ealy 2019, a new alliance between Wi-Charge, Alarm.com and Allegion promised to harness long-range wireless charging to power smart home devices like door locks, motion sensors, sirens, security cameras and smoke alarms. With this technology, many smart home products could receive constant power without the need for a wall outlet or battery pack.

Founded in 2012, Israeli firm Wi-Charge is still working on this technology, and received innovation awards at the CES technology shows of 2018, 2019 and 2021. It uses focused beams of invisible infrared light to carry power from a transmitter (fitted to the ceiling of a room, for example) to a receiver embedded into the aforementioned devices. The infrared light is then converted to electrical power using a miniature photo-voltaic cell.

Intended to power low-energy devices like sensors and door locks, transmitted power is below 10 watts, and so is not ideally suited to smartphones and other more power-hungry products.

But, while that is one solution for long-range wireless power in the home, three more tech firms want to power smartphones that way too. First to show off its technology was Chinese firm Xiaomi, which announced the Mi Air Charge system in January 2021. This also uses a base station to transmit power, this time using "extremely narrow millimeter wide wave beams" that are claimed to charge a phone at roughly 5W.

This is at the low end of what to expect from today's wireless charging pads, but if the power is constantly being fed into a smartphone battery, high speed isn't as important. The base station contains 144 antennas and can send energy "a few metres" through the air to charge multiple devices, like smartphones, at once. Xiaomi says this "isn't science fiction" but hasn't said when it plans to sell this technology to the public.

The same week, Motorola also announced a long-range wireless charging technology. Here, a pair of smartphones were shown to charge 100cm from the charger itself. The technology is based on the Qi standard; Motorola also said how up to seven phones could be charged at once, but didn't say what speed their batteries are refilled at.

As with Xiaomi, Motorola has not given any indication as to when this technology might be commercially available, but it is surely a positive thing to see it being worked on.

Most recently, in late-February 2021, we have Chinese firm Oppo, which revealed another long-range wireless charging technology. The demonstration came via a 30-second video showing a concept phone with a rollable screen charging from a distance; Oppo calls the technology Wireless Air Charging.

Where Xiaomi's demonstration appeared to show power flowing wirelessly from a base station to a phone held across the room and at an angle, it looks like Oppo's system allows less freedom for now. A video shows how the phone is held directly above the charging mat, and while it is tilted slightly to different angles, the user is careful to keep it in one place above the charger.

It is likely that these technologies will all improve in the months and years ahead, but it also seems doubtful that any will be commercially available for a while yet, and certainly not this year.

For now though, we're glad to see multiple companies working on solutions that could one day bring truly wireless power to our phones, smartwatches, smart home devices and other products.