Battery life is one of the main concerns when it comes to drones. For most applications, the flight time just isn’t long enough. Some drones are tethered, sure, but there are drawbacks to that, too.

Researchers at Imperial College London have developed a method to wirelessly power drones in midair. And they say this could lead to drone-to-drone recharging in the air.

Drones that never stop flying. What a beautiful thing.

Here’s how Imperial College London did it. They took an off-the-shelf quadcopter, removed its battery, added a copper coil, and altered its electronics. They also had a transmitter on the ground connected to a power supply that created a magnetic field. When the quadcopter, about 4.7 inches in diameter, hovered no more than 4 inches above that magnetic field, it drew a current to power itself.

“The technology uses inductive coupling, a concept initially demonstrated by inventor Nikola Tesla over 100 years ago,” the researchers write. “Two copper coils are tuned into one another, using electronics, which enables the wireless exchange of power at a certain frequency. Scientists have been experimenting with this technology for decades, but have not been able to wirelessly power flying technology.”

Imperial College says they’re experimenting with using a ground support vehicle as a mobile charging station. The drones could hover over this vehicle and recharge.

“There are a number of scenarios where wirelessly transferring power could improve drone technology,” Dr. Samer Aldhaher, a researcher from the Department of Electrical and Electronic Engineering at Imperial College London. “One option could see a ground support vehicle being used as a mobile charging station, where drones could hover over it and recharge, never having to leave the air.”

The next step for the researchers is to explore partnerships. They say this recharging technique has potential for other industries, too.

“Imagine using a drone to wirelessly transmit power to sensors on things such as bridges to monitor their structural integrity. This would cut out humans having to reach these difficult to access places to re-charge them.

“Another application could include implantable miniature diagnostic medical devices, wirelessly powered from a source external to the body,” explains professor Paul Mitcheson, from the Department of Electrical and Electronic Engineering at Imperial College London. “This could enable new types of medical implants to be safely recharged, and reduce the battery size to make these implants less invasive.

“In the future, we may also be able to use drones to re-charge science equipment on Mars, increasing the lifetime of these billion dollar missions. We have already made valuable progress with this technology and now we are looking to take it to the next level.”

WiBotic in August 2016 teased a similar wireless charging system for aerial, mobile and aquatic robots. When a robot or drone approaches the WiBotic wireless charging platform, it automatically detects its presence and wirelessly charges the battery. WiBotic claims it works “just as fast, if not faster, than a standard plug-in charger.”

WiBotic says its charging system is also more efficient than traditional charging methods as it eliminates human intervention for daily maintenance, charging or battery management. Alerts are triggered if the power systems are compromised in any way. WiBotic says this approach will even prolong the life of the battery itself.