New swappable flying batteries can keep drones in the air for a very long time

Drones can be extremely useful in many applications, but they have a minor drawback: they can’t fly for long. The amount of energy determined by their battery runs out quickly.

Due to the limited capacity of modern lithium-ion rechargeable batteries, drones have to be balanced between three basic parameters: flight time, battery weight, and payload weight. That way, they offer flight times between 20 to 25 minutes at best, before you have to bring the drone back for a battery swap.

Now, researchers at UC Berkeley’s HiPeRLab have come up with a mind-boggling system that can actually eliminate the difficulty. They invented flying batteries – flying charging station.

The concept is actually very simple. Just imagine a drone with four rotors – outfitted with its own battery and a docking station mounted on its top – in front of you! When the unit’s battery is almost out of fuel, a smaller drone as a flying battery approaches the main quadcopter. The smaller quadcopter takes a position about 12 inches above a passive docking tray mounted on top of the larger drone.

The flying batteries land on a tray mounted atop the main drone and align their legs with electrical contacts. Credit: UC Berkeley
The flying batteries land on a tray mounted atop the main drone and align their legs with electrical contacts. Credit: UC Berkeley

It then slowly descends to about 3 cm above, waits for its alignment to be just right, and drops, landing on the tray which helps align its legs with electrical contacts. Then once it lands perfectly on the upper tray, the main quadcopter is able to feed completely from the smaller drone’s battery charge.

The technology has already been tested in practice. The experimental drone, weighing 820 grams, is equipped with a modest 2.2 Ah battery, sufficient for just 12 minutes of flight.

And the smaller 320 grams-drone as flying battery features a 0.8Ah built-in battery, plus another 1.5Ah battery as cargo, reports IEEE Spectrum. The little ones can’t keep themselves in the air for long, but that’s okay because their only job is to go from ground to the big quadrotor and back again.

According to experts, each of these “flying batteries” increases the flight time of a large drone by about 5 minutes. In theory, in this way, a large drone can remain in the air almost infinitely – until one of its components is damaged.

The new method is especially relevant for military personnel who can use drones of various sizes and batteries with different capacities. Charging a large drone can be done with the help of small, very cheap flying charging stations.