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- AA will be better: scientists have created the world's first finger battery with wireless charging
AA will be better: scientists have created the world's first finger battery with wireless charging
In Russia, they created the world's first AA battery with wireless charging and solved two problems at once: the inconvenience of replacement and a deceptive "full charge" before a sudden shutdown. Most modern rechargeable AA batteries keep a stable 1.5 V output voltage until the last one, and then the device abruptly goes out without warning. The scientists did something else: their converter smoothly lowers the voltage as it discharges, and the gadget manages to send a low charge signal. At the same time, the battery is compatible with any Qi station, charges directly in the compartment and is safe in temperature. It can be used in equipment operating in the Arctic, where battery replacement is complicated by low temperatures, as well as in medical and industrial equipment. Experts note that the technology looks promising, but a number of its features still require additional refinement before mass adoption.
Finger battery with a charge without wires
Scientists at the New ITMO Physics and Technology Institute, together with students, have developed the world's first AA battery that can be charged from any Qi wireless station, the same as that used for smartphones. Externally, the device looks like an ordinary 1.5 V finger battery, but inside there is a curved receiving coil, voltage converters and a battery.
Despite the widespread use of wireless charging in smartphones, smart watches, and headphones, many household devices still use finger batteries. It is impossible to connect a standard receiver to them due to the lack of an appropriate connector. This is exactly the problem that the developers solved.
The principle of operation of the new battery is based on the same technology used in conventional wireless devices. The transmitting coil of the Qi station creates an alternating magnetic field with a frequency of 100-200 kHz, and the receiving coil built into the battery captures this field and ensures the charging process.
— It was impossible to squeeze a flat coil into the AA body — it either did not fit, or its coils turned out to be too small and almost did not feel the transmitter. We had to bend the coil along the wall of the cylindrical body — this way it captures more of the magnetic field. The induced alternating current is then rectified, converted to the required voltage, and used to charge the built-in lithium-ion battery. After that, the second converter lowers the voltage from the typical 3.7-4.2 V lithium–ion cells to the standard 1.5 V AA batteries. Thanks to this, the gadget perceives the battery as an ordinary finger battery and works without any changes," said Nikita Olekhno, head of development, senior researcher at ITMO.
Alexey Dmitriev, the lead developer of the project and a researcher at ITMO, noted another feature of existing AA batteries. According to him, many of them maintain a stable voltage until almost full discharge, and then they instantly turn off, which is why the device stops working without warning of a low charge level.
Scientists have proposed a different approach to indicating battery discharge: the developed converter gradually reduces the output voltage as the charge is consumed. Thanks to this, the device in which the battery is installed has time to detect a power drop and warn the user in advance — for example, by flashing or other signal. Usually, such schemes are implemented using specialized chips, but the project team dispensed with them and patented the solution.
The current prototype is assembled in a transparent cylindrical housing made on a 3D printer made of photopolymer resin. This material does not conduct electricity and does not interfere with the operation of the receiving coil. A 65 mAh battery is installed inside the device, which is fully charged in about an hour.
The project grew out of a learning task for undergraduate students in Wireless Technology. In 2024, the development was included in the state task dedicated to the creation of wireless energy transmission technologies for use in the Arctic.
— In severe frost, it is inconvenient to take the battery out of the device and fiddle with the wires and connectors — everything freezes, and in the cold the plastic becomes brittle and easy to break. Wireless charging allows you not to touch the battery compartment at all: just put the device on the station, and the process starts automatically," Nikita Olekhno clarified.
The prospect of batteries with wireless charging
Batteries with the function of wireless charging are an interesting and relevant solution that does not require the use of special adapters, Igor Chausov, director of the analytical department at the Center for Energy Systems of the Future, told Izvestia. According to him, one of the advantages of this technology is the ability to use wireless chargers for phones, which are increasingly found both in everyday life and in public areas, such as public transport.
— At the same time, quite a lot of user equipment still runs on conventional finger batteries or batteries with the same form factor, - said the expert.
From the perspective of prospects, the technology has potential primarily for specialized devices that are inconvenient to disassemble for charging: industrial equipment, sensors, medical equipment, devices for the Arctic, as well as individual household appliances, said Anton Averyanov, CEO of the ST IT Group of companies, TechNet NTI market expert.
— Most AA batteries today can be charged in a few hours using familiar devices, and the cost of such solutions remains low. Therefore, wireless charging by itself is unlikely to cause a massive transition to a new technology, although it looks very convenient, the expert believes.
The main issue today is the capacity of the prototype, Anton Averyanov said. The claimed 65 mAh is significantly inferior to modern AA batteries, which usually have a capacity of about 1500-2500 mAh. Nevertheless, if the developers manage to bring it closer to these indicators without a significant increase in cost, the technology can occupy its niche. First of all, in devices where ease of maintenance and ease of operation are more important than maximum energy efficiency.
The results of the development are published in the IEEE Transactions on Power Electronics journal.
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