What is a UBEC? Why is it So Important in Drones and RC Models?

What is a UBEC?

UBEC, which stands for "Universal Battery Eliminator Circuit." The name might sound a bit peculiar; it originates from the early days of the RC (Radio Control) hobby. At that time, the receiver and servos required a separate battery pack for power. The advent of the UBEC allowed you to draw power directly from the main battery used to drive the motor and convert it into the stable voltage required by the receiver and servos, thereby "eliminating" that additional battery.

In simple terms, a UBEC is an efficient, standalone DC voltage regulation module. Its core task is to convert an unstable input voltage (such as the decreasing voltage of a lithium battery during use) into a clean, stable output voltage (typically 5V or 3.3V), specifically designed to power your core control equipment.

What Does a UBEC Do?

• Voltage Conversion and Stabilization: This is its core function. It converts the unstable, high voltage from the propulsion battery (which decreases as the battery depletes) into a constant low voltage. This ensures that sensitive electronic devices are not damaged or reset due to voltage fluctuations.
• Delivers Sufficient and Dedicated Power: Compared to the BEC integrated into an ESC, a standalone UBEC can typically deliver a higher, more sustained current (e.g., 3A, 5A, or even 10A), sufficient to drive multiple high-power servos simultaneously.  
• Load Sharing: It separates the power supply task from the ESC, allowing the ESC to focus solely on controlling the motor. This reduces heat and stress on the ESC, enhancing the overall reliability of the system.  
• Electrical Isolation and Noise Immunity: Motors generate strong voltage spikes and electromagnetic interference during operation. A standalone UBEC acts as a "firewall," providing a "cleaner" power source to core devices like the receiver and flight controller. This effectively helps prevent control system malfunctions, jitter, or resets caused by power supply noise.
• Flexibility: You can select a UBEC with different output voltages and currents based on your needs to power various devices, making it widely applicable.  

Flipsky 4-20S External UBEC 20A

Flipsky recently launched a UBEC designed for receivers and devices using 4-20S LiPo battery packs. It supports an input voltage range of 4-20S LiPo, covering most voltage requirements. The output voltage is adjustable from 4-10V, with a default output of 5V. It can provide a stable 20A output current (the actual sustainable current depends on external cooling conditions: better heat dissipation allows for longer full-load operation).

Furthermore, this UBEC features a high-efficiency DC-DC regulator chip with a conversion efficiency of over 90%. The metal enclosure acts as a shield, offering good heat dissipation and effectively reducing electromagnetic interference. It also incorporates multiple protection features such as over-current protection, output short-circuit protection, over-temperature protection, and low-voltage cut-off. In summary, it combines performance and functionality, offering excellent value.

Usage Guide

Wiring Diagram

If there is a built-in BEC in the brushless ESC, please disconnect the ESC's BEC output wires (e.g. “5V” and “GND” as shown below). Connect the signal wire “S” to the receiver's ‘S’ channel at the interface. Then, connect the UBEC's input wires in parallel with the battery pack. Plug the output terminals into the receiver's “+” and “-” channels.

Voltage Output Adjustment

Adjustable output voltage (4-10V) in four levels through the calibration switch on the rear. The factory default voltage is 5.0V, shown as below:

Front View: Rotating the potentiometer clockwise to reduce the output voltage; rotating it counterclockwise to increase the output voltage.

Conclusion

A UBEC is not an "optional" accessory but rather an "invisible guardian" of modern high-voltage electronic systems. A stable, efficient, and reliable UBEC can prevent signal loss, system crashes, and can even save your equipment and ensure flight safety at critical moments.

If you are building a high-performance drone or RC device, stop relying on the weak BEC integrated into your ESCs. Professional modules like the Flipsky 4-20S External UBEC 20A are the power solution truly worth investing in.

Choosing the right UBEC is like adding a safety lock to every flight you make.

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