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Battery Eliminator Circuit

Battery Eliminator Circuit is an electronic device that eliminates the need for a battery by providing stable voltage. It converts the high voltage from the main power source to a smaller voltage. This will allow multiple components to be powered reliably without individual batteries, reducing weight and maintenance.

In this article, we will learn everything about the battery eliminator circuit. 

What is a Battery Eliminator Circuit?

What is battery eliminator circuit?

A battery eliminator circuit is an essential electronic device developed to supply very stable voltage to a wide array of components without using many individual batteries. The working of the BEC involves stepping down high voltage from the main power source into a smaller voltage that can easily be managed. This allows several components to work properly and reliably with reduced weight and maintenance. 

The most typical uses for a BEC are in radio-controlled models, drones, and other hobbyist electronics to power onboard electronics like receivers and servos. They ensure a proper power supply to the components to avoid problems such as dropping signals or acting erratically—very critical in applications where reliability is paramount, like radio-controlled aircraft or aerospace or autonomous vehicles.

Battery Eliminator Circuit

Battery Eliminator Circuit

This battery eliminator circuit systematically converts the high-voltage AC input to a stable DC output using some components. Basically, the working starts from a 230V AC input, which is transferred to a transformer to generate an AC with lowered voltage. Then, this AC with a lower voltage is passed through a bridge rectifier. This converts the AC voltage into a pulsating DC voltage. A rated 1000μF capacitor smooths the pulsating DC to get a more stable DC voltage. 

This smoothed DC voltage is then regulated by the LM317 voltage regulator to give a constant output. The output voltage can be adjusted using two resistors connected to the LM317, thus allowing customization according to the user’s needs. Adding a small capacitor (10 µF) at the output of the LM317 further filters the voltage, removing any remaining ripples and making it absolutely stable. Now, the stabilized and regulated DC voltage is available across the output terminals, which becomes ready for different electronic loads.

Components of Battery Eliminator Circuit

components of BEC

Battery Eliminator Circuit consists of many key elements that provide a regulated, consistent voltage. These components are explained below:

Transformer: Transformer steps down the input AC voltage to a lower voltage, which is required for the subsequent stage. However, in some of the below-powered applications, the transformer may be replaced by a voltage regulator.

Rectifier: In the nest stage, the AC voltage from the transformer is converted into a pulsating DC voltage. Rectifiers may be of different types: half-wave rectifiers and full-wave rectifiers. A half-wave rectifier uses a single diode, while a full-wave rectifier uses two or four diodes to convert the AC waveform to DC. In the earlier type, a pulsating DC is obtained, while in the latter, one steady DC is obtained. 

Filter Circuit: The pulsating DC voltage from the rectifier is passed through the filter, in order to flatten out the waveform and acquire steady voltage. The circuit consists of inductors and capacitors that can reduce the output’s ripple voltage (the unwanted AC component).

Voltage Regulators: Some BECs also have voltage regulators to ensure stable output voltage, regardless of fluctuations in input voltage. 

Protection devices: Several protection devices, such as fuse (Protect against overcurrent by breaking the circuit), diodes (Protect against reverse polarity and voltage spikes), and thermistors (Protect against over-temperature conditions), may as well be present. 

How Does Battery Eliminator Circuit Work?

A BEC—Battery Eliminator Circuit—changes high-voltage input AC or DC to a lower voltage output DC. It starts with a transformer, stepping down the high-voltage AC to a lower AC voltage. After that, a rectifier converts this lower AC voltage into pulsating DC. Finally, the rectified DC is smoothed by a filter capacitor, reducing ripples. A voltage regulator keeps the DC voltage steady and within the required range. 

The excess voltage in linear regulators is dissipated as heat; in switching regulators, on the other hand, the excess energy efficiently gets converted back into usable power. A heat sink is attached to the voltage regulator to dissipate heat. Protection devices like fuses, diodes, and thermistors ensure protection against overcurrent, reverse polarity, and overheating. An output filter can further smoothen the DC voltage. Finally, an indicator LED will be put on to indicate the operational status.

Types of Battery Eliminator Circuit

There are various types of battery eliminator circuits used in modern electronics. Let’s discuss some of the popular battery eliminator circuits below:

Linear BEC: This gives stable DC output by wasting the extra voltage as heat.


  • Easy and straightforward to use


  • Energy inefficient, hence wasteful
  • Needs superior thermal management

Switching BEC: It efficiently converts input voltage to any desirable output voltage using high-frequency switching.


  • High efficiency with close to zero wastes
  • It can consume currents in high-current applications


  • It has a complex design

Universal BEC: Combining linear and switching regulators is often done to cover an extremely wide range of applications. It can take a wide range of input voltages and give multiple output voltages.


  • Its applications are versatile.
  • It can provide multiple output voltages for a single input.


  • It has a more complex design.
  • It is more expensive.
  • It requires careful design to prevent different outputs from interfering with one another.

Choosing the right Battery Eliminator Circuit

We may focus on three important factors, while deciding on the selection of BEC. These factors are explained below: 

Input and Output Requirements

When choosing a BEC, first consider the input and output ratings. Any circuit will need a transformer to step down its high voltage to be connected to AC inputs, generally found at wall outlets. If it is a DC source, ensure your BEC can handle the full range of voltages your source could supply.

On the output side, determine your device’s exact voltage and current rating; this is a compatibility and proper-functionality factor. For example, something wanting 5V and 2 Amps would require a BEC that would support that continuously. To find the power requirement, multiply the voltage by:

Power = Voltage x Current

Choose a BEC rated for this power level to prevent overheating or failure.

Efficiency and heat dissipation

Efficiency is the direct influencing factor for power consumption and heat generation. Linear regulators are simple and quiet. However, they have low efficiency, particularly when the input voltage to the component is much larger than the generated output voltage. In such situations, the excess voltage is dissipated as heat. 

For instance, while converting 12V to 5V at 2A in a linear regulator, (12V – 5V) × 2A = 14W will get wasted as heat. Switching regulators are much more efficient—typically greater than 90%—compared to all of the previous linear voltage regulators. 

This is because they transfer the extra power rather than wasting it. They will work best in applications with large differences between their input and output voltages or with a higher current demand. They can generate switching noise that may require filtering. All BECs, regardless of type, do produce some heat. Hence, make an appropriate selection of your BEC based on the availability of heat sinks or thermal management solutions.

Noise and Ripple Tolerance

Noise and ripple may negatively impact the performance of sensitive electronic devices. Contrary to this, linear regulators produce a very pure and stable DC output with minimal noise and ripple, ideally suited for sensitive applications like audio or RF circuits. Nevertheless, it has the drawbacks of lower efficiency. 

Switching regulators, on the other hand,  are efficient but may introduce switching noise and ripple into the output. Although modern designs minimize these effects, further filtering may be necessary if quality output is required. Check what your application can stand in noise; for instance, a microcontroller or digital circuits will be less noise-sensitive. 

Therefore, ensure that the BEC you choose for your application meets all the noise and ripple specifications to avoid any kind of interference or malfunction.


Battery Eliminator Circuit for RC Cars

A battery eliminator circuit connects to either the main battery or the ESC to power an RC car’s receiver and servos. It drops the voltage down to about 5V or 6V. This means there is no need to have a second battery for the receiver itself, making the whole power setup of the vehicle less complex. The BECs can absorb substantial currents and big changes in loads typical for RC vehicles while keeping stable power distribution and low weight.

Battery Eliminator Circuit for Drone

BEC in drones steps down the large voltage from the main LiPo battery to an appropriately regulated lower voltage, thus making it suitable for the flight controller and other electronics. Usually, switching BECs are used. This is highly efficient and performs better while also handling different input voltages. It provides consistent power to onboard electronics without requiring extra power sources and ensures the flight is safe and efficient.


Battery Eliminator Circuit is a crucial component in modern electronics. It provides a stable and reliable power supply to various devices without the need for multiple batteries. Whether using linear, switching, or universal BECs, the right choice depends on specific input and output requirements, efficiency, heat dissipation, and noise tolerance.

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