The battery eliminator circuit is like a gadget that helps lower a big electric power to a small one. It is helpful for Contemporary remote-controlled aircraft, which use high-power batteries so that you can use the same battery to power all the different parts of the plane. There are many different kinds of these circuits to choose from. 

Do ESCs have Battery Eliminator Circuits? 

Yes! Many ESCs come with a built-in AC adapter. It means you do not have to worry much about powering your device. It would be best if you plugged the Battery Eliminator Circuit lead into the receiver, and it will provide the necessary power, usually 5 volts. However, for more powerful models, you may still need a dedicated Battery Eliminator Circuit.

 Let’s look into this in more detail. 

(Linear) Battery Eliminator Circuits

A BEC reduces power, but it wastes a lot of energy while doing it. This energy turns into heat instead of being used. So, while a BEC is simple, it’s inefficient and uses valuable power.  

BECs cannot handle large batteries with increased voltages because it would make them too hot, and they would stop working. Electronics do not like heat. So, BECs can only be used for small things. 

(Switching) Battery Eliminator Circuits

A Switching Battery Eliminator Circuit is more advanced than a regular BEC and can power high-performance models. It uses a switching current to safely reduce the voltage to 5v for the RC gear, with very little wasted power. A capacitor and coil help to keep the voltage consistent for the Remote Control gear to run smoothly.

(Universal) Battery Eliminator Circuits

A UBEC is like a Switching Battery Eliminator Circuit. It also uses a switch-mode regulator to control the current/voltage for your important electronics. Different brands sometimes use UBEC/SBEC, but UBEC is becoming more commonly used as a common term. 

The Battery Eliminator Circuits

The BEC helps us make our electrically-powered models lighter. Most radio systems come with a heavy Nickel-cadmium battery with a capacity of 600mAh & four cells battery that weighs about 94 g. It is a lot for a beginner’s electric model like a Great Planes ElectriCub/Spectra. Although lightweight batteries are available, they are still too heavy for smaller & lighter models. The model can still fly, but it won’t fly as well. 

The BEC is a device that helps us get rid of the battery for the receiver. Instead, we can use the drive battery to power a radio system. However, this means there are some restrictions on where & how we should use the BEC.

How do Battery Eliminator Circuits Works?

The BEC is usually included in the ESC, which is responsible for controlling the speed of the motor. The BEC and ESC are separate parts, but they are available together by some wires and work together. Figure 1 displays the different parts of a power system and how they connect with an ESC with a BEC.

The BEC sends energy to a receiver using the same wire to control the motor’s speed. The receiver has three pins on each channel: plus, minus, & signal. We can use the plus & minus pins of any channel to provide power, and we don’t have to use the “Batt” connector on the receiver. Some small receivers designed for use with BECs do not even have the “Batt” connector.

It’s important to observe that the throttle and BEC parts of the ESC are together with the battery’s power wires. Even though they do similar tasks, they do them differently. 

The throttle manages the amount of power that goes to the motor. An electronic device called an “ESC” helps control the speed of a motor. It works by turning the power to the motor off and on quickly, many times every second. Modern ESCs do this around 1,500 to 3,000 times per second, while older ones do it around 50 times per second. The power amount the motor receives depends on how long the power is turned on. 

The BEC controls the amount of power that goes to the receiver & servos. The BEC has to keep a stable voltage to power the radio system. It has to maintain this voltage even when the motor battery voltage and servo loads vary. Also, the power supplied to the receiver must be free from electrical noise and voltage changes. It is a challenging task since the same battery that powers the motor is also the power(energy) source for the BEC. 

A Better Way?

You might have thought about how the throttle can deliver less power to a motor, even at higher currents, while the BEC can’t provide as much power or energy to that radio without overheating. The reason is off or on switching done by the throttle.

Instead of lowering the voltage, the throttle turns the full voltage on & off quickly to reduce power to the motor. The throttle doesn’t produce any heat. It does not dissipate power.

We can use a switching regulator to do the same thing for a Battery Eliminator Circuit voltage regulator. However, these circuits are usually large, heavy & expensive. Also, it’s challenging to design a switch-mode regulator that can provide clean power to the receiver without any issues. A linear regulator is cheaper and good enough for most purposes. 

Battery Eliminator Circuits Ratings

So we understand that a BEC’s performance is limited by its ability to dissipate heat, and the amount of heat it generates is proportional to the current and the difference between the input and output voltages; we can understand why most manufacturers specify the maximum no. of cells or servos that should/can be used with their Electronic Speed Controllers with BEC. 

If there are a lot of cells in the battery, the BEC needs more power to work. It means the voltage going into the BEC is higher. It widens the voltage gap between the input & the 5 Volt output. Also, using more servos leads to a higher current draw. 

Why should you use a Battery Eliminator Circuit?

It can be useful when you don’t have any batteries for your device. If your battery is broken or dead, the battery eliminator provides the necessary voltage to turn on your device using power from another device.

It can be useful when you don’t have batteries. It can supply the voltage needed to turn on your device using a different power source. You can also use it to figure out the precise voltage needed for your circuit without the hassle of constantly removing and replacing batteries. It saves time and effort.