Newb BEC question.

Mirkdiggler

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Hey my brothers.

First time using a BEC. If I set my BEC at 8.4v does everything plugged into the receiver run on 8.4v ? I want to run my servo and fans at 8.4v…

Thanks !!
 

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BEC is (usually) a switching voltage regulator that turns on and off very rapidly so as to allow only the necessary amount of energy through at a time.

A BEC is basically a step down voltage regulator. It will take your main battery voltage (e.g. 11.1 Volts) and reduce it down to ~5 Volts to safely power your receiver and servos.

For example, take a 10-cell NiMHaccumulator with a normal voltage of 12 volts. With a peak current of 5 A, the BEC will have losses of (12 V − 5 V) × 5 A = 35 W. With a linear regulator, these 35 W will be converted to heat and so require a large heat sink. This is an efficiency of (5 V / 12 V) = 41.7%. However, a switching mode regulator with a buck step-down supply can achieve over 90% efficiency.[1] In all cases, it is a good idea to mount some large capacitors to buffer the regulated output. In large plane or ship models, another possibility is to buffer the power supply with a further capacitor near the actuators (servos).

More recent uses for R/C BECs are converting higher-voltage lithium polymer battery packs to 12 V. This has occurred due to the increased popularity of camera equipment for FPV use. Several BEC manufacturers offer a BEC (voltage regulator) for this purpose and people may become confused as this is 'out of the ordinary' to use a BEC for a 12 V application.


Hopefully 🤞 that will explain everything you need to know.
 

RedOctobyr

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Hey my brothers.

First time using a BEC. If I set my BEC at 8.4v does everything plugged into the receiver run on 8.4v ? I want to run my servo and fans at 8.4v…

Thanks !!
Yes. Is this a standalone BEC? Or the BEC integrated with the ESC? If it's the one in the ESC, then yes, everything gets the same voltage.

If it's a standalone BEC, then everything it powers gets 8.4V, in this case. But you might still use the ESC's BEC to provide a different, lower voltage to things that can't take 8.4V. But that wiring gets a bit more complicated.
 

Dan B.

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Hey my brothers.

First time using a BEC. If I set my BEC at 8.4v does everything plugged into the receiver run on 8.4v ? I want to run my servo and fans at 8.4v…

Thanks !!
Yes it does. If it’s a stand-alone BEC, don’t forget to disable the power wire from the ESC to the receiver.
 

joostin420

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I use rx bypass adapters like these from holmeshobbies:

https://holmeshobbies.com/holmes-hobbies-rx-bypass-adapter-with-auxiliary-output.html

Example 1 - using this = no disconnecting the red power wire from the esc
480FC291-8F70-458B-8BE3-57B346169DF1.jpeg


Example 2 - How i am using one right now with a castle bec pro which has 2 connectors to power the receiver. This supplies power to the devices connected to the receiver without disconnecting the red power wire from the esc. The castle bec pro is set at 8.4v.

This configuration allows the built-in bec of the esc to power the fan(s) and aux/other at a lower set voltage.
429008BE-0B31-45CB-B496-728DD745CA35.jpeg
 
Last edited:

Mirkdiggler

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BEC is (usually) a switching voltage regulator that turns on and off very rapidly so as to allow only the necessary amount of energy through at a time.

A BEC is basically a step down voltage regulator. It will take your main battery voltage (e.g. 11.1 Volts) and reduce it down to ~5 Volts to safely power your receiver and servos.

For example, take a 10-cell NiMHaccumulator with a normal voltage of 12 volts. With a peak current of 5 A, the BEC will have losses of (12 V − 5 V) × 5 A = 35 W. With a linear regulator, these 35 W will be converted to heat and so require a large heat sink. This is an efficiency of (5 V / 12 V) = 41.7%. However, a switching mode regulator with a buck step-down supply can achieve over 90% efficiency.[1] In all cases, it is a good idea to mount some large capacitors to buffer the regulated output. In large plane or ship models, another possibility is to buffer the power supply with a further capacitor near the actuators (servos).

More recent uses for R/C BECs are converting higher-voltage lithium polymer battery packs to 12 V. This has occurred due to the increased popularity of camera equipment for FPV use. Several BEC manufacturers offer a BEC (voltage regulator) for this purpose and people may become confused as this is 'out of the ordinary' to use a BEC for a 12 V application.


Hopefully 🤞 that will explain everything you need to know.
Dang bro !! BEC expert !! Thanks
I use rx bypass adapters like these from holmeshobbies:

https://holmeshobbies.com/holmes-hobbies-rx-bypass-adapter-with-auxiliary-output.html

Example 1 - using this = no disconnecting the red power wire from the esc
View attachment 271408

Example 2 - How i am using one right now with a castle bec pro which has 2 connectors to power the receiver. This supplies power to the devices connected to the receiver without disconnecting the red power wire from the esc. The castle bec pro is set at 8.4v.

This configuration allows the built-in bec of the esc to power the fan(s) and aux/other at a lower set voltage.
View attachment 271409
I literally just bought this and was going to ask if this was ok !! Before I read this. Thanks so much.
Yes it does. If it’s a stand-alone BEC, don’t forget to disable the power wire from the ESC to the receiver.
I don’t need to do this if I have the bypass harness ? Correct.
You all are so helpful. This is the best rc forum ever been on. Thank you my brothers !! Appreciate you all.
 
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