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Can I power a receiver with an ESC and no motor?

#1
I want to know if I can power a receiver with an ESC with a BEC built in without connecting a motor.
Is the motor required or does the BEC just split the voltage from the battery and regulate it?
If not then how do gliders have their receivers powered?
Would a Turnigy Plush 6A ESC with 5V, 0.8A BEC work?

Thanks!

Safe Flying!
 

c172ae

Pro plane crasher
#2
go ahead, it will work fine. just be sure that none of the leads normally going to the motor is touching each other.

also, make sure the BEC has a high enough amp rating. 0.8A may be a bit small for a normal size model (of course, that depends on what you define as normal :rolleyes: )
 

quorneng

Well-known member
#3
Gliders can use a 'stand alone' BEC that has no ESC. Usually smaller, lighter and cheaper than an ESC.

As c172ae says a 0.8A BEC is a very small capacity that would only be capable of driving 2 of the sub micro servos.
To big a servo will overload the ESC's BEC, reduce the voltage below the regulated voltage and then the radio will at best misbehave or simply stop working until the voltage comes up again. It could take a second or two to re-establish contact and an awful lot can happen to a plane in a couple seconds! :(
 

joshuabardwell

Senior Member
Mentor
#5
I'm not super familiar with gliders, but I noticed that all the gliders on YouTube seemed to fly off of NiCad packs instead of LiPo. I suspect this is because the NiCad pack has a voltage of around 5-6 volts, which is exactly what the receiver and servos need. This allows powering the plane without having a separate BEC (extra weight).

If you already have an ESC, go ahead and use it. Otherwise, do what RoyBro said, and get a separate UBEC and don't waste weight on the ESC circuitry.
 

rcspaceflight

creator of virtual planes
#7
I have a burnt out ESC that I cut off the motor leads and use as a BEC to power the Rx for gliders. Because I'm cheap like that. I mean because I'm resourceful like that.
 
#9
Thanks guys!
A UBEC sounds better and is lighter which I need.
I'm restoring an old sailing boat and needed to know how to power a modern receiver with a modern system.
Also, what battery would I need?
I know I need a 2 cell and I want it to be light, small and last for a long time. The battery will only be powering the receiver and two servos so there wont be much load on it if any. Which would you recommend? and can it be got from Hobbyking?
Thanks!

Safe Flying!
 

joshuabardwell

Senior Member
Mentor
#10
Hobbyking can sell you pretty much any battery you might need. If you are only powering your receiver and servos, then 2S is the minimum. If your BEC is linear, then you should definitely use a 2S, as the extra voltage of a 3S will just be wasted as heat. If your BEC is switch-mode, you may find you get more power density from a 3S battery, and you won't waste the extra voltage as heat.

I would guess that your total power draw will average less than 0.5 amp, and probably even less than that. So even a little 500 mAh pack would probably give you a half hour or an hour of run time.
 
#11
Hobbyking can sell you pretty much any battery you might need. If you are only powering your receiver and servos, then 2S is the minimum. If your BEC is linear, then you should definitely use a 2S, as the extra voltage of a 3S will just be wasted as heat. If your BEC is switch-mode, you may find you get more power density from a 3S battery, and you won't waste the extra voltage as heat.

I would guess that your total power draw will average less than 0.5 amp, and probably even less than that. So even a little 500 mAh pack would probably give you a half hour or an hour of run time.
Thanks :)
I've already ordered two 2s 20c 800mAh batteries from HK because they're cheaper than the 500's for some reason...

Safe Flying!