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Old Nov 13, 2013, 05:52 PM
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United States, OH, Norton
Joined Aug 2013
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Good ESC with BEC, is separate BEC required?

Say you have a good ESC with a 5A BEC, is it still recommended to use a separate BEC? For example the Castle Creations Talon 35.

If so, why?

I am trying to think of ways to eliminate equipment in my new Sirius FPV build but do not want to do so at the expense of reliability.

Thanks!
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Old Nov 13, 2013, 06:27 PM
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Dr Kiwi's Avatar
Chattanooga, Tennessee, United States
Joined May 2003
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If you have a lot of high drain servos you may exceed the 5A BEC capability. A stand alone UBEC provides good insurance especially where you are using high voltage (>4s)
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Old Nov 13, 2013, 06:48 PM
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In a situation where 5A were enough. For example, I was going to install a 5A BEC. Would a 5A BEC internal to the ESC be any better/any worse than an external 5A BEC?
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Old Nov 13, 2013, 07:53 PM
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Australia, ACT, Kambah
Joined Feb 2001
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Quote:
Originally Posted by jcowgar View Post
In a situation where 5A were enough. For example, I was going to install a 5A BEC. Would a 5A BEC internal to the ESC be any better/any worse than an external 5A BEC?
IMO, no worse if you are not planning to use a separate battery to power an external SBEC. and potentially better as you don't have an extra solder connection with dissimilar wires slicing the SBEC into the power leads. And regardless of whether it is external or internal, SBEC capacity up to their rated input voltage is not much affected by that voltage, eg 2s or 6s, unlike linear BECs which suffer from much lower output as input voltage increases.

And as long as you ensure your surfaces and linkages are not binding, you'll be surprised by how low actual servo current draw is, especially on the relatively low speed, low manoeuvring of fpv.
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Old Nov 14, 2013, 02:22 AM
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Letchworth, Great Britain (UK)
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If the BEC in your ESC is a switching one and is enough for your needs, the only advantage of a stand-alone BEC is that it won't fail if the ESC smokes.
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