Going seperates - What about pluging two ESC's with BECS into the reciver? - RC Groups
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Jan 11, 2005, 03:18 AM
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ssozonoff's Avatar

Going seperates - What about pluging two ESC's with BECS into the reciver?

Hi All,

I am rebuilding my Piccolo for indoor flying with seperates. I have a CC 10 for the main rotor and a Schulze 105He for the tail. These both have BEC's, the question is can I safely plug them both into my receiver or do I have to disable one of the BEC's ?

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Jan 11, 2005, 03:39 AM
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disable one of the becs by removing the red wire
Jan 11, 2005, 07:59 AM
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Vince Herman's Avatar
Many have argued against doing this, but if it is a possible source of glitching, I went ahead and did it.
Rather than cutting the wire as some suggest, pull the pin from the plug and place a piece of shringwrap over the pin to prevent it from shorting to anything else. (you need to lift the plastic retaining piece on the plug to pull the pin)
This lets you revert back to the original configuration later.
Look up the stats for your two ESCs to find the one with more capacity on the BEC and disable the BEC form the other ESC.
Jan 11, 2005, 07:59 AM
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I read a post by patrick (owner of castle creations) that the BEC types in the little micro ESC's are fine to connect in paralell.

Apparently they are 'resistive'. And so shouldnt interfere with each other, and if you are on the limits of the capabilities of one BEC, then having the other one plugged in is actually a plus as it distributes the load between them.

I know common knowledge says otherwise on this board and I too used to cut one of the wires, but I am pretty sure Pat knows his stuff after building and designing these things for 10+ years
Jan 11, 2005, 11:40 AM
"Simplify, then add lightness"
The vast majority of BEC's are simple linear regulators which can be connected together without problems. The CC10 actually has two of these chips connected together on the same board. When I first started flying separates many years ago I saw all the recomendations to cut one red wire, but being an electrical engineer, I realized this was mainly a myth. I have flown for years with BECs in both brushed and brushless esc's wired together with no problems.
Jan 11, 2005, 12:12 PM
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thanks for the confirmation jeffs555

Are there other types of voltage regulators, maybe a technology now superseeded that could be the origin of the advice to 'disable on BEC to prevent interference'?

Just curious, so I cant tell everyone who I fly with (rare but sometimes) why this is the case rather than 'just becuase...'
Jan 11, 2005, 12:21 PM
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I think that you shouldn't run a switching BEC along with the linear type. Like if you upgraded to a UBEC or a SBEC. I am not an electical engineer, but as far as I know it shouldn't be done.

Jan 11, 2005, 01:05 PM
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I normally recommend that one BEC be disabled, but I recently had a case where there was quite a bit of glitching and the only way to fix it was to enable both BECs. The ESCs were a TREC and CC Phoenix-10. Neither BEC would fix the glitching on it's own but once they were both enabled, everything smoothed out.
Jan 11, 2005, 01:29 PM
"Simplify, then add lightness"
I don't know if there was at one time some BECs that caused problems when connected together or not. I have been into electronics for close to 40 years, and the simple series pass voltage regulators have been the same for most of that time. It is possible that some BEC somewhere used a shunt regulator, but that would be very inefficient, and I can't imagine them being used, but I have only been into RC for a few years. If you connected a shunt regulator to a series regulator, that would be a bad thing.

There are two basic types of linear regulators, series and shunt. A series regulator is kind of like a variable resistor connected in series with the battery. It pulls the output up to the desired voltage then increases its resistance to maintain that voltage. A shunt regulator is like a variable resistor connected across the battery. It pulls the battery voltage down to the desired output voltage, by drawing more current. If you had a series regulator connected to a shunt regulator, one would be trying to pull the voltage up, and the other trying to pull it down and they would draw large amounts of current and probably burn up. I can't imagine a shunt regulator having been used as a BEC, but it is possible.

Switching regulators are more varied in design, but even with them, in most cases, you will not damage anything if you connect a series linear regulator to the output.

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