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United States, WI, Shawano
Joined Mar 2006
54 Posts
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Discussion
ESC using external battery question
I have a 90amp Castle Creations Talon ESC. Can anyone help clarify the manual statement "Always disconnect the red power wire on the throttle lead when an external battery is employed in the receiver circuit."
It appears the statement says to cut the red wire on the plug from the ESC that is plugged into the throttle channel of the receiver if I use a NiMh to power the rx and servos. Thank you |
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United States, MS, Picayune
Joined Feb 2007
605 Posts
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No need for the extension. Look at the side of the ESC connector where the crimped terminals are showing. Push in on the red wire and you should see the little plastic tab clear the terminal. Use an Exacto knife blade or a straight pin to slightly raise the plastic flap and you will be able to pull the red wire out of the housing. Fold the red wire back and cover the terminal with heat shrink or electrical tape.
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I normally use a separate RX power rather than the ESC because I still want power to the radio if anything happens to the motor, ESC, or power pack. Would it be OK if your radio dies when the engine went dead stick on a gasser? That's my logic.
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United States, VA, Springfield
Joined Aug 2010
85 Posts
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Dead stick on a gasser is not the same. The built in bec is hundreds of times more reliable than your gas engine. That being said I normally use an external bec for mid sized planes and a separate battery for giant scale. For giant scale the hv escs dont have a bec anyway.
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Quote:
It is amusing that people will go on about needing dual receivers, but then seem ok with a set up with a series single point failure mode that will kill power to their radio. |
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Interesting question I always thought it was "the rule" I never questioned it
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It's like crossing the streams
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If lipo voltage < BEC voltage - it would try to charge the connected lipo and exceed max BEC output potentially taking out the BEC.
If BEC voltage < lipo voltage, Lipo voltage would backflow into BEC, also not good. If BEC and Lipo were isolated with diodes, you could probably use both for redundancy. |
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I saw this on break at work
I wonder if this applies to RX battery Https://www.rcgroups.com/forums/show...r-multiple-ESC 'm not an EE either, but I frequently listen to Lucien Miller on the ATTF podcast. Lucien is an electrical engineer. This is from memory and not verbatim from the show. Apparently, there is a feedback loop in the circuit of an ESC's internal BEC. It reads it's own output voltage and when it see's this voltage get out of tolerance, it adjusts to compensate. When two ESC's are connected in parallel, if there is even the slightest difference in output voltage, it can trigger the feedback loop in the other unit to adjust it's output and then the conflict begins. One goes up, the other goes down etc. Basically they fight each other. If the two units were assembled with the exact same production run of components and the output voltage was very closely matched, then I think you might get away with it. |
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To hook the two toghether (rx pack and ESC) the best bet is the 'battery buffer'
http://www.western-robotics.com/BBFR |
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