<html><body><div style="color:#000; background-color:#fff; font-family:times new roman, new york, times, serif;font-size:12pt"><div><span>Myself, among others witnessed a speed control (rx off) turn on violently during an interesting test in which the pilot showed us what a ringing cell phone can do when placed next to an armed speed control. No, I don't know the brand of ESC.</span></div><div><br></div> <div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"> <div style="font-family: times new roman, new york, times, serif; font-size: 12pt;"> <div dir="ltr"> <font size="2" face="Arial"> <div style="margin: 5px 0px; padding: 0px; border: 1px solid rgb(204, 204, 204); height: 0px; line-height: 0; font-size: 0px;" class="hr" contentEditable="false" readonly="true"></div> <b><span style="font-weight: bold;">From:</span></b> Bob Richards <bob@toprudder.com><br> <b><span style="font-weight: bold;">To:</span></b>
General pattern discussion <nsrca-discussion@lists.nsrca.org> <br> <b><span style="font-weight: bold;">Sent:</span></b> Monday, February 13, 2012 9:18 AM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [NSRCA-discussion] Arming Switch<br> </font> </div> <wbr>
<div id="yiv1960397210"><table border="0" cellSpacing="0" cellPadding="0"><tbody><tr><td style="font: inherit; font-size-adjust: inherit; font-stretch: inherit;" vAlign="top"><div>Keith,</div>
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<div>My gut instinct is to agree with you on this, but I have to wonder what is the possibility that there would be a failure mode where the controller could go full throttle without an input from the receiver. For the brushless controllers, the micro in the controller must be working properly for the motor to run - period - since it has to sense the feedback from the motor and operate the outputs in proper phase for the motor to run at all (this would be a different discussion if we were talking about *brushed* controllers). The more likely failure would be that it applies power to one or more motor wires - not pulsed - that would do little more than heat up the motor and burn a winding, but not turn the motor over.</div>
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<div>Is it possible for the micro think there is a full-throttle input when there isn't? Most controllers that I know of will not arm if it powers up with anything other than a low-throttle signal from the receiver. It has to sense a low-throttle signal that then transitions to something else before it starts the motor turning. Is this a possible failure mode for an ESC - I don't know since I don't know any specifics of the circuitry or firmware programming of ESCs, but I seriously doubt this can happen and if it can, the likelyhood would be extremely low.</div>
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<div>Of course, not having the battery connected to anything is safe. Safer yet is to just stay at home, but we have to decide what is an acceptable risk.</div>
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<div>Bob R.</div>
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<div><wbr><wbr>--- On <b>Sun, 2/12/12, Keith Black <i><tkeithblack@gmail.com></i></b> wrote:<wbr></div>
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<div id="yiv1960397210">Dave, you're points are correct, but you're not taking into account a malfunction of the speed controller itself. They have been know to malfunction, so the safest approach, as Earl suggests, is to assume that anytime the battery is connected to the controller the motor may go to full throttle. Until you unplug the battery the thing is hot and dangerous regardless of your fail safe or switches on the transmitter.
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