Looking for ESC without BEC
03-15-2005 | 10:07 AM
#1
Looking for ESC without BEC
Hey folks,
I'm looking for an ESC without BEC to activate an electromagnetic brake. It will use a 9V battery and draw about 1.5A max. I want it to be proportional. It must not drain the 9V battery when the RX is switched off. Disabling the BEC feature by disconnecting the "red" servo wire is not going to work as the 9V battery will go dead very soon. Any ideas? Please help!
Dave Rigotti
I'm looking for an ESC without BEC to activate an electromagnetic brake. It will use a 9V battery and draw about 1.5A max. I want it to be proportional. It must not drain the 9V battery when the RX is switched off. Disabling the BEC feature by disconnecting the "red" servo wire is not going to work as the 9V battery will go dead very soon. Any ideas? Please help!
Dave Rigotti
03-15-2005 | 12:57 PM
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From: Emmaus,
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RE: Looking for ESC without BEC
Just clip the red (power) wire from the ESC to the RX to disable the BEC from powering the RX (you now need an RX batt pack), and install a switch between your 9V batt and the ESC, if your ESC doesn't have a power switch on it already. If you want only one switch, you can get a dual throw switch that will turn power on/off to both the RX and the ESC... a SPDT switch will allow you to turn power to both on/off, and a DPDT switch will allow you to switch the batt s from the RX/ESC in the "on" position", and then to charger leads in the "off" position (like regular RX pack wiring harnesses do).
03-15-2005 | 03:53 PM
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From: Greenbelt, MD
RE: Looking for ESC without BEC
It is not possible to buy an ESC without a BEC. The BEC is in reality a voltage regulator that powers the brains and other electronics in the controller. The regulators used in common ESCs have adequate current rating to power an RX and several servos, thus the BEC. Cutting the red wires removes the RX and servo current drain from the ESCs regulator. This results in a very small load (~10ma) on the battery and should run the ESC for some time on a 9V battery. If you are planning on using 9V "transistor radio" battery, 1 activation of the brake at 1.5A will eat the battery's lunch. BEC current drain is the least of your worries in this application. Sounds to me like using an ESC for this application is over-kill. Would you consider an alternate design?
03-15-2005 | 04:17 PM
#4
RE: Looking for ESC without BEC
ORIGINAL: wreck_em_all
It is not possible to buy an ESC without a BEC. The BEC is in reality a voltage regulator that powers the brains and other electronics in the controller. The regulators used in common ESCs have adequate current rating to power an RX and several servos, thus the BEC. Cutting the red wires removes the RX and servo current drain from the ESCs regulator. This results in a very small load (~10ma) on the battery and should run the ESC for some time on a 9V battery. If you are planning on using 9V "transistor radio" battery, 1 activation of the brake at 1.5A will eat the battery's lunch. BEC current drain is the least of your worries in this application. Sounds to me like using an ESC for this application is over-kill. Would you consider an alternate design?
It is not possible to buy an ESC without a BEC. The BEC is in reality a voltage regulator that powers the brains and other electronics in the controller. The regulators used in common ESCs have adequate current rating to power an RX and several servos, thus the BEC. Cutting the red wires removes the RX and servo current drain from the ESCs regulator. This results in a very small load (~10ma) on the battery and should run the ESC for some time on a 9V battery. If you are planning on using 9V "transistor radio" battery, 1 activation of the brake at 1.5A will eat the battery's lunch. BEC current drain is the least of your worries in this application. Sounds to me like using an ESC for this application is over-kill. Would you consider an alternate design?
Dave Rigotti
03-15-2005 | 04:58 PM
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From: Emmaus,
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RE: Looking for ESC without BEC
ORIGINAL: wreck_em_all
It is not possible to buy an ESC without a BEC...
It is not possible to buy an ESC without a BEC...
http://www2.towerhobbies.com/cgi-bin...?&I=LXTF90&P=7
http://www2.towerhobbies.com/cgi-bin...?&I=LXTF93&P=7
http://www2.towerhobbies.com/cgi-bin...?&I=LXTF92&P=7
Still, I believe the easiest/cheapest solution is the one I described in my previous post. For a non BEC ESC... if the ESC control circuitry gets it power from the RX, then you won't have any drain on your ESC battery when the RXis off, but if the ESC controller gets it's power from its own battery terminals, you still need another switch on the ESC battery connection...
03-15-2005 | 06:36 PM
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From: Greenbelt, MD
RE: Looking for ESC without BEC
Paul,
You are missing my point. All ESCs have internal voltage regulators. Most make the regulated 5V available for RX and servos (AKA BEC) and some do not. In any case the regulator is in the controller. Controllers that are "not BEC" have simply cut the red wire for you. Assuming the 9V battery is capable of 1500mah, a 1.5A brake can be activated theoretically for 1 second 60 times. Factoring in voltage droop and brake coil drop out current, 20 to 30 activations is more likely. The 9v "transistor battery" I mentioned has no where near that capacity.
You are missing my point. All ESCs have internal voltage regulators. Most make the regulated 5V available for RX and servos (AKA BEC) and some do not. In any case the regulator is in the controller. Controllers that are "not BEC" have simply cut the red wire for you. Assuming the 9V battery is capable of 1500mah, a 1.5A brake can be activated theoretically for 1 second 60 times. Factoring in voltage droop and brake coil drop out current, 20 to 30 activations is more likely. The 9v "transistor battery" I mentioned has no where near that capacity.
03-15-2005 | 09:41 PM
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From: Emmaus,
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RE: Looking for ESC without BEC
ORIGINAL: wreck_em_all
You are missing my point. All ESCs have internal voltage regulators. Most make the regulated 5V available for RX and servos (AKA BEC) and some do not. In any case the regulator is in the controller. Controllers that are "not BEC" have simply cut the red wire for you...
You are missing my point. All ESCs have internal voltage regulators. Most make the regulated 5V available for RX and servos (AKA BEC) and some do not. In any case the regulator is in the controller. Controllers that are "not BEC" have simply cut the red wire for you...
Assuming the 9V battery is capable of 1500mah, a 1.5A brake can be activated theoretically for 1 second 60 times. Factoring in voltage droop and brake coil drop out current, 20 to 30 activations is more likely. The 9v "transistor battery" I mentioned has no where near that capacity.
03-15-2005 | 09:49 PM
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From: Spencerport, NY
RE: Looking for ESC without BEC
What's needed in this case is an ESC rated for at least 10 cells. The cutoff point for BEC/no BEC seems to be right around 10 cells. ESCs that cross the boundary tell you to disable the BEC when using more than 10 cells.
03-16-2005 | 06:50 AM
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From: Greenbelt, MD
RE: Looking for ESC without BEC
ORIGINAL: -pkh-
Ahhh... I agree with you there... I never had a non-BEC ESC, so I didn't know if they typically use the RX power to run the control section or regulate the ESC batt voltage down... the latter makes the most sense to me, as you said...
You're off by a factor of 60 here... 1500mAh = 1.5Ah which means you can draw 1.5A for one hour, not one minute. So you would be able to apply a 1.5A brake for 1 minute 60 times. 9V NiMH cells have only about a 200mAh capacity... I guess alkalines probably have closer to 600-700mAh, like RCGuy said. Internal resistance of these cells is quite high, so I'd imagine you'd get quite a voltage drop with a 1C+ discharge rate. If you only apply the brakes for a few seconds each time you land, and can still get decent braking with the loaded voltage, I'd guess the batt would take the brief heating with plenty of time to cool down in between. Assuming a 1.5A braking current, that would give you a 1/2 hour of braking on one 9V cell...
ORIGINAL: wreck_em_all
You are missing my point. All ESCs have internal voltage regulators. Most make the regulated 5V available for RX and servos (AKA BEC) and some do not. In any case the regulator is in the controller. Controllers that are "not BEC" have simply cut the red wire for you...
You are missing my point. All ESCs have internal voltage regulators. Most make the regulated 5V available for RX and servos (AKA BEC) and some do not. In any case the regulator is in the controller. Controllers that are "not BEC" have simply cut the red wire for you...
Assuming the 9V battery is capable of 1500mah, a 1.5A brake can be activated theoretically for 1 second 60 times. Factoring in voltage droop and brake coil drop out current, 20 to 30 activations is more likely. The 9v "transistor battery" I mentioned has no where near that capacity.
