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Model Forum / Radio Controlled / Air Models / October 2005brushless speed controller
doze any one know if you can run two brushless motors off one brushless controller.say two axi 2208/34 off a jeti 30 amp-3p 6-10 cell .for eg. A lot of people say you cant but I am running 2 motors and one Jeti speedie in a GWS C47 with no problems. > doze any one know if you can run two brushless motors off one brushless > controller.say two axi 2208/34 off a jeti 30 amp-3p 6-10 cell .for eg. | A lot of people say you cant but I am running 2 motors and one Jeti | speedie in a GWS C47 with no problems. Are you sure that your motors are brushless? The problem is that the ESC `senses' the position of the motor and adjusts the voltage (or, to be more precise, the polarity and the duty cycle) it sends accordingly. If the motors are not in the same position, then it's not going to be able to send the right voltages to each pole of each motor. I can see where it might work most of the time if the motors and props are matched, but there's lots of room for problems. | > doze any one know if you can run two brushless motors off one | > brushless controller.say two axi 2208/34 off a jeti 30 amp-3p 6-10 | > cell .for eg.  SignatureDoug McLaren, dougmc@frenzy.com "Madness is rare in individuals, but in groups, parties, nations and ages it is the rule." -Friedrich Nietzsche >> A lot of people say you cant but I am running 2 motors and one Jeti >> speedie in a GWS C47 with no problems. [quoted text clipped - 6 lines] > position, then it's not going to be able to send the right voltages to > each pole of each motor. how does it do that without a "tach" feedback and only three leads? | > The problem is that the ESC `senses' the position of the motor and | > adjusts the voltage (or, to be more precise, the polarity and the duty [quoted text clipped - 3 lines] | | how does it do that without a "tach" feedback and only three leads? Well, the old brushless motors have three leads for the motor power, and a five more for the sensors. The new brushless motors only have three leads for the motor power, but the ESC can detect the position of the motor based on the voltages that the motor leads are putting out. The old setup had a lot more wires, but it did have one advantage -- it usually wasn't too difficult to adjust the timing of your motor, just by moving the sensors forward or back. With the new sensorless ESCs, the timing is generally fixed in the ESC (though some of the high end ones may let you adjust it.) (You can also use one of the new ESCs on one of the old brushless motors -- you just don't plug the sensor wires into anything.) http://www.ezonemag.com/pages/faq/a412.shtml goes into a little bit of detail. http://www.rcuniverse.com/forum/m_1558046/tm.htm is a discussion that goes into a bit more detail. Brushless prices have come way down recently. Give it a few more years, and the brushed motor may go the way of the dodo ... SignatureDoug McLaren, dougmc@frenzy.com Those who live by the sword die by the arrow. Doug, Looks like for equivalent performance, the mid size brushless motors have already surpassed the can motors for bang for the buck. I believe that on the very small end the same is true as well. Now, with battery prices coming down, the total package is getting better and better. SignaturePaul McIntosh RC-Bearings.com "when steel just isn't enough" > > | > The problem is that the ESC `senses' the position of the motor and [quoted text clipped - 27 lines] > Brushless prices have come way down recently. Give it a few more > years, and the brushed motor may go the way of the dodo ... thanks for the help I will try it . > | > The problem is that the ESC `senses' the position of the motor and > | > adjusts the voltage (or, to be more precise, the polarity and the duty [quoted text clipped - 26 lines] > Brushless prices have come way down recently. Give it a few more > years, and the brushed motor may go the way of the dodo ... > >> A lot of people say you cant but I am running 2 motors and one Jeti > >> speedie in a GWS C47 with no problems. [quoted text clipped - 8 lines] > > how does it do that without a "tach" feedback and only three leads? Google "back EMF feedback " >>>A lot of people say you cant but I am running 2 motors and one Jeti >>>speedie in a GWS C47 with no problems. [quoted text clipped - 8 lines] > > how does it do that without a "tach" feedback and only three leads? Two wires are energized, the third is a sensor, at any given time.. Yes im sure they are brushless I took the brushes out before I installed them in the plane. > | A lot of people say you cant but I am running 2 motors and one Jeti > | speedie in a GWS C47 with no problems. [quoted text clipped - 13 lines] > | > brushless controller.say two axi 2208/34 off a jeti 30 amp-3p 6-10 > | > cell .for eg. > ... > The problem is that the ESC `senses' the position of the motor and > adjusts the voltage (or, to be more precise, the polarity and the duty > cycle) it sends accordingly... Close but not quite Doug. The duty cycle depends only on your stick. The higher the 'ON/OFF' ratio, the faster the motor will spin and the controller has to keep up with the motor. Vriendelijke groeten ;-) Ron van Sommeren http://home.hetnet.nl/~ronvans/ int E fly-in near Nijmegen, the Netherlands Ted shuffled out of his cave and grunted these great (and sometimes not so great) words of knowledge: > doze any one know if you can run two brushless motors off one brushless > controller.say two axi 2208/34 off a jeti 30 amp-3p 6-10 cell .for eg. It depends. SOME people have done this, however, the majority of people use a controller for each motor. If you are going to use one controller for 2 motors, make sure the ESC amp capacity can handle the 2 motors - I.E. - If each motor pulls 30 amps, the controller needs to be rated for 60 amps or higher. thanks for the help I will try it. > doze any one know if you can run two brushless motors off one brushless > controller.say two axi 2208/34 off a jeti 30 amp-3p 6-10 cell .for eg. > doze any one know if you can run two brushless motors off one brushless > controller.say two axi 2208/34 off a jeti 30 amp-3p 6-10 cell .for eg. Sometimes, but mostly not. Imagine trying to run two brushed motors off one commutator.. If you flick start one or both motors, they usually synchronise and work, but starting is very unreliable, as the motors ne3ed to be in phase synchronism.. You may think thats acceoptable...till you shut the throttle on appraocah and open it up for a go around... Kontroniks sell a twin motor one controller kit though. Mostly it seems to work - with their motors. |
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