Please don't why just yet, but what would happen if I ran an outrunner
motor directly without the benefits of an ESC? That is, just connect
the motor to the battery and ran it full blast.
Need to know,
Being as an outrunner is AC with three wires and a battery is two wires DC:
A) It'll be a challenge to figure which wires to hook where...
B) You'll effectively create a direct short frying your battery and
C) If you're using lipos, you'll have a handy fire for toasting
On the other hand, people have been doing this with BRUSHED can motors for
years in RC gliders with a switch to turn the motor on and off, and in
FreeFlight, the battery determines your motor run. This is with NiCad or
NiMh cells, LiPos would be a one flight only deal as they'd be discharged
The reason, of course, is such that an electric motor needs a rotating
electro-magnetic field to work. In a brushed motor there are the changing
contacts via the brushes that switch the coils in use and thus the field,
but in a brushless there are none. The rotating magnetic field is produced
by the controller, that senses the rpm of the motor and switches current
through the _three_ coils at proper pace to make the motor turn.
It would be possible to make circuitry that does the thing. However, a
brushless controller is by far the simplest and cheapest way to make the
motor run. In free-flight electric models people use controllers to make the
motor run, even while they do not have RC. They just use elecronic timers
intended to drive servos that actuate triggers to change control surface
positions, and consider the speed controller as one additional servo to
| It would be possible to make circuitry that does the thing. However, a
| brushless controller is by far the simplest and cheapest way to make the
| motor run.
Well, the *simplest* way to make the motor run would be to hook it to
a 3 phase AC power supply -- since a brushless motor is identical to a
3 phase AC motor. (You probably want to drop it down from 110v or
220v, however.) You might even be able to make it run on standard 1
phase AC, just like you can often make a 3 phase motor run
(inefficiently) on 1 phase AC, but that's not usually a good idea.
As for the circuitry needed to make it run from a DC supply, of course
it's possible to make it -- it's in a brushless ESC. But just buying
a brushless ESC off the shelf is certainly easier than making your
own, though there are instructions for making brushless ESCs out
there, and you could just use those, but rip out the part that decodes
the servo signal and hardwire full throttle in there.
Though if you don't need speed control, it would be a lot simpler to
just use a brushed motor. Run at full speed, good brushless motors
aren't much more efficient (when you consider the ESC too) than good
brushed motors. Brushed motors just get a bad rap because we spend
too much time dealing with ones that aren't good :)
(But brushless motors are generally more efficient when run at partial
throttle than similar brushed motors run at partial throttle -- that's