Electric fliers all have one thing in common regardless of the size
or type of models they fly—the electronic speed control (ESC). It
doesn’t matter if you fly helicopters, airplanes, giant-scale, indoor,
or micro models; at the heart of your power system is the speed
control, and if it’s unhappy, you will be too. The costs and types
of speed controls vary in every aspect and that includes quality.
The one constant, however, is your understanding of how to make
them last, which in the end, saves money and your aircraft!
Poorly constructed motors can throw magnets and cause extreme current spikes that will destroy a speed control.
This pretty much covers everything. Quality motors, connectors, speed controls, installation,
solder joints, etc., but let’s talk about components. When encountering speed control
problems, we don’t often think about whether they might have been caused by a cheap
(poorly made) motor, but it can and does happen. I recently experienced a catastrophic failure
in a foam jet that caused the speed control to melt and actually burn its way out of the bottom
of the aircraft. Parts of it were left inside, but it unsoldered itself and melted completely. Upon
post-mortem inspection, I found that the magnets inside the motor were unevenly spaced
and one had actually come loose and been chewed into pieces as the motor spun. The funny
thing about electric motors is when something starts to go wrong, the motor will just ask for
more current so it can work to overcome it. My on-board data logger showed normal current
at takeoff and shortly after, it began to climb until it spiked off the scale. This is an indication
that the motor was failing and the binding of the magnet chunks caused the excessive current
spike that subsequently melted the speed control. Some speed controls have over-current
protection and others don’t. Look for one that does! This doesn’t guarantee that it won’t be
damaged by a sudden failure like mine, but it just may help save the speed control. This was an
expensive failure due to a poorly made motor.
Be cool! Install your speed control in a place where you can get maximum airflow across it. Remember that if you let cool air into the fuselage, you have to provide a place for the air to get out too. That exit hole should be about twice the size of the inlet hole. Heat is the enemy, so the cooler you keep your speed control, the happier it will be.
The speed control in this foam jet is jammed into the nose, so it’s fully insulated and gets no cooling air.
With the heavy load from the motor and too many servos, this will overheat and die quickly.
Eleven servos and an onboard LED lighting system
overtax the speed control’s BEC.
The quickest way to get experience buying
speed controls is to buy them too small for the
application—meaning the motor voltage and
current requirements along with the BEC (battery
eliminator circuit) requirements if you’re using
one. If you’re sizing your speed control based on
the maximum requirements of the system and
you’re just barely meeting them, go to the next
size up. If you can use one with a heat sink, do so.
If your BEC requirements match or exceed the
ratings of the speed control’s BEC, then choose
a different speed control or disable the BEC and
use appropriate receiver power. Remember, if
your BEC fails, you lose the airplane.
A good soldered joint between the wire and 6mm bullet
will handle a lot of current. Note that there is no excess
solder running all over the outside of the bullet and the
joint is shiny clean.
Many of the connectors in our electric power
systems need to be soldered to wires. Always
use properly sized wire gauges and quality
connectors. Even the best soldering job
can’t make up for bad wire and poorly made
connectors. A properly soldered joint is shiny!
Your components can’t be too clean, so clean the
components before trying to solder them. Your
fingers will get oils on everything, so be careful
with what you touch. Tin both surfaces before
joining them and then use just enough heat to
let the solder flow between the two pieces. If
the iron is oversized and too hot, it will end up
being a dark, burned joint. If the solder flows
and ends up nice, shiny, and bright—you’ve been
successful. Check out the soldering tutorials on
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