FREQUENTLY ASKED QUESTIONS
ESCs that the BEC has a certain
current limit, such as 1 amp. Some
specifications will say to only use four
servos to limit the current.
The specifications for my servos
don’t tell me the operating current.
What am I supposed to do?
A576: You need to measure the current
needed to operate your receiver and all
of your servos. In rough terms, a receiver
might draw 20 mA of current. Each
servo may idle (not moving) at roughly
50 mA. A receiver and four servos (at
rest) might draw 220 mA current. But
these same servos may draw much more
current when moving.
Insert a current meter between your
battery (or BEC) and your RC receiver.
After doing that, operate your RC
system by trying to simultaneously use
as many servos as possible, moving the
transmitter control sticks at the same
time. By doing that, you may find that
you have exceeded the current for that
Many modern ESCs now use a
By using the
Hangar 9 Digital
Servo and Receiver
Current Meter, you
can see how much
current is being
drawn to help
protect the BEC
circuit in your ESC.
Photo by Tom Hunt.
A good way
to measure your receiver/servo current
is to use a Hangar 9 Digital Servo and
Receiver Current Meter. The unit costs
approximately $40. It comes with
universal connectors that allow you to
insert it into your system. I’ve listed the
website for this meter in “Sources.”
This meter has many other
applications. You could insert it between
your receiver and servos and monitor the
current as you move each servo.
AUGUST 2013 www.ModelAviation.com