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refers to the capacity of energy the battery can safely
discharge, represented as a multiple of its overall capacity.
A battery that has a higher C rating delivers more energy,
and that means higher performance. ;e big di;erence
between batteries with di;erent C ratings is the fact that
the higher-rated batteries su;er less from voltage drops
under load. ;is ability to maintain a higher and more
consistent voltage is what typically generates the high
performance we enjoy. ;is is particularly important when
you have multiple motors turning multiple rotors.
A 2000mAh pack will safely deliver 20 amps continuously ( 10 times 2000mAh equals 20 amps). A 20C pack of
the same capacity will safely allow you to draw 40 amps
from it continuously. ;at’s the same capacity and twice
the amp draw. ;ere are battery packs out there rated at
30C, 45C, and even 70C that will deliver (in our 2000mAh
example) 60, 90, and 140 amps. ;is major increase in
current allows us to run bigger (or more) motors in your
multirotor for increased duration and/or payload-lifting
capabilities. A higher C discharge rating gives us that extra
“oomph” we enjoy in flight, no matter the airframe.
Although a pack with a higher C rating can often be
charged in less time because it can tolerate a higher
current rate, don’t be in a rush; you can always charge it
at 1C (one times the capacity), which will take about an
hour for a complete charge. Doing this has produced the best results in
our experience; we have some older packs that still operate well after
hundreds of charge and discharge cycles.
On my programmable radio, what features do
you think are helpful for flying drones?
Answer: To begin with, dual rates
are helpful as they a;ect the speed at
which your model changes roll, pitch, or
yaw orientation for a given stick input.
;ere are no hard and fast rules for dual
rates as they are dependent on your own
preferences. For drone racing, I like to have
a lower rate combined with a throttle
curve that’s a bit shallower. I find that a
lower rate and lower throttle endpoint can
help with tighter and smaller racecourses.
For aerial-photography platforms, having
a lower rate for roll, pitch, and yaw on a
switch can make keeping a slower subject
in frame or help produce a slower-moving
shot as easy as flipping a switch in the air.
Also with exponential, it is important to understand your model’s
flight-controller settings. Most flight-controller software discourages the
use of expo settings on your radio. ;is is because expo is already built
into the flight controller; if you add radio expo, it can make stick controls
feel jerky and unpredictable.
In general, if you have telemetry, it is important to have voltage
feedback, at the very least. Signal strength (RSSI) feedback is also a
great tool to help pilots recognize that they are flying beyond their radio
equipment’s capability. Also having a battery-current sensor can help
pilots keep an eye on the demands the model is putting on their power
system. Having this feedback display to your radio or displayed in your
video feed are the two most common telemetry setups. I think the best
telemetry setup is having a radio that will audibly report on these stats
repeatedly as time passes, such as with the Spektrum DX9. Combined
with a simple telemetry receiver, such as one of the Spektrum integrated
telemetry receivers or the Quad Racing Receiver with telemetry, pilots
can easily take advantage of valuable feedback.
Temperature sensors aren’t commonly used, but if I were to consider
using them, it would be to monitor the temperature of my flight-pack
battery. ;is way, you’ll know if your battery is going bad or cannot handle
the current draw that is being imposed upon it. ;ey start to get hot
under these conditions. You’ll also see flight times diminish and notice
abnormally hot battery packs after your flights.
brand manager K
Tom Cogswell, Spektrum
associate brand manager
When it comes to knowing what the C rating is, there’s no guesswork needed; it’s printed right on
Programmable computer radios
have several features that make
it easier to fly drones.