If your ESC has data-logging
capabilities, use it!
you must look for the reason(s) and take
Heat and Its Meaning
Heat can be a great indicator that
something in your power system isn’t
working as it should. Heat can be a
product of excess resistance from a bad
motor, ESC, or a combination of things
including insufficient wire gauge.
Some heat is normal, but if you’re
seeing battery (LiPo) flight packs
exceeding 140°, you must do something
to fix it. Sometimes it’s as simple as
providing some cooling air intake to the
Remember, if you have a hole to bring
air in, you need a bigger hole to let it
and the exiting heat out. If
you’re sure everything in
your power setup is correct
(battery capacity, propeller,
motor, ESC) and things are
still getting too hot, you need
to look further.
Real Life Example
My friend, Erik, recently
brought an airplane for
me to look at that he’s
been flying successfully for
approximately three years.
It suddenly died. He gets
some tones from the ESC,
but it won’t arm. He hasn’t
changed anything and he’s a
reasonably data-oriented guy,
I went through the airplane and
couldn’t find anything wrong with the
setup. I’ve seen it fly many times so I
knew it had been working.
I tried different packs that I knew
were good with the same result, so I
asked if he could send me his log files
since he uses an ESC that has a logging
function. There were some holes in
time where he didn’t have data logs,
but he had logs from his initial flights
and scattered flights after that until it
quit working. I dropped the data into
a spreadsheet so I could see columns
to compare numbers and some things
began to jump out. Here’s what I saw:
1. The input voltage was as expected
for the 3S pack.
2. Current was within the parameters
of the ESC. There were some spikes
showing peaks slightly above, but
nothing raised a red flag and it was
within the surge parameters.
3. Many of the flights were done at
4. Ripple current didn’t show
anything to raise concern, although
more recent flights prior to its failure
showed a slight increase.
5. Motor rpm was within normal,
expected range for the propeller size.
6. Temperatures logged in the ESC
were extremely high during portions of
On the surface this seemed to be
a normal-flying airplane, but when
looking at the data logs we could see
that, although everything seemed to be
within parameters, the heat on the ESC
board was 178° much of the time and
mostly during partial throttle operations.
We have hot days in North Carolina, but
that is well beyond what I generally see
in my logs. The data showed that the
ESC was cooked.
A call to the manufacturer’s technical
support told me that although the
component should work at temperatures
up to roughly 200°, working it
at elevated temperatures would
significantly shorten its lifespan. Erik has
been flying this airplane regularly for
roughly three years in this condition, so
I’m surprised it lasted this long.
Heat kills components at a high rate.
80 Model Aviation DECEMBER 2012 www.ModelAviation.com