ESC's - what timing to use..

[retiredVTT]

Sometimes when running up a motor you reach a point where a distinctive "screech" is emitted from the motor. This can be the esc and motor getting out of "sync"...in other words the esc zigged when the motor zagged.
The esc MUST give the motor a pulse of current at the exact moment that the motor wants it.

"Timing" is the key word here, and it generally requires that the esc timing be changed if you switch from an inrunner type motor to an outrunner type motor and sometimes even between outrunner motors having different pole counts.
(Esc timing programming is usually covered on that instruction sheet you get with the esc)

I did a search on RCGroups and this link will take you to numerous threads on the subject of "motor timing".

http://www.rcgroups.com/forums/search.p ... d=20445946


Bill

[retiredVTT]

I gleaned these settings from one of the articles referred to above...

Timing:
Low - (1*) for 2-4 pole Inrunner motors.
Medium - (7*) for 6-8 pole motors.
High - (15*) for 10-14 pole Outrunner motors.
X High - (30*) for 10-14 pole high rpm Outrunner Motors.


Pulse Width Modulation Settings:
8 KHz - low rpm, low pole count motors.
16 KHz - for most Outrunner motors.

(* = degrees)

Bill

[retiredVTT]

Just another similar tale of a motor screeching because the Esc timing was incorrect..
Bill


..from the Scorpion Motor thread on RCGroups..

I’ve got a problem,

Scorpion Esc 60A V2 is having serious issues spinning a Microdan 2505-2900 kV 10 pole motor on 4S.
This is what happens when you run 15 degrees timing with a 4.75x4.75 - 1540W 118A spike?
I can’t get more than 90% throttle on any larger prop without the esc loosing sync and screaming.
I’ve currently got these ESC settings 1.3s MAT, SS, 8Khz, 5 degrees timing
Any ideas?
What caused my spike?

Jackomeister


Jackomeister,

What is happening is that you are losing sync between the motor and ESC at the high RPM. This is common with high RPM set-ups if you do not have the timing advanced enough. You will probably want to run 15 or 20 degrees of timing to be able to keep the motor and ESC in sync at the high speeds that this motor will turn. You are approaching 30,000 RPM with this set-up, and at those speeds, you do need to advance the timing.

Lucien at Scorpion

[retiredVTT]

Here is another reason for motors to emit that horrible screech..but this time it is not corrected by changing the timing of the esc.

Once again this info came from the Scorpion Motor Question and Answer thread of RC Groups hosted by Lucien Miller of Innova8ive Designs, distributor for Scorpion products..

quote from Lucien regarding the deadly motor screech, heard by a guy running a 14/7 prop on a Hacker A40 motor with a Scorpion 60 esc, using a 4S lipo pack..

"..that motor has a dated operating current of 40 amps and a peak current of 50 amps. By running the motor this hard, you are no doubt hitting the saturation point of the motor core, and this will instantly cause the motor to lose sync with the ESC. You should probably be running no more than a 12x6 prop on that motor with a 4-cell battery pack."

So too large a prop can cause too large an inrush of motor current, lose of sync with the esc, and the result is immediately lose of take off power, a deadly screech, and possibly a crash.

Just another reason to check the run up of the motor with a wattmeter prior to first takeoff.


Bill

[retiredVTT]

Another quote from L. Miller , Scorpion Motor distributor for North America.

"Whenever you have a motor lose sync with its ESC, it is almost always caused by running too large of a prop, or by having the timing set incorrectly. Also, if you are running a Scorpion ESC on 4 Li-Po cells, you should have the internal BEC disabled and be running a seperate switching type BEC circuit to power your servos and receiver"

"..... in the future, when you ask a question, please give the full specs of your power system in the first post, since it saves a lot of questions later. I assume that you have a Hacker A30-12L motor. That motor has Kv value of 1000, and if you run it on 4 Li-Po cells, a 14x7 prop is WAY too big for it. That motor has a dated operating current of 40 amps and a peak current of 50 amps. By running the motor this hard, you are no doubt hitting the saturation point of the motor core, and this will instantly cause the motor to lose sync with the ESC. You should probably be running no more than a 12x6 prop on that motor with a 4-cell battery pack."