Photon Phil

I bought an AVIAN 60 amp esc. I installed it in my airframe and it works, BUT on full throttle and just below full it hunts. It speeds up then slows down just a little. You can easily hear it doing this.
Any thoughts on why it does this? This is my first so called smart esc. It seems that it is smarter than I am. TIA

Wildflyer

It may be warning you that the battery voltage is low.

I have an ESC that goes into pulse mode (my name) when the voltage drops, I like that better than just stopping the motor and then you have to drop to low throttle to get a little burst for landing control then it might shut off again when you need it. (Sometimes I forget the time to land)

Check your running battery voltage with a wattmeter or hook up a voltmeter so you can read it while giving your plane full power.
Tie the plane down so you don't have to think about it getting away. Seen that happen.

Photon Phil

Thanks Wildflyer I'll give it a try.

Fishbonez

Are there any tones when this begins to happen?

solentlife

I have had this happen on a couple of models but for different reasons each.

Model 1. Battery was nearing LVC (Low Voltage Cutoff) and it went into pulsing mode - you could hear it while flying as the motor varied speed. It gave me just enough warning to get model down.

Model 2 : The ESC was only just enough for the power demand and as it hit max - it started to pulse the power to motor, avoiding burn out. It also got hot which was what guided ,me to solution - bigger ESC !!

So first question : Was LiPO charged when you tested the setup ? If not maybe 1. is the answer ?

Second question : have you Wattmetered the setup to see that you have adequate spare rating on the ESC ?

Third question : Is the ESC Motor Timing correct for the motor ? Some of these 'smart' ESC's are too smart and can be a pain to get right. It may be a possibility to try other Timing settings ??

I would suggest a Wattmeter test as well.

ron_van_sommeren

Don't forget to measure current as well.

solentlife

With the Wattmeter test - we would be looking for :

1. Amp draw and its increase as we open throttle ... to see point at which it starts the problem
2. Displayed Volts and its 'sag' as the throttle is advanced ... till point problem starts.
3. Watts displayed and its increase as throttle is advanced etc.

With result of #1 : you get to really see if ESC you have is suitable or not. It is usual to have at least 30% margin of ESC rating above max amp draw of motor.
#2 - divide by number of cells and this gives average of cell voltage at that problem point ... it may show a figure close to LVC ... indicating a poor battery or too high a LVC.
#3 - gives a check on Amps / Voltage as this is a mathematical value.