ZTW Beatles 60A; calibrated OK but motor doesn't increase in speed with stick position between ~80 to 100%

[Mitchell Howard]

Hi all - I have a trainer I'm setting up with a Beatles 60A ESC in it with Ripmax Quantum motor. Using a Radiolink AT10ii which seems to functioning happily in all other ways.

 

I ran the throttle up over the weekend and it starts smoothly, increasing in RPM as I move the stick forward, but it seems to stop increasing as I near full stick forward position. I didn't check where exactly, but it felt like ~80%.

 

My first thought was the ESC hasn't registered the full stick forward position set during calibration, but I'm convinced it's right. I plan to re-do it anyway now. I'm also happy the radio is sending a fully proportional signal between the stick bottom point and top point, hitting -100 and +100 travel, the radio lets me see that dynamically on screen.

 

Can anyone think of anything else that would cause this?

 

I was toying with one of the Beatles programming cards, but I don't think it's going to add anything helpful.

[Alan H]

First thing I would do is check the actual Rx output on the servo channel. To do this replace the ESC with a servo and see if this moves over the full range.

[Nigel R]

Servo check is a good idea.

 

Next stop, re-run the stick calibration, and go from there.

[Kim Taylor]

Assuming that the servo check is ok, I would suspect that it's just due to the motor being unloaded (i.e. no prop).

The motor can't run faster than it's synchronous speed, i.e. kV x V and without a prop it may well be able to spin up to this on less than 100% throttle.

Best thing would be to (safely) run the motor with a load and see if it makes a difference.

Kim

[Frank Skilbeck]

The way the ESCs work is by increasing the time the motor is on (by switching it off and on 1,000s of times a second), the load on the battery is proportional to the square of the speed, so what could be happening is that as you increase the on time above a certain point then the battery voltage may be dropping sufficiently to restrict the power available. Also ESCs often have some low voltage protection which stops the battery voltage from dropping too low, this may be happening with your setup as you approach full load, you can check this by measuring the cell voltages under load.