Stuttering, starting torque and non-sensored motor

Hi all,

I’m trying to use a Turnigy D5035 125KV motor with a basic ESC (AeroStar WiFi 80A Brushless ESC), so the sensor wires are not connected. Just bench testing at present so using a 30A benchtop power supply instead of a battery.

I have a large flywheel attached to the motor which means it needs quite a bit of starting torque to get going, but I find most of the time it just stutters. If I spin the flywheel a little it does get going, but even then the torque is very poor and it easily stalls. The power supply is only delivering a couple of amps, even though it could supply up to 30A if required.

The cables from the power supply to the ESC are short, but the ESC - motor cables are quite long. I’ve read that this shouldn’t be a problem, but the motor does seem to start better when shorter cables are used. Perhaps the return signal on the third cable is being interrupted by inductance on the long cable which is making it not start correctly.

I was wondering if I’m expecting too much from this equipment, and perhaps the starting torque will never be that good. Would it be much better with a different ESC which can monitor the motor sensor? I was kind of expecting it to draw very high current when the motor is trying to start, or when load is applied, but it never draws more than about 10A.

I’d be grateful for any suggestions!

Many thanks,

Unsensored motors always stutter when starting from a standstill. You make matters worse by adding a large flywheel with no gear reductions.

Solutions to this problem could be:

  • Different ESC to use the motor sensored
  • Gear reduction from the motor to the flywheel
  • A higher Kv motor is often used when using gear reductions

On a bicycle it’s easier to start driving when you use low gears and turn the pedals fast, instead of using high gears and turning the pedals slowly.

Just kick start the board senors tend to get destroyed all the time. Also basic esc’s are not a good choice they will burn. Try a vesc or binary esc its going to be much better.

Sensors are pretty reliable if used correctly.

my sk3 was not sensored and l have to give a kick to help at startup and l have burn a 150A rc car esc , on 6s because voltage is going to high when braking and than l purchase external sensor for my sk3 and l burn another rc esc for no reason .

the thing l know about sensor if you motor is sppining very fast and you got a error with the hall sensor reading or a wire is damaged the esc can burn in 1-2 seconds ,

That are probably just a few milliseconds, but luckily vesc has hybrid sensor mode.