Problem with Brushless Thrusters

[gsisrov]

Hi,

We've built a motor testing rig to test brushless outrunners. To record the force, turned it on for one minute and logged the force throughout the minute. After on the first round we measured 1.7N average force. After the motor was in the water for a couple of minutes, in the last test we only measured 1.4N average force. The only difference between the two runs is that the motor was in the water for longer. Are there any obvious reasons for this?

Thanks

[SSN626B]

@gsisrov,
Possible increased bearing friction after the first run in the water?
Regards,
SSN626B/TCIII

[puzzler300]

Is your prop coming loose? Mind tends to do that, you can especially tell if there is a loud rubbing/vibrating noise at higher rpms.

[ROVER3D]

Possible increased bearing friction after the first run in the water?

Sounds logical.

Could also be a current-leakage, a heated ESC or growing short circuit. Did you seal the coils of the Motor with some polish? Do you use motors with good quality? Did you try a third test?

[puzzler300]

Are you sure that your battery is fully charged?