<html><head></head><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_ym19_1_1481877529024_2425"> My home made brushless thruster failed after 30hrs of in pool run time.</div><div id="yui_3_16_0_ym19_1_1481877529024_2430">The Kelly controller was flashing an error sequence indicating the</div><div id="yui_3_16_0_ym19_1_1481877529024_2424" dir="ltr">hall effects sensors had failed. There are hall effect sensors on a </div><div id="yui_3_16_0_ym19_1_1481877529024_2516" dir="ltr">board at the end of the motor that send information on the position</div><div id="yui_3_16_0_ym19_1_1481877529024_2517" dir="ltr">of the motor. The board is held on by a large flat nut & had come</div><div id="yui_3_16_0_ym19_1_1481877529024_2518" dir="ltr">loose so the sensors were out of position. Also the sheath of the wires</div><div id="yui_3_16_0_ym19_1_1481877529024_2519" dir="ltr">to the sensor board had melted. </div><div id="yui_3_16_0_ym19_1_1481877529024_2563" dir="ltr">Possibly the fact that oil was being thrown out of the thruster housing</div><div id="yui_3_16_0_ym19_1_1481877529024_2562" dir="ltr">& up the wiring tube by centrifugal force, caused the motor to over heat &</div><div id="yui_3_16_0_ym19_1_1481877529024_2889" dir="ltr">melt the sheathing. </div><div id="yui_3_16_0_ym19_1_1481877529024_2566" dir="ltr"> The outer can of the motor that rotates (out-runner motor) is only supported</div><div id="yui_3_16_0_ym19_1_1481877529024_2676" dir="ltr">where it is press fitted on to the propeller shaft at one end. Some out-runner</div><div id="yui_3_16_0_ym19_1_1481877529024_2677" dir="ltr">motors have a large bearing that supports the cup like other end of the can. </div><div id="yui_3_16_0_ym19_1_1481877529024_2744" dir="ltr">Due to the fact I didn't have a very snug press fit, the can was pulling off center when</div><div id="yui_3_16_0_ym19_1_1481877529024_2675" dir="ltr">the motor stopped, so that the outer can with the magnets on it was touching</div><div id="yui_3_16_0_ym19_1_1481877529024_2695" dir="ltr">the stator. This caused it to start roughly. It would center when running.</div><div id="yui_3_16_0_ym19_1_1481877529024_2778" dir="ltr"> The sheathing on the wires running out of the motor, to protect them from</div><div id="yui_3_16_0_ym19_1_1481877529024_2815" dir="ltr">abrasion, were softened & breaking up a bit. The Shell Morlina S2 BL oil I was</div><div id="yui_3_16_0_ym19_1_1481877529024_2858" dir="ltr">using must be breaking them down. I can replace this rubber sheath with a heat</div><div id="yui_3_16_0_ym19_1_1481877529024_2890" dir="ltr">resistant sheathing (as my other motors have) but can't be sure that this oil won't </div><div id="yui_3_16_0_ym19_1_1481877529024_2976" dir="ltr">break down the coating on the motor windings. Maybe I'll change to 10 cst silicone.</div><div id="yui_3_16_0_ym19_1_1481877529024_3007" dir="ltr"> On the positive, the general design of the thruster worked well, the motor performed </div><div id="yui_3_16_0_ym19_1_1481877529024_3107" dir="ltr">with comparable or better thrust per Watt than most commercial thrusters . The outside of the </div><div id="yui_3_16_0_ym19_1_1481877529024_3118" dir="ltr">can never heated up. One day it ran continuously for 13hrs. It started well initially, & could </div><div id="yui_3_16_0_ym19_1_1481877529024_3123" dir="ltr">run at slow speeds.</div><div id="yui_3_16_0_ym19_1_1481877529024_3130" dir="ltr"> Am thankful that I could identify a number of issues with just the one test & will </div><div id="yui_3_16_0_ym19_1_1481877529024_3194" dir="ltr">have a good think about this over Christmas.</div><div id="yui_3_16_0_ym19_1_1481877529024_3166" dir="ltr">Alan </div><div id="yui_3_16_0_ym19_1_1481877529024_3095" dir="ltr"> </div><div id="yui_3_16_0_ym19_1_1481877529024_2941" dir="ltr"><br></div><div id="yui_3_16_0_ym19_1_1481877529024_2859" dir="ltr"><br></div><div id="yui_3_16_0_ym19_1_1481877529024_2722" dir="ltr"> </div></div></body></html>