Motor dead short?

Brett74 · 05-27-2012, 08:23 AM

Just checking a brushless motor and measured across any poles there is a dead short, that is not right is it ?

michael503 · 05-27-2012, 08:41 AM

The resistance in the windings is so low, that it cannot be measured reliably with a pocket tester. You should get continuity between any 2 of the 3 wires and none between any wire and the motor case.

There is a more accurate way to test the windings using drycell batteries and an ammeter, but results vary from motor to motor. On a high power motor with not much wire, this test can be useless too.

Elgyn · 05-27-2012, 11:27 AM

Ohm's test is useless on most motors. You'll have to do an inductance test.

Mr.Andersen · 05-27-2012, 03:17 PM

If you look at the winding resistance on the Scorpion 4025-1100 its 0,008 ohm.
Thats in practice a dead short ohming the windings and it takes an expencive instrument to messure such small values.

05-27-2012, 08:23 AM	#1
Brett74 Registered Users My HF Map location Join Date: Dec 2008 Location: Malmö, Southern Sweden.	Motor dead short? Just checking a brushless motor and measured across any poles there is a dead short, that is not right is it ? __________________ Kasama Faifa 4525 520 Ultimate Ice 2 120Hv VBar (gov) Goblin 700 4530 540 LE Ice 2 160HV VBar (gov) Brushless MCPX

05-27-2012, 08:41 AM	#2
michael503 Registered Users My HF Map location Join Date: Mar 2007 Location: Tuscaloosa, Alabama	The resistance in the windings is so low, that it cannot be measured reliably with a pocket tester. You should get continuity between any 2 of the 3 wires and none between any wire and the motor case. There is a more accurate way to test the windings using drycell batteries and an ammeter, but results vary from motor to motor. On a high power motor with not much wire, this test can be useless too. __________________ -Michael

05-27-2012, 11:27 AM	#3
Elgyn Registered Users Join Date: Jul 2011 Location: Maple Ridge, BC, Canada	Ohm's test is useless on most motors. You'll have to do an inductance test. __________________ TT titan x50 / TT mini titan / JR Vigor CV... ...vbar'd / 700 airwolf streched JR Voyager mechanics / JR Venture CP

05-27-2012, 03:17 PM	#4
Mr.Andersen Registered Users Join Date: Jun 2008 Location: Trondheim Norway	If you look at the winding resistance on the Scorpion 4025-1100 its 0,008 ohm. Thats in practice a dead short ohming the windings and it takes an expencive instrument to messure such small values. __________________ CopTreX 450 SE V2, Pro..... real bastard. Logo 500 3D FB Blade mCPX

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