HobbyKing.com New Products Flash Sale
Thread Tools
Old Dec 18, 2005, 07:34 AM
Registered User
United States, NY, Queens
Joined Oct 2005
2,985 Posts
Bad motor or bad speed control?

How do you determine if the motor went bad or if the speed controller went bad. I've had about 50 flights with my plane, and now it doesn't have enough power to take off. I have tried two different battery packs with the same results. The batteries work fine in my other plane.
Leo L is offline Find More Posts by Leo L
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 18, 2005, 08:43 AM
Italian Member
lombafly's Avatar
Dalmine , Bergamo , Italy , Europe
Joined Feb 2004
64 Posts
Motor brushless or brushed?
lombafly is offline Find More Posts by lombafly
Reply With Quote
Old Dec 18, 2005, 08:51 AM
Tree Hater
zeuglodon's Avatar
Howland, Ohio
Joined Jun 2004
730 Posts
If its a brushed motor it's probably the motor.
zeuglodon is offline Find More Posts by zeuglodon
Reply With Quote
Old Dec 18, 2005, 08:52 AM
Hold my beer and watch this!
Jeremy Z's Avatar
Northern IL
Joined Oct 2005
2,380 Posts
It is most likely a brushed motor, right?

The ESCs are solid-state; no moving parts, hardly EVER wear out unless abused.

Brushed motors on the other hand... They have carbon brushes which transport current to a rotating commutator into the armature. There is friction & arcing, which wear the brushes down. There are springs which feed the brushes into the commutator, but they can only make the brushes so long. So a point comes when the spring has fed the brushes as far as it is able, a gap between the commutator & brushes opens, there is more arcing, and less efficiency & power.

If it's a brushed motor, replace it. It'll probably cost you around $10. If that doesn't fix it, buy a new ESC, make sure it can handle the current the motor draws while running full throttle. Make sure the plane is not over-propped, so to speak.

Brushless motors would tend NOT to go bad, unless it is a bearing problem. There is no physical or electrical contact in a brushless motor to wear out. It works through pure electromagnetic induction. This means a longer life, and much higher efficiency due to lower friction. If you have a brushless motor, it is most likely the ESC.

Jeremy Z is offline Find More Posts by Jeremy Z
Reply With Quote
Old Dec 18, 2005, 09:20 AM
Live to ride... and fly!
Tres Wright's Avatar
Forney, TX
Joined Mar 2002
15,165 Posts
Usually when an ESC goes, it dies completely and you lose all motor control AND servo control. You probably just need to replace your motor. Or upgrade to a brushless and never worry about wearing out a motor again
Tres Wright is offline Find More Posts by Tres Wright
Reply With Quote
Old Dec 18, 2005, 11:01 AM
lawn darts r' us
Joined Sep 2005
171 Posts
probably the motor. easisest way would be to swap motors with a known good speed control or vice versa, this way you can rule out the faulty component.

Speed controls are typically an all or nothing deal, they either work or they dont, In all my years in R/C (used to do high perf electric boats), ive never seen one 'loose power'.
MKMotorsport is offline Find More Posts by MKMotorsport
Reply With Quote
Old Dec 18, 2005, 07:16 PM
Registered User
United States, NY, Queens
Joined Oct 2005
2,985 Posts
Thanks for all of the replies. The plane is a stock PZ Cub that I bought used on e-bay. A replacement motor is $10, while a replacement ESC/RX is $28. I took a chance and ordered a motor. Looks like I made the correct choice.
Leo L is offline Find More Posts by Leo L
Reply With Quote
Old Dec 18, 2005, 07:53 PM
I'm dangerously carefree
SaMx's Avatar
Media, Pa/Blacksburg Va
Joined Oct 2004
1,238 Posts
yup, and a motor is usually cheaper to replace, at least if it's brushed. So if you have problems, changing the motor is usually the best bet.
SaMx is offline Find More Posts by SaMx
Reply With Quote
Old Dec 19, 2005, 06:32 PM
(My website goes here)
johndreid's Avatar
Purvis, Mississippi
Joined Sep 2005
977 Posts
I've had two cheap ESC/RX boards go bad after a crash...each one would run the motor wide open when a battery was attached.

Anyone ever heard of that?
johndreid is offline Find More Posts by johndreid
Reply With Quote

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Dead motor or bad esc on Trex ivorz Mini Helis 5 Oct 08, 2006 09:57 PM
Help! Bad motor or ESC Slope Newbie Power Systems 6 Sep 03, 2006 11:34 PM
Discussion bad Motor or ESC ? Help! killedbyboredum Foamies (Kits) 4 Jun 18, 2006 11:13 PM
Help! bad motor or bad battery beginningdave Beginner Training Area (Aircraft-Electric) 3 May 14, 2005 03:11 PM
Bad luck or bad charger? JamesD Parkflyers 7 Mar 04, 2002 04:40 AM