Motor wont hold full throttle - RC Groups
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Jun 16, 2009, 12:28 PM
Isaiah 40:31

Motor wont hold full throttle

I just finished building a mini telemaster and I'm pretty new to the hobby and when I put the throttle on full it only holds it for a few seconds before stopping. It doesn't do this on slower speeds. Is this something with the speed controller? Any suggestions?
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Jun 16, 2009, 12:40 PM
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Mark Wood's Avatar
Ensure the battery is fully charged and try again.

Jun 16, 2009, 12:51 PM
Deletedfor proving Nauga wrong
Possibly too much current demand and the resistance ofthe battery causing the voltage at the ESC to "sag" enough to trigger the low voltage cutoff.

Possibly your setup has enough servo load to cause the ESC to trip off the motor due to a thermal protection system. High power will cause higher servo power demand (even durring "static" tests)
If unplugging one servo cures it... you need to disable the ESC's BEC and use a different power supply to the RX.
You can also test for this by just moving the sticks rapidly and checking for the ESC getting hot.

Occasionally you can get a thermal ESC shutdown by demanding too much current for the motor.
If the ESC is hot when it shuts down you should consider using a lower pitch and/or smaller diameter prop.


You either have an undercharged battery or you are overloading something.
Jun 16, 2009, 01:18 PM
Isaiah 40:31
I just charged the battery last night so I'll see what happens with the essc later.
Jun 16, 2009, 05:19 PM
Isaiah 40:31
like I said earlier, I'm a beginner and I get the general idea, but how would I use a different power supply for the Rx and how do I disable the BEC?
Jun 16, 2009, 05:36 PM
Deletedfor proving Nauga wrong
to disable BEC you simply clip the center (+) wire of the 3 wire lead between ESC and RX. I clip the center lead of an extension thus making it very simple to go back.

Then you either get an appropriate RX battery (typically 4 cell AA NiCd or 5 cell AA NiCd.... or NiMh)or you get a stand alone BEC/voltage regulator (often called a "UBEC"... but thats a brand name.. Kind of like commonly calling facial tissues "Kleenex")

The new RX power source is plugged into any unused RX channel (servo slot) or you can use a Y harness to plug it in AND plug a servo or other device (ESC) in the same channel.
Jun 16, 2009, 05:53 PM
Xpress..'s Avatar
Mini Telemaster is small enough to where you can use the ECS's BEC without problems. I wouldn't disable it, and save yourself some weight (adding a seperate RX pack adds on weight and increases the flight speed, making it come in faster for landing- also make it less stable).
Jun 16, 2009, 06:19 PM
Deletedfor proving Nauga wrong
But... temporarilly using a separate RX pack is a valid troubleshooting technique. (making that modified "servo" extension a useful thing to have.)

If that cures it... something is probably making a servo draw too much power... find which one.

If that doesn't cure it then you have isolated it to something to do with the ESC/motor/battery/prop system.
Jun 16, 2009, 07:49 PM
That's me.
R/C_Addict's Avatar
Whats your power setup?
Jun 16, 2009, 09:57 PM
Isaiah 40:31
an atlas 12 amp esc, a X-cell 7 cell 1100 mah sport Nimh battery and an 8*6 prop.
Jun 16, 2009, 11:38 PM
Deletedfor proving Nauga wrong
Which motor?
Jun 17, 2009, 09:04 AM
Isaiah 40:31
An axi silver 2208/34 brushless outrunner.

would an extra cooling duct help, or would it make to small of a difference to be worth while?
Jun 17, 2009, 09:18 AM
Registered User
Jurgen Heilig's Avatar
An 8x6 prop is "borderline" for your drive setup. Recommend to use an APC-E 8x4" and try again.

Jun 17, 2009, 10:59 AM
Deletedfor proving Nauga wrong
Originally Posted by Jurgen Heilig
An 8x6 prop is "borderline" for your drive setup. Recommend to use an APC-E 8x4" and try again.

We have a winner...


Drawing too much power with the motor due to excess prop load
Jun 17, 2009, 02:54 PM
Isaiah 40:31
thanks you guys rock, well I'll head to my LHS, get the new prop, and hopefully get this bird in the air soon thanks!

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