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cogging motor


John hutchenson

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right here we go. I have a 3660 2600kv motor that was cogging under load, on the the bench works fine. uped and lowered pinion still the same. so i hooked up a new 3656 3800kv motor in to the same esc and the same problem. what could it be. have had a bit a read up and think it my be a bad solder joint on the esc? on inspection they all look ok is there any other way to be sure.

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Its unlikely to be the solder joints if it works flawlessly on the bench.

 

Cogging usually occurs when the inertia is too high for your setup ( inertia is how much resistance their is to movement / how much energy needs to be applied in order to move the object )

 

Simply put, the motor is drawing more power than your battery and/or esc can supply, this problem usually occurs when someone puts a setup designed for 1/10 scale in a larger/heavier 1/8, especially MT models

 

The main cause for concern with an mt is the larger diameter wheels increase the final drive ratio, thus increasing inertia...the same happens when you go up with your gearing, whereby a larger pinion increases your final drive ratio, thus increasing inertia.

 

A simple fix is to use electronics that are over capable.

 

You didnt mention, model, esc spec, battery, gear ratio

 

 

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18 minutes ago, John hutchenson said:

esc and motor thats not working in the model is a 3660 2600kv motor and a 120 amp esc. the one i put in over the week end that works an d runs the model is a 3656 3800kv motor and a 60amp esc. both setups run on 3s 5500mah 30c lipo

 

Hmm ....you tested the 2600kv motor with another ESC??

 

Could be a FET / cap issue????

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losi 10mt, 1/10, 40tooth spur started with a 15 pinion right down to a 12. tried 3s 3500mah 30c and 2s 5000mah 60c still the same, but as I said 3800kv 3656 motor and a 60amp esc works fine. but when I tried the q20amp esc with the new motor same prob. that's why I was thinking it could be something wrong with the esc.

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AHH well there you go dude.

 

It's not a definite that the ESC is faulty ( although it is a possibility ).

 

When cogging occurs when the setup is correct ( as in your case ) it usually occurs in sensorless ESC's, some just don't 'communicate' with a given brand of motor very well, which means the ESC cannot sense position of the motors rotor very accurately meaning it stutters when first moving as it attempts to get in sync with your motor.

 

I must say, sensorless ESC's can be great, when they're not fussy which motor they work with.

 

Although the sensorless ESC's, imo, offer the smoothest acceleration, best torque curve etc etc

 

So don't go binning the 120a just yet, it may work well with another motor down the line.

 

P.s one last thing to try, if you can plug a program card into it and alter it's timing, then slightly advancing the timing through the ESC can happen solve this issue somewhat

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don't have program card so trying to sort it out manually. but BEEP BEEP BEEP. it doing my head in. I ordered a program card for this esc the weekend but hasn't arrived yet. what's the turbo? also do you think the 3656 3800kv motor and 60amp esc would hold up in this truck?

Edited by John hutchenson
wrong spelling
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Define 'using it'? 

 

I mean, do you drive the truck like an OAP on Sunday in his volvo, or do you drive it like it's a rental??

 

You may well be ok

 

I could foresee issues in these scenarios, battery too weak of a C rating (hot battery) or, motor drawing more than the ESC could supply (ESC will heat up)

 

But as I say, alot of having RC for a hobby is not simply about the driving, it's trial and error when you deviate from stock parts, making the correct choices for what setup to buy for what RC comes with hands on trial and error experience..... unfortunately this can lead to mistakes as to gain that experience is almost impossible without travelling the road etc etc

 

Maybe you could start a build thread on the RC ? Chronicling your experience with such things...god knows the forum could do with more good quality up to date individual build threads right now....it gets fair quiet in winter!

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