T-motor alpha ESC active braking while disarmed


I have an issue with my t-motor standard arm set combo. I have the Alpha 60A 6s with MN605-s 330kv combo. The ESC came programmed for the motor when I bought it and I have set the PWM range from 1100 to 1940 as t-motor says it should be.

My issue is that two of the motor. The clockwise motors feels stiff after I dissarm. Like they are resisting while I try to rotate them by hand. The counter clockwise motors rotates freely when turned by hand. This only happens after I arm than dissarm the drone. A power cycle will make all the motors rotate freely until I arm than dissarm. Then the clockwise motors feels stiff again.

No motor will spin under 5% throttle in the missionplanner motor test.

Does anyone out there who uses t-motor alpha ESCs know of this behavior and know how the motors should feel after dissarm and at what % they all start at in the missionplanner motor test tab.


Take a look at T-motors employees at LinkedIn, now they have a whatsapp group for support purposes, maybe they could give you any answer there.


I’ll check it out

We use the Alpha 40A with MN501 motors on some drones and they always spin freely, no matter how many times we arm and disarm.
As for the motor test they normally work fine at 5% or above. Below 5% it sometimes works sometimes not.


I’ve noticed that on the motors that spin freely. Right after I disarm, the ESC makes a hissing noise which stops about 2 seconds after the disarm. The noise is a bit quiet but in a quiet environment indoors, it’s very apparent.

Have you noticed any such sound coming from the ESCs right after a disarm? You need to be quite close to the drone. I noticed it while doing motor test without propellers on the bench.

Jip, I can also hear a soft hissing noise for about a second or two after the motors stop.

Hmm, I have now heard from people who has both the freely spinning motors with a hissing noise and people who has stiff motors without noise. Maybe it’s just different firmware versions. I’ll contact t-motor and see what they have to say.

Interesting, please share the response from T-Motor when you hear back from them.

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I haven’t yet got an awnser from t-motor. I’ll write here as soon as I get one

Best regards

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Hi, I haven’t forgot your question!!!

Although I haven’t figured out why my motor behaves this way yet!

T-motor didn’t give a useful answer. They just told me that nothing was wrong, not telling me why the motors behave like this or anything else, even though something clearly is not right…

I’ll post an awnser here for you if I ever solve this issue!

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Wait a few weeks and ask again. Like the question about whether Flame ESC’s have a thrust linearization algorithm built in which would mean a change in the thrust expo setting in Arducopter. I asked and they said no, others have asked and the answer was ambivalent. So today the coin toss comes down on “yes, they do so set a lower thrust expo value”.


I’ll try that. You haven’t tried the alpha series of ESCs yourself?

No. I was helping a friend and he said he couldn’t get an answer from them. I got an answer but it ran counter to the current wisdom at the time and still today.

It doesn’t make sense to me that they would. You could use those ESC’s for any range of Motor kV/prop size so how could one linearization curve work. Now, if on their website you could download various ESC firmware’s for different applications then sure it would make sense.

you can. For the alpha you have one firmware for each supported motor! Mine, the tmotor standard arm set, with the ESC built in comes pre programmed with the right firmware. You use the datalink box to upload firmware to the esc

Is that true for Flame also? Because that’s what’s addressed with the Ardupilot configuration.

You check the box you get 0.2 for thrust expo.

I don’t know about the flame, but on t-motors page. The alpha is marketed as linear ESCs. Maybe someone got them mixed up, and it should be alpha in missionplanner.

Like you said, an ESC with one firmware for each motor should not be linear. So maybe it’s just the alpha that’s linear

Yea, not sure. Sorry to off-topic the thread!

No worries!

It’s an important question that hasn’t got a good answer yet!

You said you had a friend who uses the alpha ESCs right? Or was it the flame he used?

Flame. He switched to iFlight’s as I recall as they are BLHeli32.

Ah I see I answered your question about alpha’s talking about Flames. Sorry for the confusion.

Ah, okay. Probably a good choice. The flame has a cut off if the current gets to high, not so great for multirotor.

I’ve seen some alarming crash investigations here where some blamed the alpha ESC aswell.

Never the less, thanks! I’ll try to contact t-motor again regarding my issue