Do your motors do this?

[DucktileMedia]

Since i have had my Avrotos i have made an observation that perplexes me. When the unit is cold nor had power applied in the last hour or so the motors feel free. If you flick a prop they turn somewhat normally/freely. BUT, when I have had a power applied to them for even 30 seconds they become very tight. Not mechanically tight but more like electrical resistance. So tonight when I plugged the battery in to power the MC i noticed that the motors still have that same resistant feel to them. Is it possible that a charge is stored in the ESC's that cause some sort of electrical braking? It's really odd that just a second of plugin in the battery and not even running the motors will do this.

 

[Droider]

I dont no much about esc's but is sounds like maybe the brake feature is enabled. you will need to disable that function.

Dave

 

[DennyR]

It's for sure the brake unless you are shorting the phases somewhere. Did you by chance ever clean the esc's with contact spay. I know that MK sells this stuff. It leaves an almost invisible film that is conductive and will kill your boards.

 

[DucktileMedia]

Is it the brake if this occurs with the battery disconnected? I can see how a brake would work under power but how on earth would it do this with no power applied? I'll check again on the program card.

 

[DucktileMedia]

Well I'll be damned! I plugged in the battery and then instantly unplugged it. the motors are still harder to turn. So I un hooked the motor leads one by one and VOILA the motor became easy to turn again. So weird that the capacitors can hold enough to keep them stiff for a good 10-20 minutes or so. I was sure the brake was off on the programming card.

 

[dolby]

Ever since I switched to Maytech my AVRotos break when I disconnect power. The break is off in the firmware of the ESC's and it does not break when the power is on and throttle is zero. If I disconnect my motors from the ESC's they no longer break. I havent noticed if the brake eventually stops after time, I'd think it would.

To make sure it was the break i enabled the break on one of my ESC's an then put it on zero throttle with battery and it was the same resistance feeling when I would disconnect the battery.

 

[DucktileMedia]

thats great to know. Thanks! I was about to reprogram all my esc. I know they brake is off because i can see the jumper positions on my card. And it flies fine the way it is, but like you said when I disconnect the battery they tighten up a bit.

I have to say I am intimidated by doing the manual switch from 8 to 16 khz. Seems like a real beep fest.

 

[DennyR]

Actually it only needs to short the motor wires to create a brake.

 

[DucktileMedia]

ah, ok. that would make more sense.

 

[matwelli]

With esc's. - unpowered, if you turn the motor, it generates a small voltage, that voltage can leak thru the the power transistors (fets or mosfets) and cause them to turn on, causing brake effect, with no battery required