80b shutting down ?

[squeeforever]

Well how it works is a BL motor has a "sweetspot" as for gearing. If you undergear it the motor will run hot from no load and from a lower amp draw, if you over gear it the motor will run cool but the ESC will run hot because of the added amp draw from the excessive load of being overgeared.

[BrianG]

From an amp-draw perspective, what Squee said may not make much sense, but you have to remember that these BL motors are AC motors. As such, there are other factors like inductive reactance, power factor, etc that come into play that can make a large difference in current draw and temperature.

When motor current draw is high, but there is little motor heat, this means the motor is presenting a highly inductive load, which tends to be hard on the driving circuitry (ESC) and heats it up.

When the motor is hot, the motor is presenting more of a resistive load to the controller due to the frequency of the AC signal and loading of the motor. Resistive loads are the easiest to drive and therefore the ESC is cooler (still depends on the current draw though somewhat).

If the motor and ESC are about equal in temperature, then there is a good balance of resistance and inductive reactance, and power factor is closest to the ideal value of "1".

It's the resistive component of the motors windings that create the heat (and any other mechanical/electrical losses). On an ESC, the majority of the heat is generated by the rise time of the square wave pulses across the FETS devices. During this time, the voltage is neither on or off so there is a voltage drop AND current draw - hence the heat. When FETs are off, there is a voltage drop but no current draw so no heat. When the FETs are fully on, there is is current, but no voltage drop, so no heat there either.

This is oversimplification because there is a LOT of thought that goes into the design of an ESC and its feedback/speed sensing circuitry.

BTW: Ask any master electrician and they can tell you all about BL motors but they know them as "squirrel cage" motors and have been around for a LONG time. AC drive circuits are not new either, but their use in R/C is relatively new in comparison because we take DC and create PWM AC to drive the motor. ANY 3-phase AC motor is really a brushless motor.

[stampy]

ok guys back to me :005:. is my gearing off? whats ideal for a rusty? i plan on getting a fan for the controller, and a diff motor is in the near future so i can get rid of this 5mm shaft s can so i can run the gearing i wont.

[stampy]

nobody knows how to gear a rusty :rolleyes:

[MetalMan]

Do you have a set of pinions? Sometimes experimenting with different numbers of teeth is as better way of finding the ideal gearing that having others tell you what it is.
If you go back to 48p gears, Robinson Racing makes some nice pinion gear sets. BTW, 32p IMO isn't necessary. What's most important is gear mesh and the flexing of the motor plate (if you have the stock plastic tranny).

[crazyjr]

What motor are you running? Being able to strip the gear is pretty good power, Maybe you got too much motor for the esc

[MetalMan]

Gear stripping doesn't only come from power. If the motor plate flexes so that the gear mesh changes, then just about any brushless power will strip the spur gear. Since switching to an aluminum tranny case, the only spur gear stripping I do is either my error with gear mesh or else I didn't tighten the motor screws enough.

[squeeforever]

Yup. Metalman is right. Stampy...gear down! That will solve your problems, or should...Try 2 teeth to begin with.

[stampy]

well the issue is my motor has a 5mm shaft and 18teeth is the smallest they make in 48p. so im basically stuck until i can get a diff motor. metal, its a stock tranny case so im sure its flexing. with the slipper tighted all the way down it strips 48p gears in the first hit of full power:eek: and the gear mess is set correctly, im not a noob to rc i can set gear mesh with my eyes closed :027:

[MetalMan]

squee's suggestion to drop two teeth should do it. Mike doesn't have any 32p 5mm bore 12t pinions, though.

[stampy]

nope the thing with that is the pinoin would be so thin that the set srew would more than likly strip :(. I just need a diff motor. id like to get a 380c 8L but i dont know if they make one. i was told the 9t would work but would run alittle hot on 3s how bout a lenher 1920 what turn would work good on a 3s? there alittle pricy but if they run like the 1950s then it should be well worth it :)

[squeeforever]

Yea, a 1920 would be the best way to go.

[stampy]

what turn should i go with? there 1/8" shafts right?

[squeeforever]

I think there 4mm but I'm not sure to be honest.

[stampy]

i think your right they are 4mm lame:002: what about a lenher xl 3600 would one work in a rusty? a new motor is a must now! :035: dont know what happend but i know its bad