Mamba 5700 Technical Specs - Transfer Function
 

Hey everyone. I'm looking to better know my motor to gain some edge in programming the ESC. I've looked just about everywhere and I can't seem to fin any specs. I was wondering if anyone knew the technical specs of the Mamba 5700kv motor.

I'm looking to know the transfer function of the motor. I'de need the BEMF rating, Ke, Kd,Ra and La for the motor.

P.S. For those who dont know what a transfer function is. Its a mathematical equivilent of a system such as a motor/low pass filter. It's used to predict the output/response of a system to a unit step input.

My guess is that you won't find those parameters listed anywhere for the simple reason that in practical use they would be different from application to application and also that they would also be affected by running conditions. This would be due to the varying mechanical load imposed on the motor.

The load on the motor is going to be dynamicly changing due to a combination of factors like vehicle mass, rotating mass, acceleration/decelleration, traction, gearing, etc.

About all they give you is the kV (RPM/volt) rating, but I'm pretty sure it is specified and only valid under no-load conditions. it does however give a rough aproximation of how powerful a motor is.....

Narly1

my new Mamba max is baffling me a bit.

I like the programing that Novak does, one touch.

Can I set the end points to me controller or do I have to adjust the end points on the controller to match the "end" of the F and R on the ESC? I still can't find this.

thanks
S

I understand what yo mean. The advantage of simulating the Transfer Function of the motor is that I can plot every possible output of the motor for almost any input. Although the ESC is programmed to limit overshoot and under dampening of the motor, it's a fact that they cannot eliminate things such as the BEMF factor. This is like knowing what is the most efficient RPM to run at.

I won't get an unfair advantage knowing the transfer function. But I will gain the ability to predict what may be the best acceleration curve/brakeing curve for my motor.


Thanks for the input!

I would also suspect that the effect that the motor characteristics (as described by the no-load transfer function) would have on acceleration & braking is totally eclipsed by whatever you set your ESC settings to.

In other terms treat the motor as having a perfectly instantaneous electrical response with no mechanical inertia either. Start with a linear response on the curves and then adjust to suit your driving style.

Even the best drivers I know set their ESC's up empirically.

For the most part "best" acceleration/braking curves are dictated by a combination of driving style plus track layout and surface conditions.

Narly1

the 5700 KV means the rpms per volt @ it's highest efficiency... the motors are capable of over 1000 watts of power...
the faster the timing the more startup power you'll have, I like having low timing especially with a 2 pole motor... I find that it results in less cogging @ lower speeds/rpms with hot motors(high KV)

Make sure that your endpoints on the transmitter are at the max values for FWD and REV. for the spektrum you set 125%. Then once you set full forward and then full reverse during the initial binding setup you can back off the endpoint to reduce FWD power. But by starting at 125 and working back you have a more gradual progression if that makes sense. I hope this was what you were asking about...

Hey Dave,

The technical term in electronics for what you are referring to is "scaling".

Think of it this way:

Your ESC has a fixed range of operation, zero power to full power applied to the motor. The Spektrum controller can increment or decrement the full power (or braking) endpoint in "one percent" steps. So by setting the endpoint at 125% you are allowing the full power endpoint to be incremented by a total of 125 steps.

The math is 100% (real power units) / 125 steps = .8% of the total power per step vs 1% if you used 100% as your endpoint value. In electronics we say you have a "resolution" of 0.8% (per step).

Conversely, if you used 80% as your endpoint the resolution would be 100/80 = 1.25% per step.

Narly1

Good advice there superfly, and good explanation of the proper terms to use Narly1. :)