6 CIM + 2 mini CIM brownouts

[Roboshant]

If one runs a 6 CIM drive train whilst using a 2 mini CIMs for a separate mechanism conjunctively, would it be risking brownouts?

[EmileH]

Originally Posted by Roboshant

If one runs a 6 CIM drive train whilst using a 2 mini CIMs for a separate mechanism conjunctively, would it be risking brownouts?

The answer to this question is completely dependent on how much current you're drawing from each subsystem. If your 6CIM drivebase is using a lot of current - ie, you're pushing somebody and the drivebase is geared for a medium to high gear ratio (>10fps), while running 2 mini cims at full speed (but at free speed), yes, you may experience brownout. However, if not being pushed or not running your drive base too fast, you likely will not experience more than a momentary brownout when accelerating or turning as you drive. Do not take my word for this however - the best way to tell is to build it and test it - OR if you already have a similarly-geared 6CIM drive in your shop, just strap on 2 miniCIMs, run them at full speed and drive around, and see what the brownout characteristics are.

[pfreivald]

That's going to depend on how you're running them. You can risk a brownout (and definitely trip breakers) running one or two CIMs by themselves if you're near stall.

[jijiglobe]

While I agree that it's impossible to guarantee that you will or will not get brownouts, I'm going to go out on a limb here and say that it's a significant risk. If you plan on running these mechanisms at the same time, you should probably add some code that checks and regulates current draw.

You can also learn more about designing with motors and current draw here

Cim motor curve: http://motors.vex.com/cim-motor
And mini Cim motor curve : http://motors.vex.com/mini-cim-motor

[MrJohnston]

We've run six CIM drives quite successfully a few times, but we do struggle with brownouts when we do... We've found that if we require that much power in a drive train, we really need to limit the number of other tasks our circuits must handle... Pneumatics help a lot... We find that, when we need that much power, 4 CIMS, a drive system with good traction (6 wheel tank?) and a two speed gear box gets us plenty far... That allows us to be a bit more creative with our manipulating functions.