CIM Voltage and Motor Suggestions

[Kevin Sevcik]

Originally Posted by jakep

Hey,

I was looking at the CIM Motor specs, and I was wondering if anyone has tried running them at 24 volts? All the spec sheets I saw say 12 Volts, but I was wondering if that was just because FIRST bots are always on a 12 volt system, so performance at higher voltages just isn't reported.

For this one robotics project, we are looking at using 2 CIMs to power it. However, according to our calculations, we will need to double the Horsepower on these motors if they will ever work for our needs. They are rated at ~.34 HP, and we need something that performs at ~.7 HP. My theory was if we doubled the voltage, this would work. However, I'm not sure if this will burn out the motors.

If this is not possible, and our small team is getting a bit desperate with this summer project of ours, can anyone recommend some relatively cheap motor/gearbox combination that would have around 250 inch-pounds of torque at 40amps? I saw: http://www.npcrobotics.com/products/...at=20&mode=gfx
but those just seem way overpriced.

Any help would be greatly appreciated.

Is your estimated horsepower need at the 250 in-lb point on the torque-speed curve? Basically, do you need roughly 180 RPM at this torque or can you just gear something really low?

Generally speaking, the maximum power output of a motor goes up as the square of the voltage. If you up the voltage you up the current by the same ratio, so twice the voltage is four times the power. If you wanted twice the peak power, up the voltage by root 2. So figure about 18V, not 24V.

I think you could operate the CIMs at peak power for a reasonable amount of time at 12V, but I'm not sure sure they'd like having to dissipate twice the heat.