Limitting motor torque

[Jared Russell]

Originally Posted by JesseK

In many regional finals, you have a 6-minute match cycle time. If you have a high-current match, then your battery may not have enough time to fully recharge before the next time it is used. In the worst case, it could take 6 matches to make it to finals -- most teams (though I'm sure not all) I've seen at competition have between 4 & 6 batteries. The question then becomes, can your battery chargers properly keep up with your demand?

Also remember that as your motors transform electrical power into mechanical power, they are generating heat due to inefficiency. The more inefficient your motors (e.g. the further in the power curve from the "max efficiency" point you are), the more heat they generate. What is truly insidious is that a hot motor is less efficient than a cool one - resistivity in metals increases with temperature. So the hot motors get hotter more quickly. In FRC terms, red hot motors will produce less mechanical power before tripping their breakers (or burning themselves out for good).

[Ether]

Originally Posted by Jared341

What is truly insidious is that a hot motor is less efficient than a cool one - resistivity in metals increases with temperature.

In addition to increasing the electrical resistance of the motor's coils, the heat also affects the motor's magnetic properties.

[Hawiian Cadder]

we put mountain dew cans over our cims, at first because it looked cool, but i think it did help with cooling. the cims in this years robot never seemed quite as hot as previous drive's.

[Ether]

Originally Posted by Hawiian Cadder

we put mountain dew cans over our cims, at first because it looked cool, but i think it did help with cooling. the cims in this years robot never seemed quite as hot as previous drive's.

Unless the dew cans were adorned with fins, I can't see why it should help with cooling. Black is a better radiator.