Keeping drive motors cool

[MichaelBick]

We've been starting to have consistent drive practices, and our drive motors tend to get really hot(especially the 550s). After running the robot for 45 minutes we've been having to take breaks to let the motors cool. Considering we have been running 2.5 hr drive practices, this can get annoying, not to mention less effective because the robot doesn't drive as well as it did initially(incorrectly simulating real world drive conditions). I was wondering what tips people have to cool the robot off. We have been considering adding fans, but I was wondering what other ideas people have. Something offboard that we could use while we are switching batteries would be nice too.