[Hutch]

It depends on how many motors you use how much (basically, how much current you draw). I'm not a Vex person, so I don't know exactly but according to the IFI specs, a battery pack is 700mAh and one motor draws 1.3A max so just divide .7 by (1.3 time the number of motors you use) and you'll get an approximate number of hours. Note that assumes constant max use so the actual time will probably be longer.