control hard drive

Ok so i removed my optical drive and now have 2 hard drives(macbook pro). is there a way/utility that i can use to turn one of them off when im not using it. to save power and battery life on my macbook pro?

Not that I know of. However, if your extra hard drive puts itself to sleep when not in use for a certain period of time, that should save battery power.

Look up the specs on your hard drive at the manufacturer's web site to see if it spins down and sleeps or just spins down.

Aye you need hard drives that support it - but in System Preferences -> Energy saver ensure that put hard drives to sleep whenever possible is checked. Note that depending on how you have your drives setup you may not be able to take advantage of shutting one down (i.e. raid)