Camcorder Batteries

I have a JVC VHS-C camcorder which I have hardly used. I bought the camcorder about three years ago. Every time that I was finished taping I recharged the battery before putting it away. Sunday I went to use it and the battery is no good. I was told that if storing the camera for an extended period of time, to let all the power out of the battery first and recharge when ready to use again. I also have a digital camera, I keep those batteries fully charged too. That camera always works. Has anyone ever heard of letting the power out of camcorder batteries before storing, and why?