Nicads should be cycled at least once a year to remove possible memory. Nimh batterys don't have the memory problem so don't need to be cycled but its a good idea to have your cycler test the full capacity of the pack at least once a year so you have a starting point. As Nathan pointed out if the pack isn't putting out at least 80% capacity then it needs to be looked at. Running a cycle on it may bring it back up if its a Nicad pack. If it doesn't come up to snuff, replace it.