If they look like this, your first step should have been to clean the hell out of them, then after you wasted a lot of time on that, you should have replaced the cables entirely. Corrosion that bad is usually as bad INSIDE the battery cable lug as it is outside.



Ill tell you another thing: Running around with heavily corroded battery terminals is a first class ticket to damage to the car's electrical modules.
I'd suggest you post a photo of what you are talking about.