I know the major differences between the two batteries. But I was reading how Li-ion batteries last for about 2-3 years, 5 tops and Ni-Cd can last up to 20 years (certain ones) when taken care of. I was wondering with Li-ion, since that is in my battery pack if it sits this website says it would last any longer than if you used it everyday. But don't they wear down fast when used heavily. There are days where I will drain my Li-ion battery 3 times for the whole week. And I was thinking of getting a Ni-cad since I use my little weed wacker so much in the summer. Mostly because I thought draining the li-ion so much was bad. But How long does a Ni-cad last when drain that same amount of times each day? Basically I am wondering how long A Li-ion and a Ni-Cd would last under heavy use compared to light use. Thanks!