Originally posted by ppppsssstttt any sort of discharge/recharge cycle is a cycle, and it's the # of cycles that matters.
Sorry, I'm going to disagree on that one. A cycle is not a cycle and in fact, more recent studies have proven modern Li-Ion batteries start losing their charge capacity when exposed to full charge/discharge cycles on a regular basis quicker than batteries that are charged more irregularly or are topped off when needed.
The biggest contributor to cell death seems to be heat, and charging a nearly empty Li-Ion to full charge dumps a whole lotta heat into the battery. Top-off charges put far less heat into the cells and do it over a shorter time period.
I do agree it's not healthy to continually charge them from 97% to 100% full. By topping off I mean at least 75-80% capacity still remains. I rarely drain my Pentax D-LI90's below 50% and I am still running the original that came with my K-5 after 3 years and no sign of reduced capacity that I can notice.
Another no-no with Li-Ion is draining them near empty and leaving them in that state over a period of time without charging them. The cells can actually flip polarity under this condition.