Originally Posted by JohnDC
Avoid frequent full discharges because this puts additional strain on the battery. Several partial discharges with frequent recharges are better for lithium-ion than one deep one. Recharging a partially charged lithium-ion does not cause harm because there is no memory. (In this respect, lithium-ion differs from nickel-based batteries.) Short battery life in a laptop is mainly cause by heat rather than charge / discharge patterns.
This doesn't counter my post at all.
My post is just worded in a way that occasional full discharge is okay, but frequent full discharge is not a good idea. It's fully compatible with this, and this is another way of saying it - it says nothing about occasional full discharges.
Avoiding full discharges completely is also a bad idea; lithium batteries do perform their best when they are "occasionally fully discharged", best if done slowly to avoid overheating the battery. Heat is less of an issue with BlackBerries since they use a lot less power than a laptop; and lithium batteries are more easily worn down by high heat like when playing 3D games until the laptop suddenly dies with a heated-up battery. Full discharges on a BlackBerry won't do as much wear-and-tear as a BlackBerry doesn't heat up nearly as much in normal usage.
Cycles are typically cumilative. Four 25% charging cycles is roughly equal to one 100% charging cycle. (More or less - unless the act of going to 100% overheats the battery, then it'll do more damage). So nobody needs to feel guilty about "topping off" their lithium-ion battery.
During ongoing use, just do partial discharges more often than a full discharge and the battery, and you'll be OK.