From all my reading, with these kinds of batterys (cell phone, laptop, toothbrush) what you need to do is keep it topped up most of the time. Going all the way to empty and charging it all the way up is not that great, they are happy always being topped up. HOWEVER (and every article I read says this, in fact my toothbrush manual said this too), once in a while (every 3-6 months) you *should* let it die completely, then charge it fully and go back to just topping it up as much as you can and not letting it fully dischange.

The reason I wanted to discharge my bold completely is that it's new and, well, I have gotten horrible battery life the first 2 days I owned it just charging normally so I thought I would let it die fully and charge it up all the way. After this I plan to keep it topped up and not let it die all the time