I work with cellphones and I can tell you that you don’t have to worry. Almost all battery’s now including those on BB’s are not sensitive to the charging. So for example, you don’t have to drain it to start charging it again. Just turn it off and charge it while you are sleeping and you’ll be good to go in the morning.

the plug in will be gone.
also the green light won’t be flashing.

Look on the screen where it shows the battery life. When it is charging, there should be either an image of a plug or a lightning bolt. When your phone is fully charged, the plug or lightning bolt will go away.