Hi, I just got my D5100 on Friday and haven't had much time to play with it yet. I charged the battery fully on Friday and used it somewhat today. My battery still has about 2/3s left on it but I will be shooting a lot Today (Sunday). Do these batteries have a memory?. Will I do it harm if I charge it up fully at this point so it will be fresh when I go out in the morning, or is it better to let it run all the way down before charging?