How can i maintain my battery good
[Re-Titled by Moderator]
Charge it when not in use. Day and night. You can not overcharge it.
See this useful user tip, written by our senior member Lawrence Finch:--> When to charge your iPhone or iPad - Apple Community
My advice is that whenever you charge your phone, use it as a real charger and as long as the battery is not charged up to 100%, you will not be able to charge the new phone and you will not charge up to 10% of the battery. Do not charge for new charging, as your battery may last longer.