ARDUINO NANO V3 POWER SUPPLY VOLTAGE

i have an 11.1v lipo battery (1500 mah) and i want to directly power an arduino nano when fully charges the battery is at about 12-12.6v. if i use it at full charge will it harm my arduino nano?

Why all capitals in the title of your post (SHOUTING).
Do you expect to jump the queue with that.

Bad idea to power a classic Nano with more than 9volt.
At that voltage you can’t power anything from the Nano without overheating the 5volt regulator, with the resulting reboots (if you’re lucky).
Better use a (micro-power) 5volt buck converter, and connect it’s 5volt output directly to the Nano’s 5volt pin.
Leo…