Can I use a 9V battery to power an Arduino Nano? - Quora
Arduino Nano V3.0
Small Footprint Arduino Nano With USB Charging Circuit (Li Ion or LIPO) That Can Turn Itself Off (soft Latch Power) : 8 Steps (with Pictures) - Instructables
3.7V Li-Ion akkumulátor töltő – linuxstyler.hu
How to Power up Arduino using a 3.7V Li-Po battery - YouTube