Where can I tap in a diesel generator

my arduino mega has an operating voltage of 5V. but it says that the recommended input voltages are 7-12V. and input limits of 6-20V. and it says it has a Voltage regulator.

my question is if I use as a power supply is,lets say, a 10V li-ion battery? would there be a problem? because i was thinking we are using a battery. batteries provide steady direct voltages. so would there be any problem with this scenario?