power (lipo battery)

hell enthusiast, i have a question. how much lipo power(in volts and mAh) will be needed if i'm going to have a two 6v micro metal motor and an arduino mini? i'm planning to put only 1 lipo battery. is it okay if i will use 11.1v with 1400mAh? how long will it last? its for my sumobot.

Add a step-down regulator to get 7V for both arduino input and motors. A two_cell would be a better choice for this setup.

Motors wont like 12V for very long. which motor controller? The common '298 will drop 3V and may just make your motors happy for PWM control.

Battery life time is mostly set by your motors current. Time=1400mA/total Current