Balancing robot power source selection

Hi, I need advice on choosing an onboard power supply for my balancing robot.
I am currently using an external dc power supply set to 12V and 1.3A.

I would like to use LiPo batteries.
I need 12V for my stepper motors. I have a step-down voltage regulator that steps the 12V down to 5V for my Arduino Uno and MPU-6050IMU.