12V DC Power Supply Regulator
ok so 190Wh/3h/15V=4.2A and any LDO will drop Pd={15-12}* 4.2A = 12~13 watts of wasted heat.  N.G. either match the battery voltage to the load or match the load max PWM duty cycle to the battery voltage !!

a low loss 10A LC filter will smooth the V+ avg. Ie. SMPS load type servo motors. 

are they BLDC or BDC? they should be N phase type with N>=3 for smoothest control.

ultra low loop ESR (+motorDCR) is essential for high torque servo well-damped position stabilizer with PID loop stabilizer or fuzzy logic feedback.


  Remember that motor torque is controlled by current sensing not battery voltage.