I saw 15 Amp motor which runs on 120 VDC with 5500 rpm [This motor was attached to Miter Saw tool]. I'm not sure what's HP of that motor, but I read 5.5 HP, however the size of motor is around 6 inch long and 4 inch diameter (Is it possible this small motor have 5.5 Hp? And can we calculate torque of the motor based on above known facts?). Now my other question is : Can I run this 120 VDC motor using this 20 Volt DC with 3 Ah rating battery? If so how long I can run this motor using it? Thank you.