Guys I've got a quick question about the efficiency of DC servos, for example I am thinking of using a Tonegawa-Seiko SSPS105 (I need high torque!) in a project I'm doing. But I'm trying to select a battery for it and stuggling to work out the efficiency.
Using the specs off http://www.tonegawaseiko.co.jp/pro/e_pro02.html
Max torque = 380 kg/cm = 0.3874 Nm
Top speed = 0.95 sec/90 degs = 1.65 radians/second
Therefore the Mechanical power is Torque x Angular Velocity.. = 0.64 Watts
But the Input voltage is 12 V with 9 Amp Current which = 108 Watts
So the efficiency should be 0.64/108 = 0.00593
Surely the servo is more efficiant than that!! Probably I am missing something... I thought that DC motors were about 50% efficient.
Hope someone can explain