Our team is building a robot for a competition this week. We are using HiTec HS-475B hobby servos for some motion. The system is driven with a 7.2 VDC battery. The servos are really straining on a couple of tasks. They don't have quite enough torque to make me comfortable. We are supplying the servos with power via two ~0.7V drop diodes in series from the 7.2 VDC battery. I measured about 5.8 VDC at the servo under heavy load. My question is this - does anyone have experience or knowledge about driving these servos (or any hobby servo) with 6.5 VDC (one drop diode) or 7.2 VDC (no drop diodes)? The duty cycle for this application is pretty low. The servos will run under load for only about 10 seconds for the entire competition.
Hobby Servo Overdrive?
Feb 20, 2007
2 Replies
Yes, lots of people do this and it generally works fine.
Best,
- Joe
7.2v is outside the general spec limit of 6v for servos, but I've been powering the Hitecs on my walkers for several years from 6 NiMH AA- cells in series with no problems.
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If you don't have enough torque, usually you go to a larger servo. However, torque is also dependent upon update rate, and if your servo controller can drop it to 15-msec or 10-msec, that might help. I don't think many analog servos will operate properly below 10-msec updates, however. They do get extremely wimpish for slow updates, 30-msec and longer.
- dan michaels ===============
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