Servo motors and power consumption

[Zerobricks]

Lately I built quite a few models that use servo motors for steering, for example the coyote 4x4x4 and the new oshkosh 10x10.

I have a feeling that servo motors drain batteries quite a lot faster by these two models than for example by the fox 8x8x8 which used M motors for steering.

Anyone else noticed batteries dying faster with models that use servo motors, or simillar?

Edited March 20, 2016 by Zblj

[efferman]

sounds logical because a servo is powered permanently to hold its position. A simple M or L not

[Lipko]

sounds logical because a servo is powered permanently to hold its position. A simple M or L not

It drains power even if it doesn't actually do work?

[efferman]

when you switch the power on the servo is centering itself but maybe my conclusion is wrong

Edited March 20, 2016 by efferman

[dr_spock]

I haven't noticed my 42030 Volvo loader draining any faster than my 8043 excavator.

Servo motors generally have a position sensor built into the body to tell it the position of the shaft. The sensor shouldn't suck up large amount of juice. Use a multimeter to check if you have a parasitic drain somewhere.

[deehtha]

The servo motors should run for a brief period when blocked before they stop. During this period they do consume a fair amount of electricity.

But I haven't noticed it having an effect on my batteries.

edit: my phone apparently wants more server motors

Edited March 20, 2016 by deehtha

[Philo]

Servo current consumption should be quite low, as it consumes power only to reach its target. And even if load prevents it to achieve its goal, it soon gives up. See http://philohome.com/pfservo/pfservo.htm

[Brickthus]

There will be some current drawn from the supply rails all the time for the control circuit. The high consumption will only be when it is moving to a new target.

Mark

[Blakbird]

The servo uses power to maintain position. The amount of power depends on the amount of torque tending to want to move the servo from its current position. For example, a car with unstable caster may require considerable torque just to keep the wheels straight when driving. The PF servo also has very high internal gearing and is therefore difficult to backdrive even with no power provided. For this reason, I would not expect it to use much power when holding.

[jgw]

A very simple test showed they dont run all time. If you connect a servo and a xl to the same power, you can hear the xl slow down when the servo is powered. But afer a short time, the xl speeds up agai and the servo stays in it position