Model Boat Mayhem

Technical, Techniques, Hints, and Tips => Radio Equipment => Topic started by: Tug-Kenny RIP on March 14, 2010, 10:34:06 am

Title: Does it use Lecky power when stopped
Post by: Tug-Kenny RIP on March 14, 2010, 10:34:06 am

I am referring to Servo's.

When a servo is activated and left in any position but home, is it still using power from the battery and receiver to keep it in this position.

I have an idea to use a servo to move the levers of several switches and be left in certain positions, maybe for the duration of the sail. I know that when the transmitter is switched off, then the servo re-centres itself, but am not sure if the coil is still activated for the duration.

Ken

Title: Re: Does it use Lecky power when stopped
Post by: stallspeed on March 14, 2010, 10:56:54 am

It looks like your receiver has a failsafe position but it need not be at the centre.

Servos use a much reduced current when not moving or not pushing against an opposing force.
Some rc gadgets stop sending pulse signals to further reduce servo current.

Title: Re: Does it use Lecky power when stopped
Post by: malcolmfrary on March 14, 2010, 03:35:17 pm

Yes.  The control circuit in the servo does not switch current to its motor when at rest, but it still consumes some current, typically about 10mA, give or take.  Of course, the receiver also takes some current even if no signal is present, also the control part of the ESC even at stop.
The circuit is not so much using power to maintain position so much as to stay awake.

Title: Re: Does it use Lecky power when stopped
Post by: PMK on March 14, 2010, 03:50:55 pm

Ken, as the guys have said already, some systems still draw power in failsafe mode in order to send the servo to a pre-set position. Failsafe mode means the current AND the pulse is being sent at a constant stream, and depending on your make/model of servos, the current draw can be as much 60'ish milliamps.
When the servo is not using the failsafe system - or simply sitting at idle - is when the current draw falls to somewhere around 6 to 10 milliamps or so. So yes, servos do use lecky power when stopped (blame it on their internal circuitry), but 6~10mA should hardly put too much of a strain on your batteries.
If that makes sense.

(http://s3.postimage.org/E04O9.jpg) (http://www.postimage.org/image.php?v=PqE04O9)

Title: Re: Does it use Lecky power when stopped
Post by: Tug-Kenny RIP on March 14, 2010, 08:18:27 pm

Thank you for all the information. Just what I wanted to know.

I was a little concerned that it might overheat if left on a certain position for a long time, but the milli amps quoted won't do any harm.

Cheers for that,

Ken