Digital Servo high current draw

[Doug Sick]

Just working on a new boat and have digital servos installed. Two of the three seem to whine a lot and it seems to be due to the slight pressure my seal exerts on the control which keeps a small amount of pressure on the servo. This is causing the servo to try to maintain position and to push back hence seems to be active constantly. I checked the current draw and it's taking about 130ma. When I unplug the two whiners, the remaining rudder servo is only drawing 30 ma. I'm a bit concerned about the high current but more so about the whining. I've never had any that made this much noise. Is it damaging to the servo? I'll have to be careful with the batteries I use but right now, at this current draw, the receiver battery I use should last about 2 hours at "idle" draw rates. I would think this should be adequate.

I guess on the plus side, I will always know if the radio is on.

 

[Danny King]

Did you try leaving just one of the 2 suspect servos plugged in. And the switch them. That doesn't seem right??

 

[Daniel's Racing]

All digitals even the best ones are going to make some noise as they work to keep the servo positioned precisely where the receiver/transmitter is telling it to be.

130 mah is not much and nothing to be worried about. Wait until they are fighting the rudder at 70-80 mph then they will really be drawing something.

How many mah pack are you using?

A LiFe pack in the 1800 mah range should give you all the run time you need.

 

[Mark Bullard]

The current flow on digitals pulls as much idle as they do working. They have full load on them to hold position. It stays the same when they are moving their function load or no load. They are good servos but I do not use them because of their high load current. And they are battery eaters.

 

[seaducerpete]

Of cour see e the idea is to build a dry radio box but they do not like water at all

 

[ALLAN YUEN]

Will Mike Z grim racer help you about problem with new radio and dig servo

 

[Doug Sick]

Alan, don't know where you got your information but this has nothing to do with Grim's products.

I have unplugged both small servos one at a time and it's definitely confined to these ones. They both behave the same.

I am using some 1000 ma AAA NiMh battery packs that I put together. I'm not sure I trust LiFe yet. Saw a recent incident where a LiFe went up in smoke and put a boat on shore. Not sure if it was the LiFe or the wiring. The battery packs have an effective capacity of around 600 mah which gives me more than 2 hours of run time at the 130 mah draw. I charge before each race so I don't see the need for an 1800 mah LiFe. Don't know yet what the draw will be under load. My Futaba has a receiver battery voltage readout so I can monitor it. It's a 45 hydro so it shouldn't be bad. Main thing I was worried about was weather the servos would be harmed.

Thanks for the advice so far

 

[seaducerpete]

I think Allan recamended Mike z becomes he is sponsored by futaba and a radio guru

 

[Doug Sick]

Ok. I didn't know that link.

The servos are not Futaba, just the transmitter and the receiver. I was concerned there could be a conflict between the Futaba equipment and the non-Futaba servos. Sounds like I am not experiencing something that is totally out of the ordinary.

 

[Grimracer]

I use digital servos in just about everything. The holding power is awesome. They really do not "eat" batteries. They do draw more current but its not that high.

I do not mix and match radio goods.. (well I have some Tactic servos in a few planes).. My boats are all Futaba.

I use LIFE in EVERYTHING and will continue to do so until something better comes out. A heat race with my 1/8 scale boat from turn on to turn off uses about 60mah...(full digitals, ALL FUTABA!)

My scale helis..the same.. 250mah per flight (about 15min).. 5 servos, all digs and all screaming at the top of there lungs.

I setup my boats and helis (planes too) with between 1100 to 1800 mah packs. My rocket DD systems I use 200s..

Grim