Servo Amperage chart- is there one out there?

[Rforbes]

Hi all,

I'm trying to find some amperage specs for various servo models. It seems this isn't a widely published spec. Can someone point me to a link with amp listings for various makes/models?

Thanks
Robert

 

[Charlie-III]

I have never seen a "list", I have seen values here & there for a couple of servos.

When we get some more field techs @ work, I can find time to do some tests on servos.

I want to see what some pull at idle, fast wiggle and full stall. I will also add in accurate torque ratings. I have the power supply, frame & scale, just need the time.:roll:

Servo samples will be:

HiTec 7955, 7954 & 7950
Futaba BLS 157 (?)
Whatever else we have laying around. It's a decent sample of a range of servos though.

 

[Rforbes]

That'd be great, thanks.

I'll set my meter up and check the servo's I have as well I reckon. I can't check torque but I can do amps.

 

[k7zpj]

That'd be great, thanks.

I'll set my meter up and check the servo's I have as well I reckon. I can't check torque but I can do amps.

How are you going to do your measurements?

To be able to compare servos, you would need to have a known load on the servo. This would allow you to compare amps @ in/oz for each of the servos.

 

[Charlie-III]

That'd be great, thanks.

I'll set my meter up and check the servos I have as well I reckon. I can't check torque but I can do amps.

How are you going to do your measurements?

To be able to compare servos, you would need to have a known load on the servo. This would allow you to compare amps @ in/oz for each of the servos.

+1.

I have a high amp power supply so I have a consistent/repeatable voltage into the servo.
I have a precision shunt to measure amp draw & a calibrated meter to measure the output of the shunt.
A decent digital scale to provide force measurement recording.

Granted, you can get some useful data with simple items, I am really after some more precise data.

 

[Jayzrc]

Servo city has a pretty good bit of information on servos, but you need to look at them individually to see the amp draws. Not really a list. Here is an example of what I mean.

HS-7955TG Servo

 

[Olle P]

I think ServoDatabase.com is the closest thing you'll get.
Current consumption generally doesn't seem to be a big thing though...

Stall current and torque (at a specified voltage) is what is relevant to us crawlers!

Note that the voltages used in servo data lists are "nominal battery voltage", not the actual voltage used to reach the listed performance.
To measure performance "at 6.0V" you feed the servo ~7V directly from a fully charged 6V high power NiMH battery.

 

[Rforbes]

k7zpj - Since I don't have torque or force measurement capabilities (at least, I don't right now. I might build or buy some things later) I can only measure no load and full load (stall) currents. For the most part, these two measurements are enough for folks to get a solid set of working numbers for total power needs in a given system. It certainly isn't perfect, but it's the most critical information to have with regards to power budgeting. I'll get trap measurements using a good ole extech or fluke meter, and an adjustable bench power supply. I'll get various data sets, to make it a bit more comprehensive.

I'm currently using two Hitec HS-7980TH for steering, two Futaba S9257 for camera gimbal, 1 Savox SH-1350 for dig and a mamba max pro esc. I'm browning out my cc BEC quite often, so have order the cc BEC pro. Would have been nice to get a better amperage tally before I spent $$$ on the regular BEC.

I have other hitec, savox and futaba's lying around so I'll do those too. It might take a couple weeks, my work load is high right now.

Olle P- thanks for the link!

 

[Charlie-III]

RF, you definitely have servo load on your rig.

For most here, just knowing, "If over ~200inoz you need an external BEC" is enough.

My list was to also see if claims of torque were close or fabricated.

Olle P, while a battery pack could work, I will use an adjustable PS that supplies 35A+ @ 12VDC. This way, I can get consistent voltages as well as have enough excess amperage to not have the supply vary under high loads.
A pack or external BEC may vary enough to skew data.

 

[Foxy42]

I'll give you a current consumption chart...

Savox = silly draw
The rest = normal

(removes tongue from cheek)

 

[Rforbes]

Charlie III- Yeah, it's a tad bit loaded I've still got to set up the video transmitter, and then sensors and micro-controller too- so it's going to be interesting! I'll probably be the only guy here using a 2 cell 5000mah lipo as a "receiver pack"

Foxy42- I hear you!! I keep reading that savox is horrible on current consumption. I run them on my heli but it's rare that I drain a full lipo before smacking into something so current draw is my lowest priority battle there. My high priority fight is with gravity.

 

[Olle P]

... I will use an adjustable PS ... This way, I can get consistent voltages...
A pack or external BEC may vary enough to skew data.

That's fine if you want to know the actual data for a particular servo.

If you just want to confirm the manufacturer's numbers you'll need to do it the way the manufacturer's do to get the best looking numbers (for speed and torque) without being complete liars. Skewed data is what they aim for... :twisted: