Caution: Savox SB-2271SG Cyclic Servo Bench Test Results

[Chris Sexton]

Video pretty much explains it. But I got a PM from Rob Cherry and a call from Dave with Anythingheli.com today about my Savox servos. I decided to bench test mine like Rob did, and I am not pleased with the results.


NOTE:
For those who might be watching this for the first time, if you read a couple pages in we discussed that what you are seeing in this video ISN'T an RX Brown out, but me applying way more torque than rated and stalling the aileron servo. See Rob Cherry's video posted later for the real issue.

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[Chris Sexton]

OK Well public speaking isn't my forte, "um" and "excuse me" are not keywords for this video

[ragtop01]

I'd try higher voltage on the bec. Higger voltage means lower amps. Do the servos get hot?

[Chris Sexton]

Rob had the same results with a Quasar 75V BEC

[Rob Cherry]

Higher voltage with servos has the opposite result. They operate faster thus drawing even more current.

But none the less, this has now been confirmed to happen with two pilots. I've tried a quasar 75v bec on 6S, 12S inputs and from 5v up to 8.4v to the servos. Same with bec pro v3, all combos. Couple of quick pitch pumps and brownout! With an RX pack, it's solid, no brownouts. These servos have no ramp time, no wait period, instant on power surge drawing spikes that brown out even the largest and newest BECs.

My vbar log reports low voltage, system pauses for half a second while it browns out. Satellites start blinking afterwards. Not good!

Watching the video, yours behaves slightly different than mine. My system locks up during the brownout, and the satellites blink, notifying the user a brownout has occurred. Can you confirm this Chris ?

[Chris Sexton]

Sounds like an RX pack is in my future then. At least this will allow me to keep flying!

It's not that I don't like RX packs, I just prefer not to have to remember to charge something other than flight packs. Oh well.

[xfactor6]

Well i just tried this test with my 1267sg running them at 7.4 through bec(gryphon quasar), and they were fine. In comparison they are only a little bit slower and a little less torque than 2271. must just be those servos? Could it be the fbl unit? I have ar7200bx so not sure what everyone else has?

[Chris Sexton]

Rob's is VBar and mine is AR7200BX.

[vr360]

Hey Chris,

Sorry to see you guys are having this issue. A friend of mine is running the Savox on cyclic and tail but he is using the slower Cyclics. No issues thus far.

Knowing that the Align DS servos are power hogs, and they are savox rebranded servos, This is no shock to me at all.

Although the speed and torque numbers of the Savox are impressive, they still have some slop right out of the box. They do develop more slop over time much like the Align's.

For the same price, actually cheaper with the 3pack that outrage now offers, go with the 9180's on the Cylic. The outrage MKS rebranded are great. I transferred the 9180's and 9188 from my 700e with 90+ flights and when inspecting them there isn't a single bit of slop AT ALL! These servos were beat into submission quite a bit over the last 20 flights too.

You might also want to check the actual voltage coming out of your BEC pro.

If you have a mutimeter you can also do some load testing as well.

[Chris Sexton]

Originally Posted by vr360

Hey Chris,

Sorry to see you guys are having this issue. A friend of mine is running the Savox on cyclic and tail but he is using the slower Cyclics. No issues thus far.

Knowing that the Align DS servos are power hogs, and they are savox rebranded servos, This is no shock to me at all.

Although the speed and torque numbers of the Savox are impressive, they still have some slop right out of the box. They do develop more slop over time much like the Align's.

For the same price, actually cheaper with the 3pack that outrage now offers, go with the 9180's on the Cylic. The outrage MKS rebranded are great. I transferred the 9180's and 9188 from my 700e with 90+ flights and when inspecting them there isn't a single bit of slop AT ALL! These servos were beat into submission quite a bit over the last 20 flights too.

You might also want to check the actual voltage coming out of your BEC pro.

If you have a mutimeter you can also do some load testing as well.

Yeah I was originally going to put the Outrage 9180s on the cyclic, and I might yet go over to those. These Savox got some great reviews and were a bit cheaper at the time. For now I have my LHS soldering GURU soldering me up a custom RX harness long enough to reach from the nose to the back where my AR7200BX is setting. I will bench test again with RX pack and post my results.

[frito169]

You arent trying to power your servos through the beastx are you if so that is your issue and that would be the case with all hv servos.
when running hv servos through the beastx you need to get your +/- servo feeds from outside the beastx. They are not designed to pass through that much current. On my setup only the tail servo gets its power passed through the beastx, the cyclic Are wired directly to my 2s 7.4 V battery.

[Chris Sexton]

Interesting. That isn't what I am seeing. If I don't put load on the blade they don't even blink. /shrug

I will probably still run an RX pack to be safe.


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[irishmatt18]

Add some dirty music to that video and it will be heli porn...

[irishmatt18]

I know this is not the same but when I added an ICE 100 to my X5, I had the same issue through the Vbar. The BEC couldn't handle the voltage. Although the BEC v3 is MUCH better, it did the same thing.

[Chris Sexton]

Well I had to know. I just duplicated the test this time applying pressure to a different place on the swash. An a different, elevator this time, servo failed the same way as my aileron. I guess rob is right, i must be putting more pressure on my swash than I realize and stressing the servo into showdown.

If I perform the same test as Rob did in his video, I can bang on the collective all day, no brown out. Bec or RX pack.

Not sure what to think now.

Screw it. I am flying it. RX pack already setup so I am sure I will be fine.

I am running a 2200 2s lipo. I will fly both of my packs and see how much I have to put back in.

On a positive note, with the RX pack I was able to move my flight packs back a bit and got what I feel is perfect cg.


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[akamullen]

I wonder if this is only happening on Vbar. I may have to try this test with my BeastX and see. I cant remember if Rob said he tried testing with only the receiver and no FBL controller, just to eliminate the Vbar as the culprit..

[Chris Sexton]

I didn't take the x7 to the field today. I wanted to put some time on my e7.

I plan to take only the x7 tomorrow and now that I know my new club had power, i plan to field charge. With my ham handed collective skills, if the RX pack isn't enough with the beastx I will know it.


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[rcbirk21]

interesting stuff. i may just play it safe and use the torq servos, i can get them cheaper than the savox, and i really want to run a bec. ive heard good things about the torqs anyway

[Matt Nasca]

Just wanted to mention; JC is running these servos in two X7s one on the Scorpion BEC with no buffer and the other is a BEC Pro. He's had no issues whatsoever.

[akamullen]

Originally Posted by Matt Nasca

Just wanted to mention; JC is running these servos in two X7s one on the Scorpion BEC with no buffer and the other is a BEC Pro. He's had no issues whatsoever.

Well, that leads me to believe it could be the Vbar, since JC I think is running BeastX. I am going to test the BEC pro tomorrow with the BeastX. I will report back after I test it.