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

[airfoilz]

Just a question (flame suit on)- how can a servo with a connector that can only handle 3A handle more than 3 amps?

[akamullen]

Originally Posted by airfoilz

Just a question (flame suit on)- how can a servo with a connector that can only handle 3A handle more than 3 amps?

Nothing wrong with that question at all.. I am not positive on this, but I assume that VERY short bursts (5/100ths of a second does not really come into play when the connector is rated for 3amps continuous. there are lots of very short bursts above 3 amps but also long periods of very low amp draws as well. it also can probably handle more currant dependent on wire gauge too. I'm no DC expert though. maybe someone else will have a better explanation? I'm just guessing for the most part, but this is what I come up with for why 3amp connectors are still suitable for these high burst rate servos.

[savox]

Originally Posted by cdsexton

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.

http://www.youtube.com/watch?v=a2oIbm7EwnM

Dear Sir,
i had check with your video very clearly. the brushless servo dont move much when you gave the load on one side of blade. do you have other brand's brushless servo? could you do the same test with other servo?? i was interesting with others result. in RD explain, when you gave the load on servo, the speed will be lower than other servos which is no load. when you play fast with your transmitter, the speed of servo on load will not catch up the servo which is no load. that is why you will see the servo is not move much. but on the fly testing, SAVOX brushless servo already passed by many team pilots and big brands ( heli company ). the performance is very good. if you have any other products problem issue, welcome to contact with me at : chunhan.chen@tricore.com.tw or contact@savoxtech.com.tw any times. thanks for your video.

[Chris Sexton]

Originally Posted by savox

Dear Sir,
i had check with your video very clearly. the brushless servo dont move much when you gave the load on one side of blade. do you have other brand's brushless servo? could you do the same test with other servo?? i was interesting with others result. in RD explain, when you gave the load on servo, the speed will be lower than other servos which is no load. when you play fast with your transmitter, the speed of servo on load will not catch up the servo which is no load. that is why you will see the servo is not move much. but on the fly testing, SAVOX brushless servo already passed by many team pilots and big brands ( heli company ). the performance is very good. if you have any other products problem issue, welcome to contact with me at : chunhan.chen@tricore.com.tw or contact@savoxtech.com.tw any times. thanks for your video.

Actually if you read a few pages back, we determined that I was putting too much pressure on the servo and actually stalling it rather than causing a brown out. My video isn't a good representation of the issues discussed on this thread. Rob Cherry posted a video with a better explanation of the issue we are having.

We love the way the servos fly, don't take it the wrong way, we just want to make sure people are supplying ample power so that a crash isn't caused from brown out.

[joe1l]

IMHO there are only a few truly reliable external SBEC's on the market right now that work with 12S. The other issue is that SBEC's generate EMI which can cause many issues with your other electrical equipment requiring them be isolated for the most part. Currently the best we can expect from any of these high end BEC's is 10-12amp cont with max current 20amps.... this will suffice most servos out there but not all. I have always seen the value of HV servos in there ability to run on direct 2s lipo relieving the need for a BEC. I was all set to run a BEC because my BLS252's required 6v on the X7 but finally decided to bite the bullet and buy some BLS156HV's just so that I could remove the BEC. I understand the need for saving weight on 550 or even a 600 sized heli where your limited but not on a 12lb heli. The only way i would consider running a BEC on such a large heli is if a backup buffer battery can be used reliably like on a Jive.

[Rollin_3z]

Originally Posted by akamullen

I run the outrage servos in my 700E, been flying that hard for 100+ flights with the bec pro on 6S, absolutly no problems.. many other guys run that set up as well. never heard of any problem until the brushless savox came along. your good to go Matt!

Very interesting...I was running mine at 12s, my new 10 amp bec for logo clearly shows more continous current at 12 volts input (7 amp) and 5 amps continous at an input of 24 volts. I wonder if theres more current available if I run my pro bec off one pack and not two..I will test, thanks for the info.

[vr360]

Originally Posted by Rollin_3z

Very interesting...I was running mine at 12s, my new 10 amp bec for logo clearly shows more continous current at 12 volts input (7 amp) and 5 amps continous at an input of 24 volts. I wonder if theres more current available if I run my pro bec off one pack and not two..I will test, thanks for the info.

That little castle bec you have is not meant for serious servos. It will stall out trying to power two DS610's. It definitely will NOT handle HV or savox for that matter. Get the BEC pro.

[Nasscar]

What about the Western Robotics Super BEC?


Nas,

[vr360]

Originally Posted by Nasscar

What about the Western Robotics Super BEC?


Nas,

What about it?

[akamullen]

Originally Posted by Rollin_3z

Very interesting...I was running mine at 12s, my new 10 amp bec for logo clearly shows more continous current at 12 volts input (7 amp) and 5 amps continous at an input of 24 volts. I wonder if theres more current available if I run my pro bec off one pack and not two..I will test, thanks for the info.

The more voltage you put in to a bec the less amperage it puts out. I have never ran a bec off of 12S, there is no reason to. just wire it up so one pack powers it. also as a bonus, you can plug one 6S pack in and just run the electronics with out turning the esc on until you plug the second 6S pack in. its not as hard on bec's and they put out better amperage. win win.

[kachur779]

Originally Posted by savox

Dear Sir,
i had check with your video very clearly. the brushless servo dont move much when you gave the load on one side of blade. do you have other brand's brushless servo? could you do the same test with other servo?? i was interesting with others result. in RD explain, when you gave the load on servo, the speed will be lower than other servos which is no load. when you play fast with your transmitter, the speed of servo on load will not catch up the servo which is no load. that is why you will see the servo is not move much. but on the fly testing, SAVOX brushless servo already passed by many team pilots and big brands ( heli company ). the performance is very good. if you have any other products problem issue, welcome to contact with me at : chunhan.chen@tricore.com.tw or contact@savoxtech.com.tw any times. thanks for your video.

So SAVOX how are these team pilots powering there helis with this great performance,using your hv servos your welcome to help us out on here helifreak.com

[akschu]

Originally Posted by Rob Cherry

Makes sense, then you could just leave it mounted in the heli, and never charge it. A lipo at 4.0v /cell isn't that hard on the pack, it will last forever. Instead of leaving it at 4.2V.

I wish there was an easy way to wire it all up so you wouldn't have to do anything except plug in the main packs, lol. With this setup, you still have to plug in the main pack first, then the buffer pack. If you forget the lipo, you're not buffering. And, if you forget the correct order and plug in the lipo first, you could fry the BEC. lmao.

Yea, that's true. One way is to put a diode in place to protect the BEC, but then again, your stuff will always be powered. Seems like a simple switch would work well, but then again it's one more thing to remember.

I need to get my scope out and look at this, that way we can all quit guessing and get a solution in place.

[akschu]

Well, I got a few minutes to play with this. First my setup:

2271 cyclic
2272 tail
CC BEC Pro on 6s
7200BX BeastX/RX
Set to 7.4v

In order to test I had to remove one of the BEC leads from the RX because I didn't have my pigtails and tools available to me (I had to dig the scope and heli out of the garage since I'm moving) so this is worst case since I am doing this with a single 20gauge wire.

Anyway, the scope shows that the voltage dips to 5.60 volts for around 100u seconds then the switching regulator overruns to around 8v for another 100u then everything goes back to normal.

What is interesting is that it didn't seem to matter if I stalled the servo or not, the voltage drop happens with fast cyclic movement.

So this is an issue with the beastx, it's just not enough to cause it to brown out.

I suspect that the issue is that this setup brown outs the v-bar and when it comes back the stalled servo is still under load which causes the v-bar to slow it down or the servo goes into some protection mode. On my setup the second that I let go of the grip, the servo went right to where it's supposed to be, and while it was stalled, it didn't seem to fight as hard, so perhaps the servo does have some protection built in.

Anyway, this might be worse at 8.4v, I'm not sure, I just didn't have time to test further.

I'll probably put a cap in the system when I get unpacked and test again. I suspect that will take care of it, just need to size the cap correctly.

I'll post when I have more. For now if you have a v-bar I wouldn't fly this without an RX pack. The beastx is probably fine, but not because the issue doesn't exist, but because the beastX with an external RX or the 72000BX aren't effected enough to reset.

schu

[kachur779]

nice ill be taking off my vbar and switch it up 4 a beastx with rx pack and DC-up

[Harrow]

Originally Posted by Rob Cherry

And, if you forget the correct order and plug in the lipo first, you could fry the BEC. lmao.

Are you sure this is true, or are you just being precautionary?

If true, then what about caps on the output side of the BEC? Could they damage the BEC when the main battery was unplugged?

[Rollin_3z]

Originally Posted by vr360

That little castle bec you have is not meant for serious servos. It will stall out trying to power two DS610's. It definitely will NOT handle HV or savox for that matter. Get the BEC pro.

Thats on my 500, I have a pro bec on my X7.......read all the posts please

[vr360]

Originally Posted by Rollin_3z

Thats on my 500, I have a pro bec on my X7.......read all the posts please

Yep, I know it is. I wouldn't use a regular castle BEC on anything but a 450 or smaller.

[akamullen]

Originally Posted by vr360

Yep, I know it is. I wouldn't use a regular castle BEC on anything but a 450 or smaller.

Yep, stick with the BEC PRO, I have 4 machines that I run them on and they work perfectly. Stick to 2-6S input on the PRO and you wont have any problems.

[Rollin_3z]

Damn it! I hate spending more money on a wrong purchase

[kachur779]

lol