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Old 06-12-2011, 06:51 PM   #1
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Default Hard wired servo with no BEC?

After reading a few threads yesterday about BEC's going up in smoke, and the fact I am cheap has made me question the need for a BEC. If a guy is only running 2S lipo 7.4, or 6 cell nimh 7.2v, why couldn't a guy hard wire the servo to the battery plug? Same way as you would wire a BEC, but without the BEC. So the red and black wires you go to the red and black on the battery plug in, and the white wire to the RX. The RX of course would run off of the esc. Now, you would have to have a servo that could run off of 7.2v but most high TQ servos do these days.

Thoughts?
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Old 06-12-2011, 07:01 PM   #2
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Someone correct me if I am wrong but, I thinnk if you were using a lipo you would burn up your servo b/c a 7.4 volt lipo would peak at about 8.4 volts. A nimh or nicad would probably be alright but I am not sure, never seen it done. Try it and let us know
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Old 06-12-2011, 07:11 PM   #3
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I have run my servo in my mini crawler like this for over a year. A buddy of mine is running his in his AX-10 on 2s for longer than me. I do run a BEC in my berg, but I run 3s in that.
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Old 06-13-2011, 06:26 PM   #4
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Not sure about other servos but the Savox Ultra Torque High Voltage servo would be fine wired this way. Just pull the + and - wire out of the plug to the RX then solder them to your Esc's battery connections. The servo is designed to run off a 2s lipo and while it says in the specs it runs off 7.4v it will be totally capable of dealing with 8.4v. Just like 12v automotive stuff, when the motor is on and the alternator starts the system is charged up to 14v and you're not cooking everything electronic in the car. I think its safe to assume every other servo designed to run off 7.4v could survive 8.4 with no trouble.

Why would a company make a servo, say it can be run right off a 2s lipo and then forget that 2s lipos charge up to 8.4v?

You will obviously need a BEC if you decide to run 3s
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Old 06-13-2011, 09:01 PM   #5
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So there is no need to run the ground back to the rx? Just trying to make sure I understand how to wire this. Now I just need a 7.2v servo...
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Old 06-13-2011, 09:33 PM   #6
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Here:

http://www.amainhobbies.com/product_...o-High-Voltage

That servo has better stats then the regular high torque digital from savox and costs the same as the high torque + BEC.

The only wire that needs to go to the Rx is the signal wire. You can put the plus and negative to the plus and negative terminals to the battery. I prefer to wire it that way even with an externaal BEC instead of using the BEC to power the Rx and servo, just hook the servo directly to the BEC for power. Allows you to keep a plug open on the RX.
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Old 06-14-2011, 02:18 PM   #7
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Quote:
Originally Posted by federally View Post
Here:

http://www.amainhobbies.com/product_...o-High-Voltage

That servo has better stats then the regular high torque digital from savox and costs the same as the high torque + BEC.

The only wire that needs to go to the Rx is the signal wire. You can put the plus and negative to the plus and negative terminals to the battery. I prefer to wire it that way even with an externaal BEC instead of using the BEC to power the Rx and servo, just hook the servo directly to the BEC for power. Allows you to keep a plug open on the RX.
Screw that servo.

Buy this one instead: http://www.hobbyking.com/hobbyking/s...idProduct=9981

It's even cheaper and is designed to run off 12V. You'll only have to worry about spinning the press fit gear, but there is a fix for taht.

Then again, this is all hearsay. i have no experience with this servo, but reliable sources have talked about it with praise.

And it's out of stock and connot be backordered. so good luck.
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Old 06-14-2011, 03:54 PM   #8
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Well 12v is only good if he is running 3s. I am under the impression he is not running 3s. If that servo is run on less voltage it won't produce the advertised speed and torque. I am also very suspect of the quality provided by an HK servo. I haven't heard any glowing reviews about them. Sometimes you get what you pay for.
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Old 06-14-2011, 04:25 PM   #9
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Quote:
Originally Posted by federally View Post
Well 12v is only good if he is running 3s. I am under the impression he is not running 3s. If that servo is run on less voltage it won't produce the advertised speed and torque. I am also very suspect of the quality provided by an HK servo. I haven't heard any glowing reviews about them. Sometimes you get what you pay for.
I have been running a couple of them for a few months without any issue at all. So I am pretty happy with what I paid for.. On 2S I was not impressed, on 3S they are pretty bad ass..
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Old 06-14-2011, 05:09 PM   #10
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Quote:
Originally Posted by federally View Post
Here:

http://www.amainhobbies.com/product_...o-High-Voltage

That servo has better stats then the regular high torque digital from savox and costs the same as the high torque + BEC.

The only wire that needs to go to the Rx is the signal wire. You can put the plus and negative to the plus and negative terminals to the battery. I prefer to wire it that way even with an externaal BEC instead of using the BEC to power the Rx and servo, just hook the servo directly to the BEC for power. Allows you to keep a plug open on the RX.

HERES THAT SAME SAVOX FOR $79.00, I JUST GOT MINE IN THE MAIL A COUPLE DAYS AGO.
Savox super high tourqe servo
THERE IS A LINK TO TAMMIES HOBBIES

Last edited by CREEPERBOB; 06-14-2011 at 05:11 PM.
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Old 06-14-2011, 07:31 PM   #11
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Quote:
Originally Posted by sloppy View Post
I have been running a couple of them for a few months without any issue at all. So I am pretty happy with what I paid for.. On 2S I was not impressed, on 3S they are pretty bad ass..
Well that is good to know
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Old 06-15-2011, 12:47 AM   #12
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I would never try it. always run a bec for assurance, the only guys blowin bec's are the ones pushing the limits
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Old 06-15-2011, 05:31 PM   #13
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Quote:
Originally Posted by chilipepperfan114 View Post
I would never try it. always run a bec for assurance, the only guys blowin bec's are the ones pushing the limits
Any reason for this statment?
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Old 06-15-2011, 06:10 PM   #14
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Quote:
Originally Posted by chilipepperfan114 View Post
I would never try it. always run a bec for assurance, the only guys blowin bec's are the ones pushing the limits
Click the link to te servo I posted. Read the description, it specifically states the servo was designed to run directly off of a 2s Lipo. It's the entire purpose the servo was designed for! I really just don't understand where your thought process comes from.
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