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  1. #1
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    Would a cheap Amazon servo require too much voltage for stock TRX-4 Sport BEC?

    I have one of these cheaper Amazon servos laying around and was wondering if I could stick it in a Sport. Anyone know if it would work?

  2. #2
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    Quote Originally Posted by TeachMeCars View Post
    I have one of these cheaper Amazon servos laying around and was wondering if I could stick it in a Sport. Anyone know if it would work?
    It will work, but not to it's full potential as the stock sport electronics will only provide 1 amp to the servo.

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  3. #3
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    Quote Originally Posted by bullgearrc View Post
    It will work, but not to it's full potential as the stock sport electronics will only provide 1 amp to the servo.

    Sent from my SM-G930V using Tapatalk
    So basically it will work at the performance of the lower voltage that is listed in the description? Basically just want to upgrade the stock service but not break the bank.

    Sent from my Pixel 2 XL using Tapatalk

  4. #4
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    Quote Originally Posted by TeachMeCars View Post
    So basically it will work at the performance of the lower voltage that is listed in the description? Basically just want to upgrade the stock service but not break the bank.

    Sent from my Pixel 2 XL using Tapatalk
    No it won't even work at the lower performance indicated. The problem isn't so much the voltage. It is the 1 amp that the internal bec in your esc provides. It is just not enough to run an upgraded servo.
    If you want to upgrade the servo in your trx-4, then you must install an external bec. $20 will get you a 10 amp bec and you can water proof it with some shoe goo.
    If you have castle link you can set the voltage yourself, or your local hobby shop should be able to set it for you

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  5. #5
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    You have a big potential of frying the XL-5 HV's BEC, which will take out the entire ESC. Very much recommend getting an external BEC to run that servo off of. If you want a plug-n-play option, you can get Traxxas' external BEC kit, which should be fine. Or, you can get something like a Castle 10A BEC and wire it up yourself.

    If you do go with the Castle BEC, be careful of your voltage settings (defaulted to 5VDC), the stock RX is only rated to 6VDC.
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  6. #6
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    Quote Originally Posted by bullgearrc View Post
    No it won't even work at the lower performance indicated. The problem isn't so much the voltage. It is the 1 amp that the internal bec in your esc provides. It is just not enough to run an upgraded servo.
    If you want to upgrade the servo in your trx-4, then you must install an external bec. $20 will get you a 10 amp bec and you can water proof it with some shoe goo.
    If you have castle link you can set the voltage yourself, or your local hobby shop should be able to set it for you

    Sent from my SM-G930V using Tapatalk
    So basically just get an external BEC. Shouldn't be too bad. Thanks for the help guys!

    Sent from my Pixel 2 XL using Tapatalk

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    Actually I tested this with an inline meter a few weeks ago. The bec in the esc will dish out up to 2.5a. Maybe more but I couldn't produce that kind of torque against the servo on the bench. All I do is run an external cap (glitch buster) in my spare receiver port. This reduces voltage sag under load. Servo is a savox 1230.

    I'm also running one of those amazon 20kg servos in my sons temper 2 with just a cap and it's working well too.

  8. #8
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    Quote Originally Posted by Conradm View Post
    Actually I tested this with an inline meter a few weeks ago. The bec in the esc will dish out up to 2.5a. Maybe more but I couldn't produce that kind of torque against the servo on the bench. All I do is run an external cap (glitch buster) in my spare receiver port. This reduces voltage sag under load. Servo is a savox 1230.

    I'm also running one of those amazon 20kg servos in my sons temper 2 with just a cap and it's working well too.
    The rated amperage of the XL5 BEC is 1 amp, it can perform passed that for short periods, but every time you take it beyond that point you are shortening its life. The longer it is drawing current over the rated amperage more likely it will be to fail. To translate that into how it applied to the TRX4, you run a higher torque servo just fine as long as you are not binding it up on the rocks, but if you get it bound up, it will likely fry your ESC's BEC.
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  9. #9
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    Quote Originally Posted by Greatscott View Post
    The rated amperage of the XL5 BEC is 1 amp, it can perform passed that for short periods, but every time you take it beyond that point you are shortening its life. The longer it is drawing current over the rated amperage more likely it will be to fail. To translate that into how it applied to the TRX4, you run a higher torque servo just fine as long as you are not binding it up on the rocks, but if you get it bound up, it will likely fry your ESC's BEC.
    Yeah that's what people say... so far I haven't seen evidence of it yet though. I know I've pushed mine pretty hard without issue. My son has jammed his Temper 2 up so bad the torque from the servo actually broke the linkage.

  10. #10
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    I wont lie.wile waiting for my traxxas bec I ran my 2250 servo off the esc's bec for 10 packs without a problem maybe an occasional brown out I'm not even sure . Not recommending forgoing a proper bec just saying I ran one of the servos the aftermarket traxxas bec was made for without it and had no issues. That being said I have a proper bec now and sleep much better

  11. #11
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    Quote Originally Posted by Conradm View Post
    Yeah that's what people say... so far I haven't seen evidence of it yet though. I know I've pushed mine pretty hard without issue. My son has jammed his Temper 2 up so bad the torque from the servo actually broke the linkage.
    The fact that Traxxas has produced the external BEC kit specifically to address XL5s being fried due to the 2075's high draw and the BEC's low amperage rating is "evidence". If you look through this forum, the RC Crawler forum for the TRX4, or any of the FB pages, you will find lots of evidence of this exact problem and how people have dealt with it.
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