High Voltage Servo Question

[godale03]

Hey Guys,

I am looking at putting a high voltage servo in my next truck... a Losi 8ight T 3.0. I am going to be running a Tekin Rx8 Gen 2 paired with a T8 gen 2 2000kvm motor. I also will be running a 14.8 volt 4s lipo. Now I see that the RX8 can output up to 7.4 volts via its onboard BEC but if I set it to that won't it fry my Spektrum rx? I believe rx's can only run on 6V...correct? So if I wanted to run a HV servo and not fry my rx...what do I need to do? Or is there a better servo that will get me at least 350 oz of torque that will handle the steering capabilities of this truggy? Thanks

Tom

 

[HPIguy]

Tom, some RX's can take up to 7.4v without issue, it all depends on the RX. The bigger issue is, how many amps can that built in BEC put out? Most built in BEC circuits in ESC's put out between 3-5 amps, and the servo in my SC10 (Savox 1258TG, far from high TQ) draws around 3.5a on it's own with nothing else plugged in. I learned this after having a brownout induced crash by putting a watts up meter on it. My advice is to run an external BEC with all high TQ servos (no different than a crawler, and your power plant is much more amp hungry), it's cheap insurance.

 

[godale03]

Here is a link for the motor ESC combo for you to look at... http://www.amainhobbies.com/product_info.php/cPath/1_221_1355/products_id/263939/n/Tekin-RX8-GEN2-Redline-T8-GEN2-1-8th-Scale-Truggy-Brushless-ESC-Motor-Combo-2000kV just because I don't completely understand everything I need to know.. yet. LOL! I will look into the BEC. How do they connect? The servo I am looking at is the Savox SC-1268 MG. Not to ask a dumb question but why would the ESC have a built in BEC if you still need an external one? Thanks a ton for the explaination. Tom

 

[godale03]

Morning Bump!!

 

[HPIguy]

Here is a link for the motor ESC combo for you to look at... http://www.amainhobbies.com/product_info.php/cPath/1_221_1355/products_id/263939/n/Tekin-RX8-GEN2-Redline-T8-GEN2-1-8th-Scale-Truggy-Brushless-ESC-Motor-Combo-2000kV just because I don't completely understand everything I need to know.. yet. LOL! I will look into the BEC. How do they connect? The servo I am looking at is the Savox SC-1268 MG. Not to ask a dumb question but why would the ESC have a built in BEC if you still need an external one? Thanks a ton for the explaination. Tom

Tom my thought process is that the $20 external BEC is cheap insurance that you don't have a brown out induced crash on a high dollar race rig. Or in rare cases like when my RX bypass harness (was using them for running the servo off a BEC, but I use a Y harness now) shorted out, it takes out a $20 external BEC and not a $200 ESC. To connect it, you simply solder the + and - of the BEC inline with the + and - of the ESC. You then set your voltage with a castle link to whatever you want your servo to run at. I've had brownouts running a puny (by servo standards) Savox 1258tg, so I like the insurance it gives me. I'm running four castle BEC's at this point, including the one powering my 1270TG in the Wraith that gets worked extremely hard, and I swear by them. But, you can always try it without the external BEC and see how it goes.

 

[godale03]

Tom my thought process is that the $20 external BEC is cheap insurance that you don't have a brown out induced crash on a high dollar race rig. Or in rare cases like when my RX bypass harness (was using them for running the servo off a BEC, but I use a Y harness now) shorted out, it takes out a $20 external BEC and not a $200 ESC. To connect it, you simply solder the + and - of the BEC inline with the + and - of the ESC. You then set your voltage with a castle link to whatever you want your servo to run at. I've had brownouts running a puny (by servo standards) Savox 1258tg, so I like the insurance it gives me. I'm running four castle BEC's at this point, including the one powering my 1270TG in the Wraith that gets worked extremely hard, and I swear by them. But, you can always try it without the external BEC and see how it goes.

Thank you for the second explaination. I am going to run the BEC... I definitely trust you on that one. I was just curious. It makes perfect sense now that you have explained it to me. I mean I understand about cheap insurance.. I run a return spring and failsafe on all my nitros. Thanks again.

Tom

 

[HPIguy]

Anytime Tom, happy to help.

 

[wacmartin]

BEC's are still a grey area for me, but I'm going to need to research more into them real soon.
To answer your original question, Spektrum receivers can handle up to 9.6v.

 

[godale03]

Thanks man!