Seperate servo battery

[islandlife]

Hey folks, im having some trouble with the servo setup in used trx4 i picked up.
The truck is a stock trx4 sport, with a 35kg amazon servo. The esc motor i have running off a 1500mah 3s. The servo has its own 900mah 2s.

The signal wire from the servo goes to the rx, the ground is connected to the servo, rx and 2s lipo, and the positive wire goes from 2s lipo to servo.
Is this an acceptable way to wire this setup?

The issue im having is the steering will flutter left/right with no steering input. If there is resistance or steering input from the transmitter the flutter *usually* goes away. Other than that the truck runs and steers fine.

Thanks in advance for any insight.

 

[HumboldtEF]

You should not hook up the servo's signal wire to the ESC.

What you need is to pick up a bypass adapter (or make your own). These are intended to be used when running a servo or something directly off a battery while bypassing the voltage the receiver would be feeding the servo.

https://holmeshobbies.com/electroni...ssories/holmes-hobbies-rx-bypass-adapter.html

take a look at the 2nd pic with the wiring diagram

EDIT: On second thought you should get an external BEC to step down your 3S battery voltage which is much simpler and you wont risk draining the servo battery too low (it would have no LVC protection). Theres no need to run a separate battery if all you need is to step down the voltage.

 

[islandlife]

Sorry, my bad, the servo signal is hooked to rx, not esc. I edited the first post.
That second pic in the link is exactly what my wiring looks like, but rather than bec, there is the 2s battery.
So far the voltage on the 2s hasnt gone below 3.9v after running through the small 3s pack.
I will eventually upgrade the esc, or get a bec. But as this truck was purchased with the intention of being a cheap beater for my son to use, i would like to run it without any further investment for now, if possible. But if the way it is setup is complete garbage, i could pop the stock servo back into it until something dies and requires upgrade.

 

[DirtMerchant]

Sometimes a servo extension can cause this. Possibly the wiring used currently is too small. As Humboldt mentioned, a BEC is an option to step down the voltage from the 3S powering the ESC. Otherwise, a heavier gauge wire for the servo could help.

 

[islandlife]

Ok thanks, there is a servo extension in the mix, ill swap it out for a different one.