dual steering servos, a cc bec, a y-harness, and 4 cells of lipo power…

[mudholestomper]

Hi all! - new to the forums and a bit of a newbie when it comes to electric theory - first off, I've been a long time lurker and have learned a ton from y'all, so a big, hearty, Texas-sized thank you to the lot of y'all!!👍

I have installed/programmed a cc bec on my Losi NC thanks to the guidance I found here and feel very comfortable with the principles behind how it works - I used a parallel y-harness and removed the power wire on the male connector that goes in the receiver and am allowing my esc to power the receiver and the bec running just the servo - works fantastic!

my question is this: I have an emaxx brushless with two steering servos - I run the truck on 4S lipo power and it has a tekin rx-8 gen2 esc - I skimped on the servos and it has 2 TowerPro mg946r units - while the tekin esc has an onboard bec that can be set to as much as 7.4volts, my receiver is only rated at 6.5volts

so, in order to get more power to my very lethargic steering servos, I installed a cc bec in the truck - the servos attach to a parallel y-harness, then are plugged into the bec through a second parallel y-harness that, of course, then plugs into the receiver (again with the power wire removed, as the esc is powering receiver)

If I set the bec voltage to, say, 7volts, it is my understanding that both servos are receiving 7volts when I turn the front wheels left and right - I understand that there is some voltage loss from resistance in the wiring/connectors

am I correct in that both servos are, for all intents and purposes, receiving the full 7volts? - what about current (amps)? - are they splitting up the amperage in any way? - or do they both receive the full amperage from the bec as well?

just for conversation sake, if the servos I am using in this setup are rated to handle a max voltage of 7.4volts, would it be advisable to set the bec to, say, 8volts in order to overcome:
1. the inherent resistance in this wiring scheme
2. the extra amp draw that is being put on the bec because it has to run two servos as opposed to one

my interests lie less in preserving the servos and more in getting the most speed possible out of them - in other words, I'm willing to experiment with the bec voltage and push their limits a bit - I don't want to cook them and I fully understand that they will never be close to being racing servos as far as their speed goes - just want to maximize them until I can afford something better

Anyways, thank you for reading this and any insight you can provide as far as what is going on with voltage and amperage from the bec, through the y-harness, and on to what the servos are receiving is greatly appreciated! 😎👍

Cheers!

mudholestomper

[TacoCrawler]

If the servo(s) are wired parallel (guessing they are)
then both will receive the same voltage.

If the servo(s) can operate at a lower voltage (say 6v)
then any resistance loss @ 7.0v would be negligible.

I am however a bit confused...

Originally Posted by mudholestomper

I used a parallel y-harness and removed the power wire on the male connector that goes in the receiver
and am allowing my esc to power the receiver and the bec running just the servo - works fantastic!

Maybe I've read your explanation incorrectly ?
But it's my guess that your external bec is what's supplying power to your rx ?
( ^ not the esc's internal bec )

If the red power wire going into the rx,
coming from the ESC, is removed...
then the esc's internal bec cannot be powering the rx.

If you use the Holmes Hobby by-pass harness...
then the servo's are supplied directly by the external bec...
and also by-passes the rx in that process.
The esc's power wire (red) input to the rx remains
so that it can power the rx utilizing the esc's internal bec.

If you disconnected the esc's power wire
then the external bec must be what's supplying power to the rx ?
( ^ or you'd have no radio signal )

Both external and internal bec's cannot supply power,
at the same time, to the rx.


Tons of discussion on the net regarding series and parallel connections.
but I'm just gonna leave this
and you can search further if necessary.

[mudholestomper]

Sorry if my post was confusing - the esc is powering the rx (all 3 wires, plugged into the throttle port) and the parallel y-harness is plugged into the bec (all 3 wires), the servos (all 3 wires), and then plugged into the steering port on the rx with the red wire removed so that only the ground and signal wires are going into the rx - so the cc bec is providing power to the servos only and the onboard bec from the tekin rx-8 is the one providing the juice to the rx

Hope that clears up any confusion ��

[mudholestomper]

@TacoCrawler - thanks for the link!