voo2doo

Can anyone tell me the advantage from running the batteries straight to the servo's? I have a 2x quarter running the steering and a Hi-Tec 150oZ running the discs and throttle.Is there a better method to more power to the servos???? If so can you ppl send a diagram or two??
Thanx
Vo0[&:]

ibstar

hi voo
been looking into this
i am undecided if its better, if you look at the board on the reciver (all mine anyway)
you should find that the + and - pins are all soldered together anyway so they are connected to the battery
there was a diagram posted here somewhere but i can't find it now.
but basicaly you use a graupner switch set with 3 power feeds or
a few y leads so the servo plugs in one side/battery pack in other and single end goes to the reciver

randyg-rcu

I think it's mainly about minimizing resistance... if you connect the battery directly to the servo with thick wires, you'll probably get better servo response and torque. It could also be that some receivers regulate the voltage before giving it to the servos; on these it might make a very big improvement.


--Randy

Doohan

I'm making my own custom wiring loom, that way you can make it the exact length....the shorter the wires, the better.
Just bought Y cables, extensions, plugs and wires etc...from Tower.
Will have to cut and shorten then solder everything to length, but it will be perfect...no more zip locking all the extra wiring and jamming it in the receiver box! Got a nice switch from a local electronics store.
You should run heavy duty leads and wire the servos direct to the battery, 6V guaranteed, far better for your servos and receiver.

mbba2002

My Feedback: (10)

you can only do that one time for a special servo. You can't do it for every servo. It dos'nt work that way. Yes direct is better but only for special servos. Once the power goes to the reciever you can't put it back in.You are wasting time doing it .You don't gain anything doing it to all your servos. You just have a wireing mess. You would have to run a seperate battery to every servo to do what you want to do and that is too much power for the reciever.

ammdrew

you only need to do it if you can continually push the radio system like we do onroad racing, I have never been able to cause a receiver brownout offroad.

randyg-rcu

Directly wiring the servo to the battery pack theoretically can improve _all_ servos, but in most cases the difference is unnoticable.

Mostly the problem is at higher current levels... say you have a high-torque servo that pulls 2.5 amps. Assuming you use 26awg wire, and have 1.5ft from the battery to the receiver and 1.5ft from the receiver to the servo, that's 0.3 ohms of loss just in the wires. But that's only half the loss; you also need to consider the connectors. I can't find the specs for the connectors used on r/c stuff, but looking at similar connectors, I'd guess about 0.1 ohms/pin. Given that figure, and that you go through four pins to power the servo, that's another 0.4 ohms of resistance, for 0.7 ohms total. (about half wire loss, half connector loss). At 2.5 amps, you're loosing 1.75 volts. D'oh! your fancy nimh pack may have 4.8v on it under load, but only 3.05v of that is making it to the servo. (or, with a 6v pack, 4.25v to the servo)

Of course, for a standard servo, with current draw a tenth of that, the voltage drop is largely irrelevant. The only time it would help is on receivers that attempt to regulate the voltage internally. However, I've only seen one that does this, and it was for a car that ran off 7-cell packs, and didn't want to send 8.4v to the 6v servos. (and had large advertising on the sticker proclaiming this feature)

Short version: it helps high-current servos, but is mostly useless on little ones.


"You would have to run a seperate battery to every servo to do what you want to do and that is too much power for the reciever." that line seems to make absolutely no sense... "Once the power goes to the reciever you can't put it back in." and neither does that one. care to elaborate?


--Randy

mbba2002

My Feedback: (10)

Recievers are rated for 6 volts. the way doohan wiring diagram is putting the power back into every servo with a wiring harness. The power is already supplied by the first servo on the first wiring harness. That supplies power to the other servos with power. You ca'nt put power on power. I'ts a waste of time and money. You can only do it for 1 channel only.

Darkend1

not sure if i'm getting it right, so doohan's diagram does'nt need the Y-harness for the ch.2 & 3, he can directly plug the servos (2 & 3) there since 6v is already supplied in ch.1?

ibstar

yeap

voo2doo

Cheers Fellas ya been a great help

Vo0[&:]