Hi

Might be a dumb question but it is always worth asking...

I get that you can run your servos at 5.9v or 7.4v giving you better specs the higher the voltage it goes but for the last couple of years I have seen servo specs rating up to 8.2v such as this:

Torque (6.0V): 29.5 kg-cm / 409.7 oz-in
Torque (7.4V): 36.5 kg-cm / 506.9 oz-in
Torque (8.2V): 40.4 kg-cm / 561.1 oz-in
Speed: 0.13 s (6.0V) / 0.11 s (7.4V) / 0.10 s (8.2V)

Obviously anyone will want to run servos at 8.2v if spec’ed like this (and if necessary for the job) cos of the torque and speed but how do you setup all your servos to run at this voltage when most electronics such as power switches, etc.. only give you 5.9 or 7.4 regulated output?

8.2v is a fully charged 2S lipo, so you get those specs for a few minutes until the battery discharges some. I just look at the 7 and 8 volt specs split the difference and assume that is what I really get. All my symptoms are unregulated except the ibec on ignition

2S LiPo is 8.4V fully charged. 2S LiON is 8.2, but you can charge the Lithium Ion pack as a Lithium Polymer pack.

The only way to get 8.2V performance from your servos, is to run any type of 3S pack, LiFe LiPo, etc.... and then regulate the voltage before it gets to the Rx. Castle BEC Pro would be the way to do that. But then you are getting into more $$$ and more fail points.

So, in all honest reality, its best to just go with 2S. You will not notice the performance deterioration.

In my experience I use Li Ions and they generally charge to about 8.33 to 8.36 Volts. I fly 40% aircraft with efficient servos. Typically after 3 flights I still have 8.1 volts showing so as a general average I assume if the servo spec is as advertised I get + or minus a few percent of the 8.2 rating.

I build and setup to a spec that regardless if I was squeezing's out the last of my batteries capacity I would still have no problem in flying the aircraft.

Set up or purchase to a spec that reasonably exceeds a worst case scenario for your aircraft and you will never need to question it.

OTOTH those with skills far better than mine might regulate a higher voltage pack down to say 8.2 or even 7.4 and stay a constant speed and torque value throughout their flights!

too complicated for me to worry about. 2- 5600 to 6800 ma Li Ions, a Powerbuss receiver and a Tec-Aero Ibec or 2 in with my Quads and all is good.

I understand now.
So these figures @ 8.2v give you that performance for a short period of time, then it gets reduced as the batt voltage decreases. Ok.

I still don’t understand that if the voltage regulator, sets the nominal output of the entire system at 7.4v (when batts are over 7.6v) or lower (when batts are below 7.6v in my case) what is the point of feeding more voltage into the system (from the batts) if in then end, it gets reduced to 7.4v o lower distributed to all servos?

Wouldn’t all servos run at 7.4v max or lower all the time regardless?

Originally Posted by Loco3d

I understand now.
So these figures @ 8.2v give you that performance for a short period of time, then it gets reduced as the batt voltage decreases. Ok.

I still don’t understand that if the voltage regulator, sets the nominal output of the entire system at 7.4v (when batts are over 7.6v) or lower (when batts are below 7.6v in my case) what is the point of feeding more voltage into the system (from the batts) if in then end, it gets reduced to 7.4v o lower distributed to all servos?

Wouldn’t all servos run at 7.4v max or lower all the time regardless?

If your regulating, all your equipment sees that voltage you set your regulator to. Depending on your battery choice, voltage wise, if/when your batteries fall below the regulated voltage, then it just becomes the current depleted voltage.

Yes, your right. But also to, if you use any 3S type of battery, and use regulators to 8.2V, your batteries will never or should never be depleted below 9V. So, your servos and equipment will always see a constant 8.2V.

Also too, most everyone will fly a certain number of flights, and then charge.

I suggest you are over thinking this. I only use servos rated for “HV” and run straight 2S lipo. I used to use 3S lipos with the Castle BEC Pro’s set at 8.5V for years. Now with the latest Powersafe receivers, I want to see the voltage on each battery. With dual 2S/5200’s on my 104 with 7x Savox 2290’s (plus 1 Hitec D-645 on the throttle, and a Tech-Aero IBEC) that draw 6+ amps each at stall, the battery’s are still over 8V each after 4-5 flights in a day. The nice thing about lipos is if I want to charge them, I can hit them on a Paraboard with 15 amps and get them back up to 8.4V in minutes.

Thanks for your feedback, much appreciated!