dreadnaut

My Feedback: (5)

I'm about to order a voltage regulator for a .110/8s sized pattern plane I am building. I'll be running a Rhino 750 receiver pack, and am about to order the regulator, and am wondering if I should get 6.0v, 5.7v, or even the 5.1v. I'll be running 3x HS6965, and 1x DS9411, and a CC ICE 75 ESC. Since I am not using them in a full 2m plane, I don't think I will need the power of the full 6.0 volts, but am not sure what the advantage of running a lower voltage is. Would it extend battery time? Would it extend servo life? Input appreciated.

Dave.

edit;

I'll be flying intermediate, or possible stepping back down to sportsman depending on how thick the rust on my thumbs is.

JAS

My Feedback: (2)

If you plan on running 6V in the future, then maybe you should just get the 6V now. I just swap mine from plane to plane. This one came from my Integral, then to Eon, then to Kaos and now back in the Eon.

I'm not sure there is any difference in battery 'life' with the lower voltage regs, so hopefully an expert will chime in.

dreadnaut

My Feedback: (5)

Thanks, Jason. I pretty much thought you were an expert.

can773

My Feedback: (1)

I have ran 6v last year, and 5.7v this year, there isn't really any noticeable difference between the two. 1/3 a volt is pretty insignificant!

JCINTEXAS

I have the same questions about a voltage regulator. Is a regulator needed when using the A123 2-cell 6.4 volt battery for the receiver and servos? My radio is the Futaba 12FG 2.4GHz with Futaba Digital servos. I have the new A123 battery, but haven't used it yet. Will the receiver and servos handle the 6.4 volts OK? If I do need a regulator, which brand(s) are the most recommended? My plane is a Balsa Nova 120 which weighs about 12 pounds. Any advice will be appreciated.
Regards
JC

toddblose

My Feedback: (10)

JC,
some guys say that the 123's work fine on the Futaba stuff, but Futaba will tell you to stay under 6 volts. I have been running
the Smart-Fly 6 volt reg with out ant problems.

Jeff Boyd 2

Hi Jas . . What regulator are you using ??

I am thinking about using the Emcotec magnet switch and combined regulator in my new F3A plane. It is selectable 5.5V / 5.9V, but I haven't seen anyone using them yet, so not sure, but the specs read nice. Can get them for dual packs (redundancy) too.

Has any one seen / used them ???

http://shop.rc-electronic.com/e-vend...=6&c=541&p=541

I use Emcotec power expanders in my 35% and they work great. So I think their gear is OK . .

Cheers, JB

NJRCFLYER2

My Feedback: (42)

Dave:

Why not order a Tech-Aero programmable regulator? You can set it to what you find to work the best for you. There are 32 unique settings available over a range of 5.75 to 6.65 volts (factory default is set at 6.20V). On request, and at no additional cost, I can shift the range up or down, so for example I can set the low limit to 5V. Check it out at www.tech-aero.net

You don't necessarily need to order an E-Z Set programmer/voltmeter either. I've got a little tech tip I can email you that explains how to make your own. I just haven't had a chance to upload it to the website yet.

Jetdesign

My Feedback: (8)

Tech-aero regulators are awesome, as is the service.

ntsmith

If you use JR/Spektrum you are highly recommended to use 6V. If you use any other make (I use futaba as allways been a futaba man even after going all over to JR) then 5V will keep the voltage consistent to give good constant servo speed. The different voltage setting will not significantly change the amount of time you get. In fact with leccys you dont use much per flight even with digitals. I never go over 1A peak on a .90 sized leccy with all digitals. Personaly, I would cut the size of the lipo down or cut the darned thing out all together and get a HV UBEC.

DaveL322

Dave,

If you run lower voltage, the mah consumed by the servos will be less, they will have less torque and speed, and they will likely last longer.

I run both the Tech Aero adjustable regulators and the Castle Creations BEC which is also adjustable. I've run as high as 6.5 volts with JR with no issues.

Regards,

Dave
Team Horizon/JR, Castle Creations

apereira

If you use less than 6V the servo will loose power, more power means better centering, and a regulator with less output voltage actually burns(heat) the extra voltage not used, so there is no benefit to the battery.

Jason uses the Shullman Aviation regulator, I got them, very light and work perfectly.

Regards

NJRCFLYER2

My Feedback: (42)

Higher voltage delivered to the servo equates to greater speed and torque, however it does not help improve centering accuracy. I think maybe you are thinking of improved holding power at neutral?

In general, what Dave said about lower power consumption from the battery at lower servo voltages is true. What you are saying about wasted power in the regulator is also true, but it is not true that there will no difference from the battery point of view. The battery doesn't "know" about anything except what is being demanded of it in terms of current. If you drive the servos with a higher voltage, they do draw more current except in some unusual circumstances which aren't really worth getting into.

Let's do a simple Ohms law comparison. We'll use an 8V LiPO and to keep things simple, assume that it holds at 8V even when the load varies. Set the regulator to 5V and the servo draws an average current of 100 mA. Set it to 6V and the same servo draws 150 mA average current in our example. We'll ignore other wiring losses as well.

At 5V servo voltage, the power that the battery delivers to the combined series load of regulator and servo is given by 8V x 0.1A = 0.8 watts. The power wasted in the regulator is given by (8V - 5V) x 0.1A = 0.3 watts, and the servo does its work with the remaining 0.5 watts. Remember, we're ignoring the reality of the internal resistance loss of the battery for simplicity. If we did consider it, the numbers would vary, but the same principle would still hold true.

Now, at 6V at the servo, the power that the battery delivers to the combined series load of regulator and servo is given by 8V x 0.15A = 1.2 watts. It went up. The power wasted in the regulator is given by (8V - 6V) x 0.15A = 0.3 watts, and the servo does its work with the remaining 0.9 watts. Wait! The power wasted in the regulator didn't change, but the servo got more power to do the job. That's because the 50% change from 100 to 150 mA is not realistic with only a 20% increase of voltage to the servo. Redo the example with a 20% increase in current to the servo, i.e. 120 mA at 6V:

8V x 0.12A = 0.96 watts total power delivered by the battery to the combined series load. (8V - 6V) x 0.12A = 0.24 watts wasted in the regulator, and 0.72 watts for the servo to work with. The power wasted in the regulator went down, the servo power went up, but the power expended by the battery increased as compared to the 5V example. These numbers are made up, so the percentages aren't accurate, but it is definitely true that higher servo voltages are going to drain the battery faster.

The other point Dave made about longer servo life at lower voltage - also true! Everything is a trade off.

dreadnaut

My Feedback: (5)

That was a flurry of very good responses. Ed Alts rather lengthy response pretty much confirmed what I was thinking. As far as centering, speed, and power; for an 8s setup flying intermediate I am leaning towards 5.1 being enough. I so not have a large budget, so if I can get an extra 100 flights off the servos I'll go for that. I'll take a look at the Tech Aero.

Jeff Boyd 2

Great info, Ed.

I understand the performance of a servo is increased at it's higher rated voltage, but is the servo life dramatically effected? Is it measureable?

I run 6V (or as close as I can get to it) for servo speed and torque on most of the planes I fly, and I have yet to experience the potential ill effects of too higher voltage. Maybe I dont' fly enough (although I do fly more than the average club flyer).

JB

lojik

If the servos are rated for 6V then go for it. if they are not rated for it then its up to you, personally I have allot of good servos on 6v that were not rated for it but can take the extra volts and current.

When I was flying helicopters we always ran our gear at 6v's and between all of us the servos never went, but then again we were using US$80-100 servos.

check the manufactures website or a hobby store website, there should be some information on what difference in speed and torque you get going from 4.2 to 5.1 to 6v.

NJRCFLYER2

My Feedback: (42)

Provided it's not a servo with an explicite warning about higher voltages, you probably will not see one just give up the ghost from running higher voltages in the 6.0 to 6.7V range, but it will accelerate gear wear. That's mostly from more agressive starts/stops. It also pushes the motor harder and will naturally tend to cause it to run a little warmer. Over a long period of time, the magnets weaken from use and higher temperatures accelerate that a bit. Pattern applications are not that harsh, so the heat generated inside a servo case is minimal and therefore this is not a big concern. Applications that push servos much harder will degrade motors faster.

I've got almost 500 flights on a set of 8411SA's on rudder & elevator in a Prestige and they are still running reliably, but I am beginning to suspect that the rudder servo is getting a little weak running in one direction. The aging effects tend to be subtle, regardless of whether you run them at a higher voltage or not. I look at it this way: I want what I want from servo performance and I don't mind pushing them a little harder to increase speed and torque, but I don't push it to ridiculous levels. I accept the tradeoff that the servos will need maintenance sooner, and monitor performance as best I can. I usually run in the 6.3 to 6.4V range and have had no outright failures because ot it, but your mileage may vary.

Not an advertisement, but for the record I use JR servos almost exclusively, which are known to be able to handle higher voltages well. Other brands/models can handle it too, but I would not push those which carry explicite warnings not to. Check with their service departments to see what they recommend.

NJRCFLYER2

My Feedback: (42)

I should add that guys have been running many of these servo designs for years on unregulated NiCad and NiMh packs, quite often with 5 cells. A fully charged 5 cell pack of this type will start out at almost 7V, and stay up at/above 6.25V for a good part of it's discharge curve. If you don't mind the weight penalty and the change in servo performance as the packs are used each flight, then this is a perfectly good way to go as well.

Jeff Boyd 2

Sounds like fair and reasonable advice, Ed . . and I think 'lojik' makes a good point. Helis' would put a fair more load on servos than a Pattern plane I would imagine (particularly if flying 3D?), so I guess it is a pretty good test.

Cheers, JB

dreadnaut

My Feedback: (5)

One of the specs I looked at when selecting the servos was 6v rating. That said, in engineering they often deal with "design factors". There is always a fudge factor to the high side when a manufacturer specs a product; sometimes as much as 25%. Price was another, but I understand the difference between frugal and cheap. I got mid-range Hitec digital servo's for rudder an aileron, and found a good internet deal on JR 9411sa's for the elevator, so I got three at 65 bucks each. This is my first time using digitals.

So I am back to 6v (Thats my final answer, Regis).

DaveL322

I've never specifically measure the amount of gear slop or torque of a new servo compared to an old servo, however, it is very rarely that I've suspected a motor getting weak (tho I suspect it does happen with enough use). The majority of the wear in the servos is in the pots and gears, and careful visible inspection of the servo movement will show this. I suspect the majority of the wear is from vibration, and the added voltage is a small contributor. With a smooth softmounted 2C pattern setup, I used to change aileron and rudder gears and pots about every 200 flights (and elevator every 400 flights), and since changing to electric, the maintenance interval on servos has just about doubled. Glow setups with particuarly nasty resonances can eat up servos in <50 flights.

Regards,

Dave
Team Horizon/JR

DaveL322

Dave,

A pair of 9411sa's on elevator pretty light duty (a good thing) for that servo. With tight linkages and geometry that puts your endpoints around 130%, I'd be very surprised to see any substantial wear on the pot or gears in less than 500 flights.

Regards,

Dave
Team Horizon/JR

dreadnaut

My Feedback: (5)

Dave, it's just one 9411 for the elevator. I mounted it in the back of the fuselage to keep the pushrod short, and went to a low profile servo to get it as far back as possible. I thought long and hard on this choice, but I see them used a lot for ailerons on 2m IC planes. I am doing a build thread on it here http://www.rcuniverse.com/forum/m_9245009/tm.htm . Post #1, and post #8 show how it is mounted.

DaveL322

Woops...my bad.

1 ea 9411sa on ele and each ail should live a long time on electric 8s....I'll revise my guestimate to ~400 flights before seeing substantial wear <G>

Dave

BTW - beautiful work with the CAD drawings and construction!

apereira

Dear Ed and all interested,

A servo working on 6V, as said by you and many, as long as the servo permits,i.e. Futaba forbids that on certain servos and on some others models they do not recommend it, but it can be used; so going back to servos that can take it like JR and Hitec and most Futaba, yes, more voltage means better centering, one reason is the holding torque as you mentioned,but this is the servo ability to remain on a given position and does not cover movement only that to compensate the position if disturbed, but the power I meant is the servo ability to return to a precise position, in this case center depends a lot on the servo torque, if it has more power it will overcome the aerodinamic forces and loads more easily allowing to center better than a less powerful servo or the same with less power, this has to be taken in consideration as most dicussions on the forums are based on theoretical parameters only.

On the regulator I understand you might be an electronic engineer or at least very well qualified on electronics, but I have to dessagree about the Ohms law is it has to be calculated separetly on components on a complex circuit and then averaged on the complete board where you have to take in consideration the fact that no all components are going to change their internal resistance due to heat in the same way, and if not controlled (and is ussualy not) by a compensating circuitry to behave as a termistor to reduce the internall resistance on the whole circuit to balance it to the rated internal resistance, the temp and resistance will go up, and this is a variable that belongs to a different formula not covered under the principal an most basic formula for the phisics of electrics/electronics wich is the Ohm law, again I do not know if the regulator we are talking is a single IC or several components where my opinion is more valid, nevertheless depending on the amount of servos and their rated power consumption a regulator temp will be different and this will give a different resistance, we also have to take in consideration the internal resistance tolerance which is usually 10% on most average quality components.

I am not persuing a discussion in electronics or disrespect your opinion in any way, I do understand your point 100% and agree in a big part but not totally, but merely I wanted to express my opninion in the servo power/precision and regulators ussage, thinking that most people asking for advise wants personal opinions based on experience on the matter so they can choose what to use from the open market and not to be lectured in electronics (again for me, I mean of course) , so I apologize for this long response.