Hello all, I'm putting Together a WH Sukhoi and have installed 7 JR 8611a's and one JR Std Throttle servo including a std choke servo. 9 servos total. I'm using 7.4 Volt 2 cell lipo's and want to run 6 volts to the RX and servos. Should I use the traditional voltage regulator that is heavier and hogs power to regulate loltage or new technology BEC (Battery Eleminater Circutry)?? The BEC will regulate voltage input ranging from 50-7.4 Volts down to my desired 6 volts and provide 3.5 Amps to the Servos. I have asked this very question to many LHS guys and they just kinda answer....DUH....? They don't know. I know I can use a Smart Fly unit but I really don't want to. Will 3.5 Amps work in flight? I tested 6 servos ( 8611a's ) and could only get a max amp load of 2.8 Amps while adding almost stall resistance to 2 of them while banging the sticks violently fast on all of the other 5 for roughly 15 seconds. ( 16 Watts total Max ) I've read posts where people claim the servo's can incurr 3+ amps at stall per Servo. I did not find this to be true?

only 3.5 amps avalible to that many digital servos .......not on my plane! [X(]

A fully stalled 8611 can easily and quickly draw over 3 amps initially, backing down immediately thereafter. If all you have been able to note is 2.8 amps then you haven't tried hard enough. The standard servo connectors can take up to about 4 amps before they heat up and begin to fail. Using a regulator that can handle up to 9 or 10 amps is cheap insurance. Using a BEC to save a couple of grams that can handle less than 4 amps is at best reckless.

Personally I run 3 regulators on my 35% planes, one of which is the same Sukhoi. One on the ignition and one for each of my flight battery packs. In big planes I like some redundancy while maintaining simplicity. The flip side of the issue is that you should be able to set all your servos up where they will never stall, but still allow for peak electrical loads when all the servos move to maximum deflections at the same time. Don't forget to allow for wind loading on the flight surfaces. That boosts current consumption considerably.

Question. On a plane that can weigh in between 24 and 28 pounds, depending on the set up and parts selections, just how much will you save by looking for short cuts and minimums in current regulation? Is 1.5 to 2.5 ounces worth a $3,000.00 plus investment? Only you can answer that.

Theese answers are what I'm looking for....Thanks.
Just so everyone knows, I'm not bouncing between the two options due to weight rather but the power consumption and new technology... Yeah who doesn't try and save weight.... I know...But this is so minimal between the two. I want what will work the best here. The servos did jump up rather quickly in amperage when I banged the stiks to quickly settle to a lower draw.
I went as far as having my LHS owner call JR on this today and the "TECH" dept didn't have any amp draw specs to give me at stall or near stall? Get that?

That's because stall values vary with the load imposed at the point of stall. The older Hitec 5945's would hit about 2 amps or so during the initial stall, and the older 8611's would consistently hit 2.4 or better depending on the severity of the stall. I've been able to go quite a bit higher with both manufacturers during load tests. The deciding factor should be an anticipated max load using all the installed servos activated at the same time, and anticipated maximum loads.

A pair of ganged servos, when installed and adjusted as close as you can get, should draw in the area of 0.02-0.04, or less!, at surface neutral. That's using a pair of the original 8611's. Hold current at max deflection with the same pair can hit 0.4, with initial inputs tagging the same or a little more. Add the second wing pair and now you are at 8/10's of an amp at full deflections. Now toss in paired elevator and rudder servos for a current total. If there are no binds in the throttle linkage the draw from the throttle servo is negligible. If the linkage is improperly adjusted the current draw can become high enough to literally flame a pair of servos. I've actually seen this happen on a single servo installation as well where the linkage was of improper length and poorly adjusted. For those that don't have one, I strongly suggest obtain a Hanger 9 servo voltage and amp meter for multiple servo installations. The $28.00 spent can save thousands...

Personally I prefer the Fromeco regulators for various reasons, one of which is the high quality of components and assembly. They state that they regulate to 9 amps or so but I know they do a little higher, plus I can adjust them above 6v if I desire. The overall weight in large models is not much of a factor, IMO, but the ability to properly perform the task is everything.

Very Well Said! Excellent Data. Thank you for this info.
Shayne

Any time, and you're welcome.