kolarshooter

My Feedback: (1)

Danny,

Finishing up a 34% CA Extra and have only batteries and regulators left to install. How much current draw should I expect from each 8611? I guess I'm curious about "normal" draw and stalled draw.

Next...Reading the information provided by the Li-Ion/regulator purveyors (Smart-Fly, Duralite, etc.), it seems we need seemingly endless current and capacity with redundant everything. Part of their "sales pitch" involves the limits of current flow through the Rx, so now we need power distribution panels. Jeepers!

I will use Li-Ion w/regulators for ignition and Rx. I have plenty of faith in modern Lithium batteries and don't really want to weigh down the plane with unecessary and costly equipment. It seems we're supposed to buy these many items to increase reliability, yet in many cases if any ONE of these components fail, you've lost your plane. I'd rather rely on a minimum number of components.

If I move to 40% planes with dozens of servos, then I expect to change this thinking...but this is only a little 34% IMAC plane (one 8611 per aileron, and one 8611 per elevator half...currently with one 8611 for the rudder...although I expect to add a second to the rudder, and one on the throttle.)

So, in short, here are my questions:

1) How much current draw shoud I expect from an 8611 under normal use and when stalled (maximum workload).

2) How much current can I expect 1 battery connection to my NER-649S receiver to reliably provide? The reason I ask is that the Smartfly website states that "The standard R/C connector is rated for about 3 amps continuous operation." Do I need to provide two battery inputs so as to not overload a single battery conection at the Rx since that one connection will carry the totality of current used by all servos as well as the radio function?

3) Is there any reason, based on the construction of the NER-649S receiver that I need to back-up the Rx with a power distribution panel to run 7 8611 servos?

I'm curious to learn what JR's position on this is. Thanks!

dsnyder

1. How much draw you will see in use is entirely dependant on the aicraft and set up, and the flight conditions (how the airplane is flown). There are too many variables to put a number on it. I would say in most cases it is rare to draw an amp, likely average around 1/2 amp to 3/4 amp in most cases, but again, it varies greatly. Stalled current will be somewhere between 1.5 and 2 amps.

2. I don't have a figure on the connector rating, but 3 amps may be close to the rating, however they can exceed that for shorter time frames. In giant scale aicraft, I generally recommend running 2 batteries through 2 regulators and 2 switches, one so that the current capability of the system in increased, but also for redundancy. The receiver itself can handle extremely high current draw, a receiver can eaily handle most any aircraft.

3. No, no need at all. I have an aircraft with 12 servos right now (11 8611A's and 1 8231 for throttle), simply running dual batteries as mentioned earlier. With 7 servos, one larger battery would likely work fine, but 2 allows for some redundancy in the system.

kolarshooter

My Feedback: (1)

Thanks for your thoughtful input.

I'll go with the redundant Li-Ions.

Robert.

cap10b

Danny,
Running 5ea 8611A on 8.4 volts thru MPI adjustable regulators, what is the highest voltage at 1 amp load can I safely adjust the regulator to ? The receiver runs on a seperate circuit ala I4C so its independent of servo voltage.


Thanks

Johnny

dsnyder

I would suggest setting it around 6-6.5 volts if you want to run it at higher voltage. You can safely go over that, however you might see jittering, and the servos will wear faster.

cap10b

Danny,
Great I am at 6.2 VDC now at 1amp load and they run fine, good to know they can run higher if needed. As far as wear and slop mine are solid and quiet no gear noise or metal to metal noise. Keep up the good work.

Thanks

Johnny