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Old Feb 14, 2006, 08:36 PM
uhhh....this thing on?
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Amp draw for rx and srevos?

Anyone know what the amp draw is for a typical micro rx, and micro/mini servos. Not looking for exact, but a good "rule of thumb".

I am hearing 45mah for a rx, but not sure about servos.

I have a 4.8V rx battery 2200mah. Wanted to know approximately how long it would last with a rx and 4 servos (micro).
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Old Feb 14, 2006, 09:10 PM
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I've run up HS55's and they draw about 200mA when moving - maybe up to an amp when stalled. But at 'tickover' they draw almost nothing.

Reciever at 10-50mA sounds about right.
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Old Feb 14, 2006, 09:23 PM
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Quote:
Originally Posted by skyking1231
Anyone know what the amp draw is for a typical micro rx, and micro/mini servos. Not looking for exact, but a good "rule of thumb".
You can go to servocity.com and check the "official" values for each type of servo or receiver (assuming they carry the brands that you care about).
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Old Feb 15, 2006, 04:49 AM
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Sometimes I'll fly a new plane for an hour, and then cycle the pack to get an idea of the amp draw. In your setup, with completely free, non-binding linkages, I would give you a 200-250 ma/hr draw. So let's simplify and say 10 hours of actual air time.

A Berg 5 DSP Rx draws 8ma.
Hitec Electron 6 draws 12ma.
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Old Feb 15, 2006, 06:44 AM
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Quote:
Originally Posted by AndreyT
You can go to servocity.com and check the "official" values for each type of servo or receiver (assuming they carry the brands that you care about).
They do not list on load or stalled current though.
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Old Feb 15, 2006, 07:44 AM
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The answer to your question is..............it depends!
You've not said what type or size of plane your system is in. In a 40 sized trainer type plane a 600mah pack will last as long as the transmittter battery does if you're flying arelaxed racetrack pattern[over an hour of flight time]. In a 30% bipe with all digital servos i use over 350ma in one wild and crazy 10 minute flight.
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Old Feb 15, 2006, 07:57 AM
LcJ
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If you have $16.00 to spare this will help tremendously. Maybe a couple of buddies could go in together and buy one. You don't need to run it all the time and it is so simple to use.

If you are interest in the older version, I have one you can get for $10.00. Then I will buy the newest one!

It truly is a great little device.

Lyle
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Old Feb 15, 2006, 08:48 AM
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I'll second Vintage's servo current of 200ma each. My dual conversion receiver draws 40ma and 35in-oz torque servos drew about ~160ma each when moving but without any aerodynamic or hinge-friction load (were not connected to any surface). I did not measure servo idle current but the 40ma "receiver" number was the same with and without the three servos when idle.

When calculating servo load, keep in mind that a flap servo draws almost nothing until it moves so unless you have more hands than I (and transmitter with a flap twist knob), it means only three servos will move when lowering flaps.

Alan

LCJ Thank you very much to the Dimensions Engineering link - nothing like an idea whose time has come (for me). If you have a bit more money and want to measure inflight electrical performance, you might want try one of these: http://www.eagletreesystems.com/MicroPower/micro.htm
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Old Feb 15, 2006, 10:07 AM
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Quote:
Originally Posted by vintage1
I've run up HS55's and they draw about 200mA when moving - maybe up to an amp when stalled.

Actually much lower for HS55's:
http://www.rcgroups.com/forums/showp...2&postcount=12

Mike
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Old Feb 15, 2006, 11:45 AM
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Quote:
Originally Posted by pda4you
Actually much lower for HS55's:
http://www.rcgroups.com/forums/showp...2&postcount=12

Mike
I stand corrected. I never dared stall one..

Howevere everyone agrees that its between 150 and 200mA 'on the move'
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Old Feb 15, 2006, 12:00 PM
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Quote:
I stand corrected. I never dared stall one..
I too was shocked. I would have guessed an amp or more too. They are just efficient little dudes. Especially when compared to others.

Good to know.

Now if we could only get the 55's to turn faster My only remaining hs55 complaint.

Mike
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Old Feb 15, 2006, 12:37 PM
Southern Pride
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Quote:
Now if we could only get the 55's to turn faster My only remaining hs55 complaint.

Mike
6 volts.

I have yet to understand why ESC manufactures do not provide regualted 6v instead of 5v anyway. Well yes the amps would be up a little on the voltage regulator but the required voltage drop would be less.


Charles
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Old Feb 15, 2006, 01:15 PM
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I'd like to see an extra wire-connection between ESC and battery which would tap off a lower voltage for the BEC than the full battery pack. That way, we could have 4S or 6S packs but the voltage feeding the BEC would be no more than 2S. Yes, it would probably unbalance the pack but I'm not sure it would be enough to cause problems. Any thoughts?

Alan
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Old Feb 15, 2006, 02:44 PM
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Excellent info from Ivanc, this shows that if you had 3 HS-55's under a partial load you could easily be drawing an instantaineous current of over 600 milliamperes. Now you can see why it is so important to keep wiring and connector resistance low or you will loose lots of power in heat.
Icrashrc, I think you mean milliampere hours, not milliamperes, correct?
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Old Feb 15, 2006, 02:52 PM
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Quote:
Originally Posted by Al Offt
I'd like to see an extra wire-connection between ESC and battery which would tap off a lower voltage for the BEC than the full battery pack. That way, we could have 4S or 6S packs but the voltage feeding the BEC would be no more than 2S. Yes, it would probably unbalance the pack but I'm not sure it would be enough to cause problems. Any thoughts?

Alan
A few have done that but it is a bad idea overall unless you really under LiPolys ,pack imbalance causes and cures etc.

A 800 mAh AAA NiMH 4cell battery would weigh approx. 2 oz. and would provide close to 2 hours of flight power to the rec. and servo for many electric flyers.
A seperate 5 or 6 volt switching regulator BEC cost approximately $20 and has no problems being ran from 4S and some up to 10Cells or more..

http://www.dimensionengineering.com/ParkBEC.htm

Charles
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