what you guys do
05-30-2010, 11:46 AM
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what you guys do
hey guys... I am gonna get me a 50cc Goldwing Sbach... will be using Digital HD9150MG servos... their max current draw at utmost extreme can go up to 3.2A... I will be using a Life4PO pack from Hyperion, the 3000mah one... now my question... the receiver... its a spektrum AR7600... its contact points... will it be able to handle all that current? what do you guys do to prevent loads of current going to receiver... or how do you guys power the servos... whats the process here... thanks
05-30-2010, 03:35 PM
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RE: what you guys do
ORIGINAL: w8ye
The poor man's way is to break out the red/black wires from the servos with direct connections to the same battery.
The poor man's way is to break out the red/black wires from the servos with direct connections to the same battery.
05-30-2010, 10:58 PM
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RE: what you guys do
have you guys tested this to see what currents are drawn then? if basically half the amps theoretically end up at receiver and other half at servos... or how does it work? also what receivers are you guys using? I use an AR7600 to match up with my DX7SE... maybe some pic or drawing to describe what you guys are doing please...
05-31-2010, 07:51 AM
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RE: what you guys do
The problem is a non-problem. You will have to have a stalled servo for that much current. A 50cc plane will do fine since it only has five servos to run and they rarely run at 100% load other than the inrush to get started. The throttle is minor. The ways mentioned are great, but unnecessary. I run all my planes(33%) thru the receiver plus my 40% buddies just use two receivers for redundancy and to split whatever current there is.
05-31-2010, 08:45 AM
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RE: what you guys do
In theory, the answer to your question is no. The connectors we use on the ends of servos/extensions are rated for 3 amps.
of course, in practice, for many of the reasons stated above, you'll be just fine. The 3.2A draw is at a STALLED condition...in other words, the servo is trying to move, but can't. A servo should never see that condition on one of our airplanes.
Will they see 'force" as the surface resists movement in the air? Sure. But stalled? No.
Also, the 3A max for ouor connectors is a maximum constant draw...they can handle brief spikes considerably higher than that. So, again, EVEN if you stalled a servo or, as someone suggested above, it maxed during the initial load, the connectors would, again, be fine.
What you SHOULD pay attention to (though it's not likely to be an issue on a 50cc plane) is the TOTAL current that might be pulled from the battery through the receiver at any one time. At high deflection of all control surfaces (say, an aggressive snap roll at higher speeds) EACH servo is drawing an appreciable amount of amps. If they all need that current at one time, then the TOTAL current is what's being seen by the battery and its connection to the receiver.
Again, on a 50cc airplane, even just a bit of consideration such as using heavy duty extensions instead of cheap standard ones, and providing sufficient power (6V 5S NiMh at a minimum) will keep you well in the safe zone.
So, while it's not likely to become an issue, it IS worth understanding the idea that multiple servos pull a combined current, and one should, at least, pay attention to such things.
As for me, every 50cc airplane I own or have owned has used the standard Rx/Batt connectors and been just fine. My current preferred power setup for ANY 2.4Ghz airplane up to and including 50cc gassers is a 2S 2300 LiPo pack with a Radio South 10A switched 6V regulator. It's quick, simple, easy to install, clean power, plenty of capability to handle any current a 50cc airplane will through at it, and EVEN if the LiPo drops a cell there's at least SOME chance the airplane makes it down safely.
On 100cc gassers, I go with an AR7100 or AR9100 for the higher current battery connections, and make the choice depending upon the airplane's servo requirements.
05-31-2010, 09:26 AM
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RE: what you guys do
ORIGINAL: gboulton
What you SHOULD pay attention to (though it's not likely to be an issue on a 50cc plane) is the TOTAL current that might be pulled from the battery through the receiver at any one time. At high deflection of all control surfaces (say, an aggressive snap roll at higher speeds) EACH servo is drawing an appreciable amount of amps. If they all need that current at one time, then the TOTAL current is what's being seen by the battery and its connection to the receiver.
What you SHOULD pay attention to (though it's not likely to be an issue on a 50cc plane) is the TOTAL current that might be pulled from the battery through the receiver at any one time. At high deflection of all control surfaces (say, an aggressive snap roll at higher speeds) EACH servo is drawing an appreciable amount of amps. If they all need that current at one time, then the TOTAL current is what's being seen by the battery and its connection to the receiver.
05-31-2010, 01:36 PM
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RE: what you guys do
ORIGINAL: Switch_639
also on that 10A regulator, say for instance 3 of my servos draw the 3A max... how long will it be able to withstand over current before it burns out?
also on that 10A regulator, say for instance 3 of my servos draw the 3A max... how long will it be able to withstand over current before it burns out?
05-31-2010, 02:56 PM
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RE: what you guys do
ORIGINAL: Switch_639
I know all this, hence my question... I did say that this is my concern... but as you guys suggest its almost not plausible to happen... only if they are fighting or binding... I also thought because its Digital it pulls max amps at any given time because it has from the first degree of movement, full power torque... I use an AR7600 7channel receiver... also on that 10A regulator, say for instance 3 of my servos draw the 3A max... how long will it be able to withstand over current before it burns out?
ORIGINAL: gboulton
What you SHOULD pay attention to (though it's not likely to be an issue on a 50cc plane) is the TOTAL current that might be pulled from the battery through the receiver at any one time. At high deflection of all control surfaces (say, an aggressive snap roll at higher speeds) EACH servo is drawing an appreciable amount of amps. If they all need that current at one time, then the TOTAL current is what's being seen by the battery and its connection to the receiver.
What you SHOULD pay attention to (though it's not likely to be an issue on a 50cc plane) is the TOTAL current that might be pulled from the battery through the receiver at any one time. At high deflection of all control surfaces (say, an aggressive snap roll at higher speeds) EACH servo is drawing an appreciable amount of amps. If they all need that current at one time, then the TOTAL current is what's being seen by the battery and its connection to the receiver.
05-31-2010, 03:40 PM
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RE: what you guys do
Hi Switch,
I tend to simplify the setup on my 50cc planes a bit and use 2 x 6-cell Eneloop packs for the RX/Servos, a switch on each and a 42% 2Pac for redundancy.
I use 20kg/cm digital servos and have never had a problem with this arrangement.
Admittedly, I'm not a 3D flier but I wring out my planes fairly well so current drain is probably as high as it gets when everything is well set up and adjusted
I tend to simplify the setup on my 50cc planes a bit and use 2 x 6-cell Eneloop packs for the RX/Servos, a switch on each and a 42% 2Pac for redundancy.
I use 20kg/cm digital servos and have never had a problem with this arrangement.
Admittedly, I'm not a 3D flier but I wring out my planes fairly well so current drain is probably as high as it gets when everything is well set up and adjusted
06-01-2010, 07:15 AM
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RE: what you guys do
I skip the regulator and use A123 or Life batteries. That gives 6.6vdc at 2300mah per battery. One battery should be fine for 3-4 10min flights on a 50cc plane, and they can be charged in a few minutes at the field. The high charge rate and safety is what sold me on the Life's. Also get more charge cycles. If you want the redundancy/weight, you can add more. Your call on that.
06-01-2010, 01:30 PM
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RE: what you guys do
If you really have to be concerned with drawing this much current, your toy airplane is way to big to be safe while being flown with consumer grade junk. Life does have its limits, you know.
And before one of you accuses me of being anti large models, I presently own three gas engines over 50cc's in displacement. Some of you just don't know when enough is enough.
Ed Cregger
And before one of you accuses me of being anti large models, I presently own three gas engines over 50cc's in displacement. Some of you just don't know when enough is enough.
Ed Cregger
