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Electric Stunt => Gettin all AMP'ed up! => Topic started by: Ward Van Duzer on May 25, 2011, 11:50:04 AM
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Hi all,
Getting ready to wire up my system on my P' Force so I figger I'll learn something if I read Mike Palko's article on "wiring". In there he says try not to cut the motor wires "too" short as if you need to add back onto them you may need to rewind the motor. Similarly E flite says don't cut the motor wires, you'll void the warrantee! Then Mike says "extending the motor leads to the ESC can damage the ESC". So I don't want to shorten the ESC to motor leads too much either!
So right now I have motor leads 4 1/2 inches
ESC to motor leads 5 inches
Total 9 1/2 inches
I need about 3 (maybe 3 1/2) inches from motor to esc
I guess I could roll them up but all the set ups I've seen have both sets of wires cut back. Am I being to wussy? or should I just go ahead and whack?
Ward-O ~^
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You should make an informed decision!!
From an electrical circuits standpoint, shorter leads are better -- they waste less power, and they present a nicer load to the ESC the shorter they are. But shortening them presents the obvious problems:
- You lose "meat" that you can use to fix problems short of tearing things apart and replacing leads or rewinding motors
- You may not be as good an electronics technician as "they" have at the factory -- 'civilians' can so screw up a simple soldering job, I'm not surprised that E-flight would try to keep anyone from trying
- You lose mechanical isolation between motor and ESC -- meaning that it's harder to dress the leads for low stress, that there's going to be more vibration transmitted from motor to leads leading to faster wear on the connectors, and there's potentially a bigger chance of the leads getting yanked out by the roots in a crash
From an electrical standpoint, unless the ESC circuitry is really weird, the best connection would be the shortest possible leads from ESC to motor, with no connectors at all. From a mechanical standpoint, however, you want to have a service loop somewhere in the wiring harness to mechanically isolate the ESC and motor, and just for convenience sake you want to have connectors in there.
I'm a fairly good electronics technician (I'd say this was because I'm an electronics engineer, but any full-time technician would laugh me out of the room if I did -- it's because I had experience and training as a technician before I got my engineering degree). So if it looked easy enough to replace the wires on the ESC I'd shorten them as much as possible, and put connectors on them at the ESC side. If I thought it was worth it I'd go ahead and void the motor warantee, but keep in mind you want at least some slack, and you probably want enough for a small loop in the wire, or at least a pronounced 'U' bend. If I were doing some special-purpose, super-zoot plane (like speed) I'd strip the cover off the ESC right then and solder the motor wires straight to the pads on the ESC -- but that's a bit crazy for a control line stunt plane.
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Ward,
I've taken the motor leads completely off the ESC and soldered on the female connectors right on the ESC...just like the Schulze ESC's with no problems encountered. I have never shortened the motor leads themselves.
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OK, from what I can glean from the RC folks, long or short ESC to motor leads are no problem. In fact it is recommended to extend the motor leads where it is desirable to locate the battery in a distant position from the motor. On the other hand long battery to ESC leads are a NO NO!! These leads should be kept as short as is possible to avoid zapping the ESC. Adding additional capacitors to the ESC can help prevent the ESC from failing but short leads are the way to go. Twelve inches maximum is the rule of thumb for ESC to Battery leads according to Castle for their ESCs.
Google: ESC to Battery lead length and ESC to Motor lead length
You will get all kinds of info.
John
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I have shortened leads on ESCs and motors with no issues at all. The only thing I will warn you is both the Arrowind and Hobby Shack motors I have shortened the leads on required taking sand paper and removing the lacquer (or something) on the wires. They both use multistrand insulated wire that cannot be soldered to until they are cleaned. No big thing, just a few minutes with some fine sandpaper will remove the lacquer. On my 1/2a Pathfinder I shortened every wire and removed all the connectors from the ESC to the motor. I saved .7 ounces in the nose of the plane.
Andy
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There is an issue to cutting wires short that has not been mentioned. I ran into it on 2 different planes, one a pattern plane and one a CL stunter. Having done a lot of wiring over the years I like my wires neat and straight and nicely bundled. I use Deans Connectors between the batteries and esc. On both planes while in flight the deans connectors seperated and came disconnected. They were not under tension and neither the battery nor the esc moved. But the vibrations... yes, our electrics do still vibrate some, caused the deans connectors to seperate in flight. Niether plane was lost. Good to have an angel onboard each time. The failure occurred on landing with the rc plane. But in all my planes now I make sure there is at least a 180 degree change of direction in the section the deans connectors are in to create added tension on the connectors. Since doing this no failures. No more neat and straight where they are concerned. Your milage may vary. ... I know I would not have expected it with as snug as Deans connectors usually are, but they all vary and they do wear.
bob branch