Heres an idea for weight savings- maybe. I searched, but did not find any posts here on this. What about small aluminum tubing for esc to motor connections instead of copper wire? We are dealing with 3phase AC at this point- DC wiring specs end at the input to the esc. We are also dealing with considerable weight savings, ability to use bullet connectors (or just crimp), and minimal loss in conductivity. I'm thinking of 3, 3mm ID x 4mm OD tubing laid flat and siliconed together- but separated- at the ends and middle and use a anti-corrosion paste like No-Ox at the end connectors. Aluminum is widely used in other AC applications, could it work for us here too? Any comments?
Well for on thing you can't solder aluminum, so are you talking about crimping? If you are going to crimp them the you might as well use a OTS plated crimp splice or "butt" connectors. They are all ready insulated and optimized to do what they do.
I mean to replace the three lengths of copper wire from esc to motor- a foot or more each in some cases- 12 feet or more total on a quad. I was actually thinking just stuffing the gold plated bullets from motors or esc's into the ends of the three lengths of small Al tube with anti corrosive paste- but a crimp would work for more permanent (eek!) conection. And thanks for the reminder!!! I have soldered aluminum using LOTS of flux and rosin core 60/40 electronics solder and higher (400C) soldering iron temps- trick to it is that ya gotta keep all the O2 out. I didn't believe it til I did it. I do all sorts of unorthodox stuff just to try it tho... gonna run weight and conductivity calcs: i'll get back to ya with data...
I am for sure missing something... so dont take it personal... :)
Why don't you just cut the "excess" wire to desired length? Or are you actually suggesting replacing the "traditional" arms with the newly created connector tubes?
Either way don't get it how it will be better than wires... to me too stiff and vibration will break the connection (even for a fraction of second) forcing the ESC to reboot... not good for Quads!
Explain more, maybe you are on to something interesting but I don't follow you... :)
Well, google came through again. The tubing I referred to would be roughly equivalent to 10ga wire in cross sectional area, with safe ampacity of 20A and resistance of .0016 ohms per foot- same as 12ga copper wire.
Weight: Al 10ga wire weighs .152 oz per foot, Cu 12 ga wire weighs .809 oz per foot- yikes!! Al is 1/5 the weight of Cu for the same conductivity!?!? For my '12 feet of wire' example, it would shave off 7.8oz (220g) to use 10 ga Al wire instead of 12ga Cu. That's almost the weight of my motors!! I like those numbers! Anyone else wanna double check my math? Seems right, but...
Your weight of 10 AWG aluminum wire is correct, but your copper weight is not. For 12 AWG copper wire, I calculate 0.318 oz/ft (boo imperial units).
Aluminum has a much better conductivity to mass ratio than copper, but copper is more volumetrically efficient (and a lot easier to work with). You could shave a little weight by going to aluminum conductors, at the expense of much more effort.
John- Thanks for the double check- thats why I asked- its too easy to skip steps. Rechecked my own math again and I get your number for Al weight per foot- .318- so actually 1/2 instead of 1/5 the weight- still substantial, but not as cool as I thought.
Don- good idea- I will be paying a buddy of mine to weld up a bigger Al frame and use the frame as ground. Its likely not worth it on my current quad- I'll just go with soft copper wire- easier, faster, better conductivity...
For the current quad project, I have room inside my frame for the esc's to sit right under the motor so the 3ph wiring will only be about three inches long- the supply wires will be almost a foot long to run from esc to the batt.