Copper wires

[Ub Hauled]

has anyone used regular large gauge solid copper wires on your setups?
I was thinking about using it for a large boat, where keeping the wires short is
a problem... opinions?

[ED66677]

a solid single copper conductor is less efficient than a multi conductor one, moving electrons get concentrated on the outside of a conductor, that's the reason why good quality cables are made of numerous very thin conductors!
if you use solid copper wires you will have to oversized them, it'll be heavier.

[Meniscus]

Agreed. If you are looking for some specialty wire, give this place a call and let them know what you are looking for. I've used them in the past for all types of wire including some fancy audio wire for studio installs.

http://skycraftsurplus.com/

Website sux and only shows about 1/25 of stock. Give them a call, they have walls and walls of wire and other stuff including milspec if you want.

[ED66677]

I was about to give somehow the same suggestion, I use audio cables for my boat setup, not the one for speakers but those for power, lot cheaper than flexible silicon ones availlable in RC shop but also less flexible.

[AndyKunz]

a solid single copper conductor is less efficient than a multi conductor one, moving electrons get concentrated on the outside of a conductor, that's the reason why good quality cables are made of numerous very thin conductors!

NOT TRUE! Unless you are running high-frequency AC, this is simply not true.

High quality cables are made out of stranded wire to allow the cable to flex. It's a mechanical issue (aside from being easier to manufacture). A solid copper wire 3mm in diameter is much harder to bend than a cable of multiple .5mm wires bundled together.

For our applications, the current is carried through the whole cross-section of the wire. Current capacity is based on the cross-sectional area.

Here is a table for your reading pleasure. Note that the "Wire Area" column is in circular mils = cross sectional area.

http://www.rencousa.com/wiretable.htm

Andy

[Doby]

Some info on this topic.

http://www.rowand.net/Shop/Tech/WireCapacityChart.htm

[Doby]

And another one.

http://en.wikipedia.org/wiki/Wire

[ED66677]

Andy, I agree with you

Unless you are running high-frequency AC

, but don't you think in our applications and especially in brushless setup where the ESC is generating a frequency, the current is not really DC? it is between bat and esc though I don't think it really is between ESC and motor!

[AntronX]

NOT TRUE! Unless you are running high-frequency AC, this is simply not true.
Andy

There is high frequency AC on the motor's side. At 10 KHz PWM, I would think that skin effect would be an issue. Even on the battery side there is high frequency PWM ripple that is left from what capacitors cannot completely smooth out.

[Meniscus]

For the record, I was not refering to speaker wire. Just wanted to clear that up.

[AndyKunz]

10kHz is not a skin effect issue, but if you want to do the exercise you can pull the wire dimensions from the Renco table, use the amperage ratings and wire lengths from your favorite ESC, and have at it.

Also, you might note that even the Wiki (not exactly the best source) notes that regular stranded wire increases the losses. Litz wire is more appropriate for RF than the audio frequencies where we run.

Andy

[Ub Hauled]

Guys, since you are talking about skin effect...
I understand skin effect happens at high power,
at what power levels does it start to become a problem?
if at boat applications we don't achieve those levels then
there is less resistance on solid cables, correct? Or should I just stick to
Litz cables?

[AndyKunz]

If you can afford Litz cables, you're too rich to be playing with toy boats. Unless you're running them off your 45' yacht.

It's not a power level thing, it's a FREQUENCY thing. Audio frequencies are not going to be a problem. Just run the regular stranded wiring and BE THANKFUL that it's not an issue!

Andy

[Ub Hauled]

Long cables are a problem Andy, you know that...
I am trying to figure out ways to overcome this.
So solid cables are not a solution, is that what you are trying to say?

[10gauge]

Ub-Hauled, I agree with Andy on theory and practice.

I use at least 10 gauge (pun intented) multistrand copper wire because it's the best trade off between lowest resistance and flexibility. At the solder points, I use Mundorf high silver content solder from Germany. I use Mundorf solder and Gold/Silver Capacitors when making audiophile speaker crossovers and they make great stuff!

If you're worried about resistance:

1. Use 8 gauge multistrand copper wire.
2. Use high content silver solder.
3. Make your wire runs shorter.
4. Convert to 6mm connectors.
5. direct solder the ESC to the motor.
6. Use multistrand silver wire in your runs, but gets expensive.

Measure the resistance of each setup and see the difference. Honestly, the improvements might be marginal at the end. Good Luck!

BTW, as far as audiophile speaker wires go, I make my own speaker cables from six twisted braid of CAT-5 wire and it renders a very detailed sound across the entire frequency spectrum.