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You are talking about a motor with 5 amp maximum current? (Not 5 amp average, which would have a considerably higher maximum?)

23 AWG wire has a resistance of 0.02 ohms per foot.
That means it will drop 0.1 volts per foot at 5 amps
I guess most slot cars would have no more than 150mm/ 6 inches of lead wire each side, so that gives a loss of less than 0.1 volts at 5 amps.
(There is always some loss however thick the wire, but it can be too small to worry about.)

For that sort of application 23AWG is rated at 4.7 amps continuous maximum (lower currents will be listed for power transmission, that isn't relivant to this application). In a slot car, a motor with 5 amp maximum current would be drawing much less than that most of the time, so that's OK. For a motor with 5 amp average current, thicker would be advisable.

That's the electrical answer, you might want to go thicker for a more robust wire.
 

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I've seen proper slot cars use 26g copper rewind wire as lead wire to save weight in qualifying!
Most modern proper cars use very fine multistrand wire for flexibility and current conduction, cased in silicone rubber insulation. Overall dia is around 2.5mm, the conductive bit is around 2mm.
Are you trying to save weight/limited for space/just interested?
 

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Slot King
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We have had this little discussion before.

Some think avoiding voltage drop is most important, others that a more flexible wire is most important.

Thick wire symdrom is a recent trend, probably inherited from R/C cars (where it is important).

The voltage drop is a bit of a red herring, and as Roblees mentioned, "proper" racers are now moving back to thinner/lighter wire because apparently,the weight reduction brings more gain than avoiding voltage drop.
But, somehow many people still think thicker is better.

John Secchi previously recommended RS part#2857662 which will work fine for anything, use that.

Joel
 

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Discussion Starter · #5 ·
i was just curiose. ive got a new 12v-30amp power supply i,m wireing in, and a lot of my motors take more than 5 amp continuose. i buy the silicone wire from china, and wanted to know the thinest gauge i could get away with. john
 

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QUOTE (stoner @ 16 Mar 2012, 09:06) <{POST_SNAPBACK}>i was just curiose. ive got a new 12v-30amp power supply i,m wireing in, and a lot of my motors take more than 5 amp continuose. i buy the silicone wire from china, and wanted to know the thinest gauge i could get away with. john
Can you be a bit more specific about what motors you are using?
You can get away with the same thickness of wire the armature is wound with, but there may be advantages in going a bit thicker than that.

QUOTE (merkit the grof @ 16 Mar 2012, 08:27) <{POST_SNAPBACK}>Some think avoiding voltage drop is most important, others that a more flexible wire is most important.

Thick wire symdrom is a recent trend, probably inherited from R/C cars (where it is important).

The voltage drop is a bit of a red herring, and as Roblees mentioned, "proper" racers are now moving back to thinner/lighter wire because apparently,the weight reduction brings more gain than avoiding voltage drop.
But, somehow many people still think thicker is better.
Paulo Trigilio is the current world champion in 4 classes, all 4 of his winning cars used thick wire all the way from motor to guide.
So at least one of the many people who still think thicker is better seems to know a thing or two about making slot cars go quickly!

It might be worth mentioning that in a lot of the quicker cars (including Paulo's), the lead wire is used to self centre the guide. When used in this way, a certain amount of spring in the wire is important.
 

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Slot King
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QUOTE (300SLR @ 16 Mar 2012, 09:52) <{POST_SNAPBACK}>Paulo Trigilio is the current world champion in 4 classes, all 4 of his winning cars used thick wire all the way from motor to guide.
So at least one of the many people who still think thicker is better seems to know a thing or two about making slot cars go quickly!

It might be worth mentioning that in a lot of the quicker cars (including Paulo's), the lead wire is used to self centre the guide. When used in this way, a certain amount of spring in the wire is important.

I think it is a little disingenuous to use a world champion as an excuse to confuse the 20000 or so forum members who race Slotit Ninco, Fly, etc... Perhaps we deserve better advice.

I have seen with my own eyes a multiple world champion pushing other drivers off the road in an effort to stop them overtaking. Yet I wouldn't recommend it to anyone on their way to work.

The fact is, current draw is always quoted as the peak current which is only drawn a zero revs (ie just as the car starts)

It bears little relationship to how much current the motor actually draws in race use (where the motor speed never returns to 0).
High performance cars will go round corners with their motors still revving very high (big corners, good handling), minimizing the current draw when power is re-applied.
It would be interesting to continuously record the current draw of various cars actually going round a track, I think it would surprise a few.

The sampling rate of a peak current meter (designed to measure motor start currents) is generally 2 milliseconds, otherwise it would miss the peak current.
Loosing 0.1V or 0.5V for 2Ms at the start of the race is unlikely to make a difference to the result at the end of the race.
On the other hand running too thick/stiff a wire will stop the guide working properly in most modern plastic cars (as used by all of us on this forum)

The neat trick with thin wire is that you can use it with all your cars (regardless of the motor).
If you are worried about the 2Ms loss, you simply double or treble the wire (but you can't "thin out" a thick wire).
This is what all the fast guys used to do before it became fashionable to use thick wire.

So if you want a "universal" wire, thin is the clever way to go, thick isn't.


Joel
 

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I wouldn't recommend using the same size wire for everything, Rich's suggestion of 18 AWG for the, quicker cars is about right. Something much thinner is suitable if you have any home set type cars (which of course take much less than 5 amps even at peak).

QUOTE (merkit the grof @ 16 Mar 2012, 19:26) <{POST_SNAPBACK}>I think it is a little disingenuous to use a world champion as an excuse to confuse the 20000 or so forum members who race Slotit Ninco, Fly, etc... Perhaps we deserve better advice.
Perhaps when a slot forum member with a 23awg arm in a cobalt qualifying motor asks about what to use on that car, he should expect advice relivant to that sort of car, and his other cars which take over 5 amps continuous.
Isn't what the world champion uses on his cobalt motors relivant to that sort of car?
I for one think there is something to be learnt from world champions in their field of expertise.

Of course, had stoner asked about Slot.it or Ninco cars he would expect advice relivant to those sort of cars. Remember he told us "a lot of my motors take more than 5 amp continuose." which clearly isn't Slot.it or Ninco cars
 

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Nobby Berkshire
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Nobody is going to be able to answer this accurately due to the specialisms of your power supply, so why don't you wire a car with NSR ultrathin wire and one car with thick wire and simply take a series of lap readings to judge for yourself.
 

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thanks for the advise guys, ive got some 18awg and 22awg soft flexy silicon wire on order from china. the majority of my cars are homeset motors but even a 16D takes 5 amps to spin it. i think that the 22awg will be more than thick enough to use on all my leadwire, from what ive read here, so thanks again everyone, for the info. the ebay, euro sport set up i bought was out of curiosity, i didn,t realise it had a cobalt motor and very expensive lazer cut chassis in it. so it was a bargain at £20 even tho i could only just afford it. john
 
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