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Old 11-06-2007, 10:17 AM   #1
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Default Wiring ESC: 12ga or 14ga?

I am looking to finally rewire my esc this weekend and have always been told that the 12ga is the way to go for the obvious reasons of less resistance and such. My question is, it is such a pain in the butt to rewire my Novak GTX with 12ga wire, is there that big a difference between 12ga and 14ga for a 19t or 27t class?
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Old 11-06-2007, 11:15 AM   #2
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No...
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Old 11-06-2007, 12:52 PM   #3
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Hmm, I don't agree with you :

12AWG is ~3.31mm2 and 14AWG is ~2.08mm2, that's a big difference !
(sorry for the conversion, I'm european ;-))

12 awg is nominal 15A and max 25A, 14AWG is nominal 8A and 14A max
(depends a little on number of strands and setup (silver coated etc)

Even with a 27T your current will reach values above the 10A no problem.
If you use silicone cable, that is no a real problem, it just get's hot, but will slow down your motor !

If you have problems with the stiffness, look at 'wet noodle' really the best cable I have ever seen, very very nice to handle !
http://www.wsdeans.com/products/wire/index.html
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Old 11-06-2007, 01:07 PM   #4
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Quote:
Originally Posted by snoebel View Post
Hmm, I don't agree with you :

12AWG is ~3.31mm2 and 14AWG is ~2.08mm2, that's a big difference !
(sorry for the conversion, I'm european ;-))

12 awg is nominal 15A and max 25A, 14AWG is nominal 8A and 14A max
(depends a little on number of strands and setup (silver coated etc)

Even with a 27T your current will reach values above the 10A no problem.
If you use silicone cable, that is no a real problem, it just get's hot, but will slow down your motor !

If you have problems with the stiffness, look at 'wet noodle' really the best cable I have ever seen, very very nice to handle !
http://www.wsdeans.com/products/wire/index.html
these are 120v ratings.

while there is a measurable loss, at load, over a short distance of 12 vs. 14 gauge wire, the difference is nominal.
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Old 11-06-2007, 01:30 PM   #5
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Nope, no relation with voltage !

The current trough the wire times the resistance gives you the voltage drop you get on the wire. Doesn't matter if you start with 110v or with 1v, the drop will always be the same with the same current.

But due to the low voltages used, a .5v drop or so is noticable when you have 7.2v to begin with.

There are a lot of very expensive packs which are matched and pushed just to get those extra couple of tents of voltage. Believe me, they make a real difference !

ps. I live in Europe.. so our mains is 230 :-)
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Old 11-06-2007, 01:37 PM   #6
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I don't think there will be a performance advantage that will be noticed. I run an 8 turn in my 1/12 scale with 16 gauge wire and a 19T in my TC with 14 gauge.
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Old 11-06-2007, 02:00 PM   #7
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If you run no high-end motors and/or high-quality packs you won't notice the difference.

But for the people who look for the best possible setup, 12AWG cabling is better than 14AWG, but the gain won't be hudge.

But why spend a lot of money on great motors, very expensive ESC's with very low resistance, pushed and matched racing packs and then let the wire eat up the advantage ?

I agree, with the length of the cable, the difference between 12 and 14AWG is not big at all.

But I think you never should save on those (very inexpensive) parts on a car.

Again, there is very good flexible cable out there, which can be well molded into your car.
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Old 11-06-2007, 02:23 PM   #8
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You are a little off in your calculation. Even at 1 foot the difference in voltage drop between 12 gauge and 14 is only 0.02 volts. Based upon an allowable 2% voltage drop over 1 foot assuming 7.2 volts and 20 amps, a 14 gauge wire is adequate for the job. Sorry, to those whose brain just exploded.

here is a link that explains it: about halfway down the page is a nice calculator to plug some numbers into.

http://www.stealth316.com/2-wire-resistance.htm
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Old 11-06-2007, 02:37 PM   #9
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But I didn't do any calculation, the .5v was just as a example.

Still your are not completely correct, the 14AWG will get hot and the resistance will increase rapidly !

14AWG will not deliver 20 amps for a long time After a couple of seconds it will be so hot that it will melt any parts that are close in the car.

The guy who put in the question is just using a 27T, so I don't expect such high currents, he should be fine with 14AWG, but that was not the question here.
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Old 11-06-2007, 02:49 PM   #10
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Quote:
Originally Posted by snoebel View Post
But I didn't do any calculation, the .5v was just as a example.

Still your are not completely correct, the 14AWG will get hot and the resistance will increase rapidly !

14AWG will not deliver 20 amps for a long time After a couple of seconds it will be so hot that it will melt any parts that are close in the car.

The guy who put in the question is just using a 27T, so I don't expect such high currents, he should be fine with 14AWG, but that was not the question here.

The guy is running 27 turn and 19 turn motor. There will be no noticable difference for the application he talking about....
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Old 11-06-2007, 03:27 PM   #11
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Quote:
Originally Posted by snoebel View Post

14AWG will not deliver 20 amps for a long time After a couple of seconds it will be so hot that it will melt any parts that are close in the car.
Yes it will, or even more. At 110 or 220volts no, but at 8 or less volts it won't have a problem. I have a 30amp discharger that is wired with 14 gauge and after about 2 minutes of use the wires are only slightly warm. A good way to rate current is wattage. Watts=amps x volts. So 20 amps x 8 volts is only 160 watts. If you are comparing that to household voltage of 110 at 20 amps that would jump to 2200 watts! In that scenario the 14 gauge would quickly melt and start fires. However in an r/c car, not hardly.

So to actually answer the question:

CarKing- Can you drive for 5 minutes without crashing consistently? If not, don't bother with 12 gauge because any difference in power will have been eaten up by just the slightest touch of the boards.
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Old 11-06-2007, 03:50 PM   #12
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Not to make anyone elses head explode but the heat generated in watts is even less than the power consumption. Where the Power = (current squared) times (resistence of copper) times (length of wire) dived by the cross sectional area of the wire. This equals out to a little over 100 watts of heat generated. Once again hardly enough to melt butter over a 5 minute race let alone "parts".

AHHHHHHH! now my head hurts
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Old 11-06-2007, 05:37 PM   #13
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Quote:
Originally Posted by snoebel View Post
14AWG will not deliver 20 amps for a long time After a couple of seconds it will be so hot that it will melt any parts that are close in the car.
That is patently untrue. I have 14 guage wire connected to a Competition Electronics single cell holder I use for rematching cells. I discharge the cells as 35 amps for up to 400+ seconds. The wire gets warm, but nowhere near hot enough to melt the solder connections.
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Old 11-07-2007, 12:42 PM   #14
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Wow this turned out to be more of a debate than I thought it would. What do you guys use personally? Does anyone have a GTX that they use the 12ga wire in that they could give me some tips on when I rewire it? Those hole on the esc are a pain to get the wires in once they have had any solder in them at all!!!
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Old 11-07-2007, 01:00 PM   #15
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Little tip on rewiring ESC holes. Get old wire out. Put soldering tip on backside of one of the holes and blow hard through the hole to get rid of solder. Make sure you and anything valuable is NOT on the other side cause it will get 700F molten solder on it.

Pre-tin/solder your new wire lightly and put through ESC hole cold. Then heat up wire sticking through with iron and bit more solder. All better now.

Helpful hint: Use Serpent cleaning putty to hold ESC in place so you can have 2 free hands for the rewiring job.

BTW, I tend to go overkill on wiring myself. Use the biggest wire you can get away with in the car. You can't go wrong with over-spec'd components even if you can't feel it on the track.
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