Wire Gauge and plug Size

[Charlie-III]

Originally Posted by RickM

I am an electrical idiot so here is one for you guys who get this stuff much better than me. I am running mini mambas and I used the stock wires that came with the mini's. I did wind up using what I had to connect the motor leads. As a result I now have a smallish gauge wire coming out of the esc to a larger gauge wire going to the motor. Is this bad?

I assume you mean Mamba Micro Pro??
Keep the ESC to motor wires as short as reasonable (leave some extra to swap motors, move to a different rig). Adding in a larger wire helps reduce wire line loss, but the "system" will be limited by the smallest wire size.
Likely you won't notice the difference though.

[EddieO]

You solder your RX plugs? A transponder, I am assuming you have an AMB, just plugs into the battery spot on the reciever port....or any open channel.

I like boobs.

Later EddieO

Originally Posted by Charlie-III

Shortly after I got started in 12th pan car racing, we had no connectors (Tamiya & crappy bullets were all that was around....).
We chopped down all wires so they fit + a tiny bit.
ESC was soldered direct to the motor (a bit of wire twisting to reduce EMI/RFI), packs had solder tabs on them to direct solder to the ESC.
We used medium silver content solder to reduce resistance. The RX was soldered into the ESC & steering servo.
This was for 27T "club stock" motors.

Did it help? Who knows.
Did I feel better? Absolutely!

Granted it shafted me last fall when my son & I started carpet racing, we needed transponders that used external power. All my connections were soldered so I had to drag out an old RX connector & solder it in to power the transponder.

In crawlers, going ~14ga wire is fine. If you have an ESC that has smaller ga wires on it, keep them really short to reduce losses.
About the only time we really load a rig is when we're in a bind. That is usually a good time to limit power....BEFORE you break stuff.

[Charlie-III]

Originally Posted by EddieO

Look at this way.....wire is like tits....bigger is better.....

I do promise you though, 1/4 throttle, 1/2 throttle or full throttle....voltage drop happens. The fact you are rarely at full throttle is irrelevant....smaller wire is making everything in the circuit work harder at all times.

I spent 10 years in competitive car audio.........even worked in the business. Voltage drop is a big deal.....trust me....same thing, quarter volume, half volume or at full....just the way it works.

Now whether most crawler guys can FEEL it, whole nother matter.......


Later EddieO

As to the tits thing, I won't comment, my son is on this forum as well......

Voltage drop....yeppers. Noticeable in a crawler....not really likely.

As to automotive audio....funny & true story. I had a family member in the auto biz (worked for a European mfr) that hated the latest model sound system (not a cheap car mfr). The bass was sorta missing. I tore up some interior carpet in a ~$60K car and ran 2 runs of 12ga cable lay speaker wire from the amp to the rear speakers. Instant bass!

Signals run on the surface of the wire, that is part of why a silver or gold plated stranded wire works better than others. Lots of silver or gold plated strands carry more/better signal as well as more amps (bass is a power eater....). Using a 10ga solid wire won't give you as much sound power (cleanly) as a ~14ga high strand count copper wire will.
I frankly find it useless to run OFC wire that is plated (OFC = Oxeygen Free Copper) since the signal basically never see's the OFC part, only the plated part.

An automotive jumper cable only needs to be big, the high strand count only makes it easy to coil up.
We run high strand count wire in RC to make life easier to run the wire in tight areas.

[Charlie-III]

Originally Posted by EddieO

You solder your RX plugs? A transponder, I am assuming you have an AMB, just plugs into the battery spot on the reciever port....or any open channel.

I like boobs.

Later EddieO

We used to, back before the purple NiCads came out (back in the yellow SCE days.....SCR's came later). Any frikkin loss we could avoid we did. Thus, we chopped off all connectors, shortened wires and soldered it together.
I was running 2 channel radios (Futaba Magnum Juniors......both still work, I still run them in 12th & 10th pan cars). I had no spare RX port, thus no place to plug the AMB in....sigh. Good thing I hold onto old bits.....

[EddieO]

EddieO has been racing that long too....I still got a pack of 1200 SCEs some where (very rare, most were 1700). My first pistol radio was a magnum sport (the old boxy kind, not the hip looking ones).

While I won't say a I never saw it, soldering RX stuff was pretty rare....it's scary enough watching most people solder, watching people solder to RX port pins....oof.

Not much current goes through RX anyways, so loss would be minimal. Besides, didn't you run a reciever pack? Runtime back then in 1/12th was nutty.....I remember cars dumping in 2wd stock offroad....in 4 minute races.

Later EddieO

[Mides]

This has really turned into an informative thread. Thanks everyone.

So far, I know I won't be using Micro Deans. Still not sure what gauge wire to use. Everyone seems to be talking about voltage drop. Yes, if the motors are demanding that much power when in a bind or WOT then there will be a voltage drop, but are the motors demanding that much?

I guess what I am trying to say is if the wires were water pipes would putting in 12 gauge wire be like putting in a huge 1 foot diameter pipe, where the water trickles along the bottom at maximum demand? Could I just put in a 6 inch diameter pipe (16 gauge wire) where the water gets to 80% full at peak demand? Obviously I will run a bigger pipe if it acts as a bottle neck.

I hope that makes sense. I found thinking of electrical circuits as plumbing systems tends to help me picture it all in a practical way.

[Charlie-III]

Originally Posted by EddieO

EddieO has been racing that long too....I still got a pack of 1200 SCEs some where (very rare, most were 1700). My first pistol radio was a magnum sport (the old boxy kind, not the hip looking ones).

While I won't say a I never saw it, soldering RX stuff was pretty rare....it's scary enough watching most people solder, watching people solder to RX port pins....oof.

Not much current goes through RX anyways, so loss would be minimal. Besides, didn't you run a reciever pack? Runtime back then in 1/12th was nutty.....I remember cars dumping in 2wd stock offroad....in 4 minute races.

Later EddieO

A few of my old Futaba RX's had a wire with connector on them (small RX case) in place of a direct plug into the RX board. So, we cut the connector off the servo, ESC & RX and did soldered wire splices (NO, we didn't solder to the pins on the RX board ).

Gearing back then was nuts, change a tooth and you were fast, but dumped the pack with 1/2 a lap to go. Go a tooth the other way and you were slow, but had a few laps of power left.
Made it such that you needed a Tekin (or similar) discharger to see how many electrons were left after a run.

[Charlie-III]

Originally Posted by NicholasMides

This has really turned into an informative thread. Thanks everyone.

So far, I know I won't be using Micro Deans. Still not sure what gauge wire to use. Everyone seems to be talking about voltage drop. Yes, if the motors are demanding that much power when in a bind or WOT then there will be a voltage drop, but are the motors demanding that much?

I guess what I am trying to say is if the wires were water pipes would putting in 12 gauge wire be like putting in a huge 1 foot diameter pipe, where the water trickles along the bottom at maximum demand? Could I just put in a 6 inch diameter pipe (16 gauge wire) where the water gets to 80% full at peak demand? Obviously I will run a bigger pipe if it acts as a bottle neck.

I hope that makes sense. I found thinking of electrical circuits as plumbing systems tends to help me picture it all in a practical way.

I use plumbing as an example as well, easy to visualize for many people.
As in most things, there is a happy medium. Big wire reduces losses (usually in the form of heat) but can be a PITA to route in a rig and it adds weight.

As to wire size, I would run the same as on your ESC or a bit bigger. Keep the runs fairly short & twist the motor wires together to reduce noise that can mess with the RX.

Keep in mind, what little advantage you gain from optimum wire size can be negated by crappy solder joints, lack of motor maintenance, over tight pinion gear mesh, axle bind, low "C" packs and poor driving.

[JohnRobHolmes]

I have data logged 80 amp bursts when a crawler gets wedged down. That is on 10 hertz sampling rate. No telling how high the burst actually was at the peak.


The magnum was my first pistol too. I still have it here somewhere.

[Manning]

I try not to bind up my rig and give it full throttle..... Generally stuff breaks, so I avoid doing that, so the voltage drop doesn't really matter.

The average amp draw during a 5min comp course is around 2 to 3 amps. That's based on using 200mah on a course. Don't need much wire gauge for that. I figure that somewhere around 20 amps is reasonable to base the wire gauge on.

And I was around when 1200 SCR's and 1700SCE's were the hot batts........

[EddieO]

In my data logging sessions, some of the biggest amp spike happened at 50% throttle....you don't need to yank that thing all the way to pull big amps, just a bad bind can do it. The amount of people that just romp on it until stuff smokes or breaks is unreal.....some people just don't when to take penalty and try again.....Losi drivers seem very prone to this.

1200 scr and 1700 sce are old, but were you around the for the 1200 SC and 1200 C?

Later EddieO

Originally Posted by Manning

I try not to bind up my rig and give it full throttle..... Generally stuff breaks, so I avoid doing that, so the voltage drop doesn't really matter.

The average amp draw during a 5min comp course is around 2 to 3 amps. That's based on using 200mah on a course. Don't need much wire gauge for that. I figure that somewhere around 20 amps is reasonable to base the wire gauge on.

And I was around when 1200 SCR's and 1700SCE's were the hot batts........

I've data logged with the Novak Sentry and the Eagle Tree......I've seen bursts up to 120+ amps. Stuff can get nutty with little motors bound up and lots of voltage.

Originally Posted by JohnRobHolmes

I have data logged 80 amp bursts when a crawler gets wedged down. That is on 10 hertz sampling rate. No telling how high the burst actually was at the peak.


The magnum was my first pistol too. I still have it here somewhere.

Ok, now you are clearly older than me.....though I remember seeing some on a few cars and trucks. Did you drive your Model A to the track too?

Runtime back in the day was nuts.....I remember guys dumping in everything. Cars would just stop dead in their tracks too. I remember at the biggest race in our area one year, this guy had a huge lead in 4wd mod.....and literally just passed the line as time expired. His friends were yelling at him to NOT do it.....but he wanted to be the first to break the 14 lap barrier. His car slowed a little with about half to go....and then it was maybe 10 feet before the line just DIED...........DEAD. Under the old rules, since he didn't finish, he lost. My friend greg in Mod truck, same thing could of happened to him, but since he was so far out in front, he just stopped 5 feet before the line...time expired, he finished and won.........funny part too, 30 feet past the line, his truck died.

I took a few years off back in the 90s and came back after the 1700 SCRC was introduced. I remember being the first out to my heat, which was the first of the day. I walked my car out and sat it down, being careful not to touch the throttle....went up and waited. Next thing I know, all 9 other guys just throw their cars on the track....take two practice laps....run the race, and then take 2 more.....I am like wtf! How did you guys not dump!?? Not even 2 years and it was a huge jump in battery tech.

Originally Posted by Charlie-III

I use plumbing as an example as well, easy to visualize for many people.
As in most things, there is a happy medium. Big wire reduces losses (usually in the form of heat) but can be a PITA to route in a rig and it adds weight.

As to wire size, I would run the same as on your ESC or a bit bigger. Keep the runs fairly short & twist the motor wires together to reduce noise that can mess with the RX.

Keep in mind, what little advantage you gain from optimum wire size can be negated by crappy solder joints, lack of motor maintenance, over tight pinion gear mesh, axle bind, low "C" packs and poor driving.

Did someone say something about tits?


Later EddieO

[Charlie-III]

Another thought, wire length has an effect on ampacity. Granted, the short runs we use is minor, but.......it has an effect. For an electric drill, a short 16ga extension cord may be fine, but a longer one will need to be a larger diameter (smaller ga until you get to "0" sizes).
A wire too small will resist power transfer causing heat. The heat will raise the resistance creating more heat.
Higher amp draws will creat more heat in a given length of wire, especially with a longer length.
A short piece of small wire can be "acceptable" in our application for short bursts, longer "high amp draws" can start to create issues.

Solid vs. stranded in power applications (which is what we care about here)..... for a given cross section of conductor (AKA circular mils) there is a calculated/acceptable ampacity. This is really related to voltage & amp load, but lets keep it simple (I'm simple minded, so be it.... ).
We use stranded for a few reasons.
1-It's easy to route in a rig.
2-It's less likely to "work harden" with vibration. Thus it's more resistant to fatigue breaking. For those that ask, "work harden" happens when you repeatably bend a metal. As you do so, you change the properties of the metal until it forms cracks which lead to overstress & breakage. Aluminum sucks at work hardening......Google search "Electra" to see what happened to a commercial airplane that dealt poorly with pressurization of an aluminum structure (cliff notes, 90* angles for window corners create stress & work hardening during pressure changes, thus all windows/openings in aluminum structures have a radius for direction changes....).

Here is a calculator.... http://www.stealth316.com/2-wire-resistance.htm

Another link..... http://www.securityideas.com/howtocalvold.html

Some interesting battery related info..... http://www.vestest.com/HowConnection...oltageDrop.pdf

Info described as a "plumbing thought".... http://home.mchsi.com/~gweidner/extension-cords.pdf

Some more decent info... http://www.rowand.net/Shop/Tech/WireCapacityChart.htm I take a little issue regarding solid vs. stranded wire as it relates to ampacity.

Disclaimer...... I'm NOT a frikking engineer, I'm NOT a licensed electrician, I AM a DIY for work/hobby since the late 60's.
I have fried my share of electrical stuff.
For the weight gain/price increase, I choose to go a bit overkill. As the, "Guy that has to fix it when you let the majic smoke out", I tend to be on the safe side.
My work is UPS battery related (not the little frikkin "kick under the office desk" type, I'm talking a couple thousand amps @ 540VDC "makes a really nice arc welder" supporting data centers, etc....)

As stated before by me, the little you gain from optimum wire sizing can easliy be negated by a host of other things.
I'm just trying to help explain some of this.

[Charlie-III]

Originally Posted by EddieO

In my data logging sessions, some of the biggest amp spike happened at 50% throttle....you don't need to yank that thing all the way to pull big amps, just a bad bind can do it.
Later EddieO

True, you are at ~1/2 volts, thus ~double amps potentially.

As to tits......as I stated before (in another post here), "git yer mind outta my frikkin gutter!!!!!"

[Charlie-III]

Hmmm....beginning to wonder if this thread should get linked to..... Definitive ESC, MOTOR, and BATTERY threads - RCC's top tech threads! ??

[JohnRobHolmes]

Good call, added in to the tech.


Charlie, you just eluded to this, I might as well mention it fully. One thing that many people don't consider (or may not be aware) is that motor amperage and battery amperage are not the same since we use digital speed controllers. The basic formula ignoring inductance influence is [Motor phase amp = Battery Amps x (1/duty cycle %)]. At half duty cycle (50% throttle basically on voltage based ESC systems) the motor amperage will be 1/.5 or twice that of the battery amperage. At 10% duty cycle motor current is 10x battery current. Eddie, if you logged 120a at about 50% throttle, that is a burst of 240 amps on the motor side of the circuit.

I can't claim to have any applicable certifications either. I have taken some basic engineering courses but am a self learned hobbyist as well. My undergrad and Masters are in Business and certifications are all in Real Estate. Many knowledgeable and driven people are not formally educated but self educated or taken under the wing of a mentor.

Eddie- just grabbed my old radio. A Magnum PCM 1024. I think you are few years older, I'm a spry 29! My back doesn't think it is so young though

[EddieO]

If memory serves correct, those radios came out after the original sport, but before the new version of the sport. Those were pretty high end, only the rich guys used them really. While they had tons of cool features, they were VERY heavy compared to the magnum sport or junior...arm fatigue can be a big deal in racing.....especially in the gas classes or 1/12th scale. The other issue was they were VERY fragile (must be italian...bonus points to people who get the reference)....even slight drops would knock them out of tune.....they were damn pimp though if you could live with the slight issues with them....

And yes, that motor went boom....the whole point of the test was to see if we could fry it.....first bind and we toasted it...

Later EddieO

Originally Posted by JohnRobHolmes

Good call, added in to the tech.


Charlie, you just eluded to this, I might as well mention it fully. One thing that many people don't consider (or may not be aware) is that motor amperage and battery amperage are not the same since we use digital speed controllers. The basic formula ignoring inductance influence is [Motor phase amp = Battery Amps x (1/duty cycle %)]. At half duty cycle (50% throttle basically on voltage based ESC systems) the motor amperage will be 1/.5 or twice that of the battery amperage. At 10% duty cycle motor current is 10x battery current. Eddie, if you logged 120a at about 50% throttle, that is a burst of 240 amps on the motor side of the circuit.

I can't claim to have any applicable certifications either. I have taken some basic engineering courses but am a self learned hobbyist as well. My undergrad and Masters are in Business and certifications are all in Real Estate. Many knowledgeable and driven people are not formally educated but self educated or taken under the wing of a mentor.

Eddie- just grabbed my old radio. A Magnum PCM 1024. I think you are few years older, I'm a spry 29! My back doesn't think it is so young though

[rmdesignworks]

Ive always been on the "Bigger Wire Bandwagon". I see a noticable difference in the lipos I run...I have some with 14awg wires on them and some with 18awg wires...when I run the 18awg packs they tend to give less power to the rig for digging out of a bad tire bind...Ill get around resoldering the 18awg packs to 14awg soon...

I am an Electrician by trade and we deal with current carrying conductor calcs all the time...derating a lower current carrying conductor to the size of the higher current carrying conductor when they run in the same conduit/raceway keeps the possibility of short cicuits at a minimum.

Ive always used 14awg-12awg high strand count sliver plated copper with silicone jackets for the increased current carrying ability...which also means less current loss under load. I currnetly run a 55t single on 3S and smaller wire equates to more heat and less power from what Ive seen.

[JonU]

While i don't have the knowledge of a lot of you in here i have always been a bigger is better person as well. While i don't plan on redoing the wires on the battery/esc, any wiring i do will be 12/13g. I remember how warm my wires would get with my tc and while the motors on these aren't seeing the speed, i can see my motors easily drawing as much power as my tc motors did.

[Manning]

Originally Posted by JonU

......I remember how warm my wires would get with my tc and while the motors on these aren't seeing the speed, i can see my motors easily drawing as much power as my tc motors did.

Not even close. When racing tc 17.5 with boost timing, I would need to recharge with 2000mah or a bit more after a 5 min race. I need to recharge about 200mah after a comp crawler run, 5-6 minutes. That's 10x difference.

[JohnRobHolmes]

Average amp draw is certainly lower. Servos have higher average amp draw than drive motors. Just don't forget about peak draw too.