QS273 vs 4AWG pics

[ebike11]

Hi guys
Decided to get some 4awg for basically a heatsink on each phase. Will crimp to original qs273 phases wires roughly 15cm from outside the motor.
Here are some pics...one thing i noticed is that the 4awg wire strands are very fine but the qs273 wire strands are thicker and stiffer. Not sure which type of wire is more beneficial

 

[ebike11]

Hi...besides the wire strands themselves, is have thicker stiffer phase wires better than finer strands?

 

[liveforphysics]

For the commutation phase current frequencies (300-500Hz), the skin effect depth is not going to play an effect on your strand size.

Until your current is in RF frequencies, strand size isn't playing an electrical role beyond its stiffness in routing the wires.

 

[neowizard]

Strand thickness mostly relates to how easy it is to work with the cable, how durable the cable is to vibrations and how you terminate the cable.

A thick-stranded cable is very convenient if you can shape it, and then install it (instead of threading it into position). It's not as good against heavy vibrations since if the cable isn't well fastened into place, the vibrations can work-harden the copper and the strands can crack. It's much easier to terminate a thick-stranded wire since the lug or whatever you crimp on the end has a more solid bit of copper to bite into.

A thin-stranded cable is much easier to thread into position. It's more vibration resistant (since the smaller strands mostly flex, rather than actually deform) and you need to pay more attention when terminating them (I crimp, solder and shrink-wrap).

 

[ebike11]

Thanks for the advice..my main purpose is to use the 4awg as a heatsink when crimping the qs273 wires to it around 15cm outside of the hub. The 4awg will extend to around 80cm to the controller at the front of the bike. Im unable to put the controller any closer to the motor

 

[ebike11]

Not sure if it will make a huge difference but i think its better than 80cm of the same stock thin phase wires

 

[neowizard]

Thanks for the advice..my main purpose is to use the 4awg as a heatsink when crimping the qs273 wires to it around 15cm outside of the hub. The 4awg will extend to around 80cm to the controller at the front of the bike. Im unable to put the controller any closer to the motor

I'm sorry, maybe I'm too new to all of this, but what do you mean when you say you want to use a cable as a heatsink?

 

[SlowCo]

Thanks for the advice..my main purpose is to use the 4awg as a heatsink when crimping the qs273 wires to it around 15cm outside of the hub. The 4awg will extend to around 80cm to the controller at the front of the bike. Im unable to put the controller any closer to the motor

I'm sorry, maybe I'm too new to all of this, but what do you mean when you say you want to use a cable as a heatsink?

Copper is not only a good electrical but also heat conducting material. So the heat in the motor can find it's way outside through the phase wires.

@ebike11:
I hope you're aware of "Statorade" to help cool a hub motor even better? Maybe even add "Hubsinks".
https://ebikes.ca/product-info/grin-products/statorade.html

 

[Comrade]

So the heat in the motor can find it's way outside through the phase wires.

In theory. In practice it would be like sneezing in the direction against the rotation of the earth to extend the length of the day. :lol:

 

[ebike11]

Thanks for the advice..my main purpose is to use the 4awg as a heatsink when crimping the qs273 wires to it around 15cm outside of the hub. The 4awg will extend to around 80cm to the controller at the front of the bike. Im unable to put the controller any closer to the motor

I'm sorry, maybe I'm too new to all of this, but what do you mean when you say you want to use a cable as a heatsink?

Copper is not only a good electrical but also heat conducting material. So the heat in the motor can find it's way outside through the phase wires.

@ebike11:
I hope you're aware of "Statorade" to help cool a hub motor even better? Maybe even add "Hubsinks".
https://ebikes.ca/product-info/grin-products/statorade.html

Yes...doing those steps as well

 

[ebike11]

So the heat in the motor can find it's way outside through the phase wires.

In theory. In practice it would be like sneezing in the direction against the rotation of the earth to extend the length of the day. :lol:

Do you think its basically useless to do?
I read a lot of positive posts on here talking about this

 

[Comrade]

Do you think its basically useless to do?

I'm not a practicing engineer in any related field to be able to quickly whip out the exact math proving how absurd the idea is, but yes. :lol:

 

[neowizard]

Thanks for the advice..my main purpose is to use the 4awg as a heatsink when crimping the qs273 wires to it around 15cm outside of the hub. The 4awg will extend to around 80cm to the controller at the front of the bike. Im unable to put the controller any closer to the motor

I'm sorry, maybe I'm too new to all of this, but what do you mean when you say you want to use a cable as a heatsink?

Copper is not only a good electrical but also heat conducting material. So the heat in the motor can find it's way outside through the phase wires.

@ebike11:
I hope you're aware of "Statorade" to help cool a hub motor even better? Maybe even add "Hubsinks".
https://ebikes.ca/product-info/grin-products/statorade.html

I thought there was some terminology I was missing here. I didn't realize people are trying to use copper cables as some thermal vacuum.

Sure, copper's a great thermal conductor, but 3X4AWG amounts to less than 1cm2 of cross-section area. That's about the size of your pinky fingernail. Heat is supposed to flow up that narrow channel? If we were talking about a span of a millimeter, that might make sense, but over tens of cm? There's absolutely no way this will reduce even 0.1degC off the engine.

Say I hold a 50cm copper rod with a 1cm2 in cross-sectional area. I put one end in 95degC (the motor end) and the other end at 20degC. How much power will the rod "pull" across it? That's the temp diff multiplied by the cross-sectional area and the thermal conductivity of copper divided by length of the rod. Or 75degC * 1cm^2 * k_copper / 0.5m = 0.015*k_copper Watt. k_copper is ~400 W/mK. So that's 6W of power "pulled" across the rod. We can assume that the rod is mostly cold by 25cm, since it's open air, but we'll still get just 12W.

Even a rod of 5cm only gets us 60W, and at this point how do you even keep the cool end from heating up when it's drawing constant 60W (it's basically a soldering iron at this point).

No. Using cables to cool down a motor won't work.

 

[ebike11]

Thanks for the advice..my main purpose is to use the 4awg as a heatsink when crimping the qs273 wires to it around 15cm outside of the hub. The 4awg will extend to around 80cm to the controller at the front of the bike. Im unable to put the controller any closer to the motor

I'm sorry, maybe I'm too new to all of this, but what do you mean when you say you want to use a cable as a heatsink?

Copper is not only a good electrical but also heat conducting material. So the heat in the motor can find it's way outside through the phase wires.

@ebike11:
I hope you're aware of "Statorade" to help cool a hub motor even better? Maybe even add "Hubsinks".
https://ebikes.ca/product-info/grin-products/statorade.html

I thought there was some terminology I was missing here. I didn't realize people are trying to use copper cables as some thermal vacuum.

Sure, copper's a great thermal conductor, but 3X4AWG amounts to less than 1cm2 of cross-section area. That's about the size of your pinky fingernail. Heat is supposed to flow up that narrow channel? If we were talking about a span of a millimeter, that might make sense, but over tens of cm? There's absolutely no way this will reduce even 0.1degC off the engine.

Say I hold a 50cm copper rod with a 1cm2 in cross-sectional area. I put one end in 95degC (the motor end) and the other end at 20degC. How much power will the rod "pull" across it? That's the temp diff multiplied by the cross-sectional area and the thermal conductivity of copper divided by length of the rod. Or 75degC * 1cm^2 * k_copper / 0.5m = 0.015*k_copper Watt. k_copper is ~400 W/mK. So that's 6W of power "pulled" across the rod. We can assume that the rod is mostly cold by 25cm, since it's open air, but we'll still get just 12W.

Even a rod of 5cm only gets us 60W, and at this point how do you even keep the cool end from heating up when it's drawing constant 60W (it's basically a soldering iron at this point).

No. Using cables to cool down a motor won't work.

I see..but what if youre using the 80 to 90cm thicker phase as more for preventive measure against overheating? I mean the stock phases are fairly thin as you can see in the photos..and running 20 to 30kw of power those those smaller phases and at a meter in length seems much worse.

 

[neowizard]

It won't really make any difference. If your motor is going to overheat with those smaller-gauge wires, it'll overheat even if you hook it up with 1AWG. Especially for 20-30kW.

We saw before that pure copper gives you less than 12W on a good day (would've been about 20W using 1AWG). That's 0.1% of what you're rating your motor here.

 

[SlowCo]

So forget about the copper wire but follow the Statorade link :wink:

 

[ebike11]

So forget about the copper wire but follow the Statorade link :wink:

I am using hubsinks and statorade...

So why are there a lot of threads and posts with experienced members on here opening their hubs and replacing the full length phases wires for bigger ones or as in my case, adding thicker wire just outside the motor casing?.

 

[Comrade]

So why are there a lot of threads and posts with experienced members on here opening their hubs and replacing the full length phases wires for bigger ones or as in my case, adding thicker wire just outside the motor casing?.

Because humans are very far from perfectly rational (or well informed) beings and that often takes the form of obsessing on things that have little consequence. :lol:

This is best exhibited on car forums, where motor oil type or air filter topics are the most lively and heated discussions.

 

[amberwolf]

So why are there a lot of threads and posts with experienced members on here opening their hubs and replacing the full length phases wires for bigger ones or as in my case, adding thicker wire just outside the motor casing?.

not for cooling the motor, but for creating less heat within the phase wires themselves from the current flowing thru their resistance.

some motors that have been used for bursts of much higher power than they are designed for have such small axles holes that they have room for only very small phase wires (12g or even 14g or smaller), so those wishing to use them for very high phase currents may choose to replace the long stretch (1-3 feet, perhaps) of phase wires between controller and axle to minimize the heat generated within the wires themselves, and also to minimize voltage drop within those wires, ensuring more power by whatever small amount gets to the actual motor.

whether this makes any significant difference in operation depends on the build and usage--i expect it has more psychological effect for many of them, vs practical results, but it does make some difference during those peak power moments.

 

[ebike11]

So why are there a lot of threads and posts with experienced members on here opening their hubs and replacing the full length phases wires for bigger ones or as in my case, adding thicker wire just outside the motor casing?.

not for cooling the motor, but for creating less heat within the phase wires themselves from the current flowing thru their resistance.

some motors that have been used for bursts of much higher power than they are designed for have such small axles holes that they have room for only very small phase wires (12g or even 14g or smaller), so those wishing to use them for very high phase currents may choose to replace the long stretch (1-3 feet, perhaps) of phase wires between controller and axle to minimize the heat generated within the wires themselves, and also to minimize voltage drop within those wires, ensuring more power by whatever small amount gets to the actual motor.

whether this makes any significant difference in operation depends on the build and usage--i expect it has more psychological effect for many of them, vs practical results, but it does make some difference during those peak power moments.

Ah yes its more for benefiting the phases on the outside of the motor so not to burn up under huge power. I gotta run 3 feet and the stock phases dont look that thick. Plus qs motors are now squeezing all 3 phases tightly together and using insulation around all 3 so it looks like one giany wire coming out of the motor. I will have to cut off all of that black insulation covering to get the phase wires exposed

 

[dominik h]

The phase wires in the protective hose behind my scooters shell get realy hot. During an uphill test ride with my 5kw QS Motor and SVMC72150 they reached inside the hose 172C /342F. Scooter was running between 11-13kw for 10 minutes , Phase amps around 250Arms.
I ripped of this hose afterwards. Temperature reduction was around 30C.
With the next controller update I will install two wires per phase and make a connector box at the Swing arm, that will double the cross-section.

 

[DogDipstick]

For the commutation phase current frequencies (300-500Hz), the skin effect depth is not going to play an effect on your strand size.

Until your current is in RF frequencies, strand size isn't playing an electrical role beyond its stiffness in routing the wires.

Typical phase current frequencies are 3-500hZ? Wow I thought they were alot less than that.

What... exactly.... is a " Radio Frequency Frequency? " Eh? ( lol just poking fun I did understand the statement).


You know a thing or two, Luke. You are a professional. Could you tell me what a " current coefficient" of a wire, or copper bus bar, is, and why it matters in conductor selection? Its just something I saw in a conductor selection table. I wondered. IDK. I came to the conclusion that I should just ask someone that knows.



YOU sound like a textbook. Excellent break down. I do understand. Thankyou for this assessment.

Random textbook quote:

1. Electric current passes through a long wire of diameter 1-mm, and
dissipates 3150W/m. The wire reaches surface temperature of 126 C
when submerged in water at 1 bar. Calculate the boiling heat transfer
coefficient and find the value of the correlation coefficient Cs,f .
Known: long wire, 1–mm-diameter, reaches a surface temperature of
126C in water at 1atm while dissipating 3150W/m.
Find: (1) Boiling heat transfer coefficient and (2) correlation
coefficient Cs,f , if nucleate boiling occurs
Schematic:

As for the wire, all i can say is all wire was NOT created equal. Alot of you guys use thick, many stranded soft cable: Same (AWG rated) cable might be many diameters, I have found. For example, I have 6 gauge silicone, same dia of a 2 gauge hook up wire.

I think its all circular mil per amp and the delta temp in Kelvin that matters. Some thing like that.

The phase wires in the protective hose
I ripped of this hose afterwards. Temperature reduction was
I will install two wires per phase and make a connector box at the Swing arm, that will double the cross-section.
20220219_151058.jpg

Pump air through the hose, you may lose more temperature. Might be a option. This is a thing, welding machines, do and have done, in application, for years. My DC inverter based Tig machines pump 225A DC through an 8gA conductor... along with the cold shielding gas fluid. Continuous duty cycle. I think they do this for flexibility. The AC transformer stick machine has almost 3/4" thick leads for the same 200A, but zero cooling of any sort.

 

[ebike11]

The phase wires in the protective hose behind my scooters shell get realy hot. During an uphill test ride with my 5kw QS Motor and SVMC72150 they reached inside the hose 172C /342F. Scooter was running between 11-13kw for 10 minutes , Phase amps around 250Arms.
I ripped of this hose afterwards. Temperature reduction was around 30C.
With the next controller update I will install two wires per phase and make a connector box at the Swing arm, that will double the cross-section.
20220219_151058.jpg

Do you mean the black protective hose that covers all 3 phases wires that come with the qs motor??

 

[dominik h]

Yes, I cut the black hose to reduce temperature of the phase wires.

 

[ebike11]

The phase wires in the protective hose behind my scooters shell get realy hot. During an uphill test ride with my 5kw QS Motor and SVMC72150 they reached inside the hose 172C /342F. Scooter was running between 11-13kw for 10 minutes , Phase amps around 250Arms.
I ripped of this hose afterwards. Temperature reduction was around 30C.
With the next controller update I will install two wires per phase and make a connector box at the Swing arm, that will double the cross-section.
20220219_151058.jpg

Hi again..so after removing the black sleeving..the temperature dropped to around 140C ?

Also were you measuring with a temp. gun or just through the phone app?