How is the controller handling this? With the higher KV motor and all that amps? What does the controller temp look like?
Looks to rise pretty quickly on that clip you posted. Have you had issues with it?
The way I understand it, and This was recently explained to me the higher the KV the cooler to motor temps should be, however the esc has to do more work so it will heat up, and vise Versa for lower KV motors, motors will heat up more but ESC should remain cooler
Not really. Firstly we need to be sure we are talking about the same thing which is really rpm, not kv. What kv you have doesn’t matter since the voltage can be different. So in general with higher rpm setups you will get more heating in the motor thanks to heat generated by the magnets moving past anything made of metal. However it shouldn’t really effect the controller because higher rpm isn’t causing the mosfets to switch faster since they are at a fixed switching frequency such as 30khz, and switching the fets faster is usually how you cause more heat. That said, a higher frequency such as 60khz might be needed to run a high rpm setup like mine in FOC. Thats why I use BLDC because its more simple, so has less calculations required for every cycle and therefore should be able to handle higher electrical rpm without needing to raise the switching frequency.
My controller (DV6 Pro) runs surprisingly cool. Yes it heats up scarily fast during acceleration, but that heat dissipates really quickly. I’ve got a decent heatsink thermal paste glued to my enclosure which is 2mm thick carbon fiber, and a large section of the enclosure heats up this way and helps cool the controller
I agree, higher RPM will generally heat up the motor more due to reasons you stated, but also your controller is going to heat up more as-well if your motor is higher KV simply because you are getting less torque per amp, so you need more amps to have the torque, meaning your controller is having to supply you more motor current therefore heating up more.
With lower KV motors you have higher torque per amp, so controller has to handle less motor current for the equivalent amount of torque, you motor however has a higher coil count tho, so you have a motor with higher resistance which ends up causing the motor to heat up more.
So my approach lately has been low KV/high voltage/lower gear reduction, and I am really liking the results
My personal experience has always confirmed this, but I was experimenting with that before people were building over 12S, so i’m not exactly certain how voltage mixes in here.
Now that’s interesting.
For the controller the higher voltage is great because it does run cooler if you are comparing a 5000w system in 12s vs 18s
But for the motor the trade off is the higher rpm causing more heating.
So I am trying to see how long it takes my 125KV motors to give out at 20s constantly being heated to close to 100c I think they will last a long time
The neat thing is typically we’ve been limited by our controllers, so it’s made sense to go lower kv. Now that we have some really high current controllers (makerx) it just makes more sense to go higher kv and a super high gear reduction. You can actually use all of the extra power that the esc can dump into the motors that way. Thats the inspiration for my 16s 6.5:1 build with 205kv motors.
Another benefit is it SCREAMS.
Have people done 6.5 ratio before? Your motor rpm is going to be ~50% above a typical setup (unless geared for higher top speed too) - will that torch your bearings faster?
Probably, but the 12x28x8 bearings last so damn long anyways I don’t really mind
On 6" tires I’m gonna be at 8k motor rpm at my typical cruising speed. It’s gonna be pretty funny and it’ll SCREAM. No straight cuts nessesary.
Yeah it will SCREAM alright 
Curious so see how everything holds up, it just seems like there will be a lot of stress on a lot of components, but you are for sure maxing your performance.
My next build will also be all torque. But slightly dif approach, 18s/138kv/1:4.5
Top speed will be on the lower end, but I think it will be an extremely efficient set up, hoping to see if I can maximize things like range on a smaller battery like 18s4p maaaybe 5p
Also it will be deathly silent 
That’s a benefit?
Yes.
In all seriousness it can greatly help let others know you’re there.
The places I ride where there are people are usually places Esk8s are not really allowed, I would rather not attract more attention
I need cars to hear me, so yeah
@jack.luis and @poastoast don’t surprise pass anyone on group rides. You know they’re coming
rrrrrrrrrrrRrrRrRrRrRRrrRRRRRRRRRRRRREEEEEEEEREEEEEEEEEEeeEeEeEeEeEEeeeeeEeEeeeeeeeeeeee
-me passing by
Most likely, yes. Bearing efficiency and heat generation is not something most people are taking into account here. I would consider it pretty likely that one of the weak links waiting to be exposed by running motors at such temps and rpms is bearing capability/quality.
Motor bearings my dude
brainfart, yeah wheel rpm is the same 
Yes, but theyre supposedly easy to replace.
This is what 245kv in the first two clips sounds like, and 300kv in the last clip 
The quad bearings are fine with it. They last a long time and are easy to swap out. These motors have larger sized bearings than most which also leads to longevity. If you look at the bearings in the back of a 6389 motor they’re super thin and the balls are fish egg size
Yeah the bearings reacher is putting in these have been solid, ever at consistent heating to over 100c I have a customer that has had a pair of motors for about 5 months now and he is a bit of a mad man, motors are holding strong. We just switched him to VSS because the sensors started acting up in the early V5s
Yeah I believe I have fixed the sensors now. I changed them to a different type thats more robust, and removed a resistor that was dropping the voltage to borderline minimum