Is there a reason that running at no load will cause motors to heat up that much?
I’ve had my raptor 2.0 board since May 2018 without major issues. Ride it nearly every day up long hills etc. I had wheels from the batch with bad urethane but otherwise solid. One of my hubs was missing a spring washer which I just replaced myself and eliminated small clicking sound my motor would make sometimes. These motors were from the old factory, the new factory has much more thorough QA checks.
I’ve also been testing/sampling many of the new hub motors to get the FOCBOX Unity config dialed in perfect for the new raptor 2.1s. I currently have the demo board @Roan_Psyko took on world tour. It was handed off to me for testing. Unfortunately, I haven’t yet had a chance to test a set of new motors in combination with the updated truck/heat pipe, will get to that next week in Shenzhen. This is the urethane after a few hundred miles:
The 2.1 motors are fantastic, just a bit quieter and smoother than than the 2.0 batch. Since receiving the new 2.1 motors (few weeks back) I’ve been commuting about 6-8 miles daily on them. I’m about 6’4" 180 lbs including my stuff, so a somewhat average to heavy weight and I will say if you ride them hard up a hill for several miles (old smaller trucks, no heat pipe) heat can become an issue. I have motor thermal throttling setup with the unity to prevent them being damaged. I am pretty sure that some of the raptor 2 hub failures can be traced in part to no thermal throttling implemented with previous motors.
The 90mm hubs can do about 32-34 mph at 10s, so 12s should be something something like 39 mph top speed and 13s 42mph 
. Please, protective equipment before testing this.
So far after all the la/sf/vegas/san diego group rides I’ve noticed the thermal throttling effect three times on extremely steep and long hills (and once while I was towing a friend home uphill after dead battery). Mainly this resembles just a sight decrease in speed/power that goes away once the hill ends. Definitely rode the board hard in SF through some crazy hills with no problems. Keep in mind these are fully sealed hub motors, the benefits of this are that no dirt or debris is making its way inside your motor (no rocks to get jammed in the can and throw you 
) but it also means no airflow over the windings so a bit more heat buildup should be expected when comparing to unsealed outrunners. Overall I think the heat is well managed and the huge amount of copper in the stator keeps winding resistance low which prevents heat generation in the first place.
The internal thermistors line up with the default thermistor values expected with 3.xx vesc FW, and I recommend running motor temp limits of 85 C min and 140 max. My testing has shown that with these limits somewhere around 110C the motor current is reduced sufficiently that the motors never exceed 110 while remaining rideable over everything but the steepest of hills. You’re unlikely to ever reach these temps in anything except the worst case scenarios. Really should have some data plots to show you guys, I’ll do better in the future.
In my opinion, if you are average body weight these hubs will provide tons of power; they will be hot to the touch after a hard ride but the temps are within the design spec of the motor. They are the most powerful hub motors I’ve had a chance to ride. The only true hub motor that can match power with many of the belt driven designs.
You may think I’m biased since I work with Enertion but these are just my honest experiences with the hubs. Hopefully you guys get some useful info from this post which is potentially too lengthy 
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I think I told you I rode a set in Holland courtesy of @Surfer. They were surprisingly powerful and looked like they had been very well used. The tyres were flapping about all over the place but held on ok. Looks like the tyres are being addressed though.
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Thanks for your input , mine regularly get up to 85c and gets throttled in under 3km, flat ground riding, 95 kilo weight and 1.85m height. I did a test on a 31% hill before and let the motors cool down first to 45c and they went up to 75c in just 1 run (less than 50m) drawing 80 motor amps throughout the run. Also, any idea why even at no load and 0.1-0.2a they get up to 60+c from 25+c? I am thinking maybe my stator lamination’s insulation wasn’t applied properly and is generating a lot of current in the core itself with no where to go and ends up as heat. I also got a small electrical shock when I touched the bearing, motor can and truck together after spinning them for awhile to check for heat and I’m thinking maybe the voltage built up in the stator core and discharged to me? These are all my theories only as I don’t have my tools with me to open it up and check
Can you take a vid of the no load spinup test for me? I’ll perform the same test on my end for comparison. That definitely doesn’t sound like my experiences running no load on the bench.
exact amiunt of time on load until temp was hit would work for me as well. Starting test now
With telemetry? I have videos of clicking and knocking noises while spinning with no load but not paired with telemetry, and now my focboxes died waiting to send them back for repair so don’t think I can take another video… I have some spare vescs but phase connectors are different size and my tools are still back in shanghai and no way to swap them to test for now
I did 2 tests before without recording but the amount of time to hit 65 was just under 5 minutes once and around 3 minutes the other time (I reflashed firmware and ran motor detection between them)
This is the no load video with some knocking sounds I took 2 weeks ago https://youtu.be/1hiEPxQ8vHU
Just realized it’s midnight here, the GF will kill me if I start doing no load tests in the living room I’ll find a moment tomorrow to run this.
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This is another video of slave motor clicking after a ride they were pretty warm https://youtu.be/1CaYKZMldVE
http://vedder.se/2014/10/chosing-the-right-bldc-motor-and-battery-setup-for-an-electric-skateboard/
Let’s look at an example: Suppose an 8 turn motor has one ohm winding resistance. The winding resistance is proportional to the wire area times wire length. Making the same motor with 4 turns would allow twice as thick wire. Since that wire also is half as long, the resistance is four times lower: 0.25ohm. Further, since current times turns is proportional to torque, we need twice as high current with 4 turns to produce the same torque as with 8 turns.
Copper losses are proportional to the square of the torque produced by the motor, and at low RPM and high load they are dominant. As RPM increases, other losses start to add up exponentially. In my experience, these losses start to get significant around 60k electrical RPM, which for a 14-pole motor is about 8570 mechanical rpm (most 50mm+ outrunners have 14 poles, some unusual ones have 18). Because of the square relation, it is desirable to run at as high speed and low torque as possible as long as we stay below 8.6k RPM. To express the square relation in some numbers, having double the RPM and half the torque at a certain power output will cause four times less losses. The lesson from this is that: make sure the top speed you design the skateboard for is at around 8.6k rpm on the motor if you are using an 50mm-60mm outrunner.
Long story short: If you have no gearing, or even negative gearing (wheel diameter bigger than motor diameter), you need a super torque rich motor. If you have 1:3 gearing your motor can be designed to have 3 times less torque. Such a high RPM and low torque motor has 9 to 10 times less losses (square relation) as a torque rich hub motor of a similar diameter/size. Since inefficiencies/losses always go 100% into heat, you will get overheating issues. The only way to deal with it is have multiple motors instead of one motor (reduce torque per motor) and try to get the heat away from the motor as good as humanly possible. Combustion engines have the same issue and need a radiator (liquid cooled or air cooling fins). They are only 30% efficient and in consequence 70% the energy stored in your gasoline fuel go into heat and friction. Every time you fuel up your car 2/3 of your cost for fuel is spend on heating the universe. Electric BLDC motors have the advantage of being nearly 90% efficient if they run at low torque and optimal RPM. In consequence you can use 80 to 90% of the battery stored energy to get you moving forward. Only a small bit goes into heat. What we don’t want is the need for a radiator as seen in combustion engine cars or bikes. If you need to cool the motor a lot, the system is inefficient by design. The heat is proportional to the losses and you can express that in Watts. The hub design starts get efficient at speeds we will never reach (70+ km/h). In that case wind drag will be your issue since you will need torque to overcome it.
The only way to build a hub motor that equals a geared system is to make it a lot bigger and give it 6 times the mass. Since we can’t do that due to the size limitations we need to live with the inefficiencies.
If you rev up your motor with no load, you can see the current consumption in VESC-Tool (app or desktop). There should not be a high Amp flow under no load and the motor should stay relative cool in consequence. If it heats up at low Amp flow already, it will heat up very fast under load.
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yep! i can relate to this 
I get what you are saying, but that’s not the point here. The winding resistance in these motors are impressively low for a 28 pole(sorry 20 pole for the new silver motor) sub 100 kv hub motor so in theory there should not be as much heat as I’m experiencing coming from the windings. Therefore I am very inclined to believe its from something else. If it was friction the motor would have died by now or the part that’s rubbing would have been reduced in size from the hundreds of km I’ve ridden since and not be an issue anymore so these 2 can almost be put aside as causes of the heat so I think the only other major cause would be the stator laminations quality. On the quest for answers I read up a little on the construction of the stator and if the laminations are too thick or the insulation between them are no good the current induced in the core from the windings will be much higher and have no where to go ending up as heat
We are sorry you had problems sean, we have always tried to solve your problems in a timely manner and we have given you the opportunity to fix stuff yourself which is definitely a mistake on our part as you have failed to solve problems yourself but continue to blame us in all cases.
Please acknowledge, We have replaced all faulty parts & we have replaced your entire board.
We also have repair agents waiting and ready to solve any problems now and in the future.
Yes we definitely had stock shortages, but that has been improved now, we have learned how to manage this aspect of the business more efficiently.
Thanks for your feedback it has helped us improve our service levels.
FINALLY, please remember you are one of only a few cases, continual hijacking and spamming threads to bash Enertion products is selfish and not socially acceptable in these forums.
Please make your own raptor 2 thread and you can make your commentary there without disrupting other topics.
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It’s torque output that is the issue. The more torque you produce the hotter the motor will get. There is nothing you can do about that since you can’t cheat physics. You can try to cut down torque output by having more motors and you can try to get the heat away from the motor. You can also try to make the motor bigger. That’s pretty much all you can do to deal with the issue. There are no other options on the table.
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Torque is produced when current runs through the windings right? And heat is generated because of the current runing through wire with resistance right? My friend’s motor with a similar winding resistance do not get hot at all with similar torque output. Heat due to torque also doesn’t explain why the motor would heat up so much even under no load drawing 0.1-0.2 amps for a few minutes
I have been taken care by support very well(save the first 3 months) and had my board replaced twice. Thank you for hiring awesome people. Now can we get back to discussing why my motors get so damn hot?!?
Torque is proportional to 1/(motor kV) . So if you use a 3:1 gear ratio use a 270kV motor, if you are direct drive use a 90 kV motor. The result are more or less the same. The way 90 kV is achieved is adding more poles, so the ERPM ends up being pretty similar. Ultimately all that matters is amount of copper in the stator, quit listing a bunch of random numbers:
Not even sure where this number is coming from.
Mainly heat issues with hub motor designs are due to the reduced heat being removed from the motor since it is wrapped in urethane and sealed.
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id love a pair honestly but my streets are so bad pneumatics are my only option, even then i have sections i have to go 5mph or less 
that car is gorgeous 
the dream: offroad hubs
EDIT: quality* offroad hubs
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Right. Jason, Sean and Photorph - could you all tone it down, there are other threads for this. I’d like to discuss these hubs with some objectivity please.
Sean I appreciate you’ve had loads of issues, you’ve spoken about them before and they are taken on board, could you please let it go here for now mate?
Jason you started this.
Photorph just let it go, you’re going to get jibed for a while on the forum, don’t rise to it.
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