Air Cooling my x5

[BlackArrow]

El_Steak,

Great and amazing Job wow, it's cool to see it.

Good day!
Black Arrow

[dbaker]

Thanks for the link, BlackArrow. It looks exactly like the one I got.

[BlackArrow]

Thanks for the link, BlackArrow. It looks exactly like the one I got.

Dbaker is version for Doctorbass, El_Steak and me.

Good day!
Black Arrow

[John in CR]

El_Steak,

There's nothing wrong with measuring the temperature right in the windings like that as long as the short term peaks on steep hills doesn't fry the sensor. You can only "cook" the windings, not the rest of the stator, and it's the primary heat source, so that's the hottest place. It will just be subject to the short temperature peaks, so it might not be the best place if someone is using an alarm. If other parts of the stator were running cooler, then it will absolutely show up as cooler temps in the windings, especially after that 2 min wait period, so don't think that you're missing any data. I'd argue that you placed it very well and it's the best place for measurements. With that placement it's even more amazing that the sealed and with holes test results were so comparable.

Were you able to see the temperature gauge while riding, so you have a bit of "feel" for the peaks during climbs and how rapidly the motor self cooled in stock form, or are you like me with total focus on the road, so gauges and meters barely get glanced at?

BTW, tapering the holes is as simple as sticking the drill bit in the hole, spin it up, and tilt drill to the desired angle. Keep the speed fairly high so the bit takes away small pieces and doesn't grab a big bite and twist in your hands. Put a big L and R inside those covers, and double check yourself on which direction to angle the holes...the thickness of the metal will be visible at the trailing edge of the hole as it spins (ie visualize the trailing edge taking a small bite of air and pushing it to the outside world). With the inside face of the cover facing down on a piece of wood you can make quick work of it, just a few minutes per cover. I wouldn't worry about filing the tapers smooth with a small round file at this stage. Look at doing that as part of optimization when you're doing your permanent covers.


Arlo,
Still shooting blanks I see. You and Methods better get those Paypal accounts ready, because you're about to owe some people new motor covers. I was pushing the centrifugal fan approach back in Sep/Oct, because I knew it would work even before trying it. It's one thing to take a position, but it's quite another to vehemently shoot down another idea when you don't understand it. It's not like I didn't explain it, because I tend to over-explain for to the broader audience, not just those who actively post. Arguing against something that's already been proven by myself and ZapPat astounds me. ZapPat even got good enough results that he didn't feel the need to try to refine it further, yet you refuse to believe. Now El_Steak has proven the ineffectiveness of mid-radius holes with measured data, that he has so generously spent his valuable free time gathering and sharing for the benefit of all.

[Arlo1]

El_Steak,



Arlo,
Still shooting blanks I see. You and Methods better get those Paypal accounts ready, because you're about to owe some people new motor covers. I was pushing the centrifugal fan approach back in Sep/Oct, because I knew it would work even before trying it. It's one thing to take a position, but it's quite another to vehemently shoot down another idea when you don't understand it. It's not like I didn't explain it, because I tend to over-explain for to the broader audience, not just those who actively post. Arguing against something that's already been proven by myself and ZapPat astounds me. ZapPat even got good enough results that he didn't feel the need to try to refine it further, yet you refuse to believe. Now El_Steak has proven the ineffectiveness of mid-radius holes with measured data, that he has so generously spent his valuable free time gathering and sharing for the benefit of all.

EL_Steak is doing a great job!
#1 My inner and outer holes are not as close togetther as his!
#2 How many god damb times do I have to say I did not chose the location for them
#3 You run your motor at hi speeds that basicly No one else runs at
#4 The low speeds when my motor gets hot your cooling system would not do shit!
You are the one who needs to get some education in fluid dynamics and realize it is all relavent to rpm!
I had a problem with heat from trying low speed wheelies and I fixed it! Your centrifugal cooling bullshit does nothing at low wheely speeds why are you so pig headed??

[Doctorbass]

I've been interested in motor temp monitoring from 2 years now.. most of that when using the X5.

There is something i think is important to take account when we measure motor temp.
I personally think that it's rater the high Wh/mile in a short ride duration that really push the motor temp to the limit.

EX: hard stop and go in dirt trail... as well as having high power controller and battery.

Maybe if you want to do interesting test it would be to try to push the hiugheest Wh/mile you can in teh shortest period, until you reach the 160 degrees celsius limit or so...

Personally, i've heard alot of time my bbq temp monitor alam beeping and i think that saved my motor from cooking many times. What is my secret temp limit: 135 celsius...! I think that after i done over 5000km with that alarm temp monitor with high power, it for sure sdaved me alot of problems.

But.. my sensor is located in the middle radies of the stator.. not on the winding. What it does is that my temp reading is NOT affected by the winding current that can induce in the rtd sensor. that's why i wanted to put it not too close to the winding. and it still work well today.

Also, I think that the new X5 motor with narrower desing help alot fo rthe heat exaust cause the airgap is smaller and hest conduct to the side cover better.

Thanks EL-Steak and Arlo and john for your contribution to these motor temp tests.

Please note these Wh/mile or km you get for a given temp.. not the time you ride the bike.

Also, we should try to test the power gain on cooler motor vs the power consumed by a high pressure fan pushing in the motor holes!

I bet that the fan energy consumption vs the energy gain in the motor to wheel with cooler system is lower and that it really help!

So we must cool down the motor with forced air fans to get better power at the wheel without sacrifying our precious Wh energy.

Probably that a 20W fan motor is lower as the output power at the wheel lost due to higher resistance winding due to temp increase!

I must test that!.. guys you are pushing me to test that idea!

Doc

[El_Steak]

Were you able to see the temperature gauge while riding, so you have a bit of "feel" for the peaks during climbs

At 45 MPH, I tend to look at the road more than the gauges...

That being said I still look at the temps a bit and didn't notice any "quick jump" in temperature as I go full throttle climbing. Temperature goes up fast, but progressively. If it had spiked above 135C during the climbs, my thermometer would have beeped, which it didn't.

One thing I noticed though is that on my long 6 km stretch, the temperature would stabilize around 132-133C after a while and stay there. Then at the end of the stretch when I release the throttle and come to a complete stop,the temperature would shoot up in seconds close to 140C and then go down quickly.

On my previous motor, my sensor is placed on the stator close to the windings (similar to icecube and Doc). The behavior is different in that case; there is always a delay in the temperature reading.

As for the sensor burning up, I'm not too worried. Its not touching the winding, its just close under it. And its a BBQ thermometer so it's made to handle heat much higher than 140C. If I ever burn it up, replacement is 8$ at my local Crappy Tire, and believe me, I'm getting quite good at removing the motor covers...

[John in CR]

Arlo1,

That's why I handed you the shovel, just for the entertainment value in seeing you dig the hole deeper. BTW, just like I said before:
1. You owned those holes as soon as you made them bigger to copy your hero Methods.
2. During your wheelie sessions you're not running anywhere near the power you claim.

[John in CR]

Thanks El_Steak,

Great observations. I've yet to use a temperature sensor, and you confirmed what I always suspected, that the temps move slowly. Look how long it takes an electric stove element to heat up. Plus it's hills that are the hub motor's nemesis. My previous house had a 20%+ hill on one of my regular routes with a speed bump not far from the beginning. By the top, I struggled with pedal assist to avoid stalling completely and crest the hill at just a few mph. Performance was noticeably hindered by over heating for about half a mile. I never dared stopping at the top, because I knew the motor needed the internal circulation of air to better cool itself, so I just eased it along for a while a partial throttle. With the ventilated motor that hill wouldn't bother it at all, though I am running much higher current than back then, so I'd be able to sustain a better speed and stay at a more efficient range. Dumping current into a nearly stalled motor will kill any motor, probably even one with a high powered blower. That's what makes Doc's bus pull so impressive.

Acceleration is very different, because the more current you put in (up to stator saturation) the greater the torque and the shorter the time of acceleration. Except maybe a slight difference in losses to the wind and tire friction, it takes exactly the same amount of energy for a bike to accelerate to 20mph whether you hit the throttle hard or not. That's one of the things I love about electrics...jackrabbit starts are free.

Get yourself ready for a much cooler motor.

John

[icecube57]

That being said I still look at the temps a bit and didn't notice any "quick jump" in temperature as I go full throttle climbing. Temperature goes up fast, but progressively. If it had spiked above 135C during the climbs, my thermometer would have beeped, which it didn't.

One thing I noticed though is that on my long 6 km stretch, the temperature would stabilize around 132-133C after a while and stay there. Then at the end of the stretch when I release the throttle and come to a complete stop,the temperature would shoot up in seconds close to 140C and then go down quickly.

On my previous motor, my sensor is placed on the stator close to the windings (similar to icecube and Doc). The behavior is different in that case; there is always a delay in the temperature reading.

I agree with EL Steak about all the above experiences. There is a butter zone where you are cruising and the temp does stablelize. You stop. It shoots up about 10-15F and falls back down in a minute or too. There was always a delay with mine but it was very responsive within less than a minute cause my prob was pretty close to the windings.

If you have speed selection switches and you see yourself approaching critical especially in the flats..drop down to a lower speed selection i will limit amps and not dump as much heat into the windings. You will see a gradual decline in motor temp within a mile. I never been over 80-90C while monitoring my motor. Im surprised its taking a beating at such a high temp.

[ZapPat]

OK guys, there's one common misconception here on the ES forum and specially on this thread lately that almost everyone has been repeating and that annoys me:

Watts don't heat up your motor, it's really the motor/phase current that heats it up!

The sad news is that your average Watt's up / turnigy watt meter / cycle analist does not display this value to you, it shows *battery* current only, so it is a bit complicated to know just how bad you are really abusing your motor. And the lower your speed is, the greater your motor-heating phase current is compared to your easy-to-read battery current and your displayed watts too of course.

Keep that good testing info coming, El_Steak!!! I just hope you are patient enough to remove and reinstall the wheel and covers for each test to make it to test #5!

Pat

[John in CR]

Pat,

I understand that it's the current through the windings creating most of the losses in a motor, but since they have a torque constant, why is it wrong to look at power out from the battery as long as you consider the motor's efficiency curve? Losses at the controller can't be too significant or variable (mine are near constant warm temps), so other than a small amount of wire losses, the bulk of the losses occur in the motor (ignoring losses to wind friction). Power out of the battery - work done = heat in all its forms.

[ZapPat]

I understand that it's the current through the windings creating most of the losses in a motor, but since they have a torque constant, why is it wrong to look at power out from the battery as long as you consider the motor's efficiency curve?

The biggest source of losses in a hub motor are dependant on motor phase current squared or more (copper + magnetic eddy & hysteresis losses), the RPM dependant losses look to be mostly linear instead of squared, except for eddy losses also going up squared with RPM. Source here.

It seems hard to me to use an efficiency estimate to help you because efficiency changes with both currrent and RPM.

Anyone please rectify anything here I've said that's not exact... I'm not a motor pro for sure, I mostly know controllers pretty well.

Pat

[John in CR]

I don't think the relationship of current and efficiency can be stated that way. eg A motor's efficiency doesn't change a lot between it's points of maximum power and maximum efficiency, but current changes a good bit. Otherwise I think we're saying the same things just from different viewpoints.

I think a confusing part is how controllers do that current multiplication thing at takeoff to generate more torque, but doesn't it do that by reducing the effective voltage for a certain power from the battery? Yes those motor losses are high due to low rpm, but there's also more work getting done due to the higher torque than if the current multiplier was turned lower, making the increased losses have a shorter duration to reach the same speed. Overall losses are the same for a slower lower current acceleration to that speed, because the same work is done over the same efficiency curve related to RPM.

If that's incorrect then I need help with that explanation too.

John

[El_Steak]

Run C is done and numbers are logged !

Its cooler, with a top temp of 117, over 20 degrees less than Run A and Run B. I made the run at dusk though and at 19C is was starting to get chilly. How does ambient temp affect the results? I don't know, I guess I'll have to do another run to test it out

This latest run is with my old covers, with 6 additional 7/16 holes close to the center and 24 x 7/32 holes close to the outer perimiter. As suggested by John, the outer perimiter holes are "angled" so their edges "bite" in the inside air to push it out. Angles are in opposite directions on each side.

Go see the results for yourself in my test post:
viewtopic.php?f=2&t=9791&p=278852#p278852

I've decided I'll squeeze in another run with that same cover. The only difference will be that I'll tape over the 12 holes in the middle of the cover. As John suggested, they might be counter productive as they could be letting the fresh air out before it reaches the outer holes. Hopefully it will be a bit warmer tomorrow night as well.

If you plan on drilling your covers, here's my little jig to drill perfect holes in the curved area around the perimeter:
The "axle" in the lower piece of plywood allows me to rotate the cover and always maintain the exact position and angle for the drill bit.

Then to create the final oriented tapering as suggested by John, using a portable drill, stick the drill bit in the hole and slowly tilt it while it spins to the desired angle. Works great, aluminum is like butter.

Works great for the other holes on the flat surface as well.



OK, got to go give some time to the GF, shes not too impressed with my testing...

[John in CR]

El_Steak,

You're aces man, great follow through. I'm glad you're seeing solid positive results. I think it can do significantly better, so we should talk about interior blades specifically for the 9c. I don't think it will be about getting the air spinning as much as it will be about directing the flow away from the side cover as a more turbulent flow at the stator and maybe even at the windings too. I can't wait to go to town on my 9c when it arrives.

The higher peak amps is interesting. I wonder if that's just because of cooler windings lowering the resistance. Did you notice any difference in how hard the bike pulled?

How about the sonics, did you get any whistling? Did it change that other noise the 9c is known for, or did yours not do it to begin with?

Can I get you to do 1 pic? I'd like to see the cover from the outside but with the view parallel to the motor. I want to see where the hole placement is in relation to the flange where the cover's bolt holes are. I ask because I think you can draw the flow out from even closer to the windings by butting those holes right up to that flange where the cover is near perpendicular.

One other question, how did the covers feel to the touch? That's really all I know, since I've yet to use a temp gauge, which will change shortly.

Again, great job, and great job sharing with everyone.

John

[Arlo1]

So the ambient temp is 9 deg cooler and the last run the motor was in the 10-15 deg cooler range. So if the ambient temp was the same we could expect 1-6 deg better cooling then no holes at all? Looks to me Johns Bulshit didn't do much at all!
Great work el_Steak We are ll thank full for your work and the fact you posted the numbers and mesured them.

[Arlo1]

Arlo1,

That's why I handed you the shovel, just for the entertainment value in seeing you dig the hole deeper. BTW, just like I said before:
1. You owned those holes as soon as you made them bigger to copy your hero Methods.
2. During your wheelie sessions you're not running anywhere near the power you claim.

You kidding me? Have you seen my video? Where is you video racing a truck, car, bike, or what ever, rolling smoke show? Burnout? Dude ask anyone if I wasnt running the power I claim then how did the video happen?
I also chamfered the holes but your selective hearing choses not to hear that. I chamfered them to pull air in the inner holes and out the outer hole and on my wheel the innners are as close to the center as posstible and the outers are beside the windings so not as bad as you are trying to make everone belive.
As for methods he may not be my hero but he is a great shit he works hard for the endlessphere comunity and guys like you have to ruin it WTF?

Edit: Maybe you should read this on page 21 John!
Test #1 With fan on!
Outside temp 9.5 deg C(mesureed from outside wireless temp sensor)
Motor start temp 17 deg C (house temp)
Test point #1 temp 60 deg C
Test point #2 temp 70 degC

Test #2 With fan off!
Outside temp 8 deg C
Motor start temp 18 deg C
Test point #1 temp 59 deg C
Test point #2 temp 122 deg C
Yeh thats right 52 deg hotter without the fans and the ambient temp was 1.5 deg cooler!

[John in CR]

Keep on digging boy. Next I'll send you a rope.

[Hyena]

Great work el steak. I was watching this thread a while back but you've added alot of good info to it lately!

The holes in my GM cover aren't placed ideally - just outside the bearing on one side and about an inch from the outer lip on the other side but they have dropped the motor temperature noticably. I didnt have a temp sensor in there when it was sealed but before I'd burn my hand after a hard ride, now it's hot but I can keep it there. I'm running less extreme power - 18S lipo with a 100a limit but I haven't seen temps much over 90oC after a hard ride(max was 93 I think)

Air cooling mods aside it's good to see you having cooked any motors yet with internal temps well over 100oC.

OK, got to go give some time to the GF, shes not too impressed with my testing...

Don't I know that situation all too well. Wait until one day your GF becomes a wife and then there's a baby or 2 thrown into the equation.

[Toorbough ULL-Zeveigh]

.

Hyena:"Wait until one day your GF becomes a wife and then there's a baby or 2 thrown into the equation."

natural_parenting.png (21.31 KiB) Viewed 438 times

[ZapPat]

So El-Steak, will the next run be with the mid-radius holes plugged up? These extra holes in the middle may be reducing the effectiveness of the other well-placed holes, maybe?

[markcycle]

I'm going to add my experience with air cooling holes

it's my observation that the big problem with these motor is not the winding temperature per say, but the magnet temperature, as above 80C the magnet start to demagnetize. I have found with the motors I sell that the winding can sustain 140C measured and peaks of 160C. But if the magnets get above 80C then a degenerating effect begins because of the magnet getting weaker the motor needs more current hence more heat and this positive feedback continues until the motors finally burns out or the magnet let go and spin.

Air cooling holes in the side covers helps keep the magnet below 80C preventing this degenerating effect. With air cooling I can regularly see 125C on the winding but can keep the magnets below 70C. without air cooling I have to set the thermal shutdown at a winding temp of 100C to prevent the magnet form going over 80C.

I have been running air cooling holes on my test motorcycle for a year now (3000 miles) and have found that with good screens over the holes there is no problem with dirt or rain. I regularly inspect the windings and they look amazingly clean.

Mark

[markcycle]

for those who haven't seen the 600 series motor EnerTrac sells with cooling holes

[El_Steak]

The higher peak amps is interesting. I wonder if that's just because of cooler windings lowering the resistance. Did you notice any difference in how hard the bike pulled?

No, it felt the same. I don't think those "peak" numbers have much value, they last only a split second and vary a lot. I'm still recording them jsut for the sake of completeness (and I have to wait 2 minutes after each segment anyways).

How about the sonics, did you get any whistling? Did it change that other noise the 9c is known for, or did yours not do it to begin with?

My new 9c makes the same growl as the others I could hear in various videos. I didn't notice any difference in terms of sound with the new swiss-cheese cover. I wear a full face helmet though so my hearing is not the best.

Can I get you to do 1 pic? I'd like to see the cover from the outside but with the view parallel to the motor. I want to see where the hole placement is in relation to the flange where the cover's bolt holes are. I ask because I think you can draw the flow out from even closer to the windings by butting those holes right up to that flange where the cover is near perpendicular.

I'll take that pic tonight. I think there's still some space between the flange and the edge of the holes, I left some meat so I could enlarge those holes if need be.

One other question, how did the covers feel to the touch? That's really all I know, since I've yet to use a temp gauge, which will change shortly.

Hummm, I don't have good consistent data on that, I remember touching them a few minutes after I came back last night and they were just warm. I don't remember touching them on the previous runs though.