Air Cooling my x5

[spinningmagnets]

I plan to make a fin-and-disc similar to your design, but attached to the outside of the left side of the hub. I only plan to have side-plate inlet holes near the axle.

I would suggest that if you repeat the same style inside the hub, perhaps only have holes on the hub sideplate near the rim, and completely seal off the sides and tops of the fin/disc assembly. Centrifugal force will fling air trapped in the finned voids out the rim holes, and the lowered interior pressure will draw in fresh air. Maybe add a few inlet holes on the other side of the hub?

Best of luck with whatever you try!

[El_Steak]

Share the results of your design with us, the more info the better.

For my new 9c motor I simply did a lot of big-ass holes similar to icecube / metallover. In my daily commute, it keeps the motor under 120C which is good enough for me.

[Farfle]

Here's my side covers I did with the schools CAD mill:

[El_Steak]

Looks very nice Farfle.

[deVries]

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!

Hi Doc, ok, push!

I haven't found a post from you that documents your cooling technique for your X5 motors. Have you modded any of your motors for cooling & posted your ideas/mods with pics?

What do you think is the best way to cool an X5?

Thanks!

[hillzofvalp]

I wonder if it would be very effective to get a heat pipe with heatsinks on the outside perimeter of the motor between the flanges or a heat pipe alone..... and then have the wheel do the work of circulating the coolant to, say, the rim. If you ran low profile tubing in the rim, maybe you could use it as a heat sink. I don't know the physics of it... but I think the shape and orientation of the tubing would slosh the coolant around. Maybe there is an ideal double walled rim that can be sealed up so that you could use the rim itself as a thermal conduit..

It's far out there, and maybe just something to balk about.

[auraslip]

I'm confused by El Steak's testing. Mostly why plugging the middle holes decreases cooling instead of increasing it as was assumed.

I wonder, could the cassette or disc brake be interfering with the air flow to the intake holes closest to the axle?

[John in CR]

I used to think El Steaks mid radius holes may have a negative effect, but El Steak's results proved that incorrect. Think about a squirrel cage fan and how they intake air over a broad range.

Another thing I had to think on for a while was his lack of improvement with blades, and I came to the conclusion that the air gets spinning full rpm by the time it reaches the perimeter regardless of his blades. I still do blades in mine (epoxy plus one bolt to avoid a motor killing loose blade like happened to El Steak a while back), but I shape mine so the flow of air off of their tip is directed at the stator iron and coils. The seems far better than much of the flow moving unfettered along the sides of the cover to the exit and bypassing the stator.

John

[ambroseliao]

Hi John,

Can you post pix of your blades setup?

Ambrose

[El_Steak]

I'm the first one to be disappointed by the numbers I got in my testing, but hey numbers don't have feeling and hopefully they helped some members refine their designs.

After my motor destruction, I went for a simple design with just a bunch of large holes close to the perimeter. I can't do my test run with it because the road I was using was destroyed this summer when we had a major river flood. It hasn't reopened yet.

In my daily commute however, the cooling is suffient to allow me to ride at full throttle 100V/100A.

[ZOMGVTEK]

In terms of physical winding temps, I didn't notice any major impact with drilling a bunch of holes. The motor covers run cooler, but the windings still get awfully hot.

It didn't increase winding temp, and now I can easily smell the hub cooking when its hot, so its better than nothing.
I've been considering drilling a bunch more holes and throwing a high CFM fan on the outside.

[itchynackers]

Well if it isn't hurting, then its helping. I get a different result, and I have just perimeter holes too. 3/4" diameter between each support rib, placed over the windings. Seems to help quite a lot with keeping things cooler, and cooling down quicker. I agree though, that you can smell some of the outgassing when the motor gets warm. Also, the motor seems a bit noisier now.

[hillzofvalp]

can I ride my bike in the rain with these holes? snowy winter weather?

It can't be hard to make covers for bad weather... which I will probably do. I might try putting some steel on the other side of the motor cover so I can put a big flexibly magnet over the motor

[ZOMGVTEK]

My motor never had any issues in the rain. Unless you like riding in deep water, or hit tons of deep puddles, it shouldn't be a major issue.
Its probably fine in snow as well. Sliding and spinning around in deep snow might force some in the motor, but its not an issue unless you have a bit of liquid sitting in the motor for a while and it rusts bad. Generally the motors you are drilling holes in are running hot, so a little moisture will tend to evaporate.

The motor won't care about running underwater. It wouldn't be a bad idea to ensure the hall sensors have no exposed leads, and that the motor never sits with water inside it. If it really gets a lot of water inside, try to get most of it out, and lift the rear tire and set the cruse at a low speed while drying it out. You're just trying to avoid getting the halls wet, or rusting the motor sized.

[John in CR]

Salty water from road salt + exposed wire connections inside a motor (phases and halls) sounds like potential motor death to me that is likely to take the controller down with it. Pick up an extra set of covers to put on for the winter would be the way to go.

[John in CR]

Something that dawned on me recently is that the big chunks of copper exposed due to the overlapping winding strategy of the old style Crystalyte motors makes air cooling far more effective than with newer style motors. It's all about surface area when it comes to cooling with air and the artwork of windings on these motors leaves many times more copper surface to be exposed to the airflow. That end copper may be a detriment to efficiency, but it's a great copper heat sink for the enclosed windings.

Another beneficial aspect is the angled stator slots, which will definitely help get air flow through the gap, so be sure to consider the directional nature of this and take advantage of it in your air flow strategy.

[hillzofvalp]

I wonder if I could make an independent study out of this at school... for 3 credits...

[auraslip]

I wonder if I could make an independent study out of this at school... for 3 credits...

You could probably get covers from burned out motors for testing from us.
In other words, HELL YEAH!

[John in CR]

I wonder if I could make an independent study out of this at school... for 3 credits...

Not if you still think air flows in at the top and out at the bottom.

[Emoto]

Well this was a good informative thread of interest to all, but no posts for a while did some new air cooling tech make it obsolete, or is the new Crystalyte ht/hs models stealing the limelight. John did you finish/ test your 9c , im still keen on these as they can be half the price of a ht/hs and with good cooling should be able to handle good power.

[John in CR]

Well this was a good informative thread of interest to all, but no posts for a while did some new air cooling tech make it obsolete, or is the new Crystalyte ht/hs models stealing the limelight. John did you finish/ test your 9c , im still keen on these as they can be half the price of a ht/hs and with good cooling should be able to handle good power.

The 12fet high voltage controller fried before the first ride, and the 18fet fried after the second short and mellow test ride, so never enough to put the cooling to the test with the 9C. Since the motor has no spoke flanges it's just on the shelf while others be the high voltage guinea pigs. My son and I have refined the approach with other motors, which has worked great. One is the equivalent to a 2 turn HS40 if Xlyte made one, and my 175lb son bombs up steep mountain roads at up to 167wh/mile performance with just a warm motor at the top. I blasted most of the way up one including accelerating up the 30% grade section with Hubmonster pushing my 90lb SuperV and 260lb me. I turned around due to a battery shortage after a solid 2.5 miles of constant climb, and Hubmonster was cooler than his motor.

Hubmonster has a slightly different approach with intake only on one side and exhaust a the extreme perimeter on the other, and fan blades in both covers right at the windings. The in one side and out the other is an attempt to get more flow across the stator. It worked but the intake side is slightly warm and the exhaust side near ambient, so I need to tune it a bit by blocking much of the open space in the stator spokes. Too much flow is taking that path of least resistance. The stator is 50mm wide, so much more surface area than either side, so I believe directing half of the air flow through the magnetic gap is good goal.

I took pics and will fully disclose all the hows, whys, and results in a new thread in the pics and video section very soon. Unless the oil cooling guys add significant outside surface area, they'll never get to the performance level we're seeing with a well planned centrifugal air cooling strategy. I'm not talking about the typical holes in a pizza pan approach so frequently used which has marginal benefits.

John

[itchynackers]

Hopefully your data will include empirical evidence like actual temperatures & temperature changes, not just "warm", "warmer", "better", etc...

[John in CR]

Hopefully your data will include empirical evidence like actual temperatures & temperature changes, not just "warm", "warmer", "better", etc...

Sorry, but I've never bothered with a temp sensor since I've never burned up a motor. That's despite running faster and with heavier loads than the vast majority who have. A 5mm wider stator is not the explanation. I've done my research homework into air flow systems, and I've crunched the heat transfer numbers. Then I actually try different things and share what works, and share explanation of what doesn't.

I'm into results more than the numbers behind them, and our biggest problem has been creating a big enough load to test the limits of my centrifugal cooling approach, and have yet to get a ventilated motor close to hot. Those who have is due to 2 factors, improper approach combined with pushing motors past saturation. We don't have enough controller to push these low turn count motors into saturation.

Here's some empirical evidence for you though, and far better than simple temperature measurement of one unknown spot on a stator. Through research and calculation, I came up with a reasonably conservative estimate for heat dissipation above 350rpm (about 21mph in the 20" wheels we run) of 2-2.5kw for a common 20cm stator motor using my approach to ventilation. At 75% assumed efficiency under heavy load, that's 8-10kw input. The most we've managed using a steep 3.75 mile hill and some extra weight in a backpack is to push 1kwh through the motor in right at 7 minutes. First we rode around for a couple of miles with plenty of hard launches to make sure the motor was at a decent operating temperature before attacking the hill. The motor wasn't noticeably warmer at the top of the hill than at the bottom, and after a 2min wait it didn't feel any warmer, so there wasn't a lot of heat stored at high temp in the stator. That 8500W average input with the far heavier load in the top half where it's much steeper, proved to me that my calculations and estimates were valid and on the conservative side, though we still don't know the limit.

FWIW, I also came up with an estimate for the oil bath approach of a sealed DD hubbie using the same methodology, and even with covers reaching 100°C (a temp I don't want my magnets reaching), the max heat it could dissipate was less than 1000W. No doubt that it would be helpful for those running less than 4kw average with higher turn count windings and pushing the stator into saturation in short bursts or other intermittent low efficiency situations, but not for the continuous power I require to tackle long steep hills or to hit highway speeds in excess of 60mph. More surface area or some kind of radiator is required.

John

[Emoto]

Good to hear your still motivated and evolving the design , as im convinced this is way. no wires/ fans/ oil, especially easy for manafactures to implament at a low cost.
I still might go the 9c with centrifugal air cooling max 4kw , rather than a hs/ht.

I took pics and will fully disclose all the hows, whys, and results in a new thread in the pics and video section very soon

Awsome, i think a important point would be to provide a before and after mod results as a referance [ i know its more effort ]
im sure you know there would be many members wanting to do this mod, but hesitant before drilling that sucker! out.

[John in CR]

Awsome, i think a important point would be to provide a before and after mod results as a referance [ i know its more effort ]

I can do better that that. I've got identical motors in the same size wheel running the same voltage, one sealed and one ventilated. Even when we load the ventilated one down much heavier, it's always much cooler, including the telltale spots (between the spoke flanges and at the axle). Sometime we'll bring along a thermometer and video for the doubters. That will calibrate my fingers, so I get some benefit too.