2010 Hubmotor meltoff

The course. 1200 vertical feet gained in 4 miles. About a mile of the steepest part is 7%.
San Augustine pass near Organ NM on HWY 70, east of Las Cruces. From Brahman exit to the top.

The temperature. Over 100F official temp.

Motor temps measured at axle, and 35 F added to that. Street temp is the motor temp at the start of the ride.

Humidity. Low. Low humidity lessens air cooling dramatically. We have very low humidity in June in NM, below 10%. In June lots of air cooled stuff dies.

The ride. Full throttle, no pedaling, 48v pingbattery. 180 pound rider.

The controller. Stock kit controllers.

The motors. E-Bikekit 9 continent 2807/9x7. 9 continent 6x10. High Tech Bikes Aotema. Fusin 48v gearmotor kit.


Controller heat. I didn't measure it, but all three kits controllers got hot enough to be hard to touch for long. But nothing went poof on the direct drive motors. 8) When the gearmotor quit, the controller did not feel particularly hot.

Any others that have different motors, do a similar test if you have hot enough weather. Telling us your motor stays cool at 85F does no good, we know that already. If you must, climb a hill repeatedly till you have a similar vertical distance of climbing in.



E-Bikekit 2807 (9x7 9 continent)

Temp at start ------------------------101F -------106 out on the road.

Wind -----------------------------------10 mph tailwind. Helps the motor climb faster, but a tailwind cuts wind cooling too.

Humidity--------------------------------7%

Temp at top of pass------------------151F Adjusted by adding 35F for actual temp inside the hub.

Soak temp at top---------------------121F After you stop, temp continues to climb after wind cooling stops. I don't have data to know how many degrees to add for this number. So it represents pretty close to the temp inside, 10 min or so after you stop.

Heat gain------------------------------50F 156 minus street temp of 106.

Amp hours used ----------------------4.125

Watt hours used---------------------208.1

Volts at the top----------------------52.5 Resting voltage.

Typical watts while climbing-------1100

Typical speed. ----------------------19 mph on the 7% part. 25 mph on the flatter part.

Temp after riding back down. ----143F

Summary. Climbs good with decent speed on the steep part. Could clearly have climbed farther, since 180F is what I consider a practical limit for motor heat. The temp at the bottom after riding back down shows that direct drive motors still make heat descending with the throttle off.




High Tech Bikes Aotema kit.

Temp at start---------------------103F ---108 on the road.

Wind ------------------------------10 mph tailwind

Humidity---------------------------7%

Temp at top of the pass---------155F

Soak temp at top----------------143F

Heat gain------------------------47F

Amp hours used-----------------4.17

Watthours used----------------212.74

Volts at the top-----------------52.5

Typical watts------------------1050--1180

Typical speed------------------16-17 mph on the 7% part. 28 mph on the flat part.

Temp after riding back down---156F

Summary---------------------- This motor clearly struggles more than the 9 continent 2807 on the steepest bit, but suprisingly made about the same heat, and used about the same watthours to get up the mountain. But had I continued, the numbers for the soak temp at the top show that this motor has a harder time cooling off once hot compared to the 9 continent motor. After 10 min the 9c had started to cool back off, while the Aotema kept on getting hotter. Both got to the same top temp, but the Aotema clearly held on to that heat longer. At 48v it's hill performance is not bad at all, but clearly it prefers 5% to 7%.

Update. soon after the test a problem this motor had been having for awhile got worse. An intermittent stutter or loss of power. It seemed to get worse with more volts when I tried a different controller, or when pulling max amps. This problem was present before the heat test, but the meltoff seems to have made whatever is wrong worse. Opening it up, there was no obvious signs of toasted windings. With all the miles on this motor, I suspect it was just something more age related than the melt test. It happens with any controller I try it with so I think it may be the windings. new connectors did not fix it, so it's not likely to be that, and the wires look ok.


9 continent 6x10 motor. Very slow winding motor.

Temp -----------------------------104F-----113 on the road

Wind -------------------------------12 mph tailwind

Humidity----------------------------7%

Temp at top of pass--------------150 F

Soak temp at top-----------------117

Heat gain-------------------------38F

Amp hours-----------------------3.65

Watt hours------------------------187

Volts at top-----------------------52.7

Typical watts--------------------800-900 1000 watts on steepest grade.

Typical speed---------------------15 mph on 7% 19 mph on flat part

Temp at bottom after riding down--110F

Summary. This motor climbs cool. Slower yes, but 15 mph isn't really that slow for climbing 7%. It simply makes less heat, uses less watts, and unlike the other motors this one reached it's max temp half way up the pass and never got hotter. That means I could have rode till the battery died on that grade and never gotten much hotter since the motor could shed the heat as fast as it made it. EVEN IN 112 F ROAD TEMPS! Wow. The dramatically different soak temperature shows there was no extra heat stored inside the motor when I reached the top. With a 48v battery, this motor could cross continents and never smoke itself on a hill.


Fusin 48v gearmotor.

Distance------------------ 3 miles

Temp ---------------------104F----108 street temp

Wind----------------------- 5-10 mph headwind

Humidity --------------------10%

Temp at top of pass--------? temp at end of test. 190F

Soak temp------------------? off the scale, presumably above 200F

Watthours---------------------168.3

Amp hours--------------------3.28

Typical watts-------------------750

Speed---------------------------10 mph---20 on the flatter part

Temp at the bottom-----------190

Volts at top----------------------? ---52.8 at end of test.

Summary------- By now you must be thinking, what happened? About 3 miles up on the test the motor stuttered a few seconds, quit, then ran a few more seconds, and quit for good. I suspect I melted a hall sensor. At that point temps were nearly 160F at the axle, and assuming 30-40F hotter inside, the motor was above what I consider safe, 180F. However, gearmotors don't shed heat as readily as direct drive motors, so perhaps the actual temps inside are even more than 40F higher. Who knows? the axle is pretty skinny, and I never got a sensor wire set actually inside a hubmotor. So maybe I melted it down even hotter than I think. But the bottom line is. In really hot weather, you better be carefull pushing your small gearmotors. It clearly struggled a lot more than the direct drive motors to climb the mountain. The Fusin kit has the three position switch, where you ride in the fast one till it slows too much, then move to position 2 and the motors performance improves. Finally you bog down in 2, and switch to slow to keep the motor happy climbing steep hills. This is how I was riding it. But obviously by the speed of the climb, and the end result, this motor couldn't climb the hill with no help from the rider.

Update. Finally got around to taking the fusin motor apart. Not obvious exactly what melted, but there was some loose balls of solder rolling around in there that hadn't been there before. So clearly this motor got cooked pretty hot.

actually with low humidity you have a great way to cool your motor. Mist system. With low humidity the water will be readily evaporate and wick away that heat.

I have found the best thing to be stopping, putting a rag over the hub, and pouring water on that. Nothing cools a motor better than not making heat with it anymore. Slowing down doens't do enough, but riding slow from the start of the ride helps a lot. Once the motor is too hot, just stop. Nothing else cools it faster.

Even in high humidity the water and rag trick works, and so would a mister or spray bottle. The water gets hot, drips off the motor, and takes the heat with it. Water molecules can really absorb a lot of calories. While moving, the water slings off the motor too fast to do as much as if you stop.

Back in the day, I used to drive home from work 70 miles in a bug. About halfway up a pass called Anthony Gap, I'd pull over when the VW started vapor locking and spray down the fan on the motor with a windex bottle for 2 min, cool it down and be on my way. This was not needed in July, when the rains came, and humidity might be 15-20%. But it was a must when the humidity was 5% and the temp was 105F.

Excellent test Dogman. I'm most interested in your test results for the Fusin too. A couple of weeks ago I did 250 miles on a geared brushed motor, from Victoria to Alberni and back to Victoria, over the course of 3 days, with two vertical climbs of 1400 feet, with rather steep sections over Mount Arrowsmith on a big recumbent loaded with dual Ping batteries in parallel. The ambient temperature was below 60 degrees F, and I ddn't have any issues with overheating. It just felt like maybe 120 degrees on the outside of the hub, to touch at the hottest. I was assisting as much as possible by pedalling myself, and probably averaged around 1000 watts over the steeper sections. I suspect the Fusin will rate pretty good on this test too. I'm planning on an across Canada trek, when I retire in a few years, so it interests me which motor would be best to get over the Rockies and Coast ranges. The brushed motor is awesome for torque on the hills, but was rather loud, amplified inside the fairing.

This is a great test Dogman. I'm kind of surprised to see that you didn't burn anything up

Thanks!

Nice test which shows the capabilities of each motor however to directly compare them I think you'd have to run the test over on the 9x7 and Aetoma at the same speed as the 6x10 if possible.

-R

Russell said:

Nice test which shows the capabilities of each motor however to directly compare them I think you'd have to run the test over on the 9x7 and Aetoma at the same speed as the 6x10 if possible.

-R

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Very good point.

Yep. But I did want to start by seeing if they could do it in that much heat full throttle. Slowing down without helping with pedaling then really becomes more of a controller test than a motor test. I wanted to do it with no pwm first.

I finally got a 4th bike functional and got the Fusin installed on it. Weirdly hard this time to get it done, trying to put two cheap bikes into one that works. In the end, going back to using the cheaper of the two, only to have trouble getting enough clearance on the steel suspension forks for the Fusin. By this afternoon I should have 105 or so again, and will go up the mountain again with the Fusin. But after 24 miles of riding on streets as hot a 110F yesterday, I don't see multiple trips today to try again slower happening.

Still pretty interesting though, how much difference the winding seems to make. The fast wind motor climbed slow, and made more heat, the medium wind climbed fast, using nearly identical watthours, and the slow wind climbed slow, but used a lot less watthours and made less heat.

The slow wind has more tourqe myth is busted, but the slow wind motor definitely climbs much much better.

The really interesting comparison will be between the gearmotor and the 6x10.

dogman said:

The really interesting comparison will be between the gearmotor and the 6x10.

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If you lose the tailwind I don't think the little geared motor will make it up a 7% grade on its own.

-R

It didn't

I have no doubt that the headwind was a factor. Even on the flatter part of the ride, I could see the temp was climbing quite rapidly compared to the dd motors. The test was a bit unfair, since the tailwind did help me up the hill testing the other motors and the fusin got a headwind. At the bottom of the pass it was blowing 10 mph, but up on the steep part of the climb the mountain blocked the wind more, and it was not blowing that hard then. The sad fact is that the gearmotors just have a harder time radiating the heat away with the smaller diameter covers. I saw the same thing happen with the 36v fusin kit last summer, but in that case I stopped at about 180F estimated internal temps. One thing is clear though, the big 9 continent motors at least shed their heat better, even if they make the same amount of heat climbing the hill.

I wonder what happens if you ziptie a rag around the motor, and keep wetting that as you ride.

I'll have to try it with my Fusin 36V sometime, after I get something setup to measure internal temps.

The water slings off the rag too fast to do much good. But stopping to cool off with water and a rag helps a ton. That was how I got through some hot weather with my Aotema motor. Back then I was quite paranoid about it since I had melted every brushed motor I had for awhile there.

So does stopping in time :lol: I was just thinking, I better turn around and end this fusin test. But nooooo, I just had to see what happened if I pushed it till the axle read 160F. Previously, the motor you are riding has seen about 140f measured on the axle. That was on a day that was only about 100F.

Fortunatley Phoenix is relatively flat compared to San Agustine pass. When your 9c motor comes, you will be set for summer.

I want to actually know the true internal temps. I think I will give my bike a hard ride with 2-3k w and take the temp of the windings side cover and stator through the holes in my motor side covers. I think it would yeild some come great data on what the true winding temps are. But then again the air cooling will kinda make my data useless when comparing it to sealed motors.

True internal temps would be better. Just hard to get another wire through the axle on most hubs. With the aotema, no halls, it was easy. So my estimations of the axle temp relation to the internal temp come from many many rides over an entire summer, comparing the internal temp with readings from the axle stub on the aotema motor.

Clearly, this 30-40F hotter inside number may not apply to the gearmotors. It seemed to me like there was more lag in the reading, and when I stopped, the temp just jumped off the scale, instead of slowly climbing like it did on the other motors. So I suspect the gearmotor may be 60F hotter inside, and I may have taken the Fusin to 250F where we know motors can get damage.

I still say though, the gearmotors get hot climbing a hill. Makes sense to me, small motor working it's ass off to produce the same work as a big motor. Gearing advantage or not, it's a lot of work to climb 7%. But in fact, I had just reached the 7% part of the climb when the fusin cooked off.

I haven't had time to take apart stuff and see what died, the motor or the controller. But I suspect the motor since it was nearly smoking.

That's....pretty owie about the Fusin. I'll definitely need to put a temperature sensor in there before I try to use it for cargo runs in the summer heat. Unfortunately hauling enough weight would be almost as bad as a hill run, and some of the places I have to go on the NW-SE canal path would also require hauling the cargo down and then back up a fairly steep ramp that goes under the main roads the canal crosses. I have to *walk* those if I'm on CrazyBike2 and have a motor problem, or on DGA when I didn't have a motor on it and had the trailer with cargo, because my knees would hurt too much, so I imagine the motor gets a workout on them, too.

Good to know the 2807 won't have much of an issue with it.

Regarding the rag on the wheel, I suppose I could run a misting hose from one of those clip-on bottles meant for joggers/walkers, down the fork leg to spray onto the hub. It would never get wet enough in the heat here to get inside it, just keep it cooled off from evaporation. A small terrycloth strip wrapped and secured around the motor between the spoke flanges could be made the target of most of the mist, to keep that damp enough to make a difference. I'll keep an eye out on Freecycle for one of those misters; and somewhere here I have some misting hose I can use to extend the bottle's reach.

The one thing I never tried was a rolling mist. I only tried a windex bottle while stopped. Stopping for just 5 min and water cooling does a lot, I just found a shady place to do it on the rides home.

Bear in mind, if it's below 95F, motors cool a lot better, and have an extra 15F to start from compared to 100F. So just try to do the cargo runs in the AM.

Usually I have to do them in the afternoon or early evening, as it's typically picking up Freecycled or CL items where the people have to / want to be home for me to pick up. I try to go around in a big loop to several at a time if I can schedule them that way, so I end up riding for up to a few hours sometimes, stopping for a rest or two along the way.

Grocery runs are the only things I can do early, or really late.

dogman said:

Bear in mind, if it's below 95F, motors cool a lot better, and have an extra 15F to start from compared to 100F.

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Also, I know I'm bad at math, but where do the other 10F come from in that?

Nobody as bad at math as me. :lol: :lol: :lol: I screw up my time card at work when counting on my fingers. There's a reason I quit the science major and went for an Ag degree instead.

But even 5 F less makes a big difference how far you go before getting hot. At 100F on the ride home, I get pretty hot in 5 miles, at 95F, the same temp is reached in 10 miles. At 90F, the motor never gets near the overheat zone on my ride home. Starting out cooler helps, but the real difference is the difference between ambient and the motor temp allowing the motor to shed the heat. At 100F and dry, it seems like the motor doesn't air cool at all, till you throw some water on it.

As I've said before on threads on motor heat, the big deal is what is the equilibrium heat of the motor for the weather. At a given weather, and a given watts, the motor will reach a given equilibrium temp eventually. The motor is as hot as it can get at that point. If that temp is 200F, you better shorten the ride, or stop to cool off. If that equilibrium temp is 150F, you can keep riding all day with enough batteries.

In the summer, I just ride my temp guage and stop when I think the motor is above 170F or so. Shoulda done that with the 48v fusin. I did do that with the one you have.

as an older hvac guy i can measure the dif in a blower motors amp draw at higher humidity
ie the weight of 1 cu ft of air increases with higher humidity
maybe like .07 lbs per cu ft (kinda a old school number if i remember incorrectly)
so a few things come to mind
higher humidity = increased air density
greater air density = greater resistance to motion
perhaps the heat gain on motors less the ability to transfer heat to the air is much less than you might think at low humidity
as the air is also more dense for you to flow though at higher humidy levels
generating a higher drag at a given speed

damm i am getting too old for all this math

justadad1957 said:

higher humidity = increased air density
greater air density = greater resistance to motion
perhaps the heat gain on motors less the ability to transfer heat to the air is much less than you might think at low humidity
as the air is also more dense for you to flow though at higher humidy levels
generating a higher drag at a given speed

damm i am getting too old for all this math

Click to expand...

From wikipedia:
The addition of water vapor to air (making the air humid) reduces the density of the air, which may at first appear contrary to logic.
http://en.wikipedia.org/wiki/Density_of_air

It would seem humidity causes a reduction in cooling. Its good for brush commutation though. :?

Ohhh god! Don't make me think about density altitude again! That was hard to get straight in flying school.

The rule of thumb here is, hot summer air is like flying several thousand feet above your actual altitude, lessening the payload you can fly. The winter is much nicer, where aircraft perform better than the indicated altitude. Not sure how humidity affects it, but it does..

On air cooled stuff, basicly the N and O molecules do squat to cool anything. But the H2O molecules in the air have an amazing ability to soak up calories, and transfer heat away from a hot motor. Once June was over, and humidity got above 10%, I could leave the windex bottle at home when I drove the VW bug or van.
But in June, in 5% humidity, you had to stop an squirt down the motor every 40 miles or so in afternoons.

I'm starting to remember this debate again. John in CR posted a link to a study that seemed to confuse the issue thoroughly:
http://www.endless-sphere.com/forums/viewtopic.php?f=2&t=119&start=360#p68526
http://www.springerlink.com/content/xug76jcyea6n5qgq/

What I got from that^ is that some humidity helps, but increasing it beyond a point is either neutral or bad. So, humidity makes less wind resistance and improves cooling (up to some point)?

Anybody here old enough to remember water bags hanging on front bumpers?

Canvas water bags hanging on vehicles were very common around here. They are still manufactured by Jones Tent & Awning.

I don't agree with there being some limit to the ability of more humid air to transfer heat. Think about it for a minute. A radiator cooling increases from 10% humidity right up to 100%. If you don't think so, put a radiator in water and see the incredible amount of cooling it can do. A water cooled heat exchanger is a small fraction of the size of a radiator on the same motor.

Our neighbour had a radiator in a creek and another in his house with insulated pipes in between. A little undershot paddle wheel ran the pump that circulated the water in the system. This worked far better than any swamp cooler 5 times the size.

Well, I know for sure humid air, even *wet* air, does plenty more to transfer heat away than dry air: My little window AC unit (which I have to use when there is more than a 15F difference between outside and what inside has to be to be livable, as the swamp cooler only makes a 15F difference at best), will struggle to produce 60F air coming out of it when it's a dry 100-120F out there, but when I use a single misting system head spraying near the airstream I get at least 40F air out of it, so it doenst' have to run *nearly* as long to cool the bedroom to livable. And thus my electric bill is MUCH less. Even with the slight uppage of the water bill it's still well worth it.

It worked on the main house AC back when I could afford to run that, even better than the window unit. I could just water the ground around it (which was needed for the grass, bushes and nearby tree) and even just that could give me 20F lower air temps coming out of it. Actually misting the water into the air going into it could freeze up the heat transfer plate in the house, even at 120F outside!

At one point I had built a little box for the window AC unit with a washing machine's input solenoid valve controlled by a 555 timer delay that was triggered by the compressor relay, so that it would wait about 30 seconds after the unit kicked on to start spraying, but would cut off right away (because it was powered by that relay) when it shut off. Somebody stole that and my front garden hose a while back though, so I need to build another one for this summer, soon, so I don't have to manually go turn it on and off.

Despite the watering laws restricting lawn watering to after 6:00 pm, Ive been known to put a sprinkler on my window AC at 2:00 PM. I keep meaning to rig a mister on it.

There are house AC units that combine water cooling of a swamp cooler with freon. They swamp cool the freon radiator. I never get any aguments about this concept of dry air doesn't cool from a desert dog. We know. Ask any old hippe who drove his WV across Arizona. Either you stop for every other hour, or you wet it down.