vanilla ice
1 MW
Ice up your leathers too..
Something like this could be good.
http://www.webbikeworld.com/r2/joe-rocket/sahara-vest/
Something like this could be good.
http://www.webbikeworld.com/r2/joe-rocket/sahara-vest/
How To Ice Up Your Motor? (Cooling Ideas)
- Thread starter safe
- Start date
docnjoj
1 GW
Man I just found this thread and even without Safes comments it took a while to read. I believe MY1018 is advertised as earth magnets (my quote key just died) therefore it probably is Neodyme, which means the mags are also very heat sensitive! I guess Im gonna go drill some holes in my motor and look to steal a hair dryer from someone who has hair! I gotta worry about noise as well as heat! Oy vey!TylerDurden said:
otherDoc
TylerDurden
100 GW
The 1018z is neo.docnjoj said:
I was at Goodwill today and scoped-out the hairdryers... good selections... they're only a couple of bucks.
tostino
10 kW
Oh my, that was a LONG thread! Just got done reading it.
If there were a way to have below ambient cooling that wouldn't be heavy as can be, and take up gobs of power (or have to be shoved into the freezer), then i'd love to have it. However, from the sound of it forced air cooling is the way to go for me. If anything, i'd just run the air through a copper pipe submerged in water/ice to cool it, but I don't really think that's necessary.
If there were a way to have below ambient cooling that wouldn't be heavy as can be, and take up gobs of power (or have to be shoved into the freezer), then i'd love to have it. However, from the sound of it forced air cooling is the way to go for me. If anything, i'd just run the air through a copper pipe submerged in water/ice to cool it, but I don't really think that's necessary.
safe
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Confirmed: It Definitely Works!
I rode in the morning and got the motor all heated up. Then I simply placed a bag of ice on top of the motor while I charged. It's almost 90 degrees now and yet the motor cooled down to (my guess) about 40 degrees. You could actually feel the motor as being quite cold. Seems that you don't need to worry about "perfect" contact with the motor because the metal transfers heat so quickly that whatever it gets it spreads around.
This is a 100% validation just on the heat transfer side alone, but then it gets better.
On my second run the power was excellent and by the time the run ended I actually had some battery energy left over. In the morning ride I was running really low. A voltage check confirmed that the final voltage was about 0.2 volts higher in each cell. (on my bike they are all a little different... but I've memorized what's going on)
And it was not a lazy ride either:
Trip Time - 22 minutes and 30 seconds. (1350 seconds)
Trip Distance - 10.47 miles.
So... 10.47 / 1350 * 3600 = 27.92 mph average.
Up until a few days ago this would have been a new record for me...
The motor ended up only luke warm...
And a note here:
This was placing a bag while charging... I didn't even have fresh ice for the ride. Had I used ice while riding this would be even better. (so the cheap plastic grocery store bag ice pack was removed before the ride)
The "lesson learned" is that a motor has a high level of thermal mass and you can force a "negative" temperature onto the motor and this will operate as a coolant when you ride. By "pre-cooling" the motor you might not even need other types of cooling if your typical ride time is short. (this is more of a racing trick than what the casual rider might use)
I rode in the morning and got the motor all heated up. Then I simply placed a bag of ice on top of the motor while I charged. It's almost 90 degrees now and yet the motor cooled down to (my guess) about 40 degrees. You could actually feel the motor as being quite cold. Seems that you don't need to worry about "perfect" contact with the motor because the metal transfers heat so quickly that whatever it gets it spreads around.
This is a 100% validation just on the heat transfer side alone, but then it gets better.
On my second run the power was excellent and by the time the run ended I actually had some battery energy left over. In the morning ride I was running really low. A voltage check confirmed that the final voltage was about 0.2 volts higher in each cell. (on my bike they are all a little different... but I've memorized what's going on)
And it was not a lazy ride either:
Trip Time - 22 minutes and 30 seconds. (1350 seconds)
Trip Distance - 10.47 miles.
So... 10.47 / 1350 * 3600 = 27.92 mph average.
Up until a few days ago this would have been a new record for me...
The motor ended up only luke warm...
And a note here:This was placing a bag while charging... I didn't even have fresh ice for the ride. Had I used ice while riding this would be even better. (so the cheap plastic grocery store bag ice pack was removed before the ride)
The "lesson learned" is that a motor has a high level of thermal mass and you can force a "negative" temperature onto the motor and this will operate as a coolant when you ride. By "pre-cooling" the motor you might not even need other types of cooling if your typical ride time is short. (this is more of a racing trick than what the casual rider might use)
TylerDurden
100 GW
safe said:
You "guess".... Perhaps a thermometer might lend a better assessment of the difference.
Quite a breakthrough. A bag of ice made you motor colder.
safe
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Aaaaah, but my little angry one, the secret is that pre-cooling a large mass of metal works as a coolant even when the ice is removed. The heat transfer of metal is really high from water/ice to metal, but the heat transfer of air to metal is slow. So you are literally forcing "negative temperature" into the thermal mass of the motor. You are using the motor mass like a reservoir of cold.TylerDurden said:
Checkmate... 8)
safe
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Tips That Should Work
I'm guessing that the most important thing is the relative mass of your motor. So if you have something like a Unite motor (like mine) there is enough mass to be able to ice it down and get it's core temperature below the outside temperature. (close to freezing in the best case)
If you have a very small motor that has little mass then it's probably not going to work as well and the opposite extreme of something very, very large like a hub motor would be so large as to not need it.
But I will say that you only need about one quarter of the motor shell to be exposed to the ice before the effect takes place. Steel is such a good conductor of heat that you don't need to have a complete wrap because the metal transfers the cold just fine.
For many people who are pushing the upper limits of their motors and want to make them work better this little trick might be the easiest high performance modification you can do.
All it takes is some ice, a plastic bag, and enough time so that before you start the ride the motor gets cooled. On my test it took about half an hour overall to melt all the ice and get the heat down.
Seriously folks.... if it's a hot day and you want more power... this trick really works.
I'm guessing that the most important thing is the relative mass of your motor. So if you have something like a Unite motor (like mine) there is enough mass to be able to ice it down and get it's core temperature below the outside temperature. (close to freezing in the best case)
If you have a very small motor that has little mass then it's probably not going to work as well and the opposite extreme of something very, very large like a hub motor would be so large as to not need it.
But I will say that you only need about one quarter of the motor shell to be exposed to the ice before the effect takes place. Steel is such a good conductor of heat that you don't need to have a complete wrap because the metal transfers the cold just fine.
For many people who are pushing the upper limits of their motors and want to make them work better this little trick might be the easiest high performance modification you can do.
All it takes is some ice, a plastic bag, and enough time so that before you start the ride the motor gets cooled. On my test it took about half an hour overall to melt all the ice and get the heat down. Seriously folks.... if it's a hot day and you want more power... this trick really works.
Ypedal
100 TW
Yeeeeahhhh.. lets see. a cold pack that sweats in humid enviroments, dripping water on an electric motor. 
If you need to cool down an ebike motor in order to gain.. say.. x % ( see.. no guessing ) your motor is not up to the job required of it. get a bigger motor.
If you were drag racing in weight weenies category.. you might have something there..
If you need to cool down an ebike motor in order to gain.. say.. x % ( see.. no guessing ) your motor is not up to the job required of it. get a bigger motor.
If you were drag racing in weight weenies category.. you might have something there..
safe
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Ypedal said:
Bigger motors weigh more...The trend is to get smaller and smaller motors that give more and more power. You've seen Recumpences motor, that's the direction people are getting interested in. (why carry around a 25 lb motor when you can do the same job with 5 lbs?)
Any time you push the power upwards you have to deal with more heat. With this trick you can get a definitely noticeable improvement in power without adding any weight.
There are no downsides to this... it's 100% beneficial...
I think the main surprise was that it worked so well. There had been many people who doubted the concept and so by testing it out and finding the results excellent it's just a win for everyone.
safe
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Just Try It
Whether you have a big hub motor or a small motor, just give it a try. Get some ice out of the freezer and put it into a secure bag that doesn't leak and then just place it onto the shell of your motor. Let it sit for about half an hour or until the ice melts and then go for the fastest ride you can.
When you get back see how hot the motor is and consider how efficient and powerful the ride felt. (if you have good measuring equipment then that's even better)
Then if enough people try it then we can see some more feedback... I'm just saying that in my case the results were very good.
Whether you have a big hub motor or a small motor, just give it a try. Get some ice out of the freezer and put it into a secure bag that doesn't leak and then just place it onto the shell of your motor. Let it sit for about half an hour or until the ice melts and then go for the fastest ride you can.
When you get back see how hot the motor is and consider how efficient and powerful the ride felt. (if you have good measuring equipment then that's even better)
Then if enough people try it then we can see some more feedback... I'm just saying that in my case the results were very good.
EMF
100 kW
Add this to the list of ideas to never be adopted by the general, rationally thinking, ebiking community. Cooling a motor can reduce the resistance in the windings, but we are talking VERY small increase in performance by doing so, at these temperatures and there is no way in hell you are going to detect the diference via "seat of the pants" diagnostics, available to the general public.
I think that a very efficient cooling arrangement, would yield possibly a 1% increase in overall performance, providing you could maintain an artificially low internal temp, without expending the said 1% in energy to do so. A La - a fan on the armature shaft and strategic cooling slots. Assuming you got 1% increase in efficiency either way, you are going 101 miles rather than 100 for a given unit of energy. Pfft!
Having said that, the best way to do this is from within the windings as it runs and not by letting a bag of ice sit on it, this is impractical and also foolish, due to condensation problems that would arise in humid environments. Kiss your bearings goodbye as they will have a shortened life.
If I had a motor overheating to the point that I thought it was going to burn up, I would get a bigger motor, or gear it down. Regardless of how much ice you throw at it, the windings are going to get hot deep inside as they are still pulling high amps under load and the insulation on the windings will begin to deteriorate. This insulation is very thin and delicate too.
I have seen people that are running 3 phase motors, that are so hot from high amps, that the heaters trip on the starter. Rather than deduce what the problem is - bad bearings, Low voltage, bad contactor, or too much load, too little horsepower, they actually ran a water hose on the motor to "keep it cool" ! Needless to say, the heaters still tripped.
Where I work, we use a lot of energy, we get all kinds of ideas on how to save energy - in 35 years, this super cooling has never come up. the only thing I ever saw that made a motor do the same work with less energy, *and we tried it* was big ass capacitors. These worked!!! We saw a dramatic drop in power consumption with before and after tests. this involved a non changing load and an amp meter strip tape. But, then the capacitors started failing and they were expensive, yada yada yada.
This is no "solution" to an overloaded motor, padding it with ice. It is also a negligible gain in efficiency. In fact, it's just plain silly. Recumpence has proven ( to me at least ) that a small RC motor, carefully chosen for the task, can be both lightweight and powerful enough to drive himself and an ebike down the road at impressive speeds and efficiency - without any overheating issues. He did his homework, got the right motor for the job and geared it right. Problem solved. The ice at his house goes in the drinks, not on the bike motor.
I think that a very efficient cooling arrangement, would yield possibly a 1% increase in overall performance, providing you could maintain an artificially low internal temp, without expending the said 1% in energy to do so. A La - a fan on the armature shaft and strategic cooling slots. Assuming you got 1% increase in efficiency either way, you are going 101 miles rather than 100 for a given unit of energy. Pfft!
Having said that, the best way to do this is from within the windings as it runs and not by letting a bag of ice sit on it, this is impractical and also foolish, due to condensation problems that would arise in humid environments. Kiss your bearings goodbye as they will have a shortened life.
If I had a motor overheating to the point that I thought it was going to burn up, I would get a bigger motor, or gear it down. Regardless of how much ice you throw at it, the windings are going to get hot deep inside as they are still pulling high amps under load and the insulation on the windings will begin to deteriorate. This insulation is very thin and delicate too.
I have seen people that are running 3 phase motors, that are so hot from high amps, that the heaters trip on the starter. Rather than deduce what the problem is - bad bearings, Low voltage, bad contactor, or too much load, too little horsepower, they actually ran a water hose on the motor to "keep it cool" ! Needless to say, the heaters still tripped.
Where I work, we use a lot of energy, we get all kinds of ideas on how to save energy - in 35 years, this super cooling has never come up. the only thing I ever saw that made a motor do the same work with less energy, *and we tried it* was big ass capacitors. These worked!!! We saw a dramatic drop in power consumption with before and after tests. this involved a non changing load and an amp meter strip tape. But, then the capacitors started failing and they were expensive, yada yada yada.
This is no "solution" to an overloaded motor, padding it with ice. It is also a negligible gain in efficiency. In fact, it's just plain silly. Recumpence has proven ( to me at least ) that a small RC motor, carefully chosen for the task, can be both lightweight and powerful enough to drive himself and an ebike down the road at impressive speeds and efficiency - without any overheating issues. He did his homework, got the right motor for the job and geared it right. Problem solved. The ice at his house goes in the drinks, not on the bike motor.
Ypedal
100 TW
JeffD
10 W
Ypedal said:
Wow! What a testament to your commitment and passion to this field.
I'm not worthy. I'm not worthy.
:lol:
EMF
100 kW
Ypedal said:
This reminds me of my single days in another time. :lol: I actually tore down a 750 honda in my kitchen and rebuilt the engine on my kitchen table. Had it bored out to a 900 and added an RC Engineering 3/4 racing cam and had the heads ported and polished. Then I painted a lot of the parts, like the oil pan with plasticote and "baked on" the finish in the oven! LOL It came out like black chrome. 8) I sent out all the other covers to a chrome plating place in Ocala Florida and then assembled the bike and rolled 'er out the front door of my apartment!
I guess you might be a redneck if you have a motorcycle tore down in your house.
Ypedal
100 TW
You should see my garage !!!! 
.. and the shed... :lol:
.. and the shed... :lol:
EMF
100 kW
Hahahha! OK got any beer? I'm on my way over. :wink:
John in CR
100 TW
Quite a discussion you guys have been having in this thread, and at a minimum you've reinvented the terminology used in thermodynamics, if not attempted to bend some of its laws. I too started my electric bike pursuits with an MY1020 motor, but a 750W 24V model. I even entertained the idea of buying a 1000W 36v or 48v model for more power, since they are so cheap, and the smaller one was overheating too easily. I tried both ram air ducting and forced air ventilation using fans to no avail, and my next step was to add aluminum fins to the exterior to sink the extra heat away, but the motor burned up with only 30 amps at 40V with short 5-10min rides in less than 2 weeks. I quickly realized these cheap motors weren't a route to anything durable. They are cheap for a reason, and not only does the low efficiency waste your batteries, but it translates directly into a heat problem that makes the motor fail.
If you want to ventilate a motor, just look at the ways it's already done. If you have a heat problem, here's a good place for the tools you'll need, http://www.engineeringtoolbox.com/thermodynamics-t_36.html . What you'll find though is that lot's of surface area is required to transfer heat to the air at these relatively low temperatures, and forget about thinking that all those windings add much surface area, because very little of it get exposed to air flow. Instead, most of the air flow goes through the large gaps between the magnets of these motors.
If you're going to stick to 5-10min rides, then pre-cooling the motor or even using an ice pack will work, because you do have a significant mass to heat up before overheating occurs/ and ice will sink 80calories/gm or 335 joules/gm before melting. You need a lot of ice though, since even at just 1200W, assuming an efficiency of 72%, each gram of ice will get you 1 second of cooling.
My suggestion is to forget the junk motor, and if you want something of similar size and type, but more power, spend the extra $ and get something like this http://www.robotmarketplace.com/products/NPC-4200.html
John
If you want to ventilate a motor, just look at the ways it's already done. If you have a heat problem, here's a good place for the tools you'll need, http://www.engineeringtoolbox.com/thermodynamics-t_36.html . What you'll find though is that lot's of surface area is required to transfer heat to the air at these relatively low temperatures, and forget about thinking that all those windings add much surface area, because very little of it get exposed to air flow. Instead, most of the air flow goes through the large gaps between the magnets of these motors.
If you're going to stick to 5-10min rides, then pre-cooling the motor or even using an ice pack will work, because you do have a significant mass to heat up before overheating occurs/ and ice will sink 80calories/gm or 335 joules/gm before melting. You need a lot of ice though, since even at just 1200W, assuming an efficiency of 72%, each gram of ice will get you 1 second of cooling.
My suggestion is to forget the junk motor, and if you want something of similar size and type, but more power, spend the extra $ and get something like this http://www.robotmarketplace.com/products/NPC-4200.html
John
safe
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By My Calculations
This is for my current bike at 48 volts:
10 degrees C, 50 F
Resistance 0.196
Power Out - 1425 watts
Range 8.0 miles (full throttle all the time)
30 degrees C, 86 F
Resistance 0.212
Power Out - 1415 watts
Range 7.8 miles (full throttle all the time)
70 degrees C, 158 F
Resistance 0.243
Power Out - 1374 watts
Range 7.4 miles (full throttle all the time)
So from coldest to warmest we get:
1425 - 1374 = 51 watts
And so we have 51/1425 = 3.58%
...not a huge advantage, but it all depends on how long it takes to warm up.
3.58% is 3.58%... when you are already maxed out all the time it's an advantage. Races are won or lost with this sort of thing. For the casual rider.... forget about it! But for me where I have my own "personal best" to strive to beat all the time it's a way to give myself an edge. My best average speed for a distance over 10 miles is just a fraction over 30 mph, so this might help me get to 31 or 32 mph. You never know. Plus it's a nice insurance policy to be sure the motor stays cool on the hot and humid days we get here in the midwest. (high humidity makes air cooling less efficient too)
I should add that the ending temperature was noticeably cooler, in the range of about 20-30 degrees F, so it does seem to take some time to heat up the motor mass.
This is for my current bike at 48 volts:
10 degrees C, 50 FResistance 0.196
Power Out - 1425 watts
Range 8.0 miles (full throttle all the time)
30 degrees C, 86 FResistance 0.212
Power Out - 1415 watts
Range 7.8 miles (full throttle all the time)
70 degrees C, 158 FResistance 0.243
Power Out - 1374 watts
Range 7.4 miles (full throttle all the time)
So from coldest to warmest we get:
1425 - 1374 = 51 watts
And so we have 51/1425 = 3.58%
...not a huge advantage, but it all depends on how long it takes to warm up.
3.58% is 3.58%... when you are already maxed out all the time it's an advantage. Races are won or lost with this sort of thing. For the casual rider.... forget about it! But for me where I have my own "personal best" to strive to beat all the time it's a way to give myself an edge. My best average speed for a distance over 10 miles is just a fraction over 30 mph, so this might help me get to 31 or 32 mph. You never know. Plus it's a nice insurance policy to be sure the motor stays cool on the hot and humid days we get here in the midwest. (high humidity makes air cooling less efficient too)
I should add that the ending temperature was noticeably cooler, in the range of about 20-30 degrees F, so it does seem to take some time to heat up the motor mass.
John in CR
100 TW
Safe,
Interesting results. What surprises me most is the difference in resistance. How and at what points did you measure it? The reason I ask is that the temperature coefficient of resistance for copper is only 0.004041 per degree C, http://www.allaboutcircuits.com/vol_1/chpt_12/6.html. My guess is that starting at the lower temperature is your biggest benefit, since it's a lot of metal to heat up and with a cooler start it takes longer to heat up to the critical point where the windings reach a high enough temperature and resistance starts to spike.
I'd also be inclined to think there's a high likelihood of testing bias. With wind resistance such a high portion of the overall picture, it would only take a small shift in riding position to unintentionally skew the results.
BTW, convective heat transfer from a metal surface to a flow of air increases with humidity, not decreases. http://www.springerlink.com/content/xug76jcyea6n5qgq/ . This makes perfect sense because it's much easier to transfer heat from a metal surface to water than to air, and higher humidity means more water content in the air. Get humidity up to 100%, so that it's raining, and you'll really keep your motor cool.
John
Interesting results. What surprises me most is the difference in resistance. How and at what points did you measure it? The reason I ask is that the temperature coefficient of resistance for copper is only 0.004041 per degree C, http://www.allaboutcircuits.com/vol_1/chpt_12/6.html. My guess is that starting at the lower temperature is your biggest benefit, since it's a lot of metal to heat up and with a cooler start it takes longer to heat up to the critical point where the windings reach a high enough temperature and resistance starts to spike.
I'd also be inclined to think there's a high likelihood of testing bias. With wind resistance such a high portion of the overall picture, it would only take a small shift in riding position to unintentionally skew the results.
BTW, convective heat transfer from a metal surface to a flow of air increases with humidity, not decreases. http://www.springerlink.com/content/xug76jcyea6n5qgq/ . This makes perfect sense because it's much easier to transfer heat from a metal surface to water than to air, and higher humidity means more water content in the air. Get humidity up to 100%, so that it's raining, and you'll really keep your motor cool.
John
docnjoj
1 GW
I wonder what aerosolized spray water injected directly into the armature opening would do? I just keep thinking that our bike electronics and water dont seem to play well together!!!!!
otherDoc
otherDoc
safe
1 GW
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I used 0.00393 in my calculations... this was not measured on the bike.John in CR said:
As for humidity, the problem is the ability to lower the temperature when the air is at 80-90 degrees F. The higher air temperature combined with the higher humidity means that any air that moves through the motor will be warm and moist to begin with. If you could get cold moist air into the motor that would help more. Ice on the shell would tend to keep things below air temperature.
The benefits in peak power are relatively small, but when the motor heats up dramatically after the first ride it can often still be heated when I start the second. By forcing the motor temperature down to near freezing while I charge it guarantees a full power ride each time without overheating.
It's not for everyone... :?
Ypedal
100 TW
I learned in grade 3 that there is no such thing as " coldness " .. just less heat..
Heat transfer.. the cold pack is extracting the heat from the motor.. not the other way around.
Heat transfer.. the cold pack is extracting the heat from the motor.. not the other way around.
TylerDurden
100 GW
Aside from corrosion, it would be very good. Non-corrosive liquids like alcohol, that evaporate above 50C would kick ass, but cost $$.docnjoj said:
As Reid pointed out, humidity is good for brushed motors. He suggested a wetted -ponge intake humidifier.
An ironless motor could use aerosolized spray water injection, without armature corrosion concerns.
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