Samd
10 MW
About 1500usd macribs but it is packing a bit more punch than the stock dlc28
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Make a watercooled high kw motor and I'll buy it !
- Thread starter Jestronix
- Start date
hillzofvalp
100 kW
John in CR said:
John is right, generally.
Although if you are pressed on space, I can see where complex thermal solutions are useful. It's a shame how much space is wasted in most hub motors. Even 20% increase in cost could go a long way. Pushing the limits of material usage and getting that last bit of oomph out of an object is what fuels the lycra industry (did you say $200 seatpost?)
minde28383
10 kW
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- Apr 2, 2010
- Messages
- 700
macribs said:
me can't play the video.
Just wanted to add about using larger motors to create less heat.
The issue is there is a tradeoff when using larger motors on an electric bike. The tradeoff is worse handling at the rear and it makes a big difference.
You can use a smaller motor and get very good performance out of it at the expense of more heat and wasted electricity.
For me, I would rather have the smaller motor for the lighter weight and then just add more batteries in the center of the bike, and use a cooling solution to deal with the heat. That is the best tradeoff for me because I off-road the bike.
The different between a MXUS Turbo and a QS 205 huge motor, is about 8lbs, which is a lot of weight.
The issue is there is a tradeoff when using larger motors on an electric bike. The tradeoff is worse handling at the rear and it makes a big difference.
You can use a smaller motor and get very good performance out of it at the expense of more heat and wasted electricity.
For me, I would rather have the smaller motor for the lighter weight and then just add more batteries in the center of the bike, and use a cooling solution to deal with the heat. That is the best tradeoff for me because I off-road the bike.
The different between a MXUS Turbo and a QS 205 huge motor, is about 8lbs, which is a lot of weight.
macribs
10 MW
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- Jul 22, 2014
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- 3,702
Weight is an issue for sure. The dlc 28 and its clone is mid drive motors. 15 kw continuous and 38 kw peak. Weigh in at about 15 kilo, or about 3 kilos more then the QS 205 DD hub. The nice thing with a mid motor is you got all the weight of the motor out of the rear rim, and can centralize mass for better inertia, better handling and more easy and faster responding bike. Yet with the power and torque to match the better handling.
As OP asked for watercooled motor and high kw the dlc 28 might be right up his alley. If matched with ie mobipus 72600 or the cheaper APT 96600 you get motocycle/dirtbike power on tap, water cooled motor and controller and even in the harshest dessert sub blazing conditions you know your bike will keep running no matter what terrain, road/trail surface or hill you climb. Cos that kind of power and centralized mass is not free, it will run you about 2.000-2.300 $ or something but a mxus/205 with Adapatto Max e will easily run you 1200+ $. Then you will have weight penalty, possible heat issues, less handling bike due to the added weight in rear wheel and off set inertia.
All in all not bad if you think about it. Sure 2K for motor controller only is a lot. But such a buy in will for sure give you your moneys worth in return regarding handling, power, acceleration, climbing abilities. And remember that DLC 28 motor is a liquid cooled mid drive motor.
As OP asked for watercooled motor and high kw the dlc 28 might be right up his alley. If matched with ie mobipus 72600 or the cheaper APT 96600 you get motocycle/dirtbike power on tap, water cooled motor and controller and even in the harshest dessert sub blazing conditions you know your bike will keep running no matter what terrain, road/trail surface or hill you climb. Cos that kind of power and centralized mass is not free, it will run you about 2.000-2.300 $ or something but a mxus/205 with Adapatto Max e will easily run you 1200+ $. Then you will have weight penalty, possible heat issues, less handling bike due to the added weight in rear wheel and off set inertia.
All in all not bad if you think about it. Sure 2K for motor controller only is a lot. But such a buy in will for sure give you your moneys worth in return regarding handling, power, acceleration, climbing abilities. And remember that DLC 28 motor is a liquid cooled mid drive motor.
Jestronix, What I don't get is everyone who is trying this Ferro FLuid + hubsinks are claiming that they do not have any overheating issues. While you are the only person claiming that you overheat with oil + heatsinks.
I agree that FF + hubsinks will be limited, but just saying you are the only person who still overeheats with oil + sinks. Maybe you need to add bigger sinks or something.
I agree that FF + hubsinks will be limited, but just saying you are the only person who still overeheats with oil + sinks. Maybe you need to add bigger sinks or something.
Ohbse
10 kW
Offroader said:
Bigger sinks won't solve the problem, issue is motor is too small/too inefficient for the required use case. Beyond a point additional phase current is generating *mostly* heat and next to no additional thrust. Bigger motor with more active mass will make useful thrust from that additional current, vastly reducing heat load (and increasing speed!)
Replacing a few KG of active motor with a few KG of complex cooling is a road to misery, broken parts and a slower bike.
liveforphysics
100 TW
Get the right sized motor, then add hubsinks and FF and you're going to be doubling heat shedding for way less complexity and and added failure modes.
Jestronix said:atarijedi said:
Yeh I was hanging out for them to shrink one down, however it leans me towards a moto build
I think we need to try and take it upon ourselves to do it. Not necessarily water cooling, as that would necessitate in creating a new ported axle shaft, and then sealing the motor. But we can certainly try to just seal the motor and fill it with an oil, like mineral oil, so that more of the surfaces act as heatsinks. Especially the 2 huge side covers. It seems to me it would only necessitate sealed bearings and some RTV liquid gasket.
A trip to mcmaster.com and a trip to your local auto parts store should do it.
Ohbse
10 kW
atarijedi said:
What you're describing has been extensively tested and while it works, it's hard to seal and makes a mess. FF delivers essentially the same results with much less mess and less parasitic drag. Oil cooling is no longer relevant with FF available.
Ohbse said:
I've read the forum entries from others, a majority of people never really put the effort into properly sealing the hub motor, and those that did, have no real issues with leaking.
I also can't imagine FF would deliver anywhere near the same results, as it only provides a radial heat path, whereas an oil filled motor would provide both radial and axial heat paths, and the axial heat path would be far more important as heat the side covers provide massive surface area compared to the radial "ring".
Another issue is that regular oil can be drained out of the hub. FF, while technically it can be done, would be a huge undertaking in comparison. Heat destroys oil, so at some point you need to replace it, or do a complete flush and replace it.
Ohbse
10 kW
atarijedi said:
I have personally tested both and can assure you my motor was well sealed. Oil permeates everything and wicks along stranded wire, it seeps through bearings, it's impossible to stop completely in conventional hubs.
FF in comparison is mess free and does work as well. It is also much, much easier to clean up.
It may be difficult to imagine, but it's effectiveness has been proven
I've decided to air cool my Mxus motor. While FF will work good for most, I decided I wanted the maximum performance.
I can't see how FF can do better than a strong airflow constantly directed through the windings. When I'm pulling up that long steep hill at a slow speed, there will probably be more airflow through my motor than on the outside heatsinks of a hubsinked motor.
I'm ready to test, in a contest, my setup against a FF user. Yes I know you FF users seem to think your setup is better or best, but I disagree and am ready to test it. I don't want to get into the theoretical discussions about how FF + hubsinks are better, I want to see actual performance numbers.
My setup works by blowing cool, outside ambient air, over the windings and then exhausts the air out side, bringing in only fresh cool air.
I can't see how FF can do better than a strong airflow constantly directed through the windings. When I'm pulling up that long steep hill at a slow speed, there will probably be more airflow through my motor than on the outside heatsinks of a hubsinked motor.
I'm ready to test, in a contest, my setup against a FF user. Yes I know you FF users seem to think your setup is better or best, but I disagree and am ready to test it. I don't want to get into the theoretical discussions about how FF + hubsinks are better, I want to see actual performance numbers.
My setup works by blowing cool, outside ambient air, over the windings and then exhausts the air out side, bringing in only fresh cool air.
Chalo
100 TW
Offroader said:
Would it cook a steak faster to position it vertically over a burner so that hot gas was streaming over it, or would it cook faster if you plopped it in a fry pan of hot fat on the same burner? The heat source is the same; only the heat transfer efficiency is different.
To me, it seems obvious that air cooling will only beat liquid cooling if there's a whole lot of forced air moving through at high speed.
But all this nonsense is just that: nonsense. If you're heating up your motor too much, you're doing it wrong-- probably using the wrong motor for the job.
macribs
10 MW
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- Jul 22, 2014
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While I am fairly certain FF + heat sink will win, I applaud the effort Offroader. Now lets hope there are riders with FF+heat sink in the north east that will do a ride along to compare real life results. The result will speak for itself.
Where have you dug your thermistor in the motor? I guess thermistor is required to get results worth comparing?
Where have you dug your thermistor in the motor? I guess thermistor is required to get results worth comparing?
Chalo said:
Like I said, I don't want to debate the theoretical advantages of FF. The reason is there are too many variables in a hub motor. The windings are not sitting in oil directly on a frying pan.
There are thermal bottlnecks for the heat transfer, the windings are inside the hub are surrounded by plastic and somewhat air gaps. The heat has to transfer through about 10mm or more of steel. It has to also transfer through the FF probably by mostly convection.
Too many variables here to just use a simple chicken boiling on a frying pan.
My cooling method is simple, blow the hot air right off the windings and out of the motor with a very high powered RC jet fan.
If you had to cool chicken, would you rather blow air directly on it to blow the heat off of it or would you slap it on a frying pan, better yet slap a chicken on 5 mm of steel with no oil on the chicken, that would be like the windings are suspended in the stator by plastic and air gaps., and then use some FF to connect the 5 mm of steel to the frying pan.
I've thought about this for a long time, and in my opinion, I can not say for certain FF + hubsinks would be better. That is exactly why I want a contest with someone. It could be better, I could be wrong.
WoodlandHills
10 kW
If I was going to cool chicken I would drop it into a pan filled with ice and water, I could put it on the shelf in the refrigerator but it would take a lot longer. If I was going to defrost chicken I would drop it into a pan filled with water. I could leave it out on the counter, but it would take a lot longer to defrost.
Can anyone explain why?
Can anyone explain why?
macribs
10 MW
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- Jul 22, 2014
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- 3,702
WoodlandHills said:
I will try to explain the best I can in laymans terms as I am not an engineer or paid much attention in science class.
If you defrost sunk into water or in air it will have different outcome. Air is the key. Submerged there are no air around the frozen item. Water surround the frozen item and transfer the cold into the hotter water. Because there ain't no air between the frozen item and water heat transfer get a direct route to the water. Water will wrap around the item. So water can soak up the cold more easily. Or the water will heat up the frozen item. If you leave the item on the counter top letting air defrost, like heat radiate so will cold, making a "cold blanket" of cooler air surrounding the frozen item. To defrost ambient air will first need to heat up that "cold blanket" before heat will start to penetrate the frozen item.
It is just like the principle for sous vide cooking. Meat or whatever is placed into a bag, vacuum is applied to remove all air. No air inside bag makes no extra thermal path, plus the item inside vacuum bag does no longer float and will be submerged under water getting a very evenly temperature rise. That means core of steak or whatever cooked will heat up slowly to the same temperature as the surrounding water ensure you don't end up with tough steak but a tender slab of meat perfectly cooked.
If you leave air inside the bag the thermal pathway will be from water via bag + air trapped inside. Result will vary at best.
The same thermal coupling is caused by the Ferro Fluid inside the hub. FF is a much better thermal coupling then air and will ensure more heat are transferred faster to the back iron (yeah steel and iron are not the best heat conductors but in a hub motor we got plenty of it the size works in our favor) and from that large thermal mass of the outside motor shell directly to the thermal mass of the heat sink. Now the heat sink got a greater outer area due to the fins and that allows more air to cool down. Also heat sink is alu so heat sink heat up and cools down faster then iron or steel.
Awkwardly explained but I did the best I could, I am sure someone can do a more technical version.
macribs said:
I'm just using the thermistor where MXUS placed it in the windings. You see the biggest issue I have with FF is the peak cooling rate, this is when you are riding at full throttle, 7,000 watts on my bike, and only going 10 MPH up a steep hill.
The problem with FF is the windings are wrapped in plastic and there are airgaps around the windings because of this. FF is not going to be able to do much for this, so when you start really heat those windings up there is going to be a thermal transfer problem with just FF.
With air cooling, the windings will be getting hit with high air flow, so when the windings are at 110C and getting hotter, they will quickly be hit with cold outside air and the heat blown right off them.
Remember, my motor will also cool the stator, at the same time the windings. So I have the same buffer as FF, that is the stator soaking up some of the heat. I'm just cooling both the stator and the windings, while FF is just cooling the stator. But the argument for FF is that it will shed heat off the stator faster than forced air. This could be true, but it won't shed heat also off the windings like forced air will, FF will do nothing for the hot windings, or the rest of the stator that FF does not touch.
I've already used for 2 years the same cooling setup on my cromotor, and it worked perfectly where I never had overheating issues. So the air cooling works, I just modified it in my MXUS motor with a bigger fan and a more efficient air flow to really cool the motor down quicker when I need it. This isn't a question if my air cooling works, it works great. It is just that my new setup is much better, and I want to prove that it will easily blow away a FF hub motor.
FF will work for most people because they don't push their motor in extreme conditions like these, and after they heat the windings somewhat, they can wait for the heat to transfer out of the motor.
We shall see, I can always switch over my motor to FF and hubsinks, and just epoxy up the holes in no time.
