Definitive Tests on the Heating and Cooling of Hub Motors

[Buk___]

My next goal is to work out how not to fry my brakes. My last ride scared me. A long 50 km ride with repeated steep 200 metre descents climbs and repeat with ambient temps of 30+degreesC... when my rear started grumbling and then the worst my hydraulics just completely went on the front... The front somehow came back after 20 minutes of me freaking out how to get home in a place I wasnt sure where I was with no front brake! no regen with my controller Vs

I just recall one of the bomb squad had extended fins on the brake pad bits. my saints aren't enough...

The black diamond symbol pretty much sums up the elevation changes..

Sounds like you boiled your brake fluid. When that happens, you create a vapour pocket in the system, and it acts like an air spring.

You should change your fluid (and perhaps upgrade from mineral oil to DOT brake fluid if you currently have the former.)

See http://www.epicbleedsolutions.com/blog/dot-brake-fluid-vs-mineral-oil/.

 

[John Bozi]

pretty sure it is DOT.

Once the rear started grumbling, I had no choice but to squeeze harder on the front....

These are the rear pads lol

I miss regen... don't think it works over 90v for my lyen...

 

[sketchism]

My next goal is to work out how not to fry my brakes. My last ride scared me.

we have a solution man, should have a beta test ready for you soon!

goes with the hubsinks now you can ride longer brake fade is a real problem, same as me and matt

 

[Volts]

has anyone done a system where you shoot water at your hub with a water pump, water on the hub is very effective at cooling the motor, I find that the hub motor with fins and ff work well with no Re Gen but as soon as that Re Gen kicks in the hub becomes a grill pan, although it does stop the motor from dying its still to hot, the problem is exacerbated if you are living in hotter climates like in OZ, was thinking about doing a system where a mist is sprayed on the motor using garden irrigation nuzzle and a 12v water pump of sorts, will start this project soon will report back once tested.

 

[macribs]

For special occasions water mist cooling has been done. For real life the problem is added weight by adding watertank, lines and pump. Real estate on an e-bike is premium, and me personally I rather fill that space with something that makes ride goes faster, longer or pull stronger.

If FF and hubsink does not meet your cooling requirement may I suggest another alternative? Make a heat sink/hub sink with embedded heat pipes. Heat pipes works on both thermal conductivity and phase transition. Phase transition is very effective way of cooling, weight is near to nothing, and for all practical reasons the heat pipes works as a closed loop water cooled system.

Liquid heats up and phase changes to gas form. Pushing outward from the heat source. As the gas travels along the heatpipe and reaches cooler parts of the pipe it returns to liquid form and returns to the warm heat source. So you get the benefits from FF, and you get the benefits of a hubsink. But you also get the benefits of phase transition to rapidly and effective cool down the entire heat sink, meaning more heat from motor will travel out to the heat sink and vanish out to the air.

Heat sinks will improve cooling even when stationary, say you done some wild city riding and climbing and reaches a red light. While you wait for the green light your heat pipes keep on working and the closed loop cooling system make sure you don't see a rapid spike rise in motor temperature because rear wheel is stationary.

 

[minde28383]

Yes there are water cooled hubs. This cooling way is not new. Pump and little radiator attached to hub.
For ex.: Mxus 45mm constant 6kw, 12kw peaks. No overheating issues with water cooling.
Year ago price about 700eu with pump and radiator.

 

[macribs]

@minde yeah that is a full on water cooled system, with pump, hoses and a radiator and possible a reservoir tank. That has been done too. And works well despite added costs and complexity.

What I think Volt was asking for was just spraying cold water onto the outer shell of a warm motor. Like Luke or someone did on the drag strip. If this water mist is pumped onto the the hot outer shell it will vaporize and leave motor shell temperature lower.

If actually going this route, use FF and heatsink as well and try to fit a cloth of some sort between the motor flanges and the heat sink. Make sure that the cloth is mist at all times when riding hard. It will be easier to keep the cloth wrap moist and wet then the motor shell. And the vaporizing process will be the same when a cloth wrap is used.

 

[Volts]

where can you buy this water cooled hub motor?

 

[macribs]

where can you buy this water cooled hub motor?

https://endless-sphere.com/forums/viewtopic.php?f=31&t=91479&p=1336979&hilit=linukas#p1336979

 

[Volts]

The green compound the copper is in cased in looks like it, would no doubt, be detrimental to the over all cooling process, claims of 6k continuous, has anyone got one of these can report findings?

 

[macribs]

Linukas is well known on the forum, one that I personally would trust with my money.
Iirc he used to build these by using mxus v1 and that is hard to come by, so he sorted out another source for the same motor. Basically a clone. I've not tested his water cooled motors, but he have sold those for a few years so I am sure others can go into details.

the mxus 3000 motor is capable of 10-12 kw peak power. But heats up rather fast compared to the larger QS v3 205.
With the water cooling you can rider harder for longer.

Have you heard of Neematic? Look up Neematic. Linukas is behind that.

 

[minde28383]

Yes, stator is incased as you called it. Water cooling helps a lot regarding heating. There is little bit more complexity installing and maintaing it due water pipes and radiator.
Water cooling works fine, dont doubt it. Its just double the price of motor without cooling. If there was real demand than all hubs could be available with water cooling. Buyers determines whats in stock. And its 99% air cooled / self cooled hubs.

 

[Cowardlyduck]

Has anyone else running Ferro Fluid noticed an increase in drag as it get hotter?

I have 3 motor's with FF now, and I notice it with all of them that the drag seems to increase noticeably as the FF get over 80C.

Cheers

 

[markz]

What comes to mind is ATF system with radiator for ultimate cooling.

Damnit, shoulda quoted the fella.

 

[Jestronix]

To my surprise this worked out quiet well on today's hill climbs , the vector is now active cooled

I was able to climb far beyond my normal overheat locations on just ATF and hub sinks alone. I did manage to peak out at 110c on one section after pushing really hard, but the cool down period is wayyyy quicker.

The high CFM fan cools the entire right side of the hub and most of the hub sinks, some directly. The fan runs on a small 2s 18650 pack I made, runs the fan for hours.

I'll try and do two videos of no fan and fan for comparison on the cool down.

To tomorrow I'm going to insall the second fan on the left side and see if dual fans is worth it.

With a smaller rim and these fans I could be close to heat freedom

 

[Cowardlyduck]

Now imagine what installing the fans inside the motor could do for you.

Cheers

 

[markz]

neat idea, light weight pc high cfm fan, running off a small battery, flick it on when needed.

*thumbs up*

 

[Jestronix]

neat idea, light weight pc high cfm fan, running off a small fan, flick it on when needed.

*thumbs up*

Yep took all of half hour to setup, lightweight fan, will be interesting to see how it puts up with dirt etc. thinking maybe the smallest ever raidiator fan could work, maybe a motorbike one if they make them, dust and weather proof.

I've also had thoughts of a 3D printed shroud that's attached to the hub, basically push the air equally to all hubsinks.

 

[markz]

Good points, you need some shielding. Think offroading and see what they do. Air intake inside the cab, air intake ducted to roof, radiators on the side wall of bed truck. Make a box for the fan, bend intake and point it backwards, add mesh. Or duct intake to bottom of seat or bottom of rack, pointing the hole straight up, that'd make it bulkier. Comes from vertical big rig exhaust pipes, or tractor pipes.

neat idea, light weight pc high cfm fan, running off a small fan, flick it on when needed.

*thumbs up*

Yep took all of half hour to setup, lightweight fan, will be interesting to see how it puts up with dirt etc. thinking maybe the smallest ever raidiator fan could work, maybe a motorbike one if they make them, dust and weather proof.

I've also had thoughts of a 3D printed shroud that's attached to the hub, basically push the air equally to all hubsinks.

 

[DasDouble]

What is the biggest problem of having a opened hubby? Rust? Dust? Dirt inside it? Could you not just put some membrane infront of the openings, so there can´t get some dust throught it??? Seems like a damn simple idea.. Too good to be true :lol:

 

[wturber]

neat idea, light weight pc high cfm fan, running off a small fan, flick it on when needed.

*thumbs up*

I've also had thoughts of a 3D printed shroud that's attached to the hub, basically push the air equally to all hubsinks.

Yep. Mount a little scoop to the top of the fins that shoves air past them when they rotate. Heck, if those fins were simply rotated bit I'd think they'd tend to flow air past the fins better.

 

[amberwolf]

What is the biggest problem of having a opened hubby? Rust? Dust? Dirt inside it? Could you not just put some membrane infront of the openings, so there can´t get some dust throught it??? Seems like a damn simple idea.. Too good to be true :lol:

As has been discussed in previous posts in this thread (and elsewhere), anything that covers a hole, even screen mesh, is going to block airflow quite a lot, requiring higher power fans to push or pull air thru them than if they were clear.

As for which problem, as has been discussed before, it depends on where you use it and under what conditions which problem would be worst.

 

[amberwolf]

Heck, if those fins were simply rotated bit I'd think they'd tend to flow air past the fins better.

A pair of needlenose pliers might make quick work of a test of that, twisting each one diagonally in the same direction, making it like a fanblade of sorts.

 

[Rix]

What is the biggest problem of having a opened hubby? Rust? Dust? Dirt inside it? Could you not just put some membrane infront of the openings, so there can´t get some dust throught it??? Seems like a damn simple idea.. Too good to be true :lol:

As has been discussed in previous posts in this thread (and elsewhere), anything that covers a hole, even screen mesh, is going to block airflow quite a lot, requiring higher power fans to push or pull air thru them than if they were clear.

As for which problem, as has been discussed before, it depends on where you use it and under what conditions which problem would be worst.

CD can get you high performance fans

 

[Cowardlyduck]

CD can get you high performance fans

Yeah (Racing)...they are actually called Yeah Racing! fans, and I've still got a bunch of them hanging around from before FF+hubsinks became the bees knees.

They apparently push 5.13CFM each, which is pretty impressive for a 25mm fan:
http://www.rcmart.com/rc-yeah-racing-ya0201-tornado-high-speed-25x25mm-p-29521.html

Although I would (and am going to) use FF+Hubsinks given the choice from scratch again, these little fans are still going strong and keeping my '1500W' Leaf motor cool enough to pump 6-7KW peak and 3-4KW sustained through it. It will still occasionally overheat (i.e. 140C) on the steepest long climbs, however the cool down time is usually just a minute or two before I can continue.

Cheers