Keyne's DH Comp Build - now with liquid cooled HX35! :)

[kfong]

Modding the motor plates with CF sounds like a great idea for saving weight, but sounds bad for heat dissipation. I will be courios on how it holds up.

[Alan B]

But this motor is liquid cooled.

[keyne]

Modding the motor plates with CF sounds like a great idea for saving weight, but sounds bad for heat dissipation. I will be courios on how it holds up.

I guess someone didn't read the thread title Carbon fiber side panels would be a bad idea for stock hub motors which have a bad thermal path for cooling.

Here's a picture:

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Larger version here:

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[Sacman]

Sounds cool.
Yes show some pics please.

Edit: Ahhh... thanks. Very nice!!! But yes it would hamper motor cooling since it doen't conduct the heat to the outside as well as the original covers.

I'm curious about how do you kept the steel threaded collar (for the freewheel) perpendicularly aligned to the face of your side cover so it doesn't wobble. I guess also applies to the axle bearing to the other side cover you'll be making.

[grizmoblust]

How does one simply build radiator cool motor?

[sn0wchyld]

hey mate
any updates on this one? how's it running/holding up? Did you get the CF in?

Love to see some more vids, I miss the nz countryside.

[keyne]

Yeah I should really post some updates:

Not a lot of riding in the last couple of months, I managed to kill a cell group a while ago though lack of battery management during discharge. It happened to coincide with buying a house that needed a bit of work and somehow the kitchen got higher priority than the garage so I didn't fix it until recently (thanks to full throttle with his plastic ruler trick for separating lipo packs). Now my garage is finally in a state I can work in I hope to get everything up and running again soon.

The carbon fiber motor panels have been removed because there is just the tiniest bit of slop (my molds were't made on a lathe) which I found always ended up with the stator rubbing on the rotor at some point during a bumpy ride. I'll make some new ones with nice molds once my new lathe is set up.

It's turned very wintery here recently so I'm going to try a metal studded rear tyre with a ski up front and see how that goes should make for some interesting vids.

Just this morning I'm building a roll-able scissor-lift stand for the bike to make it easier to work on and have installed a sealed regen switch on the front brake. I can't think of a time when I use the front brake and don't want regen (maybe if I wanted to do a burn-out?), but to allow wheelie control I didn't put one on the back brake.

[sn0wchyld]

......

pump.jpg

1x 12v solar water pump - pc cooling pumps have great specs but are usually only rated to 65degC, this one is rated to 110degC. With the whole system hooked up I get a flow rate of about 1.7L per min with water, a bit less with the 33% antifreeze I use.
For those who don't know, antifreeze is also antiboil, so the 33% coolent I'm using is good from -15 to 105 degC. It also stops corrosion which is pretty important given how the cooling tubes work in the motor.
...
gotta go...

hey mate
can I ask where you got the pump (and the rest of the cooling gear, for that matter)?

Yeah I should really post some updates:.....
Just this morning I'm building a roll-able scissor-lift stand for the bike to make it easier to work on and have installed a sealed regen switch on the front brake. I can't think of a time when I use the front brake and don't want regen (maybe if I wanted to do a burn-out?), but to allow wheelie control I didn't put one on the back brake.

damn... thats a good idea. ive got my switch on the left (rear) break, but really it'd be better off on the right, as with a left hand throttle I too have trouble with wheely control. Hell... I could even just have 2 switches...
whats the weight looking like now? any more ideas for jenny craig?

[keyne]

The pump was from ebay - (just search for 12v water pump), the rest of the cooling stuff was from frozencpu.com

In terms of the weight, it's a bit under 40kg. There's not much unsprung weight that I can take off without changing to a different motor, using narrower tyres or dropping the derailleur. There is a lot of sprung weight to be lost, but I'd be better off with a different frame. So I'm going to just use it for a while and see how the current configuration holds up.

[mikebikerad]

radiator! DH team e-bike owners are definitely wooping the stealth owners with build like this

[binlagin]

I'd say we are somewhere between the fighter and the bomber!

[crusoe]

Hey Keyne, how goes the

...roll-able scissor-lift stand for the bike to make it easier to work on

I need something similar!

[keyne]

The scissor lift works ok, but I might redesign it some day, it's just not wide enough to be completely stable.

I've been gearing up to do some efficiency tests to see how much more range I get because of the cooled motor - it could be quite a bit!

[Stielz]

Really nice build Keyne, keep up the good work!

How does your controller hold up to a bit of thrashing?

Just an idea, have you thought about liquid cooling your controller also? You've got all the hardware there, all you would need to do is make a channel through the FET heat sink and run the cooling liquid through in series with the motor. Then you could up the current limit and possibly push a few more kW through your system

[keyne]

The controller temperature has never gone over about 55C, but yes, liquid cooling my controller is on my list, mainly so it doesn't have to be an external component on the bike.

[megacycle]

I was thinking to put a copper jacket over the fins on the side of the controller were the fets are bolted, the fins then making the coolant channels ( no pulling the controller apart )or burst fire freeze spray with a hydrocarbon propellant and piezo igniter for afterburn and faster heat draw, for buyouts .

[liveforphysics]

Nice job! I've seen a couple water cooling hubmotor attempts before this one that looked like they would be less effective than simply drilling the covers or adding oil, but this one is exceptional in how you bonded the outer layer of water jacketing in a location that can absorb some stator heat effectively.

My favorite way to know if a cooling system is working is to simply watch the delta between water into the radiator and water out of the radiator. If you know the flow rate, and you know the delta, you know it's ~4.2J/gram of water raised 1 deg C. A Joule is a watt-second of energy.

So, just as an example calculation if you measure your flow rate at say 100L/hr through the cooling loop, and you observe a peak delta-T you can hold across the radiator continuously of say 10degC difference between inlet and outlet temps, then you know the rate your system can shed heat.

Crude calculation example would be something like 4.2KJ/Kg*100L*10degC = 4200KJ/hr of heat transfer, which is ~1.1Kwh of thermal energy transfer per hour capability. If you were operating the motor at a point where it was say 80% efficient, this would enable it to handle 5-6kw of input power continuously. That would make it better than any air or oil cooling alone setups to the best of my knowledge, but of course these are just make-up guess numbers just to show how to do the math. For the numbers to mean something you will need to take real data from your setup of course.

Great job!

[keyne]

Thanks Luke,

It's been a while since I've posted here, also a while since I've ridden the bike. (Damn PhD getting in the way )

The best cooling numbers I saw were about 700W (8deg drop, 1.2L flow). Done by measuring temp difference between entry and exit of the motor (to include heat loss from the tubing). This was however before adding the themal epoxy to the windings and the motor definitely cools even better now (I was seeing up to 25degC delta T between coolant and windings, this has dropped to 15degC max), I just haven't formally measured it since the change - I should probably do that. I wouldn't be surprised if I'm getting 1kW of cooling now.

I doubt my bike ever gets ridden for long at the 80% efficiency point, but then on my trails there's no way to keep 6kW on for long either!

Oh yeah, just to make it go faster I've added blue flames to the side panels