Idiots guide to water cooled mid motor making

Electric Motors and Controllers
larsb
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Re: Revolt RV120 rotor remake

Post by larsb » Aug 26, 2017 1:16 pm

I think the plug will be OK, need to sand a liittle bit on some spots. Thanks a lot for the effort!
image.jpeg
image.jpeg (48.25 KiB) Viewed 849 times
Magnets have left china now and are on the plane. I will have to check the true measurements of the magnets when they arrive, i've seen some suppliers do really poor dimensional control.

I realized i made an error on the prints, the magnet pusher and spacer rings were made for 3mm magnets so i need two new spacer rings for 5mm magnets and a new pusher. Do you feel like printing some additional parts?

I can make some stls next week if you do.

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Wheazel
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Re: Revolt RV120 rotor remake

Post by Wheazel » Aug 26, 2017 1:48 pm

Yeah, no problem!

larsb
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Re: Revolt RV120 rotor remake

Post by larsb » Sep 06, 2017 11:40 am


Karolis
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Re: Revolt RV120 rotor remake

Post by Karolis » Sep 29, 2017 1:52 pm

Is there any news about new rotor?
Currently made rear swing arm with RV160PRO and looking for a reason to continue my project or just dump it. I'm in crossway.
https://www.youtube.com/watch?v=TWaFExhQsjg

larsb
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Re: Revolt RV120 rotor remake

Post by larsb » Sep 30, 2017 1:01 pm

I just got magnets!

But it will be quite a while before there's any real progress.

I am convinced that it won't be a huge improvement though! These motors just aren't top performers. If you can wait until christmas time then i will have some results.

Whats your main issue with the rv160?

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Re: Revolt RV120 rotor remake

Post by Karolis » Oct 02, 2017 3:31 am

The main problem for me is the rotor. It is completely inaccurate. I tried to balance it. So it is on the limit for me. Also there is a huge magnetic flux leakage.

larsb
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Re: Revolt RV120 rotor remake

Post by larsb » Oct 02, 2017 5:38 am

Ah, have you contacted Revolt? they should give you a new motor on warranty. I remember your picture, that's not possible to explain in other terms than it is a defect motor
Then you can try to fix the bad one if you feel like it :D

larsb
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Re: Revolt RV120 rotor remake

Post by larsb » Oct 19, 2017 12:55 pm

I have been busy with making a gearbox, rotor remake is on hold for a while. I maxed the revolt yesterday and the rotor got so hot that i couldn't touch it. I think my odds to get a large improvement on the rotor are quite good!

larsb
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Re: Revolt RV120 rotor remake

Post by larsb » Nov 20, 2017 3:43 pm

I had too much time to think about it.. Once i start to make a new rotor i might as well extend the stator. I have enough magnets..
So i contacted Revolt to see if i could buy some extra laminations. Apparently they are improving their motors so they now have 0.3mm stator laminations available for the RV120!

I bought a 60 mm stack of laminations, i will get in in roughly a week.
It will be a 33% longer stack than original and i hope to fit it in roughly the same space. Should be possible with some creative milling of the end covers.

If i could find some lathe assistance then i might just do a watercooled stator hub.
Anyone up for it? :D
Should be relatively easy job, just an alu cylinder with 50mm diameter, around 100mm long, two end stubs for holding and two grooves for snap rings to secure the sideways movement. I'll glue the stator stack once it's in place so the snap rings are then mostly to keep the bearings from going too far in.

I'll mill the cooling channels and make new end covers if i do it. Could be fun!

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macribs
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Re: Revolt RV120 rotor remake

Post by macribs » Nov 20, 2017 4:14 pm

Wow you just took this remake from absolute hard core, way into the next galaxy.
Less eddy current so even less heat at high RPM and liquid cooling to top, I like it a lot. Now make sure that thing gets a controller worthy of your Remake. The controller you choose must have a lot of peak amps to give you the acceleration you so deserves after putting in those man hours and lang nights.

Man I look forward to see how this turns out. Keep on making good choices for your motor and your stamina will stay high and safeguard you to the finish line.

John in CR
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Re: Revolt RV120 rotor remake

Post by John in CR » Nov 20, 2017 9:14 pm

Now that I have the last 12 in existence, I should send you 2 of my MiniMonsters 150mm X 50mm stators for a rewind to a Kv of 30-35, one for you and one for me. Sure they're heavier than a 120, but you'd be guaranteed a 20-25kw (even at just 74V) high efficiency motor. Wound to a higher Kv and dumping the 2 speed wiring would increase efficiency beyond the 93% the original tested at, as long as you meet or exceed the factory copper fill. I have faith in you. The lams are .5mm, but are top quality Japanese laminating steel, not ? quality stuff from people who already let you down.

Karolis
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Re: Revolt RV120 rotor remake

Post by Karolis » Nov 21, 2017 3:44 pm

I don't think it is a good idea. To start from beginning again. You already have rewinded your motor. You only need to check first even if it is worth doing by making new rotor. If you will find that there is some improvements, then you should step it up. I would do that way if I was in your position.

larsb
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Re: Revolt RV120 rotor remake

Post by larsb » Nov 22, 2017 6:04 am

It is not worth doing, i agree!

I have been riding the new motor for several months now and it works great for me. But i have decided to try a new rotor and from there the next step is easy except for the water cooling.

I plan to rewind the motor i don't use and give it a star connection.

The reason for this is to be able to use the retro direct gearbox i am designing

Delta winding is difficult to switch directions on as it needs a 30 deg phase shift from CW to CCW rotation.
I might just use the existing stator hub and skip the water cooling to keep it simple. Haven't decided yet..
Last edited by larsb on Nov 23, 2017 4:14 am, edited 1 time in total.

Harold in CR
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Re: Revolt RV120 rotor remake

Post by Harold in CR » Nov 22, 2017 8:00 am

I have been riding the new motor for several months now
Are you referring to the rewound motor with square wire or a completely new factory wound motor ? Really nice thread on the rewinding. Thanks for the details.
Thanks to Justin, the forum is open source and NON-commercialized.

larsb
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Re: Revolt RV120 rotor remake

Post by larsb » Nov 23, 2017 1:10 am

I am referring to the square wire rewound motor as "the new motor" :D

I paid 35usd for the laminations which i think is ok if they are at least as good as the 0.5mm lams steel.

@john in cr: what's the dimensions of the motor (not only stator)? winding (to me) is the worst part and i don't think i have what it takes to do several motors..

larsb
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Re: Revolt RV120 rotor remake

Post by larsb » Nov 24, 2017 12:40 pm

Santa came early this year!
And he made me pay for the stuff myself..

60mm stack of 0.3 lams and a custom axle to fit the gearbox.
image.jpeg
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I plan to wind it star but haven't decided on the turn count.

Guesstimation..
Original turns: 12t delta
Original kV: 45
Original stator: 45mm
New stator: 60mm
Stator change effect: 45/60 = 0.75
Delta->wye effect: 1/1.8 = 0.56

10 turn, two parallel should be possible to wind as i got on 24 single turns in my previous rewind .

New kV = (12/10*0.75*0.56)*45 = 23 kV

I think that's too low. Maybe i have to switch wire type and do something like a 10 strand 8Turn 0.8mm wind

larsb
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Idiots guide to water cooled mid motor making

Post by larsb » Dec 04, 2017 4:02 pm

I might as well change the thread title :D
i'll do a new motor with the laminations and magnets i have sourced.

Stator hub, first draft:
stator hub ver1.JPG
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Stator:
stator hub and stator.JPG
stator hub and stator.JPG (51.94 KiB) Viewed 190 times
Water is to pass from side to side through the stator hub. End stubs are fixed so they can be clamped, no need for precision tolerances.

A #35 sprocket for 3/4" axle will be bolted to the drive side cover, the large axle hole allows it to rotate freely around the end stub. It can still be optimized in many ways to limit the weight and size. I need to do some measurements.. :D

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macribs
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Re: Revolt RV120 rotor remake

Post by macribs » Dec 04, 2017 4:07 pm

I like how you keep doing an extreme makeover, and then you go and change things on the final stretch to make it even better.

Respect!

John in CR
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Re: Idiots guide to water cooled mid motor making

Post by John in CR » Dec 05, 2017 4:18 am

#35 Chain??? Since you're going to all the trouble of building a motor from scratch, the least I can do is offer a couple of slices of the aluminum pulley stock at cost that I've been hording for a few years. Let me know what kind of gear reduction you want, and I'll see if I have the right combination of sizes. It's easy to source just about any tooth count belt length for the 8mm pitch Gates Polychain GT stock that I have, which I believe matches what Zero Motorcycles uses, so even a 12mm wide belt of the carbon belt will work.

Send me a msg if you're interested.

larsb
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Re: Idiots guide to water cooled mid motor making

Post by larsb » Dec 05, 2017 5:40 pm

Thanks John, i'll have a look at the belt options!

I looked for some stator installation data, found this:

larsb
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Re: Idiots guide to water cooled mid motor making

Post by larsb » Dec 06, 2017 9:53 am

Coming along nicely! i have found some help by a fellow ES:er so the turning is fixed. You've got to love this forum and it's members :D

I have started to sketch the motor assembly, it's really fun to see it coming together.
motor assy.jpg
motor assy.jpg (140.15 KiB) Viewed 114 times

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macribs
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Re: Idiots guide to water cooled mid motor making

Post by macribs » Dec 06, 2017 2:17 pm

What is your targeted numbers? Kv, efficiencies and peak power?

What is the most painful and time consuming task of making a motor? winding? would there be any chance to have a mechanical winding bot doing the grunt work? That way you could do a bigger batch and spread some of those puppies around for adventurer spirits to help test out the motors to the max. If any mechanical "bot" would be too expensive, even the most simple ones maybe a motor design where copper could be wound around "a stick" for consistent length and mass then transferred easily to the motor, sliding copper on then bolt on a tooth to keep it in place.

I would love to see a purpose build motor for the e-bike community made for the ground up by forum members. Without shortcuts taken to save quarter or a dime. Where focus is premium parts, great magnets and quality thin steel. Where bearings are chosen by performance rather then base cost and where peak power, life span and ability to withstand heat is main focus. And I really think there is a market there too. From about 30 kw and upwards there are a few good options motor wise. But if targeted peak power is somewhere between 10-25 or even 30 kw there is slim pickings today.

A well designed mid motor build by ES members would surely get a lot of attention.

larsb
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Re: Idiots guide to water cooled mid motor making

Post by larsb » Dec 06, 2017 3:00 pm

The winding is the worst part for sure.. It would be good with a winding bot, could work well if there are removable teeth. I've read it affects the fields in a negative way so it might not be the best overall.

kV is a big factor as i'd like to try a wye wind. I might go to double LRK winding, wye connected and two controllers, i've seen it called 6-phase here, but it's actually not.

I think that should give med roughly the same kV as i have today, 45.. but the rotor build is a total unknown and that affects kV
I can't even know if the magnets i bought have the correct performance since it's from an unknown seller..

Efficiencies, power etc is therefore impossible to calc. I don't know what the RV120 honestly puts out in power and efficiency, i only know this motor should be a lot better since it will have better laminations and fill factor.

I think the pros of water cooling in real figures might be hard to motivate because of the complexity it creates.
Let's say the cooling system weighs 1kg, then it must give a lot better continous power potential or i might as well have a larger motor.

It is a gamble for sure. :wink:

larsb
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Re: Idiots guide to water cooled mid motor making

Post by larsb » Dec 06, 2017 4:43 pm

I have sort of a complete motor now :D
Some adjustmets needed still but it looks good. It will fit nearly the same space as a RV120 pro, it's actually not as wide and only slightly larger diameter due to the thicker magnets (dia=128 vs 127 for RV120).
complete motor.jpg
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macribs
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Re: Idiots guide to water cooled mid motor making

Post by macribs » Dec 06, 2017 5:26 pm

Thx for sharing the term LRK. Every now and then I have tried to read up on the term 6 phase motor. As you might have seen not much on the topic, neither written articles or even youtubes explaining the how and why there are benefits to a 2 x 3 phase winding over a traditional 3 phase winding. Maybe the new term LRK will give me more details. What little I know about those motors are mostly from reading those hubmonsters threads by John in CR. The load splitting between controllers I find very appealing. Iirc there was some talk about smoother take offs, more power down low as well as mid range.

Hopefully I can gather some light holidays reading material on the topic and educate myself more on the LRK topic.

Look forward to see how this motor turns out. I really hope you a big return on all your hard work.


Found this after a quick search. Sharing https://www.rcgroups.com/forums/showthr ... -Try-it%21

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