Cooling, ruggedizing, the Unite MY1018 motor

[Reid Welch]

Force cooling of this motor was first accomplished
with the technical help of fechter some months ago.

I'll repost pictures of the motor modifcations later on in this thread.

the first lash-up

Illustrates the original blower plan

It worked well enough to run the motor hard on 36V without overheating.
Yet, it was sub-optimal in terms of air flow--the small hose diameter, the run...

...and where to put that bulky blower?
I doublestick-taped it on the seatpost rack.
The airflow was modest, but enough.
I wished for more airflow.
Then the seatpost rack broke off (SLA load did that) and I've been on 24V since then.


Now that I'm going back up to 36V with a new lipoly pack
I need to lash on a blower again to air-through cool the armature
of the brushed, 250W output Unite MY1018 gear motor--commonly found on cheap new Currie bikes.

If these 24V motors are run too very hard they can and do burn out;
they're only rated for 250W of power output. The windings go black.

If overvolted and run at extremes (bike speeds in the low 'twenties)
the waste heat generated by this undersized motor is considerable.
No amount of external heat sinking can carry off that several hundred watts of wasted power from the armature and its commutator.

Therefore we must air-through cool,
the same as other small motors run at high power levels.
An additional benefit: brush dust won't befoul the motor.
Commutation will be optimized by the presence of ample water vapor in the cooling air.
Humid air is also a more efficient heat-soaker than dry air.
This motor will run cool even with 1,000 watts power input.
It will become rate-able as if it were a 750W/1HP motor--
albeit at the cheat of considerable wasted battery current.
It's that wasted power that must be carried off continuously
at power levels much greater than design center.

Also,
the cooler the windings the more efficiency retained.

_____________________


Ideals: short air path, few bends, large diameter airway, ample airflow.

_____________________

Although the fan assembly of this old hair drier will protrude from the side of the motor
and possibly get kicked off in time
it will be easy to pop back in place.

Designing as it goes along with progress reports via pictures:

 

[Reid Welch]

now to get a large PVC pipe elbow.




The motor and fan, tucked into the end of the el, will thus be out of direct sight.
I'll orient the elbow at like 4 o'clock position, and... it will look about like...

if I put a chrome tip on it!


The small brushed PM motor of the hair drier runs powerfully at 12V.

Will need to decide only whether to run it from the water bottle lighting battery (14.4V), or run it from controller's output---
in which case a dropping resistance will be required.
A lamp will work well for that.

 

[Reid Welch]

Luck of the Irish at the hardware store,
finding that a two inch fitting will serve:

 

[Scooterman]

I wonder if one of the RC electric ducted fans would work as well?

 

[BrendaEM]

It's not clear where the air comes out in the pictures.

 

[knightmb]

If these 24V motors are run too very hard they can and do burn out;
they're only rated for 250W of power output. The windings go black.

If overvolted and run at extremes (bike speeds in the low 'twenties)
the waste heat generated by this undersized motor is considerable.
No amount of external heat sinking can carry off that several hundred watts of wasted power from the armature and its commutator.

My wife has (or inherited) my mongoose e-bike from me, and loves it. But she (of course) wants more power. I rigged up a 36 volt SLA pack right to the controller and it does work at 36 volts. We at least the controller doesn't have a meltdown, but as you've already said running the motor at full power turns it into a toaster. Luckily, she never takes the bike over 20 mph because she's afraid of the higher speed (LOL) but anyway since she isn't reading this. Do you recommend a drop in replacement that can handle the extra power without (36 volts @ 35 amps vs. 24 volts) needing to air cool the motor?

 

[knoxie]

Hi

There must be an easier way to do this? as far as I am aware you can not fit a currie USPD key motor to these bikes as the shaft is different, maybe a coupling or drive plate adaptor could be made so you could drop in a high power BMC motor or a modified motor with external controller?

Have you a photo of the motor face and shaft with dimensions, the big problem with running brushed PM motors like this is the brushes, you will burn up so much energy in heat I still cant think but this was a backwards step IMHO as brushless motors are so much more efficient.

The Kol motor can be picked up for 30 dollars and if an adaptor was fitted could be bolted straight on, its more efficient but probably not quite as powerful in which case you could try a modified BMC or the high power one

Check out Scott at EV Deals, http://www.evdeals.com in any case if you really want to rip up the dust the full external modified motor like mine is the top choice, I am sure I could make something up on the CAD to mate the 2 of them together.

Happy Hunting

Knoxie

 

[Reid Welch]

Do you recommend a drop in replacement that can handle the extra power without (36 volts @ 35 amps vs. 24 volts) needing to air cool the motor?

I don't know of anything that'd just bolt on, other than the 36V "long range" version of this motor normally fitted only to the red retro cruiser (Currie would have it in stock).
It will still have the heating problem--the power ratings are identical;
with the matching "36V" controller, that one is also a 15mph bike.

______________
Hi Brenda, The PVC will be grafted to the motor in place of the existing L.
Fan sits flush inside the flanged end, the other end to be puttied to the plenum. It may look like a stubby exhaust pipe after painting it all black again.
__________________

Unless I run into some unforseen problem--it will work out OK.
I don't want to rip this motor apart again; it's running so sweet at present.

_______

Am using this blower because it's here, it's brushed, has the fan, and it fits
without fiddling it too much.

Don't know how long it will last in service--if it fails, I'll get another hair drier.
It's all so low tech that it's kind of fun. We'll see....

 

[Reid Welch]

Hi

There must be an easier way to do this? as far as I am aware you can not fit a currie USPD key motor to these bikes as the shaft is different, maybe a coupling or drive plate adaptor could be made so you could drop in a high power BMC motor or a modified motor with external controller?

Have you a photo of the motor face and shaft with dimensions, the big problem with running brushed PM motors like this is the brushes, you will burn up so much energy in heat I still cant think but this was a backwards step IMHO as brushless motors are so much more efficient.

The Kol motor can be picked up for 30 dollars and if an adaptor was fitted could be bolted straight on, its more efficient but probably not quite as powerful in which case you could try a modified BMC or the high power one

Check out Scott at EV Deals, http://www.evdeals.com in any case if you really want to rip up the dust the full external modified motor like mine is the top choice, I am sure I could make something up on the CAD to mate the 2 of them together.

Happy Hunting

Knoxie

Hi Paul, I'm sure you are correct, certainly-so in the theory department. There was and is nothing hard about this work. No machine shop was needed; no custom special stuff.

I did this basic modding months ago and it did work well--not battery-efficiently, no, it's not efficient. I'll find out just how wasteful it is when the new battery pack comes. These days I have that Drain Brain to quantify things.

The brushes hold up under the doubled current just fine. No perceptable wear over a couple hundred of high-powered miles--credit goes to the ventilation.

This is on the cheap, yes, but I don't care yet to adventure into a totally sealed BL motor--$30 sounds more than fine, but then, what for the gear reduction? Cost? Certainty of fit and good service?

And that could cost several hundred dollars by the time it is gotten to work. I'd save battery current, sure, if I stay in the design range of the Kollmorgen, but probably not go any faster or stronger. I might burn out the new motor, too.

The Unite is robust, simple, perfectly tractable (silent) at starting-off speeds (no groans, etc). The use of a brushed motor allows a cool running controller size of a pack of playing cards, hidden away in the original cubby space above the cruiser's bottom bracket.
The wiring is all so simple and short

Well--this works.
For now, it's the way I'm going because---it's been operating sweetly for hundreds of miles.

The next motor, a spare, should be another $45 Unite MY 1018,
with more holes in the casing, ha ha.

It's really a nicely engineered little thing. I can understand it.
And it wears quite well. It just wastes some watts when shoved hard.


as it was ventilated last summer.

today, if it were to be torn down again,
I'd make many more holes.
It is diecast zinc, easy to work.

Thank you for ideas Paul. Everything is a hobson's choice.
As busy as you are, you took time to evaluate this job and even offer services.
It's not yet time for me to impose a project on you. You are top drawer.
Rather, let's see how this does over time. If it's just too much current wasted,
I'll consider doing it "right" with a BL motor, etc.

Thank you so much.

 

[Matt Gruber]

the Unite MY1018E comes in
300w
400w
500w
24, 36, or 48v.
But, it doesn't have the gear drive. Have u looked into fitting their armature into your gear drive?

 

[Reid Welch]

Not seriously, no, Matt. Custom machine work is beyond me.

I haven't looked at the Unite lineup for some time now.
If I recall, the bigger motors are much bigger--and will project out from the side of the bike a lot. Good for kneecapping pedestrians, AND more power and efficiency, grin.

Yet, if the 250W Unite is run within its design center, it's not so inefficient.

Dredging through an archival thread, here is an old report of the bike's performance from back when it had the three fresh 12/12 SLA bricks.
I had no metering on the bike at that time, just a cyclometer.

Range test, Unite MY1018, 36V:



Posted by: Reid Oct 22 2006, 09:07 PM


The present three 12/12 SLA gels give about 7miles at full throttle,
being 24mph for the first 3.5 miles or so, then dropping to 22mph until
about mile seven, where the speed falls precipitously. Peukert effect.

---

Informal test of cruising range at 15mph average speed

The bike was run at moderate speed for 1.5 miles distance to the local
school's running track.

There I ran in ovals for an hour and eighteen minutes, holding more or
less to 15mph average.

At times I'd give it a burst of full throttle for the straight leg of
the track to break the tedium of going round and round.

At 19.8 miles on the track the potential top speed had decreased to 16mph.
I called it quits then rested for a minute, and biked home.

By running at an average of 15mph, the three bricks carried the bike for a little more than 21 miles without pedaling.
There was no wind to speak of, and no grades to climb.



In hindsight I will guess that the cruise test drew something like 8AH from the batteries.
They were really flat by the time I got home.

 

[Matt Gruber]

OK reid u r not interested.
if anyone else is
read the blueprints on the Unite site. Would be fun to swap armatures and get a 500w24v and run it at 36v for 750w!

 

[Reid Welch]

It's not that I'm not interested; it's that I'm not motivated at present to lunk up the bike with a bigger motor, because I have adequate speed and power as it is, once the new pack goes in.

Although the new battery pack will surely propel the Currie cruiser at 25 to 28 (est) mph, I realize that, without a lot more capacity than 8AH, such high speeds are only for larking for a few miles at most.

Have no hills, and it will go far and well at 20 or 22 with the new pack plus some pedal spinning (the singlespeed gearing tops my legs out at about 22).

The much bigger motor proposal cannot much aid W/hr efficiency at 18mph cruising speeds,
I don't suppose. Dunno.

It works as it is now, it's fun to ride, it will rocket up to speed pretty fast. I'll document the new performance, then weigh all options.

But, if the stock 250W motor is enough to get me to the store and back at top speed, and it is, there's the fun of it.

If I can do that run at 25 or 26 mph, and quite surely I can with the ne pack, dandy.

We know it costs a great deal more for every mph added on top of say, 20mph.

I ride fully upright--so this is losing propostiion, cost-wise, to shoot for big speed plus range. I'd need to pair the lipo pack with a twin brother and go to a bigger motor.

_________
Will go to the Unite site now and study motors anyway.
I don't expect it's a matter of an armature swap--they machine the armature shaft as an integral drive pinion and harden it.
A bigger motor's pinion may not mesh with the 1018's reduction gear.
Look at the die cast housings above--not amenable to an "armature swap" so far as I can imagine. I will go look at Unite's stuff now.

Thanks!
_________

PS: I come from a Model T Ford mentality. Have thrown a good deal of money into a cheap, sturdy entry level bike. Upgrading the motor may happen in time. For now there is no pressing need but to enjoy the ride.


UNITE Electric Motor Co.

The Little Motor that Can

 

[Matt Gruber]

i think u r right about that splined shaft. not able to swap.

 

[knightmb]

Well good news for me I think. The modified 24 volt mongoose from wally world has been run on 36 volts everyday since last week. From my wife riding around to me trying to blow up the motor by running full throttle everywhere. I even had an area where there is a remote hill and would ride up and down it over and over to see how hot the motor would get. At best, it does get hot to the touch, but when I measure it with a digital temperature gauge, it never gets above 110 degrees F. The temperature that day was 80 degrees F, so I'm not sure what would happen if this were tried on a really hot day.

But I figured by now the insides where toast, so I decided to open it up and inspect the damage. I was surprised to see everything was just fine. I figured after running it up and down that hill and making the motor hot it would have toasted something on the inside. Then I noticed a sticker on the side of the motor that read "450 watt motor", but from what I remember here everyone said it was just a "hype", that the motor was really only 250 watts.

Do I somehow have a model that has the "real" rating of the motor and it's really 450 watts? Would that explain why the motor hasn't cooked itself yet? My wife is the main rider and she never rides fast enough to really heat the motor up. I'm the one that hot rods around everywhere trying to melt it, :lol: :lol:

So I'll see if my wife's riding habits will let the motor live and if it finally does melt down (from me I suspect), I'll report back here or another new topic.

 

[Reid Welch]

OK,

time to pry off the dummy cover

fastened with two 8/32 self tappers and sealant.



such craftsmanship I never saw...

..when I can grind



there's a lot more pipe here than is wanted




now to shorten and bevel the pipe
and hog out the plate for a crude fitting

neatness does not count, not yet.



to be continued...

 

[Matt Gruber]

knight
unitemotor.com only lists a 250w on their site.
They could have an exclusive agreement w/currie for 450w.
email them and ask.

 

[Reid Welch]

knight
unitemotor.com only lists a 250w on their site.
They could have an exclusive agreement w/currie for 450w.
email them and ask.

:lol: The motor is designed to run all day at 315W in, 250W out. Sustained 450W output will burn it out in a short enough time.

Currie: lies
Currie: does not reply to inquiries
Currie: sells decent bikes for fair prices
Currie: is all about selling sizzle

Currie is hot. This motor now is not.

so there :wink:

 

[Reid Welch]

I wonder if one of the RC electric ducted fans would work as well?

Hi Scooterman. I am not familiar with that yet.

Reason here for using a brushed fan motor: I worry that a BL fan may act poorly if I wire it in parallel to the bike motor. The hash from the motor might upset the thing to fail. I don't know. If I parallel, the BL motor must be robust enough to operate over a widely variable range of voltage.

For now, to get me going, the hair drier is purpose-made to blast a major volume of air. And it was free, ready for new adventures, having already given many years of service.

I'll look into ducted fans. Thank you for the tip!

___________________

Michael, I did not see until now your report on the bottom of the previous page. Thanks for that--showing the clean internals of the Unite.

If you had a long enough hill and put about 600W through the motor for long enough, which is roughly what is required to gain a 450W output,
it will begin to fail.

My failed armature seemed hottest in the winding slots. If heat has been excessive there the insulators may show discoloration or partial shifting. Look closely at the color of the wire enamel. It should all be of the same hue.

______________check here later for more pictures of this hack job I'm doing. It won't be a fashion statement. It's gonna look bizarre.

As it is, people don't know that the bike has a motor. They think it's a ???? generator? With a tail pipe? "OH, it's a hot air engine!"

(no, that would be me)

:lol:

 

[Reid Welch]

zinc is very easy to work




the oval hole was finished with a dremel drum sander band

the hole was beveled; "undercut" as a dentist would term it.
this makes a jerk-proof joint.

 

[Reid Welch]

The fit was good enough for quick setting epoxy paste instead of putty.







ready for a quick-dry coat of Krylon




first coat, ten minutes to dry

night is falling now

------------
It's in the oven on low heat to speed the cure.

Almost done!

------

PS:

see prior pictures: that toy motor sure was dirty.
how to give it a quick clean?
why, soap and hot water, that's how.
does not hurt a thing.

 

[Reid Welch]

Lead out of the wire pair will be through the hole in the rim.
It's at the 6 o'clock position.

 

[xyster]

Looks blowfully cool -- in the positive way.

 

[Reid Welch]

 

[Reid Welch]

:wink:

Looks blowfully cool -- in the positive way.

Man, it looks so weird--people will gawk,

"There! THERE! There, see? That man is a CRANK"