Cheapo motors..............

[recumpence]

OK, I may be opening a can of worms here, but I cannot help but start this thread. :?

I am curious as to why there is such popularity [with the E-bike crowd] of these cheapo HXT (and similar) motors? I know they cost less than high end motors, but the list of problems is stagering;

-Magnets coming loose
-Bad windings
-Bad bearings

What else could possibly go wrong with a motor? And these are problems right out of the box!

I mean, come on! Sure you are only paying under $100 rather than $300 or more, but now you need to buy new bearings and install them, rewind the friggin thing, reglue the magnets...............

Maybe I am just more open with spending money (and no, I am not wealthy). But, I cannot understand why these things are so popular. Maybe for someone who is retired and has huge time to put into the motor it may be worth it. But, man, I cannot understand why these motors are so highly defended and recommended by so many people.

Sorry, this has turned into a rant. But, I am getting kind of tired of email after email after email I recieve about HXT and other bargain motor problems. I find it funny that a $600 Ping battery is fine, but heaven forbid anything over $100 is spent on a motor.

Who else finds this strange?

Matt

I do not mean to insult anyone who has bought one of these motors and rewound or repaired it in one way or another. I am just shocked how many people find it perfectly fine to recommend them to anyone and everyone who asks for a decent motor.............

 

[spinningmagnets]

Matt, just for camparison and conversation, if someone was willing to spend $300-$400 for an RC motor, what are three of them that you might recommend as a "best buy"? 3 sizes,...adequate, sweet, and hot rod (brand, model # and approx price)

 

[EVTodd]

Actually, I don't think there are THAT many stories about bad motors yet. I'm only seeing a handful of completed rc motor builds so far. Lots of planning but not a whole lot of completed bikes.

I can answer why I went with a Towerpro motor. It's a cheap way to mess around with an outrunner without spending a lot of money. My motor was only $48 which is over six times cheaper than a $300 motor. I'm hoping I can get by with extra glue on the magnets but only time will tell with the other issues. I'm also willing to spend a few bucks on better bearings but if the windings end up being an issue I'll bite the bullet and get a more expensive motor.

For me, part of the fun I'm having with this whole e-bike thing is just being cheap about it. That's why I like friction drive (another thing people say doesn't work), my "cheap" Bosch batteries, etc... etc...

I'm willing to try the cheap way first if I know I won't be out a lot of money in the end if it doesn't work. I can live with a $48 mistake.

 

[EVTodd]

Maybe for someone who is retired and has huge time to put into the motor it may be worth it.

And not to be a jerk (because I really like your builds) but how many hours do you have machining mounts and all the special parts for your bikes? Like you, many people like tinkering with this stuff. For me it's not just transportation, it's a hobby too.

 

[swbluto]

You have to remember that a powerful, reliable X5 is comparable in performance and cost as a 400 dollars RC motor and much easier to install, so a significant segment for an RC motor on a bike would be due to price differences(And it's true there's another significant segment due to weight differences, which the relatively wealthy appear to indulge in. Not the average student, however...). Honestly, though, I won't be buying a "cheapo motor" in the future until it's shown they can be repaired and maintained with relative cost-effectiveness.

I bought the one I currently have because it was the only one that within my price range and a suitable size at the time. But I wouldn't heartily recommend it until it's shown long term reliability with the proper maintenance and upgrading. Anyways, any motions that make something "better" I so heartedly support. Among the traits I consider to be "good" is cost-effectiveness, performance, reliability and maintainability. As long as the cheap motors are made better by end users and the more expensive motors are made better by the developrs, I appreciate all advances in the field. And to advance the cheaper motors requires working with one...

 

[swbluto]

-Magnets coming loose
-Bad windings
-Bad bearings

The two emboldened ones appear to be the only critical problems shown. "Bad windings" aren't critical in any sense, it's just people's OMG, MY MOTOR IS FALLING APART rash reaction. Also, it seems many of those with problems are those that are running their motors beyond its recommended rating(i.e., running 3 kW through the 2 kW $50 models) because they were cheap-skates in the first place, so that might be an understandable dynamic.

Anyways, bearings are easily replaceable. Now whether or not magnets can be adequately secured is another check on the list before I consider it adequate. There's also those who are running 6 kW having problems with a bending shaft, but I don't think that's going to be a problem for those running 3 kW.

 

[EVTodd]

I have to believe there's a simple solution for the magnet problem. I'm hoping it's as simple as the 300 degree epoxy I used but how do the expensive motors hold their magnets in?

 

[swbluto]

Well, the expensive motor that recumpence is referring to is an inrunner, so it's on the inside. But, even so, it appears you can throw those magnets if you over-rev it as it appears "Dave" did.

 

[MitchJi]

Hi Matt,

I am curious as to why there is such popularity [with the E-bike crowd] of these cheapo HXT (and similar) motors? I know they cost less than high end motors, but the list of problems is stagering;

-Magnets coming loose
-Bad windings
-Bad bearings

What else could possibly go wrong with a motor? And these are problems right out of the box!

You left out soft shafts and circlips :lol:

 

[swbluto]

You left out ... circlips

uuuuuhhhhhhh?

 

[liveforphysics]

For me, it was because I actually had a pair of them laying on my project shelf

The clips were not made of spring steel, and the shaft was very poor, and the bearings were sloppy.

By the time I bought super high-end bearings, and machined custom shafts from 4340 stress-proof steel, it would have been cheaper to buy a pair of $300 motors.

I think the windings are actually pretty good on my motors. I better secured them in a few places, but they are wrapped pretty damn well, and the laminations are very thin.


But yes, you are right, overall, it would have made more sense, and saved a lot of time to buy some top notch motors right from the start.

I had been planning on buying a pair of Davids motors all along here, but it seems that they are going to remain vaporware?

If a pair of Davids motors becomes available with sensors built-in, I will send paypal right this second.

Otherwise, I'm thinking I'm going to go to just go with a little 6.5" custom 50kw induction motor.

I think induction motors would yeild the highest efficiency, due to it's ability to run more efficiently at very low power levels (cruising speed).

 

[kfong]

Seems to me it's as similar as buying a cheap hub motor. The limitations can be corrected on these motors with initial prep work and better bearing support. I don't see why a coupler isn't used on some designs so you move the bearing loads off the motor itself. Since these motors weren't really designed for sideloads anyways. They sell so many of these motor to the RC crowd, which they generally work from the start. Quality control may be off but it's usually not horrid. The design is so simple that they are easily repairable. I've custom wound some of my own motors and it's really quite simple to do. There are threads on RCgroups that show you how to do this. Now that we can actually install sensors on them, they open up for better performance. I plan to use them on my next build, because of the power to weight ratio is just too enticing.

 

[recumpence]

Good discussion.

Todd,

My PK has about 40 hours in it total including lacing my wheels. My recumbent has about 60 hours in it (if I had to guess). I hope I did not offend you. I purposely worded my innitial post in an irritated tone to get the discussion flowing. :wink:

I do understand wanting to tinker with something. If that is the reason to buy one of those motors, I can understand. But, I am concerned with how many people are recommending the HXT (for example) to people who may or may not have the ability to repair it (before they even run it).

Oh, and the windings do suck BAD on some of these. I installed one HXT for a customer with the worst looking windings I have ever seen. They were super loose.

Again, maybe it is just me. But, I do not understand this. However, I do totally understand budget concerns. I have built many projects that I went the innexpensive but more time consuming route. If that is the entire reason for it, I understand. I just do not see how (as I mentioned before) a $600 Ping is fine, but a $300 motor is not. Of course, you cannot buy a big battery for less than a Ping unless you want to go with no-name Lipos...........

I will say that the answers given so far are pretty good.

Matt

 

[TylerDurden]

I rekon we all can appreciate getting better stuff for less cash (free market and all that jazz). People will always try; eventually finding the point of diminishing returns.

There are generally components that are too cheap... and components that are too expensive. Getting them all in the view of the group will help everyone find a good match for their interests and push the suppliers to deliver more value.

It might be worth encouraging PMers to post questions to the board where all can get the benefit of the dialogue and repeat questions get covered.

 

[dontsendbubbamail]

My pockets are not deep, but I am out there ridding on the road with a cheap RC motor instead of saving my pennies waiting for the day when I can afford the high end stuff. If I decide that I like my current design well enough, I can always buy the expensive motor. Most of the problems with the cheap motors have cheap fixes.

Bubba

 

[12p3phPMDC]

For the price you pay for them, the quality is amazing.
I have a friend whose a mechanical engineer and the director
of engineering for a manufacturing company.

I showed him the motor and he just shook his head because
he could not fathom the quality for the price.

They do make a great platform for learning.
But yes, they do have quality issues. The second motor
I bought has much better windings than the first.

I do want to buy an Astro 3220.. But that'll have to wait
until I finish this. Buy American as well.

You could also buy the Shulze expensive controllers vs. the CC controllers.
I bet you they don't pop under high loads as easy.

 

[disndat]

I would like to see a base starting point for this RC stuff ala X5 hub motor.For example buy this kind of motor,one of matts mounts,this kind of ESC,this voltage and this freewheel assembly with these sprockets and this gets you such and such top speed and great acceleration.I myself am experimenting but with a currie scooter motor.I eventually would like to get into the RC stuff but have no clue about it.I have seen some of the motors that you are talking about but some have been $800 I guess we will have to wait and see on methods and garys experiments,until then I will take matts pk ripper as a base point.And I dont think spending $300 on a reliable motor is too much.I prefer to do things right the first time,but that always seems to bite me in the ass :wink:

 

[MitchJi]

Hi,

You left out ... circlips

uuuuuhhhhhhh?

http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=8347&start=180#p138491

Things were going great. I was very happy.

I mixed up a batch of artic silver epoxy, and added a drip of loc-tite to all my screws and a drop on each bearing/shaft connection. I began final assembly, and things couldn't have been going better. Both motors were locked on, and I began to press the rotors of the motors into place. Then "TINK", and the shaft freely slides forward... I first thought the rotor slid on, but then I saw my sprocket poking out 3", and saw the empty snap ring groove on the shaft....

RAWRRRRRR!!!!!!!!!

That's the sound I make when I'm less than pleased.

So, I rapidly started to disassemble everything again, wiping off loc-tite from every screw, and removing the thermal epoxys with acetone and a rag. When I get to the snap ring area, I find that the inside edge in a few places has mushed over. Yes, just mushed over, like it was made of silly putty. I have never seen a snap-ring do this before. I put it in my snap ring pliars, and opened it up a bit. Did it spring back? No... It stays sprung. I can crush it back into shape just as easily. I was able to twist it like a pretzel with my fingers.

This was the only mechanical part from the original motors that I didn't replace. Now I know not to trust ANYTHING from these motors. These snap rings are made from anealed mild steel, that seems to have the strength of softened copper.

It was 10:00pm, and no where is open to buy REAL snap-rings, so I spent the last hour wiping all the epoxy and loc-tite clean from things before it hardens. I work 12-16hr shifts for the next few days, so this is going to set-back my completion time by a few days. I'm pretty frustrated. I'm going to hit that snapring with my .50cal desert eagle. It might take me a full clip just to hit the twisted dime sized thing, but it's going down.

http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=8347&start=195#p138606

So far, in these motors, the bearings are crap, the shaft is crap steel, and the snap-ring is fashioned from modeling clay. By the time you spend $200 to upgrade these pieces on the $130 motor, you are double wishing that CNCguy would hurry up and release his uber-motors that are all high quality with massively oversize bearings.

http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=8347&p=126155#p126155

You can see the pair of hobbycity 7000w motors are taken apart. This is to swap out the cheapy bearings, and swap in the class 7 bearings I ordered today. They were $55/bearing for the class 7 precision bearings! Each motor uses 3. The mounting plate will be fitted with a support for a much larger diameter class 5 bearing, which should carry most all of the drive loading on the shaft.

http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=8347&p=126433#p126433

So, working with the motors today, I decided that the metal used for the shafts is not really as strong as I would like. It seems to be mild-steel.

Looking over receipts, I found it funny that I paid more for just the new class 7 bearing upgrades for the motors than I paid for the motors themselves :? Strange how those things work sometimes...

http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=8503&p=129282#p129282

I would stay away from cheap motors for such a fantastic project. Not that you need a Plettenberg Terminator. But, a higher quality motor would be good. You could even go with a smaller Plettenberg motor in the 3kw range. Heck, even David's 40 series is good for 3kw burst or 2kw sustained and is far better quality than the HXT. That motor is $195.

Maybe David should:
1. Start shipping his larger motor
2. Make a 40 series (or 45 series) designed from the ground up for Ebikes.
3. Sell kit versions.

 

[EVTodd]

. I hope I did not offend you. I purposely worded my innitial post in an irritated tone to get the discussion flowing.

Matt, nope, you're not offending me at all. I enjoy discussions like this too. To be honest, I know you may very well be right about the cheap motors being a waste of time but like I said, I'm willing to put $48 into it (well, and the price of the glue) to find out. I'm hoping we can find some cheap motors that work (at least for lower power applications like mine). If not, I doubt you'll get many people wanting to try the rc motor route. If you figure the price of an top of the line motor, esc, custom mounts, etc, it starts getting expensive quick. Heck, those three items alone would be over $800 (much more if you have custom machine work done) and that's before batteries.

Now I'm not going to tell you if my magnets come loose. :lol: lol.

 

[Link]

Again, maybe it is just me. But, I do not understand this. However, I do totally understand budget concerns. I have built many projects that I went the innexpensive but more time consuming route. If that is the entire reason for it, I understand. I just do not see how (as I mentioned before) a $600 Ping is fine, but a $300 motor is not. Of course, you cannot buy a big battery for less than a Ping unless you want to go with no-name Lipos...........

I'm guessing that's pretty much it in a nutshell. Most of the people here can perform basic to complex repairs and upgrades to the motors, and I'm guessing a fair number of the more senior/technical-minded members would be capable of designing and putting together their own motor without issue, given the right tools.

Ironic you should mention a Ping, since that just corroborates the above point. Yes, they're more expensive than SLA, but they're still cheaper than the majority of other batteries. Granted, unlike a motor, batteries aren't so easily improved or even fixed by the end user, which is why most have become pretty cautious about which and who's batteries they buy.

Obviously, a higher quality is desirable, but you pay for it dearly. Those two motors on your PK Ripper alone cost more than everything my bike and its drive system is made of, and then about half of the battery. Much as I'd like that kind of performance, I simply can't come close to affording it.

Oh, and you're still significantly richer than me.

I do understand wanting to tinker with something. If that is the reason to buy one of those motors, I can understand. But, I am concerned with how many people are recommending the HXT (for example) to people who may or may not have the ability to repair it (before they even run it).

He's got a point. Add disclaimer/stop it. >:|

 

[recumpence]

Absolutely great discussion! This is what I wanted. I wanted to hear everyone's perspective on this. I am glad I am not insane in my thinking, though I knew I would hear from a few who disagree.

My pocket depth is based on the fact that I sold off a huge amount of stuff as well as using the profit of my drives to fund the Ripper. Of course, at this point, my budget for that bike is pretty much spent. Good thing because I would definately buy other stuff for it.

For me, I love the building aspect as well as the fact that even a high-end project E-bike is still about the same price as a typical motor scooter (about $3000 or so). So, in the end, the performance and fun versus value is quite good. Figure into that the fact that a useable E-bike can be built for $500 to $600 if you really shop around and do your homework, now the value really starts to get good.

All in all, I think we are mostly on the same page in this.

It is funny, I am building a bunch of drives for customers right now. A few of them want innexpensive and a few want higher performance. I am setting a two stage drive up right now for one customer with a Terminator. So, obviously some people do not mind paying a bit. I am also working together with a customer and a custom frame builder to build an entire high-end bike from scratch! Fun times.

Anyway, this is not a thread about my stuff. Sorry for getting side-tracked.

Actually, I am not trying to sell drives at all. They are here if anyone wants one. Also, I am not trying to push anyone to any specific motor. I just enjoy this hobby and wanted everyone's opinion. :wink:

Matt

 

[12p3phPMDC]

Why so much focus so much on negative stuff....
what about the good things about the motor?

CNC anodized ends
Thin Stator Laminations
Nickel/Chrome plated outrunner housing
6kw for $130
bigger phase leads than the astro (astro looks like 12/14 ga???, seems puny to me)

Luke spent a bunch of money improving the motor
with class 7 bearings and custom shafts.

normal bearings with seals are good enough can be had for $5 a piece = $15 total.
Custom shafts from Misumi can be made for $20
Snap rings are $1 for hardened steel.

or you can run it till it breaks, then fix it.
This is not unheard of either. Hell, I just had to drop a kilobuck on a new brake system
on my truck because the factory warranty has expired, Nissan won't fix it anymore,
and the fix is the same old $H1#. So, you buy better parts, and upgrade. It's with
08 factory parts, not a 3 kilobuck stillen brake system, but better.
Or you continually repair, which in my opinion is worse, but sometimes necessary.
Its not rocket science.

So, practical upgrades are feasible, without having to go uber high end.

 

[recumpence]

Very true.

However, I have a hard time spending ANY money for something that is bad from the factory. There have been plenty of complaints about motors with locked bearings or bad windings right out of the box. That is unacceptable at any price.

Matt

 

[TylerDurden]

what about the good things about the motor?

CNC anodized ends
Thin Stator Laminations
Nickel/Chrome plated outrunner housing
6kw for $130
bigger phase leads than the astro (astro looks like 12/14 ga???, seems puny to me)

normal bearings with seals are good enough can be had for $5 a piece = $15 total.
Custom shafts from Misumi can be made for $20
Snap rings are $1 for hardened steel.

So, practical upgrades are feasible, without having to go uber high end.

Great basis for a how-to thread (hint-hint).

 

[MitchJi]

Hi,

Why so much focus so much on negative stuff....
what about the good things about the motor?

Luke spent a bunch of money improving the motor
with class 7 bearings and custom shafts.

normal bearings with seals are good enough can be had for $5 a piece = $15 total.
Custom shafts from Misumi can be made for $20
Snap rings are $1 for hardened steel.

So, practical upgrades are feasible, without having to go uber high end.

Can the $5 bearings and $20 shafts handle the load of a belt drive?

The issue with the snap rings isn't the cost. The issue is they are indicative of the overall quality. Isn't it shocking to you that anyone would sell a motor with junk snap rings which probably saves them under $0.50 per motor?

How about the magnets coming loose?

What about the bad windings?

or you can run it till it breaks, then fix it.

Or if you want a reliable ebike you can spend a little more.

This is not unheard of either. Hell, I just had to drop a kilobuck on a new brake system
on my truck because the factory warranty has expired, Nissan won't fix it anymore,
and the fix is the same old $H1#. So, you buy better parts, and upgrade. It's with
08 factory parts, not a 3 kilobuck stillen brake system, but better.

Completely different. Replacing good quality parts at a reasonable service interval is different from rebuilding a new motor to get it to a decent level of quality.

If anyone wants to purchase an inexpensive low quality motor and spend a couple of hours and a substantial portion of their savings for parts thats fine. But some people would prefer to spend a little more upfront to avoid that. Making these problems known is potentially valuable information to those people.

Your posting cost effective options for bearings and shafts is also valuable information for someone who wants to save a little money and is willing to upgrade and replace as necessary.

Great basis for a how-to thread (hint-hint).

I think a thread on that topic is an excellent idea.

Its valuable to post both the good things and the bad things about products.