zzzt, wow what a trip

[wiredsim]

These kinds of attitudes like the OP possesses almost make me sad, I know these kinds of people all too well. The excitement they possess at thinking they understand something is only tempered by the fact that a substantial part of their understanding is flat out wrong. But if they don't have knowledge of the subject that is beyond mere mortals they cannot be happy. No ability to be contented with just being on a journey of knowledge and being a part of a community that possesses a variety of skill levels unless they are at the top. Reminds me of my younger brother!

 

[Jeremy Harris]

I took the time to write a politely worded comment on his blog, pointing out one or two of the inaccuracies in his posts that he might want to look at correcting.

Unsurprisingly my comment seems to have been moderated out and has never made it on to his blog...............

It saddens me to see such misinformation spread around, and, to be honest, annoys me a fair bit too, because there are links there to ES, which just means folk here will probably have more work to do in trying to re-educate anyone who's read all that duff gen and then followed the links to ES.

Jeremy

 

[Hillhater]

Seems like the OP took the time and effort to return long enough to delete his original "musings" and change the title !! :lol:
Hopefully this will cause him to review his knowledge set on a few of those points ! :wink:

 

[amberwolf]

It's a little late, but I'd like to cover a couple of points that Jeremy didn't, just so that future readers don't misunderstand:

All hub motors are geared too high to keep you under 20mph

They are not geared for any speed at all, in that you may run them at any voltage you wish to get a particular speed out of them. That is how the speed is controlled, by changing the average voltage applied to them, for any typical brushless permanent magnet motor.

and unless you limit the amps to control the speed, they are illegal.

Limiting amps does not control the speed, limiting voltage does. This is what the throttle control does (in the average ebike controller), by changing the pulse width of the voltage pulses from the PWM controller to the motor, so that it's average motor voltage will be higher or lower, in relation to the back-EMF.

Limiting amps will essentially limit the applied torque at startup for the motor, limiting it's maximum power. It may also limit it's top speed under some conditions, if there is sufficient load on the system (hills, wind resistance, etc) to cause it to draw more amps than the limit imposed.

And if you are in a wreck using an illegal vehicle you will get the blame even if it is not your fault.

Dunno about that. You'd potentially get cited for whatever legal violations of using the vehicle, but it doesnt' change the responsibility of any other vehicle operator/etc. that causes a wreck. They'd still get cited for whatever violations they did that caused it, exactly as if they'd had that same wreck with any other vehicle. (depending of course on if the police correctly note and report the incident, which does not always happen, depending on witnesses/etc.)

Besides--the vehicle itself wouldn't be illegal if it had more power or could go faster. It would just not be legally registered as the correct type of vehicle, and perhaps the operator might not have the correct class of license to operate it (or perhaps no license at all). In some places, like here in AZ, there is no limit on how fast a vehicle is capable of going, only in how fast the operator actually drives it.

Here, there *is* a power limit, but I am not aware that there is any reason for the police to worry about or enforce that limit, as long as the vehicle is operated within the speeds and other bounds of traffic law for that vehicle type. In most cases when I've spoken with them, they aren't even aware of any limitations on electric bikes (though they often do on ICE-powered scooters and bikes).

 

[Jeremy Harris]

Jawnn,

I see that you've deleted your original post and changed the title of this thread to one that is plainly intended to mislead and express your frustration at having got things so incorrect in the first place.

If anyone want to read your original post I see that it is still pretty much all there in its error-filled glory on your blog, here: http://commutercycling.blogspot.com/2010/10/secrets-of-motor-pedal-hybrid-design.html

I'm sure your intentions were fine when you wrote that post and blog entry, it's just a shame that it purports to be a definitive list of truths about electric propulsion when it's so very deeply flawed. Perhaps checking things out with some reliable reference sources, before posting to a reasonably well-informed audience might have been a good idea.

If you want to try and put together a proper, truthful and accurate summary then feel free to PM me and I'll try and be more constructive than I was in my original reply on this thread.

Jeremy

 

[Toorbough ULL-Zeveigh]

'Chuck' is his test pilot.
"natives are on the war path, start the plane Chuck! START THE PLANE!!!!"
(or ebike as the situation warrants).

why do I try?

that is a most excellent question.
why do people insist to try & erase the past?
especially when they know damm well in todays digital reality there will always be millions of copies.
can't erase em all.

Secrets of high torque design.


Secrets of high torque design.
Discussions related to motors other than hub motors.
This includes R/C motors, botttom bracket, roller and geared drives.
4 posts • Page 1 of 1
Secrets of high torque design.

Postby jawnn » Tue Jan 18, 2011 8:10 pm
Thanks to this forum and Chuck in particular, I have learned just about everything I need to know to build a high torque power system that will last for 20 years.

Peak efficiency

All motors have a peak efficiency rpm, when powered past that rpm the efficiency goes down sharply and they start burning out. Cars use tachometers because they have so many different gears. With a single gear configuration it is easy to know what the motor’s RPM is by the speed, if you know what that peak efficiency speed is. It would be better to use a tachometer if you can get one. Actually an ammeter with a volt meter is more important.

If you want to understand the math, go to page 105 of 'Build your own electric motorcycle' by Carl Vogal viewtopic.php?f=2&t=19368

Cheap controllers and batteries can also burn out if under sized for the maximum current flow.

Heavy vehicles on steep hills need batteries with a high discharge rate, not cheap lead acid batteries that end up costing more than you think. Thundersky batteries are best.

Gear reductionCalculate wheel speed needed then find ratio of gears:

Wheel diameter x pi x motors peak efficiency RPM / 12”per foot x 60min. / 5280ft per mile = wheel speed without gear reduction / 15mph = ? to 1( gear reduction needed.)

20mph is the legal limit for pedal assist bicycles; a motor can be forced to drive 5mph faster than the peak efficiency so 15 ‘should’ be your cruising speed if not using a Cycle Analyst http://www.ebikes.ca/drainbrain.shtml

A 20” drive wheel maybe needed for a single stage reduction, or a sheave made from a wheel rim on bigger wheels. If the rpm goes over 2000 the motorcycle chain may be too noisy.

The lower the voltage the slower the RPMs but it will increase the amperage. Most electric motors can’t be run on 12 volts because the windings can’t handle the increased amperage of the lower voltage. So they may need a two-stage gear reduction, which could loose at least another 10% of the energy into the gears.


HUB MOTORS

Hub motors cannot use 12volts because the thickness of the wire needed for the higher current will not fit through the axle. 48-volt motors are not more efficient than using lower voltage, but it is good for a motorcycle that you don't need to drive slowly up steep hills (4 to 500lbs fully loaded).

The largest gear reduction hub motor is far from enough to do what the same gear reduction would do at 12 volts, because the difference in RPMs created by different voltages.

The good hill climbers use three planetary gears to lower the RPMs and those gears use up as much energy as a three stage reduction. All hub motors are geared too high to keep you under 20mph and unless you limit the amps to control the speed, they are illegal. And if you are in a wreck using an illegal vehicle you will get the blame even if it is not your fault.
viewtopic.php?f=7&t=23357
http://www.x-tremescooters.com/techdocs/adobe/e-bicycle-fed-regulation.pdf

If you do limit the amp flow to make them legal, you limit the hill climbing torque. The ‘Cycle Analyst’ maybe able to control the speed without eliminating the slow speed amps. But there is still a chance you could burn out power system if you run too many amps threw it at too low of a speed. A good meter will help keep your vehicle alive. A heat sensor would be good also.


.


The Scott 1hp upgrade is the motor to use http://www.cloudelectric.com/product_p/mo-4bb3995.htm

I have seen no evidence that hub motors are good for anything but light weight vehicles on light duty hills. Or just for racing.


And if you want more info, go to my blog: http://commutercycling.blogspot.com

when i first read this along with the handful of comments shortly after it was initially posted i had briefly considered & would have suggested cutting the guy some slack.
if only he just hadn't included the line "I have learned just about everything I need to know..."
yeah, that does sound remarkably similar to safe's "I've completely masterbated the PWM 'effect'."
he's definitely a disciple.
how u can tell that you've actually mastered anything is when u reach a point where u realize & appreciate exactly how precious little u FN really know.
u would know better than to ever make such a pompous & downright impossible claim.

honestly, anytime i read something so blatantly wrong by someone passing himself off as some sort of expert (like ES's biggest booster jrickard) it's always lingering in the back of my mind if they're a shill working for an oil company or some such to spread this sort of disinformation.
cuz if they're not they're doin one helluva outstanding job giving it away for free.

 

[gestalt]

Why do I try

 

[recumpence]

I know the OP was pretty hammered in this thread. However, Jeremy's explanation was more than civil and polite.

Actually, the attitude of the OP by removing his post and posting his "666" is a sign of extreme immaturity.

I went through a bit of his 70% efficiency thread and was equally disturbed by the comments given by Chuck. He made more than his share if incorrect statements that were also worded as authoritative. This is disturbing. It is one thing to be wrong, it is another thing, completely, to have an attitude about it and refuse correction. These kind of people are unteachable. Being wrong is nothing. We are all human and wrong about many things. To be wrong and teachable is a sign of greatness. To be wrong and unteachable is foolish and immature.

I hope he takes this to heart and learns how to learn and take correction from the proper sources and apply them.

Matt

P.S. Man, there is a HUGE amount of talking in that thread and almost nothing actually gets said or settled. Weird...........

 

[liveforphysics]

I will never forget hashing it out with Miles (never a good idea) about motor winding. He was telling me it's only copper fill% that determines the continuous torque handling of a motor. I only understood a couple of the many concepts involved in understanding what he was telling me, and I thought he was totally nuts. lol A month or two later, the missing concepts fell into place in my mind. Then, Ooops... Sorry Miles, you had it all right from the get-go, and I hope I didn't throw off other people who may have thought my arguments when we were debating were correct.

Sometimes we get owned. Generally when we think we have a solid understanding of something, that's when you're so clueless you can't even recognize that you're wrong. Once you actually become a guru of something (like Bigmoose), you generally will never again make the claim that you understand or have something all figured out.

 

[pankaj_india]

why did he deleted the first post . jeremy sir corrected him wherever necessary so he could have posted the new versions of first post rectifying the blunders.

 

[amberwolf]

P.S. Man, there is a HUGE amount of talking in that thread and almost nothing actually gets said or settled. Weird...........

At the beginning of the thread, I tried to help but was completely ignored, so I gave up. I don't think I ever went back to it after the first couple of pages, as it just seemed like nothing was being settled--the problem itself just kept getting changed, every time a solution (or path to one) was presented.

 

[j3tch1u]

It is one thing to be wrong, it is another thing, completely, to have an attitude about it and refuse correction. These kind of people are unteachable. Being wrong is nothing. We are all human and wrong about many things. To be wrong and teachable is a sign of greatness. To be wrong and unteachable is foolish and immature.

I will never forget hashing it out with Miles (never a good idea) about motor winding. He was telling me it's only copper fill% that determines the continuous torque handling of a motor. I only understood a couple of the many concepts involved in understanding what he was telling me, and I thought he was totally nuts. lol A month or two later, the missing concepts fell into place in my mind. Then, Ooops... Sorry Miles, you had it all right from the get-go, and I hope I didn't throw off other people who may have thought my arguments when we were debating were correct.

Sometimes we get owned. Generally when we think we have a solid understanding of something, that's when you're so clueless you can't even recognize that you're wrong. Once you actually become a guru of something (like Bigmoose), you generally will never again make the claim that you understand or have something all figured out.

yes! letting go of the ego is a prerequisite on the path to enlightenment.

 

[chuck]

Wow,
I am the person who was helping Jawnn. First, if you read any of Jawnn's posts you will see that he edits many of his posts after replies have been made. This makes it somewhat difficult to follow the thread correctly. Actually somewhat confusing.

If I made errors, point them out to me.

jawnn wrote:
Peak efficiency

All motors have a peak efficiency rpm, when powered past that rpm the efficiency goes down sharply and they start burning out. Cars use tachometers because they have so many different gears. With a single gear configuration it is easy to know what the motor’s RPM is by the speed, if you know what that peak efficiency speed is. It would be better to use a tachometer if you can get one. Actually an ammeter with a volt meter is more important.

Jeremy wrote:
Not at all true. Running a motor at high torque load BELOW it's reasonable efficiency rpm range will burn it out, not running it at high rpm.

jawnn wrote:
If you want to understand the math, go to page 105 of 'Build your own electric motorcycle' by Carl Vogal viewtopic.php?f=2&t=19368

Jeremy wrote:
I understand the math fine, but that doesn't change the fact that the statement about rpm and burning motors out is incorrect.

Running a permanent magnet brushed motor at a given voltage past it's efficient rpm because of incorrect gearing can easily overheat a motor.

jawnn wrote:
The Scott 1hp upgrade is the motor to use http://www.cloudelectric.com/product_p/mo-4bb3995.htm

Jeremy wrote:
That looks to be a pretty crappy brush motor, most probably based on a cheap Chinese MY series with some mods. Frankly it's hard to imagine a less efficient or reliable motor for an ebike.

Jeremy, until the eteks, this was one of the more common motors in electrathon racing, still competitive today. I find these motors on ebay pretty cheap and use them for most of my builds with no problems.

Liveforphysics wrote:
Who is the "Chuck" guy who he says helped him?

Is this Chuck guy someone equally clueless/mislead, or did this guy just badly misinterpret what he was reading.

Well, I am the Chuck guy. I have a minor in Physics, a minor in Math, Bachelor of Science in Accounting, also took electives in electrical and mechanical engineering, along with chemistry. I am pretty confident that what I write is correct. I have been working with power transmission of all types for 30 years. If you ever find that I have made an error, please inform me,,I will make the corrections as soon as possible.

Jeremy wrote:
To be fair, that thread seems to have started right in at the deep end, with some stuff that probably served to confuse more than it helped. Rough estimates of power and gear ratios required, right at the beginning, would have sufficed for sizing and selecting components and made it easier to reach some more meaningful conclusions as to how things really work.

Thanks Jeremy. I tried to present the information in a simply way using 9th grade algebra. I gave an answer and then Jawnn would re edit the post, you can see what this leads too.... confusion..

Toorbough ULL-Zeveigh wrote:

honestly, anytime i read something so blatantly wrong by someone passing himself off as some sort of expert

Is this directed at Jawnn? Or, to me?
I have the education, the resources, the experiance to call myself an expert in power transmission. I would never call myself an expert in electronics although I had a somewhat decent education in that field.

Recumpence wrote:

I went through a bit of his 70% efficiency thread and was equally disturbed by the comments given by Chuck. He made more than his share if incorrect statements that were also worded as authoritative. This is disturbing. It is one thing to be wrong, it is another thing, completely, to have an attitude about it and refuse correction. These kind of people are unteachable. Being wrong is nothing. We are all human and wrong about many things. To be wrong and teachable is a sign of greatness. To be wrong and unteachable is foolish and immature.

Pretty strong lanquage in my opinion. Be specific, I cannot find any errors in what I wrote. Recumpence, if you find any errors, let me know and I will correct them.

chuck

 

[recumpence]

Here is a cut and paste from that thread;


"There are fundementals to good power transmission design that jawnn does not know yet. I know that jawnn is considering an etek type motor. That is a very powerful motor, hooked up to the correct batteries and the final gear ratio jawnn his considering would render bicycle chain useless in a very short time. I have got to run, I'll continue with good transmission design when I get back."

I have run over 40 hp into a bicycle chain without problems. I have been running bicycle chains in many high power applications for years without problems.

This is, but one, issue I found in that thread (just a quickie to show one specific error).

Matt

 

[Jeremy Harris]

Chuck,

I took a lot of time out to try and help this guy get things straight, as he clearly seemed to have a serious problem with understanding motor basics. All of the observations in my original response are correct. If you have a problem with anything I posted there, then please be specific and demonstrate where I've made an error and we can discuss in specific detail who may be correct.

Jeremy

 

[chuck]

Recumpence,

There are fundementals to good power transmission design that jawnn does not know yet. I know that jawnn is considering an etek type motor. That is a very powerful motor, hooked up to the correct batteries and the final gear ratio jawnn his considering would render bicycle chain useless in a very short time. I have got to run, I'll continue with good transmission design when I get back."

Recumpence wrote:
I have run over 40 hp into a bicycle chain without problems. I have been running bicycle chains in many high power applications for years without problems.

Do you feel Jawnn can use bicycle chain, accelerating from 0 tp 15 mph up a 16% grade, with a load of 550 lbs on board, and expect this bicycle chain to last?
I can, if you wish, calculate the tension on the chain in this scenario. Bicycle chain is not constructed the same as the chains that I was discussing. I am certain that bicycle chain would be an extremely poor choice for Jawnn's vehicle.

If you chose to use bicycle chain at 40 hp and are not having any problems with it, let us know, here, all the specifications of your vehicle. I am sure that there are superior grades of bicycle chain, I do not have any specifications on them.

I am using #41 chain at 1.6 hp at just past its recommended power and gear ratio. I have about 8000 miles on a 1 hp bike with #41 chain, no problems. At 1.6 hp the #41 chain is showing signs of accelerated wear.

Recumpence, support your theory and I will change my post. Otherwise, that post stands.

Jeremy wrote:

I took a lot of time out to try and help this guy get things straight, as he clearly seemed to have a serious problem with understanding motor basics. All of the observations in my original response are correct. If you have a problem with anything I posted there, then please be specific and demonstrate where I've made an error and we can discuss in specific detail who may be correct.

Jeremy, what you wrote on the scott motors as not being a good motor. As to who is correct? I guess it comes down to personal preferences. Neither Jawnn nor I were discussing the scott motor as an ebike motor. I have found the scott motors to be very dependable. I also use them within their ratings.

Jeremy, I thanked you for your support on my previous post.

chuck

 

[recumpence]

Recumpence,

There are fundementals to good power transmission design that jawnn does not know yet. I know that jawnn is considering an etek type motor. That is a very powerful motor, hooked up to the correct batteries and the final gear ratio jawnn his considering would render bicycle chain useless in a very short time. I have got to run, I'll continue with good transmission design when I get back."

Recumpence wrote:
I have run over 40 hp into a bicycle chain without problems. I have been running bicycle chains in many high power applications for years without problems.

Do you feel Jawnn can use bicycle chain, accelerating from 0 tp 15 mph up a 16% grade, with a load of 550 lbs on board, and expect this bicycle chain to last?
I can, if you wish, calculate the tension on the chain in this scenario. Bicycle chain is not constructed the same as the chains that I was discussing. I am certain that bicycle chain would be an extremely poor choice for Jawnn's vehicle.

If you chose to use bicycle chain at 40 hp and are not having any problems with it, let us know, here, all the specifications of your vehicle. I am sure that there are superior grades of bicycle chain, I do not have any specifications on them.

I am using #41 chain at 1.6 hp at just past its recommended power and gear ratio. I have about 8000 miles on a 1 hp bike with #41 chain, no problems. At 1.6 hp the #41 chain is showing signs of accelerated wear.

Recumpence, support your theory and I will change my post. Otherwise, that post stands.

Jeremy wrote:

I took a lot of time out to try and help this guy get things straight, as he clearly seemed to have a serious problem with understanding motor basics. All of the observations in my original response are correct. If you have a problem with anything I posted there, then please be specific and demonstrate where I've made an error and we can discuss in specific detail who may be correct.

Jeremy, what you wrote on the scott motors as not being a good motor. As to who is correct? I guess it comes down to personal preferences. Neither Jawnn nor I were discussing the scott motor as an ebike motor. I have found the scott motors to be very dependable. I also use them within their ratings.

Jeremy, I thanked you for your support on my previous post.

chuck

http://www.youtube.com/watch?v=WKAMus3oSdw

It is funny, it seems like every time I hear someone say something cannot be done, I know one or more people doing that very thing. I went through this when I was designing and building RC helicopters. I had engineers telling me this heli would not fly or that rotor head design would not work. I hate to say it, but, every single time I was told something would not work (by someone who had never tried it), on something I had a hunch would work, they were wrong.

I have a huge amount of respect for engineers in their various fields. Heck, I consult Luke, Miles, Methods, etc on my builds all the time. However, what I get from them is real operational data, not just design specs, and they are not arrogent about it.

Matt

 

[John in CR]

I was trying to get up to speed and was about to ask "who's Chuck" and here he comes.

Chuck,

I'll just address one for now. I can run any of my motors faster than peak efficiency all day long without a care in the world. The furthest point fast peak efficiency is no load speed. There is no load, so no work is done, and efficiency is zero, but the motor is spinning at maximum rpm. The current is very low due to high BEMF preventing it, and the motor will never burn up.

The other end of the spectrum is the point most below peak efficiency. That is 0 rpm. Efficiency is again 0, because no work is being done. Current is at it's maximum and very dangerous to the motor. Low rpms under high load are the problem. During operation, the further above the peak power point that rpms go the better. If you reach peak efficiency, great. Past peak efficiency is very difficult except going down will because wind resistance presents a geometrically higher load, and power falls off pretty rapidly above peak efficiency.

 

[chuck]

Jeremy,

[quote

Jeremy wrote:
]Not at all true. Running a motor at high torque load BELOW it's reasonable efficiency rpm range will burn it out, not running it at high rpm.

jawnn wrote:
If you want to understand the math, go to page 105 of 'Build your own electric motorcycle' by Carl Vogal viewtopic.php?f=2&t=19368

I understand the math fine, but that doesn't change the fact that the statement about rpm and burning motors out is incorrect.

[/quote]

Jeremy, a permanent magnet brushed series wound motor has a peak efficiency at a given applied voltage. Let's just throw out a scott 1 hp motor at 24 volts which is about 82% efficient at 3000 rpm . I have the KTA services performance chart and there are many charts for this motor on electrathon websites. If I apply a load to this motor of 1 hp and gear the motor to run at 3300 rpm the motor is about 65% efficient. I also lose a lot of acceleration due to the load not being large enough to allow currents to increase the torque in the motor. Running a motor in an overloaded state, as you state, also will burn in out. Limiting the current in an overloaded dc permanent magnet motor will also burn it out.

Recumpence,
I am trying not to be arrogant. I read what you wrote, perhaps you should reread it. What you wrote is, in my opinion, very arrogant. I do have an extremely hard time understanding how you are able to apply 40 horsepower to bicyle chain. Post your motor, your controller, your drive, your mass or weight, your batteries, wire size and I will calculate the load on your chain.

Do you think that this did'nt ruffle my feathers

I went through a bit of his 70% efficiency thread and was equally disturbed by the comments given by Chuck. He made more than his share if incorrect statements that were also worded as authoritative.

Bicyle chain in Jawnns situation would wear out quickly, and could possibly snap. That is from experience. I should not need to tell you what a snapped chain could do.

I spent a lot of time trying to help Jawnn. I was extremely careful to look up and validate the designs that I posted. I quit posting on that thread when it became apparent that I was going to have to calculate the center of mass of various styles of 3 wheel vehicles to show Jawnn the rotational forces that affect the 3 wheel vehicles' stability in corners. I just don't have time to do that.

I was also hoping that someone else on this forum would help Jawnn on the battery side, as I have no experience with the lithium chemistries.

Recumpence, Read that thread carefully and you will see the statements I made regarding the charging, maintenance and implementation of lithium batteries. I was very careful to tell Jawnn that I had no experience with the chemistries.

Recumpence, I need a little more than, I did it and it will work for you too. As to the engineers you discussed your problems with on RC helicopters, how does that apply here? I see it as being irrelevent and goes along with your statement to me as being "incorrect and authorative."

The engineering in 'That Thread ' is extremely simple and it is correct. Is this arrogant? (I may have made of made a math error or two)
I want you to understand that the engineering in that thread only applies specifically to the vehicles that Jawnn was invisioning.

There was a thread, recently, where I may have ruffled Jeremy a little. It was about welding aluminum. I was concerned about failure of the part to be welded. I felt that I needed to step in and clarify the process in order to prevent a catostrophic failure. I have more to say to the poster there. That I feel his method of fortifying the weldment and that his method of welding will probably be more harmful than helpful. The last I read there the poster has put the project off.

The above is an example of where my concern overides the feelings of a poster. I pretty much put my foot down in that thread. I took a year of metallurgy so I have a pretty good understanding, far more than the average welder, as to the acceptability of a weld process.

I come on to this forum maybe once a month. I browse around, I see a lot of mistakes and incorrect information. If I felt someones information was dangerous, I am quite sure I would jump in. Would that be arrogant?

chuck

 

[chuck]

John,

I steered Jawnn away from brushless dc motors, 3 phase, due to cost/benefit. Perhaps a 5% increase in efficiency at double the cost. Put the money in batteries and get a doubling of the range, not a 5% increase in range.

It has been 30 years since I took any physics, I once was very well studied in 3 phase motors. Perhaps someone here can steer me to the rpm load characteristics, math, not theory of brushless motors.

A brushed series wound permanent magnet motor becomes extremely hot with as little as 10 % overgearing, ie 9 to 1 ratio ideal, 10 to 1 what I once used, to reach 25 mph. The chart I posted above shows the inefficiency.

I was very upfront with Jawnn in that thread that I was unfamiliar with hubmotors, to ask others of their experience. I am not aware of a brushless off the shelf hubmotor and controller that would propel Jawnn, (using his parameters) front wheel drive, 550 lb load, up a 16% grade with little weight on the front of the vehicle. At 15 mph.

chuck

 

[recumpence]

Chuck,

That trike weighs 105 pounds. I weigh 190 pounds. In that video it was geared for 70 mph. I would run 0 to 60 in a touch over 3 seconds (when on fresh pavement so I could get decent hook). The motors (two of them) are Astro Flight 3220, 4 turn Deltas. The battery pack is a 12S, 30 amp-hour, 30C lipo pack. According to my data logger, it pulled 800 amps at 42 volts under hard acceleration.

My illustration about my experience with my RC helis is, indeed, valid. I am tired of people who insist something cannot be done when I have seen that very thing being done!

I would assume the wear would be higher on a system like mine versus a huge #40 chain. I will readily admit that.

My post may have come across as arrogent in your eyes. However, your posts in both of these threads comes across as arrogent. You continue to post "I have 30 years experience in this or that". You do that repeatedly. That is one thing that sounds arrogent.

By the way, I am a high school dropout. But, I have been designing and building projects in RC, bicycles, motorcycles, etc for years. Your degree of education does dictate some things, for sure. However, higher education does not mean you are right. You asked me for an application to demonstrate my power claims. Well, I posted my video and my specs. I am not talking from lack of experience...............

Matt

 

[chuck]

John,

When I posted on your welding aluminum thread I was'nt familiar with your vehicle. I saw a picture of a blue bike, I don't even know what motor you use. I just did a quick web search on dc brushless motors. Appears to me that brushless hub motors are wound in series, and have similar characteristics to brushed motors.

I looked up brushless dc motors in my Marks handbook, silent.

There is a possibility, perhaps, that you are still in the efficient zone of your brushless motor? Not close to the no load speed?

According to wiki, at high load the characteristics of the brushless motor, Y connected , jeez, I hope I have that right, is very similar to brushed.

To make it perfectly clear to everbody here, this leads me to believe, at this point, that John, even at high speed, is still in the efficient range of his motor.

chuck

 

[chuck]

Recumpence

Again, I don't know what these other engineer's said, it will never be relevant to me or to Jawnn.

The context is what I said in my posts to Jawnn, and it applies to Jawnn. One of Jawnns parameters was long life. My parameter is safety.

I sacrificed a lot to get my education. I had a very good job lined up once, the owner told me without an education you cannot have the job. I was a subcontractor. Quit the bastard. Went back to school and got my degree in accounting.

I got a good job in accounting. The company was'nt doing real well, I kinda became the head accountant, everyone else left. The owners asked me to doctor some financial documents to procure a loan. I walked out.

Me and offices, desks and computers don't mix.

All I ever wanted to be was a carpenter. Life is what one makes of it.

I love numbers, I like to figure things out. Love math too.

This is funny story. Ok, I am not the best storyteller, and maybe you may not find this funny. I was kind of the class hero after this incident. I went to the U of N Texas for accounting. We have to take some advanced economics. A lot of business majors take business calculas. This Doctor of Economics is teaching this course. Really making it tough. The math was'nt tough for me, practically elementary. Very tough for non math majors. Well beyond business calculas. Day after Day, this Doctor of economics sat at the board, doing pretty heavy calculas, I think his ego got away from him. Well, one day, after a chalkboard full of calculas equations, I said to myself, that's not right. Went home, busted out some calculas books, yep, Doctor of economics, is very wrong, wrong math, and wrong solutions to the wrong math. I put my hand up the next day. Explained the errors. Doctor said I was wrong. Well I had my notes, walked up to the board, put the correct math with the correct solutions down. He folded like a house of cards. He really had no choice.

I need the wheel size, and the drive specs, ie sprocket count. the type of chain, brand and specs of the chain if you have them. Helpful if you could weigh the rear end of your trike with you in it. Give me an idea of the maximum thrust your vehicle can put to the pavement without wheel spin.

60 mph in 3 seconds is very impressive. Just watched your video

I have built go karts, minibikes, motorcycles, restored cars.

As Jimmy Carter said, "you now have some common ground, let's work from there" not an exact qoute, something like that.

I just sold my 750 94 model Ducati. Once I started wearing glasses the Ducati just was not fun to ride, limited visibility in that riding position with spectacles. Still have my 82 Virago, nicest bike I have ever owned. Restoring my 82 fxrs harley, currently. Just bought a 2007 Honda 1100 shadow, its a pig. Bought a 97 savage 650 to electrify. Fixed it up, such a blast to drive around town, I may just get another bike to electrify.

I enjoy my hobbies. How about you.

A lot of us here on this forum are building vehicles to suit their needs or desires. I built my bike, which falls under the moped law in Texas, to just get me around in my local area. It is not fast. 30 mph. I use lead, a 110 pounds worth. It goes up hills, steep long ones, weighing in at 450 lbs about, at 30 mph. It gets up to 30 mph in about 10 seconds or a little less I think. Hills or flats, does'nt matter. Current limited by my Alltrax controller during the first 5 seconds of acceleration to protect my motor.

Nothing to write home about. But it suits me fine. Very comfortable. Practical. Once I upgrade my chain to number 40, the only maintenance is tire changing and inflation. At this weight, I buy a lot of rear tires. The reason I am embarking on a motorcyle conversion is the constant wear of my bicycle tires. Getting tired of it. Brakes wear out too fast. Also, will be able to drive it work, not possible with my bike within the limits of the moped law here.

Jawnn is confused. My symathy to him in his quest. I think that He may have ADD, it runs in my family, and I see it in his confusion.
Ramble over,

chuck

 

[Jeremy Harris]

Jeremy, what you wrote on the scott motors as not being a good motor. As to who is correct? I guess it comes down to personal preferences. Neither Jawnn nor I were discussing the scott motor as an ebike motor. I have found the scott motors to be very dependable. I also use them within their ratings.

Jeremy, I thanked you for your support on my previous post.

chuck

The bottom line is that the base motor that the Scott is built from hasn't got a great reputation for reliability or efficiency. They struggle to get better than around 80% efficiency, which means they run hot if used at anything close to their rated power for any period of time. Running them at lower power levels is OK, but they still waste a lot of battery power when compared to many of the far more efficient motors available in this price range (this is a $600 motor, which is pretty expensive for the power it will deliver). I understand that Scott improved one or two of the worst parts of this motor design, like the brush holders (the original brushes and holders failed with monotonous regularity), but AFAIK they did not address the poor efficiency that results from the motor using low flux density ferrite magnets and poor copper fill on the armature. They also didn't change the commutator design, another part of this motor that runs hot at anything over a few hundred watts.

Jawnn wrote: "The Scott 1hp upgrade is the motor to use". This isn't expressing a personal preference, it's telling all of us that this motor is better than any other. Sorry, but that is plain wrong.

BTW, the equations for a PM brushless motor are exactly the same as those for a PM brushed motor. Both motor types are electrically identical, the only difference is that the brushless motors are commutated electronically by FETs in the controller, whereas brushed motors are commutated electro-mechanically via the brushes and commutator. The primary advantages of brushless motors are that the coils don't need to rotate and there are no brushes or commutator to get hot and wear out.

Jeremy

 

[chuck]

Jeremy,

Are you discussing the unite motor?,,
The scott motor was the motor used on many winning electrathons until the eteks took over. There are still teams competing with the scott motors.

The scott 1 hp motor that was on my bike was used for about 8000 miles, at its design rating with no problems. I will use it on another build. I now use the scott 5 star 1.6 hp motor, at its design rating with no problems. I bought the 1 hp scott from KTA services for $270 dollars. I bought the scott 1.6 hp motor from Cloud Electric last year for $295 dollars. They sometimes pop up on ebay, for quite a bit less than this.

Scott motor company is somehow related to Imperial Electric, which is related somehow to the Kinetik co.
http://www.imperialelectric.com/
http://www.thomasnet.com/heading.ht...1462;CNONE&PrdS_SEARCH_PHRASE=Electric+Motors
As to the motors efficiency as it relates to its applied voltage. Cloud electric, Thunderstruck ev and other ev suppliers have the perfomance graghs for the mars and etek motors at various voltages, very little difference in efficiency on these charts.

Your analogy to transmitting electric power on the grid does not apply to the efficiency of an electric motor. The 909 mars motor will run just fine for Jawnns' application at 12 volts nominal.

chuck