Science, Physics, Math, & Myth

[johnrobholmes]

Kiwifiat, you are comparing two different motor winds with a fixed amperage controller at the same throttle. If you adjust the amps to 37.5 and the throttle to 67% for the 3004 motor the curves are almost identical. The throttle and amp amounts need to be adjusted by 4/6 and 6/4 respectively for an apples to apples comparison.

The battery is the same, the controller is the same, the copper fill is more or less the same, only the wind is different. How much closer to apples V apples can you get, do you really expect the guy who chooses the higher N.m/A wind to drive around the place using 67% throttle so he gets the same poorer performance as the faster wind?

I was trying to illustrate one method of comparing watts to watts if you have a fixed voltage but programmable controller. Many controllers have a speed setting that makes running a high speed motor at lower max speed a simple change. My wife's ebike runs a 30mph on 36v "fast wind" MAC that is limited to 65% throttle, and with higher phase currents it acts no different than any other setup. Range is the same, acceleration the same, top speed the same. I don't expect anybody to do anything at this point in my life, but why waste your time on the forum asking questions just to dismiss the responses?



John's method of selecting battery voltage for each wind that result in the same speed is also a watt to watt comparison. If one has the luxury of many packs to choose from, then it is always best to select the voltage that matches the wind to meet your speed needs. But in some cases, like my wife's bike, you make it happen in other ways because the battery is already purchased. 67% throttle limit and reprogrammed current is the cheap way out

 

[John in CR]

Running the same voltage and current settings into 2 differently wound motors is an invalid comparison, because that means there's been no attempt to optimize the system for one or both motors, which isn't worthy of discussion. The discussion originated in a hubmotor thread, and the overriding limitation of hubmotors is heat. The main performance measure is torque. Since different winds of an otherwise identical hubmotor can only make the same torque for the same heat, a simple fact you can't dance your way around no matter what invalid constraints you try to introduce to make yourself appear right Kiwifiat, there is no such thing as a torque wind motor. For your slow motor to make more torque in your example it makes more heat, and if the controller was set up to maximize performance of the speed wind motor, then the slow motor would easily get burned up on the first long hill and make zero torque. Assuming it was a really slow wind motor, it wouldn't make appreciably more torque even before it failed, because it would be pushed to full saturation.

 

[Chalo]

What you say is true, but it ignores the issue of practicality. 50V*20A is a kilowatt, and is immensely easier to furnish than 1V*1000A.

Fast wind motors make sense if you want them to turn really fast. They should only turn really fast if they have enough power to turn really fast under load. That means, for all the noise about "same motor" and amp-turns and whatnot, the implied systems you are comparing are not comparable. To make the same torque with a fast wind motor as with a slow wind motor, you need more battery and more controller to provide a lot more current. That's not the same, even if the motor core iron is the same.

 

[Stevil_Knevil]

I am so excited to see questions being answered correctly now.

You guys make me so proud!!

I feel like grasshopper to the mighty Shaolin Preist on this thread.

"Try to fetch the pebble from my hand, grasshopper!"

I feel like someone is constantly moving the chairs around.

 

[Alan B]

What you say is true, but it ignores the issue of practicality. 50V*20A is a kilowatt, and is immensely easier to furnish than 1V*1000A.

Fast wind motors make sense if you want them to turn really fast. They should only turn really fast if they have enough power to turn really fast under load. That means, for all the noise about "same motor" and amp-turns and whatnot, the implied systems you are comparing are not comparable. To make the same torque with a fast wind motor as with a slow wind motor, you need more battery and more controller to provide a lot more current. That's not the same, even if the motor core iron is the same.

Half right. More controller yes. More battery no. Battery provides same power. Controller provides more current at lower voltage, same power.

 

[Rix]

I am so excited to see questions being answered correctly now.

You guys make me so proud!!

I feel like grasshopper to the mighty Shaolin Preist on this thread.

"Try to fetch the pebble from my hand, grasshopper!"

When I achieve such a feat, I will be destined for greatness then.

I feel like someone is constantly moving the chairs around.

This are some disagreements true enough. But in general, there is more knowledge on this thread talking shop then any others I have sub'd to.

 

[flathill]

case closed

I am still waiting for Kingfish to apologize to John for being such a.......

"OK everybody... shows' over.
We all now know John is not an engineer or a scientist.
No doubt he has credibility in other areas, but certainly not in motor theory.

Thank you for clearing that up.

For the record - I am an engineer, I do know my math, and there's a very high probability that you or your kids are using product that I developed.

Good luck with that myth busting.
~KF"

 

[John in CR]

case closed

I am still waiting for Kingfish to apologize to John for being such a.......

"OK everybody... shows' over.
We all now know John is not an engineer or a scientist.
No doubt he has credibility in other areas, but certainly not in motor theory.

Thank you for clearing that up.

For the record - I am an engineer, I do know my math, and there's a very high probability that you or your kids are using product that I developed.

Good luck with that myth busting.
~KF"

Thanks Flathill. I doubt he's man enough. What you quoted is mild compared to the ridiculousness he posted in the original thread he split from to start this one where he actually laughed that I included the formula for computing heat in the copper.

Some good came out of their insistence in maintaining the wrong side, because more people saw the thread and accurate info was repeated in many different ways, so more people are better informed. It also forced me to dig in deeper into the heat creation side of our systems, and I came away with some eye opening realizations that are seldom, if ever, discussed in the forum. I love learning new stuff about ebikes, because the applications are new enough that there's still plenty of unexplored territory. I can't wait to share what I've found. I just need to apply it to a bike first for real world verification and examples.

 

[flathill]

case closed

I am still waiting for Kingfish to apologize to John for being such a.......

"OK everybody... shows' over.
We all now know John is not an engineer or a scientist.
No doubt he has credibility in other areas, but certainly not in motor theory.

Thank you for clearing that up.

For the record - I am an engineer, I do know my math, and there's a very high probability that you or your kids are using product that I developed.

Good luck with that myth busting.
~KF"

Thanks Flathill. I doubt he's man enough. What you quoted is mild compared to the ridiculousness he posted in the original thread he split from to start this one where he actually laughed that I included the formula for computing heat in the copper.

Some good came out of their insistence in maintaining the wrong side, because more people saw the thread and accurate info was repeated in many different ways, so more people are better informed. It also forced me to dig in deeper into the heat creation side of our systems, and I came away with some eye opening realizations that are seldom, if ever, discussed in the forum. I love learning new stuff about ebikes, because the applications are new enough that there's still plenty of unexplored territory. I can't wait to share what I've found. I just need to apply it to a bike first for real world verification and examples.

Yeah now there is only one person on this board I pity.... :wink:

"John, you have fallen on your sword and missed this by a wide frippen mile. I can't believe you actually posted the equation P = I^2R :lol:

I love that Astro reference! Keep hittin' the Kool-Aid if it makes you feel good. It's pointless for me to continue questioning you when you have done yourself out so well. I almost feel pity. "

 

[amberwolf]

It's already been pointed out, but the personal stuff doesn't belong here, just the technical discussion. :/

 

[John in CR]

It's already been pointed out, but the personal stuff doesn't belong here, just the technical discussion. :/

Talk to the person who posted the original and either force the edits it or censure them. Safe was far less a problem and he got run off because he got under the skin of a very few. KF otoh ridiculed someone trying to prevent members from being robbed of their hard earned gold that has cost members countless tens of thousands of dollars, and KF has been proven absolutely in the wrong.

I ask you AW, what is going to be done about it. AFAIC nothing short of having all of his erroneous posts deleted or edited, combined with a public apology to the members he mislead, is acceptable.

Like I said earlier I doubt he's man enough to own up to his mistake, and if like Kiwifiat, who is looking more like a troll with each post, he refuses to acknowledge his mistake after being so openly hostile in his attacks on the person simply trying to help others by righting a long-term wrong with factual info, then he gets what's coming to him.

BTW, where were you and the other mods when KF was making his ridiculous statements? Was it just missed, or was it that you were an innocent victim of the myth too, so you let him slide thinking he was right? In any case, drawing some kind of line now isn't going to work. Either force the idiot who purchased his engineering degree at 7-11 to fix the posts he made and make amends or he has to suffer the public consequences. There's exactly zero % chance I'll allow myself to be censored when I'm in the right and started no attacks, especially since we're talking about simple fact, not opinion.

I'm sorry that you chose to put yourself in the middle of this now AW. If corrective action is necessary, it needs to start with 7-11, aka KF.

 

[teslanv]

Kingfish is a smart dude. I have no doubt of this.
I don't always agree with his methods, and the way that he deliberately picked this fight, but he is no "7-11" engineer.

[youtube]kQFKtI6gn9Y[/youtube]

 

[maxwell92036]

I think they went from moving chairs to throwing them! I now know less about winds than I ever thought possible.

 

[amberwolf]

This post (and my previous one) is not aimed at any specific person, but is a general reminder to all participants:

I'm not censuring anything in the way of the technological discussion. And I am not going to censor anything, either.

I'm simply pointing out that calling names, by anyone, for whatever reason, isn't what we're supposed to be doing here--we're supposed to be discussing the technology itself, and coming to whatever conclusions there are.

Apologies from anyone will or won't come as they choose--nothing to be done about that. If members continue to call each other names and taunt each other, it isn't going to help anything--it just fans the flames and obscures the issue at hand, which shouldn't be what people think of each other, but what technological principles underlie our transportation.

I might be mistaken, but I had thought that Endless-sphere as a whole isn't supposed to be about "us" against "them", but rather the sharing of knowledge and discussion to further the whole end-user electric vehicle technology advance.

I do understand that this particular discussion at hand is important, as it is about the basic way that motors/controller/battery systems actually work to create motion, and I understand the emotions are high between participants for a number of reasons. I think that all involved might want to step back and consider setting aside those emotions and any personal considerations, so that the technological discussion itself is at focus, and not the disagreements and insults that have already passed.


Everyone, at some time, has been wrong about something. Sometimes they'll admit that, sometimes they won't. There's no good way to force them to sincerely admit and apologize for it--they have to do it on their own, and everyone else will accept or reject them as we choose, as well.



If members want to continue arguments about who is to blame for what, and how badly or well each other member has behaved, I propose that it be continued in the Other Toxic Discussions forum section, rather than in a technical forum.



I have no definite opinion one way or the other on the general technological subject at hand, as I have not been able to perform sufficient detailed physical experiments with complete instrumentation and documentation to know what is absolutely true and what is not. Given my time and monetary constraints, it's unlikely I ever will be able to do that, either--and I expect the same is true of almost all of us here. I do think that if we were to all cooperate in such an experiment, every single point could be proven true or false, categorically, and possibly even other things we never expected could be discovered.


That's the rest of what I have to say regarding all of the issues in this thread. The rest is up to all of the participants individually to decide to continue a technological discussion, or a personal one, or some combination of both. I hope it stays techological, as that's of the most benefit to the most people.

 

[flathill]

The problem is KF has made this 100% personal from the start of this thread. It was a direct challenge to "you" a.k.a. John, along with some sort of public shaming.

KF has 3 options:

1) apologize
2) have his guru access permanently revoked for abusing a member
3) resign as a guru

"Generally, moderators are present to prevent users from going off-topic or posting abusive or offensive material."

un·be·com·ing adjective \ˌən-bi-ˈkə-miŋ\
: not attractive : not becoming

: not appropriate or acceptable for a person in a particular job or POSITION

"
The red ones are admins, and the green mods. Then blue are gurus, with no special powahs except ability to post in a restricted-write-access forum for technical reference stuff. KnightMB shows as green, but he's also an admin."

 

[Miles]

Safe was far less a problem and he got run off because he got under the skin of a very few.

I don't think that was the case, John. IIRC he was banned for expressing his racist views... We certainly don't want to go down the road of banning people just because they are irritating to some....

KF seems to have constructed his own punishment. I'm still waiting for him to express himself coherently.....

 

[John in CR]

Safe was far less a problem and he got run off because he got under the skin of a very few.

I don't think that was the case, John. IIRC he was banned for expressing his racist views... We certainly don't want to go down the road of banning people just because they are irritating to some....

KF seems to have constructed his own punishment. I'm still waiting for him to express himself coherently.....

Oh wow, I didn't realize safe did that. Banning him makes perfect sense now. Thanks for clarifying.

 

[John in CR]

I think they went from moving chairs to throwing them! I now know less about winds than I ever thought possible.

Maxwell,

It's quite simple. They're the same motor. Several years ago Miles shared the motor comparison chart below done by Astro based on actual tests of many different winds of their little 3110 motor, and that's what clicked it into focus for me. Even then it took a long time for me to let go of all remnants of the myth. Everything comes down to torque and heat, and for me it required understanding that different winds of the same motor make the same heat for the same torque to exorcize the myth.

Note in the chart that simply varying voltage and current for the same power input makes performance identical.

 

[maxwell92036]

I think they went from moving chairs to throwing them! I now know less about winds than I ever thought possible.

Maxwell,

It's quite simple. They're the same motor. Several years ago Miles shared the motor comparison chart below done by Astro based on actual tests of many different winds of their little 3110 motor, and that's what clicked it into focus for me. Even then it took a long time for me to let go of all remnants of the myth. Everything comes down to torque and heat, and for me it required understanding that different winds of the same motor make the same heat for the same torque to exorcize the myth.

Note in the chart that simply varying voltage and current for the same power input makes performance identical.

That chart is fine and dandy but most of us deal with 24, 36 and 48 volt systems and controllers that deliver from 15 to 40 amps and batteries that can supply from 15 to 40 amps continuous. Are you saying the manufactures are selling us a load when they talk about what a high speed motor and a low speed motor is and their applications?

 

[Alan B]

Nice chart John.

Keep in mind that the current they are quoting in the chart is motor current, not battery current. For example a "40 amp" ebike controller usually means 40 battery amps, and the phase current limits may be 2.5x that, or 100 amps.

Manufacturers present their products in various ways to make them look good and categorize them in simple ways, but it is important to understand the full context and what the specs really mean. If you take motor current as a fixed quantity then a high turn count motor will produce more torque, and the lower turn count will produce more speed (if it doesn't run of torque). So in that perspective their description is not wrong. But, as has been discussed, the motor's actual maximum speed and torque capabilities aren't related to the winding, but to the magnetic and mechanical design. It really depends on the constraints that are most important for your application.

At the end of the day we must pick motor, controller and battery, so understanding how these variables interact is helpful.

 

[gogo]

Are you saying the manufactures are selling us a load when they talk about what a high speed motor and a low speed motor is and their applications?

You need to be specific about the claims being made.

 

[Rix]

I think they went from moving chairs to throwing them! I now know less about winds than I ever thought possible.

Maxwell,

It's quite simple. They're the same motor. Several years ago Miles shared the motor comparison chart below done by Astro based on actual tests of many different winds of their little 3110 motor, and that's what clicked it into focus for me. Even then it took a long time for me to let go of all remnants of the myth. Everything comes down to torque and heat, and for me it required understanding that different winds of the same motor make the same heat for the same torque to exorcize the myth.

Note in the chart that simply varying voltage and current for the same power input makes performance identical.

John, I see what you are saying and this chart clears up a lot. I think what some of the guys here, me included are wanting to know is results of Fixed Volts and Amperages and how it affects motor output. For example with this chart your posted, lets say we apply a fixed amount of current, say 72 volts at 60 amps DC through the 4 wind and 6 wind motors. The power out put will affected by the different winds. Provided that inductance load isn't the limiting factor for current demand, then my real world experience suggests that the 6 turn motor would pull harder off the start and the 4 turn motor has a higher top speed. This was my findings with the 5403 and 5404, So when we look at motor output from this perspective, all motor winds aren't created equal, but can be made equal my manipulating the Volts/amps input. Am I correct?

 

[teslanv]

I think many here are still confused by Battery amps vs. motor amps.

You can have a fixed Battery Voltage and Controller Current Maximum of whatever Voltage and Current you desire.

It is by changing the programming of the controller and thus what the controller does with that battery voltage and current that makes the difference.

It's controller input vs. output.

Let's assume 72V Battery, and "60-Amp capable Controller" for two different motor winds. This would equate to a maximum power input to the controller of 4320 Watts. (I will ignore losses to keep the calculations simple.)

For the High Kv motor (Low # of turns): You would program the controller to output a high motor current by increasing the current multiplier. i.e. 2.5 X battery current. So you effectively get 150 Amps to the motor, but at a lower voltage (4320/150=28.8V effectively)

For the Low Kv motor (High # of turns): You would program the controller to output a lower motor current by lowering the current multiplier. i.e. 1.5 X battery current. So you effectively get 90 Amps to the motor, but at a higher voltage (4320/90=48V effectively)

What many guys mistakenly do is set the motor amps too high for a Low Kv (High Turn-Count) motor and then fry the windings.

 

[gogo]

I think many here are still confused by Battery amps vs. motor amps.
…
What many guys mistakenly do is set the motor amps too high for a Low Kv (High Turn-Count) motor and then fry the windings.

Yes, but the physics (acceleration) are awesome right up to the release of the magic smoke.

 

[teslanv]

Ha!

Yes, and if you have a "wheelie machine" chances are your motor current setting is probably too high. You don't need a "Throttle Tamer", You just need to reprogram your controller and lower the Phase Amp multiplier.