Triple Rewind of Unite 500W Motor

[safe]

The normal controllers control motor voltage, not current,therefore the input current is determined by current overload protection in the controller if any.

You don't know very much about the details of these controllers it seems.

Ebikes use PWM (Pulse Width Modulation) controllers and that means the voltage never changes, but the pulse width changes depending on:

1. The throttle setting. (0% duty cycle to 100% duty cycle)

2. The current limit that the controller sees based on the battery side of the current and not the motor side. (the duty cycle percentage is adaptive so that the current limit is not exceeded)

The controller actually uses the lower duty cycle of the two.

...some ebike controllers have no current limit, but those are very rare because they destroy motors too easily. All the controllers I use use have battery side limits built in. (usually 30 amps or 40 amps) AussieJester is using an emotorcycle controller (Kelly) and so his current limit is really high, but that's not normal for ebikes.

Now things get more interesting because when you battery side limit the current it ends up giving a "current multiplication" on the motor side when the duty cycle is lower. The "peak deviation" from a linear curve occurs at around 50% duty cycle.

This is a blessing and a curse...

The "blessing" is that you can get a little more low end torque than normal, but the "curse" is that you are getting the extra current in a part of the powerband that is inherently less efficient and most of it ends up turning into heat and not power.

duivendyk, until you "get up to speed" on the actual way the controllers are being used (experience) you're not going to see the value of a lot of the tricks of the trade that have been presented. Most of the value of a Rewind is that you are exploiting the controller behavior so as to make it perform better. As I've been saying again and again... they tend to run these motors too "rich" which means the "real world" controllers provided are given current limits that are waaaaaaaaaaay too high compared to the optimal configuration.

All I'm really doing is being skilled at "tuning up" these little motors to get the most out of them.

...discussions of motors and voltage without the "real world" discussion of the actual parts on real ebikes doesn't do much good.

Try going here and studying the parts that are most easily available (and a good place to buy them cheaply):

http://tncscooters.com/partsdb.php?type=ES

The true test in on the bike... on the road. What can it actually do?

(like AussieJester, he's going to do a head-to-head shootout of two different Rewinds to see which is better)

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This is why the WalMart bike is so attractive to me. So many people treat with disdain such a "poorly tuned" vehicle, but what I'm saying is that if you did the right Rewind and gave it absolutely "perfect tune" that all of a sudden that lame machine starts to look pretty good.

I think that a well "tuned" WalMart bike could outperform many of the more expensive ebikes offered when those other offerings are stock.

 

[duivendyk]

If you had bothered to take the trouble to READ what I actually said, you would not have proclaimed that I need to bone up about controllers.I stated the "MOTOR" voltage is being controlled.This is the average voltage coming out of the controller.It controls the motor speed which is approximately proportional to the average input voltage. I was designing PWM power modules over 25 years ago which are basically the same thing.If you stuck volt meter on the motor input it would read a varying voltage depending on the duty factor.This input current overload control scheme is stupid &dangerous because it does not limit the motor current which can be much higher at low duty factors,so you can fry your motor crawling uphill and never know it.The only acceptable control scheme as far as I'm concerned is to use a motorcurrent sampling feedback PWM control scheme,giving inherent overcurrent protection.I would have no trouble at all designing&building one.I don't see the relevance of your "tuning schemes".So what if the response isn't exactly linear,who cares? The best way to run a motor is to use a variable speed drive to thewheels to keep the motor speed and voltage up and the current low as much as possible and I'm rather surprised that it does not seem to find much application.Cost probably, also you don't get those jackrabbit starts

 

[AussieJester]

AussieJester is using an emotorcycle controller (Kelly)

^^^ Pretty much all i care to comment on is that YES i do use a Kelly an NO its NOT an emotorcycle controler YES it is used by many that have emotorcycles BUT it is originaly designed for use on light electrical forklifts...

have fun fellas..



p.s duivendyk best of luck ... many have tried to get through many have failed... i give up...

 

[duivendyk]

AJ, you were mentioning a single rewind with 1x?? AWG 19 and a double with 2x11 AWG20 if the first one has also 11 T and fills the winding space how can the double wind fit in the same space it takes 60% more room for 22T #20 than 11T #19 what gives?I'm puzzled,according to my AWG tables 17T AWG 19 would fit in the same space as 22T AWG20.So what is going on ?.Are they identical motors?
I have decided not to get involved with WM/Currie. I have a NuVinci variable speed hub has a 3.5:1 range with dual inputs one for pedal input the other for motor input + 19:1 gearbox to mess around with.

 

[AussieJester]

Without checking theworkshopca website i couldnt tell you how many winds the AWG19 wound motor is suffice to say its not 11 wind its closer to 20. I was actually on Skype call with Frank when i got the notification email through and asked him he couldnt even remember LoL...sorry im toooo hung over this morning to scroll through pages to find out LoL...I will say im hearing EVERY bloody car this morning that drives by im waiting for several deliveries particularly my 20x4.25 rims and tires from ChoppersUS that cleared customs in OZ yesterday morning i usually get delivery the next day ;-)

KiM

 

[safe]

...This input current overload control scheme is stupid &dangerous because it does not limit the motor current which can be much higher at low duty factors,so you can fry your motor crawling uphill and never know it.

Exactly... these ebikes ARE stupid!

You got it!

That's why the real goal is to form a bridge from the absolute stupidity which is the reality and fill the gap towards the ideal.

The stuff we use is real junk... very far from the ideal... and so when I'm "tuning" these motors all I'm really doing is making them perform up to their potential.

My point is to get you to look into the flaws of the actual machines more... the "real world" on these ebikes is far from the ideal. (so talk about perfect behavior is of less importance than the actual)

duivendyk, it sounds like you just don't want to deal with such low quality stuff and would prefer to work with top of the line parts and I can understand that... junk can be frustrating sometimes...

The NuVinci is an expensive part... like $400... and I'm sure you will have some great results with it. It's nice to start with high quality parts in the beginning.

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I think it takes a certain type of person that is willing to actually get themselves involved in stuff that is really junk to begin with. There have been so many postings on so many ebike forums where people get to the same point and lose their patience with low quailty and decide to go up the price scale just to eliminate the frustration.

My goal is to try to discover a machine setup that can achieve remarkable performance but at a WALMART price. Ideally I'd like to build an actual EBRR (Electric Bicycle Road Racing) bike to sell and do it in such a way that it's legal. I'd love to be able to sell a bike like the one in my avatar for under $500.

So from my perspective I need to "eat the dogfood" that exists at the low end because those are the cheap parts that I would need to draw upon.

I'm approaching this process from a different perspective than other people because I want to make a cheap bike, sell it and still make a profit.

I need to be able to sell "junk" parts but turn it into something beautiful.

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We all do ebikes for different reasons...

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What frustrates many people about me (who don't understand my psychology) is they assume that I'm some sort of "American Idol" contestant searching for "ebike fame" in order to indulge their fragile ego. For me the "fame" would only be useful if it advanced the cause of the eventual product development. My "ego" is in effect subservient to the greater goal. I in effect serve an abstract goal. (that I might not ever even achieve) It's just the way I roll.

Another way to look at it is that I'm an ebike addict... I serve my addiction... (I'm a junkie)

(both perspectives are probably true)

 

[AussieJester]

Meant to ask a while back what method do you use to adjust the timing on the rewound motors safe? Frank filled me in on how to do it using a multi meter a method for memory Fletcher from ES told him about ?

KiM

 

[safe]

There isn't anything like "timing" to adjust to my knowledge.

I alway just line up the little lines outside the case before I put things back together, but's that's just to get the slots between the magnets to line up right. (allowing the bolts to make it through to the other side)

The way these things work the rotation of the motor moves the brushes and that advances the position of the "spark" (magnetism) forward.

If you had wired the coils favoring one side of the center (from the commutator pole) it will spin in one direction, but if you favored the other side it will spin backwards.

Other than that there's nothing to know...

At least I don't know that I should know any more... if that makes any sense.

The commutator offset is built solidly into the physical makeup of the motor. The only way "timing" would be adjustable is if the commutator could be rotated relative to the iron core... which it cannot do...

I think that some RC motors have adjustable timing, but I don't think we do...

duivendyk, this is an area where your knowledge could help. Have you ever worked on any electric motors with adjustable "timing"?

 

[AussieJester]

ooooh boy :-| ... you can indeed adjust the timing on an electrical motor safe, and the reason they can run backwards is when they are out of phase by 90 degrees :-S You might have heard of this lil app. called Google?...now might be a good idea to Google "Timing electric motors" ;-)

KiM

 

[duivendyk]

No I have not,and I think it's dubious proposition,but I'm NOT a motor expert&specialist.I could imagine that in a motor without commutation poles,there could well be an optimum brush position,but that's just a hunch.You reverse a motor by reversing the input,with reversal of the current the polarity of the torque reverses,simple as that.
AJ, if these motors have different # turns (my 17 guess is prob. not far off).you will be comparing 11T vs 17T,either diff. motors or diff. operating voltages or both.I don't see that this exercise will settle anything really as far as multiple vs single wind goes.I think it's a minor issue really,just a way to get more copper an the armature,and of course a lot more work too.Take it easy.