Triple Rewind of Unite 500W Motor

[duivendyk]

Yes Fuzo that is true, at low rpm ( low voltage from your controller) the efficiency is inherently low (in the absence of gearing down to maintain motor speed).So for the same energy expenditure you will have less range.However when you get to higher speeds above 15km/hr the air resistance which rapidly increases with speed (square law) becomes a factor.So let's say your max speed was 25 km/hr.Then there would be an optimum speed for max range at which the efficiency gain associated with higher motor speed is negated by the increase in required torque(current).Also when you get above 2/3 of max speed further efficiency improvement is not that substantial anymore.It's below30-40 % of max speed where you begin to start taking a beating.

 

[AussieJester]

Fitted the AWG20 DOUBLE wound motor (11 x 2=22) into the trike yesterday was unable to test due to bad weather (rain) spun the motor up revved nicely.

This morning had a break in the weather so took it for maiden voyage and have only one thing to say about double rewind ... GARBAGE... ALOT less torque and i mean ALOT BUT yet manages to pull more than double the amps doing what the stock motor does (i guess Safes unaware of this as he has no monitoring as it means nothing apparently :-S)? 100amp reported on the WattsUp gave me less than 20km/hr top speed (was up hill but not a biggy, stock motor happily hums up it WattsUP reporting 30amp speedometer ~40km/hr) What a complete and utter waste of time and money that little experience was. With the slightly larger tires IT SHOULD of produced stunning top speed. Frank was 100% correct in what he said to me in that the double wind will be worse than stock performance....**** im hanging for the second motor too arrive more than ever now...hopefully early next week. Will be pushing for new setup entirely now i should of listened to Frank and done a single wind with the AWG20 ..AAAAGGGHH.

KiM

p.s How many feet of wire does it take to wind one of these motors Safe? I bought ~400foot will there be enough to rewind a single wind on it with whats left on the spool hard to tell whats been used.

 

[duivendyk]

The only objective performance comparison possible between a multiple&single wind motor is to take basically IDENTICAL motors with the same number of turns per winding between commutator segments, but one with single and the other with multiple parallel strands.If the number of turns is significantly different, this ceases to be the case.I am of the opinion that the possible increase in crossectional copper area will account for any improvements with multiple windings,but it is conceivable that the controller characteristics could play a role too.But that would occur only at low power operation.

 

[AussieJester]

Well...according to Safes spreadsheets a AWG20 11 x 2 wind should of produced alot better performance than it did...it didn't its far worse performance than a stock wind ... I took it for a short run today again after pulling the motor from the trike, at ~ half throttle the WattsUP meter read 137 amp a new personal record as i FLEW along the road a staggering 23km/hr WOOT ->insert sarcastic grin here<--- what a ball tearier of a motor. Its almost like a v8 ....but not...if you gas up a v8 it'll use heaps of fuel geeenerally you get some forward motion happening...not in this double rewinds case LoL...uses copious amounts of power to get nowhere fast LoL

I will have to do something i didn't want to ever do again now, i had thought i might be able to 'live with' the double rewind till new motor arrives this won't happen. I checked the sppol of magnet wire i bought, it looks to be about half used from a 400 foot roll. So what i will attempt is a single 20 wind config. This will still be a big improvement on stock (AWG23 20 x 1) If this is successful ie. i have enough wire on the spool. Ill be happy and have a trike to ride while waiting for the 'new' AWG19 wound motor to arrive. Real ****ed about the whole thing TBH, i had wanted to get into build a CNC mill this week having bought the last of the items needed to construct it :: sigh ::

KiM

 

[safe]

Must Have Done Something Wrong

The math is pretty simple. If your performance doesn't exactly match the math then you did something wrong in the rewind. (mine all fit the math perfectly)

You might have not worked the motor in enough to get it to run at it's peak yet. (so you might keep trying because the magnet wires near the commutator need to wear off their insulation)

If it doesn't work as predicted then the problem is with the build not the math.

Mine delivered excellent power (top end) and managed to allow me to break the 60 mph barrier on my bike for the first time. (of any motor tried) My results were fantastic.

And also... don't forget that the motor is supposed to give it's best power up top at about 5000 rpm. If you are screaming the motor all the way to it's redline you should be getting tons of power. Low end torque is best with Singles and not the Doubles or Triples.

Don't expect a MotoGP motor to pull like a tractor.

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I used my motor at the ideal setting of 40 amps for a current limit. At 100 amps its not going to match your motor very well.

Part of the problem AussieJester is that I don't think you've spent the time to really follow the math on all of this. It's all about having a "custom" fit for your needs. You can't just sort of blindly apply solutions unless you know where it takes you.

The math should be right... and the math also paints a rather "less than ideal" configuration when you use 100 amps as the current limit. (the heat is going to be terrible with such a high current limit)

All that said, you should be getting 3500 watts of peak power at about 5000 rpm and that translates to about 4.7 horsepower.

Are you screaming the motor all the way up to the no load speed?

Did you remember to lower your gear ratio? (the motor needs to spin twice as fast to deliver power) You're not still running the stock gearing are you?

The results you are reporting make no sense at all.

 

[AussieJester]

Must Have Done Something Wrong

The math is pretty simple. If your performance doesn't exactly match the math then you did something wrong in the rewind. (mine all fit the math perfectly)

You might have not worked the motor in enough to get it to run at it's peak yet. (so you might keep trying because the magnet wires near the commutator need to wear off their insulation)

If it doesn't work as predicted then the problem is with the build not the math.

Mine delivered excellent power (top end) and managed to allow me to break the 60 mph barrier on my bike for the first time. (of any motor tried)

And also... don't forget that the motor is supposed to give it's best power up top at about 5000 rpm. If you are screaming the motor all the way to it's redline you should be getting tons of power. Low end torque is best with Singles and not the Doubles or Triples.

Don't expect a MotoGP motor to pull like a tractor.

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I used my motor at the ideal setting of 40 amps for a current limit. At 100 amps its not going to match your motor very well.

Part of the problem AussieJester is that I don't think you've spent the time to really follow the math on all of this. It's all about having a "custom" fit for your needs. You can't just sort of blinding apply solutions unless you know where it takes you.

The math should be right... and the math also paints a rather "less than ideal" configuration when you use 100 amps as the current limit.

How do you explain it pulling over 130 amp whilst doing little over 20km/hr If i limited the controller 60 amp it wouldnt get up my driveway !...And for gods sake stop comparing an electric motor to MotoGP motor its ridiculous, you have a bicycle with an electric motor not a quarter of a million dollar 800cc powered motoGP bike...they are NOTHING alike FYI: safe...without traction controller to limit the motors in MotoGP bikes they would shred tires in a handful of laps they have ALOT of torque my friend. :-S

It revs fine not questioning that, fact is it doesn't have the grunt to pull the skin off a bowl of custard!

There is nothing wrong with the wind, there is nothing wrong with the connection of magnet wire to the communicator each was tested with multimeter to ensure there was contact, the wire has been filed very well and no insulation needs to be 'burnt off' The motor was balanced and timed<--(*i might not know much but i knew electric motors could be timed safe...something you were completely unaware of! Brushed RC motors come with rotating brush plates for this exact purpose) Simple fact is safe, it DOESN'T perform anywhere near as well as what the stock motor does. OH i didn't mention either it gets REAL HOT REEEAL fast, not surprising since its pulling over 100amps soon as you get over 1/4 throttle :-S

Motor sounds pretty much the same as the stock no 'whistle' sound NOTHING like an outrunner RC motor if thats what your eluding to. Simple fact is its worse than the stock motor safe plain and simple. As for yours matching your graphs well.... what monitoring have you used to collect data?

I personally think it's a mistake to use too much monitoring equipment too soon. I'm probably at the point where I ought to get a WattsUp meter just to validate what I'm doing... but I've found that not knowing what is going on exactly has been to my benefit.

Not having everything fed to you as far as information allows you to imagine what is going on... (and from that you get ideas)

After reading that i immediately lost all interest in your graphs and spreadsheets all the data in your spread sheets were assumptions not hard factual data.... I suggest you get some monitoring equipment...tachometer/CA/WattsUP/Eagle Tree or similar rather than continuing to "imagine what is happening"
as it appears your 'imagination' is not quite accurate as you want us to believe.

I don't think you've spent the time to really follow the math on all of this. It's all about having a "custom" fit for your needs.

HAHAHA...dear me...I can't be bothered searching for your post telling me that the rewind i was doing would perform well and how surprised i would be...you were right on one front, im surprised its so bad!

furthermore...I did a DOUBLE rewind as i already have a single on route, i wanted to see for myself how much improvement a double would give. I didn't expect it to perform well off te mark, I wasn't attempting hard launches to get 130amp readings safe I WAS CRUISING ON FLATish GROUND!!! If i kept it at 40amp i would be going walking pace, be great to get it too 5000rpm range to 'exploit' the benefits, i dont think i have a controller able to handle the amps to do that it the Kelly i have has a 200amp limit <--sarcasm in case you missed it ;-)

I'm not in anyway at all annoyed at safe here, I guess in hindsight though I should of listened to someone else that has proven their rewinds with factual data rather than imagined data :-S For anyone contemplating rewinding a motor i would suggest going with a single wind and increased wire diameter you will be alot happier with the results. Me personally im done... ::unsubscribed::

KiM

 

[safe]

You Must Have Made Some Error

This is exactly what you should have gotten.

The math is correct.

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Hey look. I'm sorry your rewind was done wrong (somehow) but we've gone over the math many times and between duivendyk and I have arrived at the correct answers for rewinds.

You're not disputing the math right?

Somehow you're projecting an emotional argument that says that somehow because your own effort didn't work out that the math is wrong and that's something that needs to be corrected.

Note: Just looking at the motor performance shape it's pretty obvious that 100 amps is too high of a current limit if you want a cool running motor. With a battery side current limit of 100 amps it's perfectly reasonable that you would get 150 amps going to the motor itself.

Another thing is that these cores tend to saturate at some point, so you might be wasting energy with excess core saturation when you pull so many amps like that. (adding to the heat)

If the math isn't correct, then let's hear your theory about why it should be different.

I know it's hard to accept, but the odds are that if things deviated from the math then it's probably not the math that is at fault, but your work. (sorry... but rewinds can be hard to get right)

 

[safe]

Timing is FUBAR?

The only difference that I can think of that might have caused your motor to fail so badly is that if you altered the timing.

Maybe the timing is now way off?

Try going back to the Stock timing and see what happens.

Again, my rewinds have all performed like the math projected.

 

[duivendyk]

To the best of my recollection the original winding was 16t AWG 19 changed to 2x11 AWG 20 .The crossectional area was increased by 16% and the resistance is reduced to about 40% of the original value (a 60% reduction).The nl speed was increased in the ratio of 16/11=1.45 For the SAME motor current (not battery current) the torque went down to 0.69 of the original value,over a 30% decrease,made up for in increased rpm for getting the same output power.
All this serves to point out is, that changing the number of turns represents a significant overall design change,which also affects mechanical aspects (gearing) and possibly the controller also.The motor has been redesigned in effect for an operating voltage of about 70% of the original one,in terms of power in/out , rpm &torque and efficiency.
What all this boils down to is that at the SAME speed&torque (output power)both behave about the same,as far as power from the battery is concerned.Disregarding the increased loss in the controller in converting to the lower voltage/higher current the "downvolted" motor requires.If the speed is increased above the original max speed,then more output can be obtained while the efficiency also improves.But this requires that it HAS to be kept in the "efficiency" (high rpm) mode as much as posible by changing gears in order to realise any benefits in terms of power output and/or efficiency.

 

[safe]

I don't think that AussieJester is just struggling with a minor error as far as how he did the rewinding. His results are soooooooooo bad that there has to have been some serious error in how he put it together.

The errors are likely:

Weird Timing Change - He did say he messed with the Stock timing.

Spiral Wound the Winds - When he posted the picture I had a distinct feeling by looking at it that he offset the first layer and the second layer so that they went out of alignment. I've done that myself and when I tried the motor it was hopelessly bad. Extreme heating took place and low power. This error cannot be detected by using a multimeter because the wires end in the right place, but they pass through the wrong grooves in the core. The magnetic fields end up fighting themselves and that uses a lot of current and produces very little actual power while creating lot's of heat. (exactly the description he's given)

...so I think at this point we are best to just wait and see if he can get FrankG's motor to work successfully and that rewind (already done and proven) should rebuild his confidence.

At this point I think AussieJester lacks any belief in the math that has been presented here. I'm in total agreement with your calculations and in the end rewinding simply shifts things around. You do not create or destroy performance by doing a rewind. However, you can find combinations that work so as to match the rest of your bikes hardware. (battery, controller, gearing)

Once FrankG's motor does well he'll either become dependent on FrankG for everything or he will summond the energy to try again.

If at first you don't succeed...