Triple Rewind of Unite 500W Motor

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Thanks for the compliments AussieJester, and I return them all in praise of your own custom made Trike.

This is a photo of the core after having sanded the old paper insulation material from out between the grooves and then applying a thin layer of epoxy into the grooves followed by a layer of high heat black paint to make it look clean and smooth. The core is now ready to be wound.

For more information be sure to follow the mirror site as well:

http://www.ebikehub.com/forum/viewtopic.php?f=4&t=886&p=1586#p1586

http://www.ebikehub.com/forum/download/file.php?id=385

 

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Some Pictures

http://www.ebikehub.com/forum/download/file.php?id=387

[http://www.ebikehub.com/forum/download/file.php?id=388

http://www.ebikehub.com/forum/download/file.php?id=389

http://www.ebikehub.com/forum/download/file.php?id=390

...jump to the other forum for more details.

 

[AussieJester]

Better than a "bought one" safe ... might be just the ticket for my next ride
if i go ahead with what i was discussing with you yesterday :: wink ::

KiM

 

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The 200C wire is the highest temperature wire (short of some specialized ceramic covered wire) that you can buy. I'd guess the stock wires are probably near the low end of the temperature rating. This is why you can blast huge amounts of current through the motor and the color of the coils doesn't change.

Between the naturally lowered heating due to the motor redesign and the increase in quality of the wire the only thing left to fail is the brushes.

The main thing is that you can get RC motor like performance out of the low cost Unite motor.

And the BEST thing is that there are Unite motors with BUILT IN geardowns like the MY1016Z3:

http://tncscooters.com/images/106115.gif

...or the MY1018Z:

http://tncscooters.com/images/106118.gif


...and it's these motors that really are at the greatest need for a rewind because they tend to be weak motors. Geardowns are essential to get the rpms down low enough to match the pedal rate which is 100 rpm maximum. This is another reason that overvolting does no good... when you overvolt you increase the motor rpm and that screws up any chances of getting your gearing to work right. Going with the Triple wind tends to increase the motor power dramatically, but keeps the rpm low so these geardown motors will be able to be integrated directly with the bicycle chain.

I've done the rewind of the MY1016Z3, but I don't have the bike ready to test it yet...

 

[skyl4rk]

Do you have any advice for rewinding one of these motors to make a generator? Something that would put out about 60V at 3000 rpm? It could be geared up or down so the rpm is not critical.

I guess my question is, if you take a permanent magnet brushed motor rated at 36V, and you want to spin it with a motor to make it generate power at about 60V, how do you calculate how to wind it?

 

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More "turns" means that as a generator it would take fewer rotations of the shaft to generate a given voltage.

Maybe a better way to think of it is that there is such a thing as a constant "K" that for every volt there is a relationship to motor/generator rpm. The faster you spin the "device" as a generator the more voltage you "get". While in the other direction the more voltage you "supply" the more spinning takes place.

So there is a relationship to "turns" and shaft speed.

You would work backwards:

1. Figure out how fast the shaft will be spinning. (which you seem not to care)

2. Divide that speed by the voltage you desire.

3. You now have that constant "K" of volts per rpm and can then figure out how many "turns" you would need to match that constant based on the way your motor is designed. (the strength of the permanent magnets, etc)

...since all this stuff is specific to the motor you are using there is no simple answer. However, you could figure it out.

I seriously doubt that multiple winds are going to help though because that's mainly a thing to do to get extreme power out of lightweight and undersized motors. My guess would be that a Single wind would be the most efficient as a generator.... however... I could be wrong... I haven't thought about it much.

 

[AussieJester]

Do you have any advice for rewinding one of these motors to make a generator? Something that would put out about 60V at 3000 rpm? It could be geared up or down so the rpm is not critical.

I guess my question is, if you take a permanent magnet brushed motor rated at 36V, and you want to spin it with a motor to make it generate power at about 60V, how do you calculate how to wind it?

Don't know if its of any help or not but there are 60v Unite motors already you can buy straight off the shelf, they are alot larger than what safe is working on TNC Scooters have them if your interested, there max rpm is ~3k also I use the 48v version of the motor myself ...


KiM

 

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I've seen those 60V motors over at TNCScooters and they look like the same size as the 1000 watt motors, but they cost $130. It would be interesting to take one of them apart and see what they are doing.

The old 1200 watt Unite (discontinued) used a Double wind, but was otherwise identical to the other motors which all were Singles.

Generally speaking you tend to create a 60V motor by using MORE turns (so that the constant becomes lower) and having more winds means you get a higher resistance value. So I could guess that the 60V is probably a 1000 watt motor (shell) rewound with about 32 turns in a single wind compared to the 28 turns (or less) you normally get. They might even use thinner wire, but it's also possible they just wind it really tight.

Anyone own a 60V Unite that can tell us?

 

[AussieJester]

Yeah i would put money on them being identical to the complete 1000watt range with exception to the windings, wouldn't make alot of (business) sense manufacturing different housings and armatures if re-configuring the windings got the required result would it :: wink :: I wonder though why they were discontinued? My thinking is they didn't sell a great deal of them, once you get up over that 48volt territory you starting to"wander" towards some high voltage/amperage levels that most sane people (riding scooters anywayz) would probably steer clear of?

KiM

 

[safe]

After the discontinued 1200 watt Unite (Double) I suspect all the motors are now Single winds. Maybe it cost a little more (was more labor intensive) to do the Double winds?

Can anyone name a Unite motor (currently in production) that is anything but a Single?

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When they sell a motor that is "higher voltage" that tends to mean "higher resistance".

Higher resistance usually means more turns for a Single and that's why they end up with moderate no load speed even though they are higher voltage motors.

It's all about how you wire these things... the way they market them makes it seem like they are doing something "special" but it really just comes down to the number of turns, winds and wire thickness.

That's why you can take a low priced motor and rewind it and get something totally different.

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The only other thing is the width of the magnets. I measured the magnets on the 1200/1000 motors and they are 3.5" wide. The 500 motor is only 2.5" wide. So you have to figure that the narrower motor will behave differently.