New to the forums: Wye/Delta questions and I have a 9C clone?

[recat]

A while ago i encountered the only other guy in my city with an ebike with 9C clone motor, and he said his was 1.5 kW and it reaches 70 kmh.. but then he said his controller was 25 amps and 48 volts. Exactly the same as mine at the time, except mine was sold to me as supposed "1kw" and it only reached 45 km/h. My theory is that his supposed 1.5 kw motor is the same except wired in delta.. because 45 * 1.7 = 76.5 kmh. aaand that my motor was wired in Wye?

I'm wondering if anyone here has tested re-wiring their motor lately, and if they have any tips and tricks to share? And also any interesting videos? Maybe also some real-world tests comparing before and after? I've seen it in really old threads, but I don't think I should necropost, and back then youtube almost didn't exist.


I'm also wondering if anyone can help me figure out what the winding of my motor is. I'd like to find out in order to get a sense of what power you can squeeze out of it with various mods. It's of "Voilamart" brand, sold as "1kw". Stator width is 27mm. I've opened it up and I counted 9 strands of copper for each phase wire, but I'm not sure how to count the turns. So far it seems like it's a clone 9C 9x7... but i'm not sure.

Here's a pic of my stator:

 

[SaabGuy]

Looks like WYE to me. the three ends are tied together right there in the black heatshrink.

 

[flat tire]

Wye is standard. Termination won't affect power handling.

 

[HK12K]

He was probably either guessing or lying. It sounded fast to me, so I googled and it highlighted this snippet:

"With 9c type 9x7 motor. Doing the math, 1500w from 72v 20 amps simply would not be enough watts to hit 40 mph. It gets harder and harder to get 5 mph more speed the faster you go. 0-25 mph easy, after that, it starts to take a lot of watts." Dogman Dan Aug 30 2015 4:31am

https://endless-sphere.com/forums/viewtopic.php?t=72315#p1091621

If 72v @ 20a won't do it 48v has no chance in hell, unless it's off a cliff.

 

[amberwolf]

If you want to experiment with what your motor can do in different windings, controlllers, batteries, you can go to http://ebikes.ca/simulator , read the entire page so you know what everything is/does, then play with different setups using your motor (or the closest one you can find to it in the list).

 

[recat]

I've been looking at that motor simulator, but i'm not too sure which would be the closest match to mine even after reading it. I'm guessing one of the 9C ones, but i'm not sure what the 4 numbers after it represent. 2705 2706 and 2707. What's the differences between these three?

Looks like WYE to me. the three ends are tied together right there in the black heatshrink.

Sorry, I miswrote my original message. I knew it was WYE I was just trying to figure out if it really is a 9C clone.

Wye is standard. Termination won't affect power handling.

As I said above, I'm just trying to figure out the general power handling of my motor regardless of termination. (If it's a 9C clone and hence if it can handle the power other people push into their 9C clones)

Also do you mean that Wye is what most motors come with as their standard configuration?

He was probably either guessing or lying. It sounded fast to me, so I googled and it highlighted this snippet:

"With 9c type 9x7 motor. Doing the math, 1500w from 72v 20 amps simply would not be enough watts to hit 40 mph. It gets harder and harder to get 5 mph more speed the faster you go. 0-25 mph easy, after that, it starts to take a lot of watts." Dogman Dan Aug 30 2015 4:31am

https://endless-sphere.com/forums/viewtopic.php?t=72315#p1091621

If 72v @ 20a won't do it 48v has no chance in hell, unless it's off a cliff.

I see. Well I've installed a power meter on mine, and I noticed that even if I have a 2+ kW power limit (running 60A 48V at the time), while I accelerate I reach it (peak 2.8 kW) once I reached 45 km/h my current draw would drop to 800 watts or around 20 amps, which is less than 50% of the current limit I have set with my controller. Going to see how this changes when I re-wire my motor to Delta from Wye and post here.

 

[HK12K]

Sorry, that statement was presuming they were the same motor, same wind, same voltage. With different winds, I couldn't say, but your results should be interesting.

It does beg the question, to me at least, of how losing 170% of your torque will effect the performance. ie: Will you run out of road before hitting top speed while the motor struggles to overcome all of the various resistances it's up against? Probably not a tradeoff I'd be willing or able to make under my topological circumstance, but I'm still really curious to see your results.

 

[recat]

From what I understand, it can be compensated for just by increasing the amps. Based on what I read here: https://www.electricbike.com/motor-tech-part-2/

A long time ago, some ebikers pondered Delta/Wye switching “on the fly” to help their low-current battery packs to provide better performance (Wye at low speed, Delta at high speed).

But now? high current batteries make that a thing of the past. Which is better? Most ebike DD hubs (that you can actually buy) are terminated in Delta, but…it all depends on what you are going to do with it.

It does beg the question, to me at least, of how losing 170% of your torque will effect the performance. ie: Will you run out of road before hitting top speed while the motor struggles to overcome all of the various resistances it's up against? Probably not a tradeoff I'd be willing or able to make under my topological circumstance, but I'm still really curious to see your results.

Yeah, I'm also wondering about this, which is why i'm so eager to test it. I plan to upgrade to a 19S system soon for more speed anyways though.

Also, I'm getting more certain it must be a 9C clone or at least similar since the stator width also correlates as well as size (and shape and construction etc)

28mm, MXUS 1000W (mine is 27mm)

35mm, Edge 1500W (click here to read about this motor)

45mm, MXUS 3000W (click here to read about this motor)

50mm, QS 205/50H V3

 

[amberwolf]

I'm guessing one of the 9C ones, but i'm not sure what the 4 numbers after it represent. 2705 2706 and 2707. What's the differences between these three?

The first two are the stator/magnet width, and the last two are the winding number (number of turns). Lower number of turns is higher speed, given same controller, battery, load, throttle setting, etc.

I have some old 9C (actual brand) motors, one 2807, one 2810, and antoher I don't know but it is almost the same speed as the 2807 so it's probably either the same wind or a 2808.

 

[recat]

I'm guessing one of the 9C ones, but i'm not sure what the 4 numbers after it represent. 2705 2706 and 2707. What's the differences between these three?

The first two are the stator/magnet width, and the last two are the winding number (number of turns). Lower number of turns is higher speed, given same controller, battery, load, throttle setting, etc.

I have some old 9C (actual brand) motors, one 2807, one 2810, and antoher I don't know but it is almost the same speed as the 2807 so it's probably either the same wind or a 2808.

Thanks! Is there a technique for counting the number of turns on a motor? I know it's 9 strands but the number of turns is still not very certain.

 

[amberwolf]

OFten it is written in marker on the stator itself somewhere.

You can also measure the loaded speed of your motor at full throttle for your battery voltage, and compare that to the same conditions of the motors in the simulator that you think are close to yours. for a particular motor, if the speeds come out the same for the same conditions, then that's probably a good match for yours. You can then verify it's speed at a couple of other throttle positions (low, medium) for the same conditions are also a match for yours, then you can assume it's the same or similar winding.

If not, you can find it's kV (rpm per volt); I forget the exact procedure but basically you determine it's RPM unloaded at full speed off ground (if speedometer is on that wheel, take the speed reading and calculate that down to RPM for your wheel size, if you don't have a tachometer you can use).

That can be used to compare to the kV to other reports of kV for similar motors (if you can find any; unfortunately the simulator does not provide any of the motor characteristics of those it simulates, which can be quite frustrating since the data is in there).

 

[recat]

Based on a variety of tests i've done testing the speed in the air and comparing measurements, I suspect it must be a 6 turn motor. Closest match is definitely a 9c 2706.

Modified the cheap Voilamart controller I have with 100V caps and IRFB4110's:

Just changing the two out worked for mine luckily enough. Now runs well at 84v.

Then I did some in-air RPM tests on my spare motor-testing-bike: it instantly hits the 100 km/h limiter on my controller so I've changed the speed detect settings to let me go as fast as I want.. interestingly when accelerating, while it hits the approximate area of 100 km/h it resonates in a really strange way. The delta conversion definitely worked and it worked fine with my controller. I was afraid i'd need an openVESC or something to thoroughly reprogram the motor. I had to reverse some phases going to the controller otherwise it would spin in reverse and have HUGE power consumption when just spinning in the air, and it wouldnt go past 80 km/h. Cables were hot, and my IRFB4110's were hot. Spinning in the right direction solved it, in-air power at max speed is around 200 to 300 watts at an RPM nearing 1500. Less than 60 watts at more reasonable speeds.

[youtube]-Ugb3e2xAno[/youtube]

So far all seems normal.. Next i'll add it back onto my main bike with my new controller and test things out on the ground.


Edit: Delta is horrible! Inefficient as hell, the consumption is horrendous, and my mosfets and motor cables get hot even with a 25 amp current limit! I've changed back to star. Guess that's the end of this experiment. Maybe if I were going to run a wheel size that's like, 13 inches or less it would be worth it to change over. Otherwise, hell no. I guess I couldve predicted this using the simulator.

 

[recat]

Well, I've tested it well. Changing from Wye to Delta is utterly and completely pointless if I'm keeping 26" Wheels. It's absolutely abhorrently bad. Motor wires nearly melting from 25A battery current, absolutely abysmal acceleration. It's far worse than the 1.7:1 ratio due to the extra losses of efficiency. I guess I could've simulated it and found this all out ahead of time.

Original Motor Simulation: (Settings are nearly spot on matching mine)

Motor Parameters:

Now, I change this motor around from star to delta...

Top speed actually drops slightly. This matches my tests in reality. However, efficiency is abysmal... 27% Efficiency at 10 km/h, 42% at 20 km/h, and still 50% at 30 km/h. Nearly 700 watts to just melt away into heat everywhere. It chewed up my battery like absolute mad.

In retrospect, the motor running in Wye.. 40% at 10 km/h, 55% at 20 km/h, 67 % at 30 km/h. The much higher torque seems like it makes a huge difference in acceleration time, which further improves efficiency since you reach 75+ % efficiency in a matter of seconds.

Well, that's the end of that. Maybe it will be interesting to explore again if i change to way smaller wheels.

Delta, however, would perform very efficiently on 12" Wheels. :wink: *eyes these tiny ebikes*