muxus 3000 chugging ?

[John in CR]

John I do understand and read most all of your posts. I'm triing. Plus I did the long math of 36 combos just to check. I found only two working forward matches.

If you found only 2, then you didn't try 36. When trying combos, pick halls or phase, whichever is easier to swap. Alligator jumpers work great for swapping by making it simple, plus they also act like a fuse to limit high current so nothing can blow. Be systematic swapping those 3 wires only changing to at a time and try all 6 possibilities. Using one as an anchor to try with all 3 colors makes being systematic easy. You will get a valid forward or reverse. If reverse, then swap 2 of the static wires, and then go back to the original 3 and find the right combo for forward. You'd have to be unlucky to try the max of 12 possibilities this way. No need to take notes or use a ridiculous spreadsheet.

 

[John in CR]

But then you might as well go with a smaller lighter motor too, because torque per amp is exactly the same for motors with the same Kv. The reason to go with a bigger motor is to get more power and speed.

Well, there is that...

I have to say, I was surprised to find that Kt is inversely proportional to Kv, regardless of motor size.

For every motor, Kv x Kt = 7.04375, or Kt = 7.04375/Kv so Kt (Ft-lbs. of torque per Amp) can be calulated if you know the Kv of a motor.

What matters is how much current the windings can handle, and larger motors can handle more current, and therefore produce more total torque with less waste heat.

Where that last part falls down is that the thickness of the stator steel (the primarily increase for the bigger motor of the same type) has little effect on current handling. That's because Kv changes only gradually with additional laminations, and the thickness of the copper doesn't change at all. The thickness of the copper determines the current handling, because the exterior surface area of the shell changes negligibly so the motor can't dissipate heat faster. Sure the greater mass sinks more heat for the same temp, but it's just a timing difference and so what if you can run a couple more minutes before getting too hot. If you want to handle more current, then you need thicker copper, and those who want more torque don't need it at 0 rpm, because they already have more than the bike can handle. Where more torque is needed and welcome is in the mid-range where it will be felt, and at that point the speedier wind starts embarrassing the slow wind, and has a more controllable launch as well.

Then there's the guys who don't want crazy launch torque or high speed, just not overheating motors at lower performance. The speed wind wins there too, due to smoother take off, less copper losses at modest currents, and smooth steady and strong acceleration up to their cruising speed. Simply don't use the higher speed potential, and if you can't control yourself by not using WOT, then limit top speed artificially. I've been preaching all these things for years, but only recently was I armed with the mathematical proof after I fully understood the relationships of Kv and torque constant, and how heat is created in our motors to the tune of current squared times resistance. Yes I've had to endure hotter controllers, but I was running 2 turn motors, and pushing heavier loads in terrain where flat roads are rare.

 

[teslanv]

The MXUS 1000W motor and the 3000W motor share the same diameter of stator & rotor. The 3000W is just 61% wider than it's 1000W counterpart. The Copper magnet wire is also the same, although obviously the wider motor will have more copper, since each stator tooth is 17mm wider.
What happens with larger motors is that for a given winding pattern (Say the common 9X7 of a 28mm 9C clone) as the stator and magnets gets wider, the Kt of the motor increases and the Kv of the motor decreases (since the two are linked together inversely) to the point where if one desires a specific Kv (Like ~9 RPM per Volt), to maintain this ratio, you need to reduce the number of turns around the stator tooth (and thus you can increase the number of strands [cross section] of the winding). A larger motor forces the reduction of the number of turns to keep the same Kv as the narrower motor, and this is where the additional current handling comes from. Not the heat-shedding mass of laminations of the motor, but the change in winding pattern from 9X7T (28mm Stator) to a 16X4T (45mm Stator) which both have roughly the same Kv and Kt values. The larger motor has 16 strands of copper to carry current whereas the smaller motor only has 9 strands. So effectively, the larger motor can handle 16/9 or 78% more current than the smaller motor.

 

[999zip999]

JohnCR it does not hurt a thing to check the 36 combos. I did it because I have a very clean and simple wire adapter for fast and very ez wire changing. I did this to find the lowest no load amp draw. Plus Wes and Teslanv had voiced their concerns and to put the phase, hall combo to rest for them. The original combo I used is the one with 1.70 amp draw.
Which is the same combo used by Paul of em3ev for his Muxus. I also did so there would be No false positives as you had ran

 

[John in CR]

Teslanv,

You're right that I wasn't giving enough consideration to the difference in strand count compared to the sub 30mm wide stator motors for the same Kv, though going to wider stators didn't prevent people from burning up motors.

Zip,

While there isn't anything inherently wrong with wasting time trying all wiring configurations, it leads others to believe that figuring out the wiring is a daunting task when it's so simple. Think of the man hours wasted and cumulative frustration of ERers as a group when it comes to wiring up motors.

 

[999zip999]

It's doesn't take long with all of these.

 

[wesnewell]

Quick follow up on my test. Got my tach in and checked rpm on both my motors. On my yescomusa 48V 1000W (GM 901) I got 870 rpm on 90V and on the mxus 3000 got 827 rpm with the same battery. So the motor rpm is right on. I'll investigate my speed issues a little more later on. It could be because my almost 3 years old battery sags a lot more now because of age and cold temps out. I'm replacing the battery pack in June anyway, and may go with a stronger controller just for kicks.

 

[999zip999]

I think it needs 5000watts to wake up or 80 plus amps. Is it a 4t or 5t ? Plus I want a motor my fat ass plus w.o.t. style can't burn up.

 

[Icewrench]

Just today I had a look at Zipmans stator.
Looking for anything odd with the windings or who knows what.
Stumbled onto a likely problem.
A poor solder joint where all the windings connect.
It came apart very easy when tugged on.








Need to button it up and take a test ride soon....

 

[John in CR]

Unbelievable!

 

[999zip999]

Yes sounds right. I couldn't see it. I put 3-4 weeks on fixing it. First bearing then replaced three halls. I didn't have a wire harness for the motor as that was my next step. I would have butchered it up without a new goog harness to pull through the axle.
Glad you found it and hope it works. It was making me crazy and was at wit's end when Teslanv offer an other stator. It's been working fine, but is a heavy motor with 24s of lifepo4.

 

[Icewrench]

Converted another bike to test this mxus on and after 25 miles all is good.
I think it is safe to say that the poor solder joint at the wye termination point was the culprit.

 

[999zip999]

Love it. Thanks Bro.
Yea after the redilling of hub and rim, first rim lacing then halls, plus pulling the 8in of phase wire,thru the axle. Plus new bearing, two controllers and 36 wire combos and the needed sanity sack plus some beers. Then you posted and I me me couldn't get over thinking it was my bad solder job. I was looking at a 200 ft cliff jump with no parachute. Sometimes ebikes make the inside of my brain hurt.
Thank you everyone and would like to try a 4t at 72v 40amp with my 20ah A123.

 

[999zip999]

Bump for sacko. Bump me back later. Lol