Gilera dna to electric

[Mozart]

This is the result...

[Teh Stork]

Well, you've got less copper in your motor now - something I'm quite sure isn't a good thing.

Most likely you reduced the inductance of the stator by such a substantial amount it is now in the category "Super hard motor to drive" because of a extremely low time constant.

[Mozart]

Well, you've got less copper in your motor now - something I'm quite sure isn't a good thing.

Most likely you reduced the inductance of the stator by such a substantial amount it is now in the category "Super hard motor to drive" because of a extremely low time constant.

Sorry I lost you in the end...The motor was turning very easy...what do you mean "Super hard motor to drive"...?
this is what I started with:

[Teh Stork]

Since you have only 3 turns there now, the inductance of the stator is seriously reduced. If I get this right, you have reduced the turn count from 41 to 3. This means you only have 1/256 of the inductance you had earlier. This makes the time constant of the motor insanely small, making the motor uncontrollable since the current rise is too fast for the controller - unless it's built for it.

[Mozart]

Since you have only 3 turns there now, the inductance of the stator is seriously reduced. If I get this right, you have reduced the turn count from 41 to 3. This means you only have 1/256 of the inductance you had earlier. This makes the time constant of the motor insanely small, making the motor uncontrollable since the current rise is too fast for the controller - unless it's built for it.

Ok now I understand you, but you misunderstood me, the stator when I bought it was a generator for 250cc scooters not destined to be used as a motor.
That's why it had 41 turns, check the D.C. photo it says 19.9 Amps in WYE. That was the max amp I would get when used as a generator.
So when I was powering it up as a motor it wasn't running more than 20rpm and for 10seconds.Too many turns=low kv/rpm. That's why I rewound it,to make it a real motor for my application.
I used thicker wire to make it easier on the current draw but I couldn't wind it more with only my bare hands...So I thought it's ok, less turns=more kv/rpm right?
You are right about the current draw ,since it's in DELTA it is supposed to draw more current and have less torque.
Maybe I'll connect it in WYE and see what I'll get...Less rpm,less current draw and more torque.Thing is I was aiming for a motor of around 10,000 rpm and with WYE I'll get less rpm (or so I think...).

[Teh Stork]

I see. Well - let me put it like this.

Lets say your motor(generator) had a inductance of 256uH before your modifications. Its resistance was 0,6ohm. Time constant is found by plugging these values into L/R; 426microseconds. And this is to reach 63% of maximum current given by I=U/R. Say you put 50V on it. 50v/0,6ohm = 83A. Say you have a current limit on 40A. Current rise is given by 1-e^-t/tau. Tau is the time constant. 300 microseconds is the time it takes to reach 50% of maximum current. 1-e^-(300/420). Reach for your calculator and try this...

Now, ~0,2A per microsecond (40A/300us = 0,13A/us) of current rise is easy for a controller to sense. Delays

Now; remember that the inductance I used earlier could be different for your motor, but this is to illustrate my point. The inductance goes down to 25% for every halving of the turn count (rule of thumb). You have halved turn counts 4 times - giving your motor about 1uH of inductance (EXTREMELY LOW). Your resistance is now only 0,005 ohms. Your time constant is now 200 microseconds(L/R). Might not sound so bad, yet. Maximum current, 50V input; 50/0,005 = 10000A (!) Now, say you have the same current limit on 40A. The current is now reached after 800nanoseconds! Or 0,8us. Current rise is some 50A/us now - or some 250 times faster than before.

The controller would need to sense the current extremely fast and act, something it cannot do - and the fuse pops.

[Bluefang]

This may turn out to be very interesting, i cant say much about the turn count vrs controller but if the copper weight is something to go with you might just be able to put a couple of Kw thru that motor. All i can suggest is try and run the motor with nothing connected to it to try and find out what you max rpm/KV is. Assuming its somewhere in the ball park of ~300kv then you may just have a winner there

[Mozart]

Well after some time, I finally made some progress !
I made a new winding and it's turning normally with lots
of torque. One ball bearing broke so I'm waiting for the new one.

I'm currently trying to find a good bms for my lipo.
I'll post a video when it's all working again!