mizlplix wrote:As you use more wires in the bundle you wind with, you decrease the voltage necessary, but increase the current draw.
(I hope I didn't confuse the issue) Miz
I think I got that. So voltage isn't only dependent on the number of turns, but also the number of wires "in hand"?
Very curious to see what sort of performance could be coaxed from my 36-slot 132 frame at around 40-60v. I'll keep an eye out for your results, though I doubt they'd be directly applicable to my motor.
Winding your own motor is not that hard, but it is mysterious until you have that last puzzle piece fall into place. Then you are amazed at how easy it was and why you didn't see it in the first place....
OK, A 3 phase motor has 3 separate phase loops of wire. (loop, circuit, coil, whatever)
Each phase loop has it's own start and finish (wire ends).
3 phases X 2 wire ends each = 6 wire ends (3 starts and 3 finishes)
We combine each start end with a finish end of the next adjacent phase giving us 3 larger bundles of wire.
which we pull up out of the case and call our three motor leads, "W"-"X"- & "Y". (are you with me so far?)
That emulates a Delta winding pattern.
Each phase starts at a point and goes around the whole stator and ends near where it started.
The second phase is wound on top of the first.(except moved over some slots)
The third phase is moved over some more and placed on top last two. (3 layers of windings)
These 3 layers (Phases) plus the top insulating stick, should fill the slot fully.
Other than the pattern of slots where you lay the wire, that is about it.
I am trying to get Ivan to do a video of winding a phase and use a piece of wood cut to emulate a stator out flat to make it clearer.
Motor insulation comes in different heat ratings. Get the best you can.....
Motor supplies (in the states) cost about $400. That and 8 hours of hand work will save you a lot of money.
And the satisfaction you get every time you drive the car, knowing you built the motor.
I spent the day taking my stator to
Ivan's Garage in Tucson to get it rewound
for try number four.....
(as you remember,even though it performed
well in traffic, #3 tended to run a little
warm at 107C and pulled too much current-115 amps @ 40 MPH.)
So Miz, how did you go? Did you work out what the best winding configuration was for a direct drive motor? I gather you had trouble with high currents, and thus went to 12 strands 'in hand', which should be good for 180 amps?
Sometimes progress is slow and other times progress is even slower...
We finally got our motor rewound for the fifth time. Every time used a different variation of our first winding pattern. Every one ran but had some type of performance issue.
The first one was the best all-around. It used 12 in hand, two turns around. It had killer torque up until 1200 RPM and good current draw at cruise. But it only had a 3,100 RPM top speed.
(The wire gauge made almost no measurable difference.)We used 18 Ga. as the largest yet easiest to work with.
At this time, the motor is at Ivan's shop being rewound to that. It will get dipped and baked before he calls me back for pick up.
To make this motor work, I will then change out the differential gears from 6:14 to 5.13 ratio. That will give me a 58 MPH top speed. (93 KPH) Which will work fine as I never go above 50 MPH (80 kph)in town.
I found out that in a standard industrial motor, trying to push it above it's design RPM, makes the saturation problem much, much worse.
SO it is important to get your priorities right....Low cruise current draw (first), ability to absorb high amps for a decent duration (second) and decent torque over most of the RPM range (Third).
If you want a high top RPM too, you must give up one of the others.
I selected to gear the car to suit the motor and keep the first three.
I will get the new stator back by wednesday probably.
OK so the new wind has 12 wires in hand (higher current capacity), and is wound with two turns. Is this the same pattern that Ivan covers in his video tutorial?
And what would be the effect of doubling or even tripling the voltage? Would this improve the efficiency and give more speed?
Yes. More voltage and frequency would mean RPM.
The new windings would be good for it too.
But I am stuck with a Curtis controller, and that is not possible.
They are maxed at about 70 volts RMS.
No matter what the DC input is........
I am running a pack of 36/CALB 130AH cells. They will only put out 600 amps for a half second even if just off charger. They simply can not transfer lithium as fast as the motor can use electrons.
But, it CAN provide 140 amps almost continuously.
So, most motors with 18 ga wire and wound with 12 strands can handle this.
( 8 strands can not, I fried a motor with 8 strands)
If I had double the pack and had double the potential current, I would need to use some self restraint or wind the motor with a few more strands. The same for hilly terrain or a heavy vehicle.
Like the AC50 which has all in hand and one turn, for about 25 volts.
(Just a guess on the AC50, it looks that way on inspection)
mizlplix wrote: I am running a pack of 36/CALB 130AH cells. They will only put out 600 amps for a half second even if just off charger.
as far as i know the CALB cells do 3C continuous current 390 amps
and 10C impulse current for 30 seconds 1300 amps and i saw a vid of a guy testing a CALB180 at over 2000amps till he melted a MASSIVE spanner to jelly soft (i thing it was like 1.5 min) and it still charged up and discharged to its as new capacity
i carnt seem to find it but here is one showing over 1500 amps out of a CALB180
There is even a video of arcing a wrench across the top of one too, but I am talking about real world usage.
I can do a 10-12 second, full throttle burst before I sag down to the 2.5 Volt mark and the BMS yells at me to cut back some.
It is a function of needing another pack in parallel to really put out what my motor can use. But in a normal drive-around-town car, My pack is perfect.
What I have in reality is a zero to 60 in 9.5 second car. If I wanted to do a full throttle 1/4 mile run, I would need another pack in parallel (or risk cell damage).
"So if I don't die on the first attempt....or have my hands blow off or something..."
Impressive cell. He got 2200 Amps before it hit 2.0 volts and held 2.6 volts at just over 1500 Amps for many seconds.
Edit: I expect your wiring would contribute to sag at those currents Miz.
Last edited by Johny on Wed, 17 Jul 2013, 05:49, edited 1 time in total.
True, the wiring and all connections will have an effect.
Those guys "testing" their cells do not care about damage either....
I have $7,000 invested in mine. I try to take reasonable care of them. They need to last me a while.
Miz
Last edited by mizlplix on Wed, 17 Jul 2013, 08:21, edited 1 time in total.
mizlplix wrote: True, the wiring and all connections will have an effect.
Those guys "testing" their cells do not care about damage either....
I have $7,000 invested in mine. I try to take reasonable care of them. They need to last me a while.
Miz
he also said they had no noticeable loss even after abusing them that bad
"I have $7,000 invested in mine. I try to take reasonable care of them. They need to last me a while."
I am referring to their ultimate life span. So far in this Lithium cell usage, there is not one instance where they have been used long enough to declare that they went >5,000 charge cycles or even anywhere near where the manufacturer says is their usable life.
There IS many, many instances of failures due to mistreatment.
overcharging. over 4.0 volts
overdrawing. under 2.5 volts
case bulging. cause not yet determined to anyone's satisfaction.
outright case failures. due to internal causes.
I am just being reasonably prudent.
Besides, they can declare that there is not any reduction in current due to a severe event. They can not as yet declare no reduction in lifespan because it is simply too early to say.
I have returned from Tucson with the newest motor type.
It is nicely wound, dipped and baked.
It is 12 wires in-hand and two turns. 18 Ga.
We decided to do the motor cables this way instead of the HPEV way of bringing them out of the case for termination. Both ways has their good and bad points.
Our way, you need to be careful not to rotate the studs and ground out the inside leads against the case.
The insulators are lathe turned and good for 500C.
I will be putting it back in the car this morning.
Miz
Last edited by mizlplix on Wed, 17 Jul 2013, 17:44, edited 1 time in total.
Very cool. One thing I've not yet seen documented in the motor-rewinding things I've read/watched is whether or not the stator core laminations come out of the oven clean like that, or whether lacquer needs to be removed somehow so as to not foul the airgap. Is this the winding configuration where you were going to skip slots to "pick up back-iron"?
Lol....that was the last try...it did pick up top RPMs, but there was no torque up there. That beast would run 6,100 RPMs no load.
It would only do 3,500 RPMs or so under load. That was a bust.
We then tried to change the phase spacing , but the controller went nuts.
After the unit comes out of the oven everything is charred black and powdery. After you yank out the copper, it needs wire wheeled and coated with the red spray varnish.
After winding, it gets soaked in motor varnish and baked(350f for 2.5hrs)
Then the stator flats get gently wire wheeled clean. The gap is .010" or less. There is no real work given to the individual stator lamination plates or between them. They seem to do just fine.
The shops doing regular rebuilds do not address this issue either.
We are back to our favorite motor. 12 in hand, 2turns, 18 ga mag wire.
Miz
Last edited by mizlplix on Mon, 22 Jul 2013, 19:14, edited 1 time in total.
I'm stuck with a 50 kw 650v electric transaxle I can't do much with because most of the controllers & EC accessories (pumps, aircon, etc)are 420v. I'd get it rewound if I knew what size wire to go for & could find someone with the know how to do it. Some background here
Plan: I just took time out and read your entire thread.
It sounds like a really good project to simply rewind the stator to a lower voltage level and run a controller of your choice.
Which controller do you want to run?
What is the RMS voltage range of the controller?
My motor is a 48 slot stator also and it was easy to work with.
If you simply take it to a regular motor shop, they will normally not be able to change it over, as they are used to just "Remove and replace" type of repairs.
They can (and will) not alter the windings as they do not have the knowledge to do the engineering involved and will tell you it is impossible to do. (We know as we tried early on)
If you can tell me your requirements, I can tell you how to wind it.
Voltage- (RMS, not pack)
Pole count wanted (I have found that 4 pole is best for lower voltage systems as it picks up torque (but loses some top RPM).
I was able to re-gear to suit, where you are fixed at what you have.
Miz
Last edited by mizlplix on Mon, 22 Jul 2013, 19:18, edited 1 time in total.
