Direct Drive to Diff E Revo Build

[sikeston34m]

Originally Posted by johnrobholmes

It IS very difficult to determine what the KV will be before winding, although basing it from similar sized stators and magnet strengths does help. The hardest part is that every stator fill is different. I don't think I can have any more wire pushed into my stator, the 5 strands of 22awg is such a tight fit I have to thread some of the last winds in.


I kinda eyeballed the fit of my wire. Put in a chunk of strands and said "that looks enough". My math was that 40 strands would barely fit.

That's an 8 turn motor?

An 8 turn factory motor is 988kv. Your motor's amp carrying ability should be better with a Total CSA of .020258024

Good Job! You beat the factory on fill.

[aqwut]

Originally Posted by sikeston34m

That's an 8 turn motor?

An 8 turn factory motor is 988kv. Your motor's amp carrying ability should be better with a Total CSA of .020258024

Good Job! You beat the factory on fill.

Maybe off topic.. Lehner won't fix my 2280.. you guys know how to rewind inrunners?.. my 2280 needs a new can or to be rewound..

[johnrobholmes]

Lehner is slotless if I remember. You need a winding jig and press for that, those are compressed and baked windings.

[johnrobholmes]

Originally Posted by sikeston34m

That's an 8 turn motor?

An 8 turn factory motor is 988kv. Your motor's amp carrying ability should be better with a Total CSA of .020258024

Good Job! You beat the factory on fill.

Yeah, I went with an 8 turn so I could compare it to the 8 turn Wye I have from the factory. I still haven't finished the last phase, another 1.5 hours of winding.


If you want to get a ballpark for kv, a motor that is twice as long with the same wind count will have half the kv. Same formula works for a motor that is 1.5 times as long. As for wind count, the formula is really stinkin complicated so I'm not going to even attempt. When you change stator diameter it messes with things. When you change magnet strength it messes with things too.

[sikeston34m]

I've been making some progress winding the 3530 stator. This one will fit in the E maxx, so that is the platform I'll be testing it on.

Factory wind was 20 strands of 28Ga. at 5 turns. This yielded the following specs:

715Kv
Max Voltage: 30 volts (8S Lipo)
Max Amps for 20 seconds: 55 amps
Max Continous Watts: 1000 watts
Efficiency: 85%

In motor winding, the awg of the wire versus it's max. Amp rating tells that it is REALLY being pushed hard.

In the factory winding, 20 strands of 28 awg are rated to carry 28 amps even though the motor is given a 55 amp Burst Rating. See? This cuts efficiency and generates heat.

I am just dying to know how wye versus Delta Terminations perform. I know how the Delta performs. I've got a good taste of that. So with this wind, I'm working with 22awg wire. 3 Turns with 7 strands with a Wye Termination.

On my winding, 7 strands of 22awg is rated to carry 49 amps. In Factory spec comparison, this translates into right at 100amp Burst rating. Since amp rating are based on resistence, I feel good about this wind.

Here's what it looks like so far.



Yep, I'm using the Broom stick trick. I first lay out all 7 strands, tape one end, then I roll them up on the broomstick EXACTLY parallel, the way I want them to lay in the winding.

It really helps to pull the wires and make a nice neat radius to make the turn with.

As you can see, I've removed the bearings, installed a bolt with a couple of washers. I also numbered the poles so I can be SURE that I wind according to the DLRK diagram.

I clamp the bolt in a vise, wind a pole, then turn the stator for a fresh grip on the bolt.

[sikeston34m]

I can't imagine being a motor winder and doing this all day! LOL

Now to make the terminations.

[sikeston34m]

My first Wye wind. She's done!

What's even better is, it runs! Seems to be pretty smooth just running no load.

The Motor on the left is a Factory Wind.

[MTBikerTim]

That is really cool. Nice work. Do you balance the rotor or anything?

[sikeston34m]

Originally Posted by MTBikerTim

That is really cool. Nice work. Do you balance the rotor or anything?

Since I just rewound it, the factory Rotating Endbell was already balanced.

The Stator part is stationary. It doesn't turn.

[zeropointbug]

Originally Posted by sikeston34m

Since I just rewound it, the factory Rotating Endbell was already balanced.

The Stator part is stationary. It doesn't turn.

Precisely. And nice work Sike! Makes me want to get another project going for a slotless/halbach array Bl motor... they have up to 98% efficiency these things!

[sikeston34m]

Originally Posted by zeropointbug

Precisely. And nice work Sike! Makes me want to get another project going for a slotless/halbach array Bl motor... they have up to 98% efficiency these things!

Thanks ZPB. How's your Revo doing these days?

[sikeston34m]

We finally got a break in the rain, and even though those nasty puddles are scattered around, I had to try this custom wind.

I have ran the factory 5 turn Delta wind on the 3530 in the E maxx before. It performs well. I ran it alot, so I'm really familiar with it's performance.

Today, I found out how the 3 turn Wye wind performs. It runs cooler than the Delta wind. I know the math says that the KV is supposed to be slightly lower, but top speed and acceleration are much better.

This motor makes MORE power! It also starts better.

I can easily take off in 1st gear OR 2nd gear. I can grab WOT from a standstill in 1st anytime and it responds perfectly.

When starting in 2nd gear, it still doesn't like the 1st or 2nd step in the throttle, but anything beyond that is just fine. I can grab WOT starting in 2nd gear! It blasts out of the hole with great control about 90% of the time. The other 10%, it kinda screams at me like Metalman described his was doing.

My conclusion is, several things add to the improved performance.

1. Lower internal winding resistence. Any wind irregardless of number of turns or termination will perform better, the lower the resistence is. I have a feeling this makes it draw more amps, but also produces more Watts of total power!

2. I believe the Wye wind is MUCH better for this type of application. It starts under a load better. I also believe it is more efficient, hence cooler running.

I did the test run on 15C 4000mah 4S configuration. I ran it hard and it lasted 25 minutes. This motor performs like the factory wind on 5S Lipo, but does it on 4S and starts better.

I will now proceed with the AXI 4130 rewind. I found a different brand 4130 6 turn Delta that's rated at 515kv. I'm thinking about 3 or 4 turn Wye termination should be just about right.

More on that as soon as my winding wire gets here. I believe the mail is pretty congested in some areas right now because of the holidays.

[johnrobholmes]

That is great news! Looks like I should be testing my crawler motors to a Y termination too.


As for the wind resistance, each wind will have lower resistance because of the larger amount of copper and lower wind. The phase resistance in comparison to a D termination would be higher of course. The combination of changing wind count, termination, and copper netted you better startups, better acceleration, and a higher top speed? I would say either your efficiency went up or your amp draw did, maybe both. Got any old data logging from the previous setup?

[aqwut]

98% Efficiency is beautiful.... I want one... build me one...

[ilpufxit]

I've been following this thread as I continue to experiment with my e-maxx. I'm starting to think that a centrifugal clutch might be just the answer. If the outrunner's only real problem is startup, why not let it "idle" like a nitro (just set your throttle trim up a little) and then just grab all the throttle you want to take off. If you can't really use the ESC brakes on a direct drive anyway then it seems like a natural fit, no?