Direct Drive to Diff E Revo Build - RC-Monster Forums

zeropointbug · 06:00 PM

Quote:

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 · 12.13.2007, 07:21 PM

Quote:

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 · 12.13.2007, 07:36 PM

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 · 12.13.2007, 09:09 PM

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 · 12.13.2007, 10:04 PM

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

ilpufxit · **Spin-up -** 12.13.2007, 10:46 PM

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?

lincpimp · 12.14.2007, 01:23 AM

Actually the esc brakes work fine on my redcat/axi setup. But the clutch idea would be nice. I am going to do a twin outrunner, twin hv85 setup. We will se how well the castle air controllers work!

sikeston34m · 12.14.2007, 02:23 AM

Quote:

Originally Posted by 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?

The problem with a clutch and this setup is, current clutch designs are up on the factory drive train where torque levels are much lower. How do we design a clutch that is inline with the shaft to handle the higher torque?

ESC brakes work fine with this setup. I've never had a problem with that aspect.

sikeston34m · 12.14.2007, 02:20 AM

Quote:

Originally Posted by aqwut

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

How do we figure or gauge efficiency of a motor?

Huh? What do you want? Build you what? LOL

sikeston34m · 12.14.2007, 02:18 AM

Quote:

Originally Posted by 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?

I have read on the Croco site and other sites, that you want the wind resistence to be as low as you can get it without resect to how many turns it is. That is a goal with motor winding.

Manufacturers make compromises at the cost of effeciency with motors. Small wire is used because it is easier to work with. The larger wire is harder to work with but produces a wind that has a greater Cross Sectional Area. Less Resistence.

This Raises the Power Handling ability and efficiency.

I also feel like they steer away from the Wye wind because of the added termination point that can create problems if not done correctly.

They settled on a Delta termination, because in their testing with a prop, they are only measuring thrust at top speed and total amp draw.

They don't start the motor under a load at all compared to a Monster Truck. The amp draw doesn't come up hardly at all until some rpm's come on to the prop and make the load.

This makes the Delta wind easier and more profitable for them.

I have reached a point where I need a data logger. I have a brand new factory delta wind in the 3530. It would be VERY interesting, to collect some data from several runs with this custom wind. Then put the factory motor back in and collect some more data. Comparing that data would tell alot of things I'm sure. The difference is enough to see for sure. It performs alot better.

I put the factory wind on 6S one time and blew the transmission on the first run. I'm tempted to bump up to 5S on the custom wind, but I think that would be enough to make the transmission go Poof. I'll try to get some video soon.

The new E maxx should be hitting the market anytime. One of them has my name on it. I'll do this conversion with it. A transmission that can handle 2 1/2 times the torque of the original? Let's make that thing dance! LOL