Direct Drive to Diff E Revo Build

[sikeston34m]

Originally Posted by JERRY2KONE

it is so quiet that it almost makes you want to put a sound system in it that makes the sound of a nice muscle care to match the awsome power that it has. Maybe a Shelby Msutang GT, or a Dodge Viper RS. That really is a cool setup though Sike. Where to go from there?? That is the question??

Where to from here? The only way to go is UP.

Up in voltage. I'm going to be playing around with this setup for awhile before I get the money for a HV ESC. I want to try it on the 4S A123 setup. I really like the A123's.

I also feel more confident now about the diffs, so we can proceed.

HV ESC choices that I'm considering are either the Jazz or the MGM.

The truck will get really crazy on HV. On HV, I might decide to go back to the 4130/20. It will have more torque than the 4120 does and get all kinds of crazy since HV will spin it up very well.

[johnrobholmes]

Glad to see how well this turned out with the proper rollout. I picked up a 4ft section of L channel today. Time for more "research" into this. Got any taller tires you could throw on your rig to test a higher rollout ratio?


Maybe I missed it, but what ESC did you use in the vid? Sounded like a quark to me.

[sikeston34m]

Originally Posted by johnrobholmes

Glad to see how well this turned out with the proper rollout. I picked up a 4ft section of L channel today. Time for more "research" into this. Got any taller tires you could throw on your rig to test a higher rollout ratio?


Maybe I missed it, but what ESC did you use in the vid? Sounded like a quark to me.

Did you find it at Lowes?

I would really like for you and the other guys that plan on doing a Direct Drive to Diff conversion to share our findings with each other. I think if we compare notes along the way, we can all learn from it.

In remembering our conversations about Wye and Delta windings, I think you will have a vantage point in building your conversion. I suspect the Wye Termination wound with fewer turns to match the Delta kv rating would work better with this. MUCH more torque.

I tried the Phaltline tires that are 5.5" tall, then I put the E maxx tires on that are 5.75" tall(same as the Revo). They both work well. I don't think I would want to go any higher geared than this.

Even an outrunner needs to spin up a certain degree to make it's power.

With the 5.75" tall tires, roll out is 4.2" per revolution of the motor. Think about that. That's alot.

I think this helps to confirm the statement that "An outrunner motor makes 5 to 7 times the amount of torque as an inrunner does".

Increasing the ratio would just bring back cogging on startup. This cogging could completely be eliminated by the creation of a custom sensor based outrunner setup OR possibly be improved with some internal mods to the ESC. The resistors in the feedback leads could be changed to ones of less resistence.

Most ESC's on the market are designed to work well with a wide variety of motors, inrunners and outrunners alike. I really think startup routines AND Anticipated spool up speed of a motor are based on a curve that is a rough average of how most motors perform. I don't think this "curve" fits every application ideally.

I'm using the 80amp Quark ESC on this right now.

[johnrobholmes]

It's funny you mention the averaging of an ESC startup to fit most motor types. That is how it was described to me by Pat @ Castle. Having different settings for slotted, slotless, and high pole count motors would give the best performance.

Im glad you brought back up Wye vs Delta winding. I need to look back into that. I have an empty 3032 stator sitting here ready to wind.


Lpimp- The 3032 is almost 8 ounces. It will be plenty of motor for most any smaller builds, and very robust from the front ring bearing. Think of the motor weight about the same as an inrunner. You would want 6 ounces of motor for a stampede, so stay with that same heft and maybe add a bit since you will lose gearbox weight. Motor weight is a pretty good indicator of how much power it can produce.

[lincpimp]

Originally Posted by johnrobholmes

Lpimp- The 3032 is almost 8 ounces. It will be plenty of motor for most any smaller builds, and very robust from the front ring bearing. Think of the motor weight about the same as an inrunner. You would want 6 ounces of motor for a stampede, so stay with that same heft and maybe add a bit since you will lose gearbox weight. Motor weight is a pretty good indicator of how much power it can produce.

Ok, but I would like to have a lower kv motor, somewhere around 600 - 650kv, so that I can power it with 5s and run taller tires. Not looking to do 70mph, something in the mid 40s with good low speed driveability and less heat production than the current motor.

[sikeston34m]

Originally Posted by johnrobholmes

It's funny you mention the averaging of an ESC startup to fit most motor types. That is how it was described to me by Pat @ Castle. Having different settings for slotted, slotless, and high pole count motors would give the best performance.

Im glad you brought back up Wye vs Delta winding. I need to look back into that. I have an empty 3032 stator sitting here ready to wind.


Lpimp- The 3032 is almost 8 ounces. It will be plenty of motor for most any smaller builds, and very robust from the front ring bearing. Think of the motor weight about the same as an inrunner. You would want 6 ounces of motor for a stampede, so stay with that same heft and maybe add a bit since you will lose gearbox weight. Motor weight is a pretty good indicator of how much power it can produce.

What are you going to use to lock the stator to the bearing holder?

Scorpion uses 30awg wire to wind their motors with. What Ga. wire are you planning to go with?

I've asked some questions and did some research on winding wire size. Lucien told me they use 30awg because it's easier on the workers fingers.

There is only so much room between the stator arms for wire. IMO, a larger wire size might be better. Something like 24 Ga or 22Ga.

If you look at the amp chart for wire sizes. Winding wire is really being pushed to it's limits, but the coating is high temp so it works.

There is an entire science to motor winding. I do want to try it. Maybe get a kit from Lucien, and fix the stator to be removeable. I could wind it, try it, then take it back apart and re-do it. Recording results like this could be very educational.

[johnrobholmes]

Choose the 12 turn then, or wind your own for even higher voltage handling. They come in kits too. I don't think changing the Kv will change the max usable height of tire either, only the motor size and voltage used. Time will tell on that though.

http://www.innov8tivedesigns.com/pro...products_id=83

[sikeston34m]

Originally Posted by johnrobholmes

Choose the 12 turn then, or wind your own for even higher voltage handling. They come in kits too. I don't think changing the Kv will change the max usable height of tire either, only the motor size and voltage used. Time will tell on that though.

http://www.innov8tivedesigns.com/pro...products_id=83

The winding does have alot to do with how much torque she makes.

In comparing this, think about the "turn" ratings on brushed motors. The fewer turns meant you had a high speed motor. If you have many turns, then you have a low speed motor that makes more torque.

A "Race" motor in the 540 size might have as few as 4 turns. But a Lathe motor for a rock crawler might have as many as 30 turns.

Remember the "wrap the wire around the nail" experiment? How did the number of wraps affect amp draw and how strong the magnet became?

[johnrobholmes]

The reason I say Kv probably won't have an effect on tire size is this: we are working within a fixed stator size and copper saturation for any given motor. Whether it produces 1200 watts with amperage or voltage is up to the wind count and matching voltage. For your nail example, if we fix the weight of wire to wind around the nail we shall get different wind counts based on the AWG used. At least for a fixed voltage, the larger AWG wire will have a stronger magnetic feild.

I do know that kt is directly relational to kv, but as kt goes up the amp draw of the motor goes down too- making torque guessing impossible without actually testing.

Not sure where I am going with this really, I think I have convinced myself that wind count might actually change how hard you can gear the motor I do know for a fixed voltage a higher turn motor can be geared a bit higher, but that is based on heat and wattage loading of the motor from my understanding.


I ask this: do you think a 10t on 20v or a 5t on 10v would have any startup differences assuming the cells and ESC can deliver the power? In my time I have messed mostly with gearing and voltage and kept wind count constant.


As for building the 3032, I was gonna fix the stator with 30min epoxy or green locktite. The 3032 isn't something I want to take apart multiple times as the ring bearing is pressed in. My plan was to use 24awg wire most likely, I have a 5lb spool of it. Another thing we could mess with is magnet count and arrangement. Probably want to stick with dLRK or 12 slot /16 pole ABCx4 construction for direct drive.

[sikeston34m]

Originally Posted by johnrobholmes

The reason I say Kv probably won't have an effect on tire size is this: we are working within a fixed stator size and copper saturation for any given motor. Whether it produces 1200 watts with amperage or voltage is up to the wind count and matching voltage. For your nail example, if we fix the weight of wire to wind around the nail we shall get different wind counts based on the AWG used. At least for a fixed voltage, the larger AWG wire will have a stronger magnetic feild.

I do know that kt is directly relational to kv, but as kt goes up the amp draw of the motor goes down too- making torque guessing impossible without actually testing.

Not sure where I am going with this really, I think I have convinced myself that wind count might actually change how hard you can gear the motor I do know for a fixed voltage a higher turn motor can be geared a bit higher, but that is based on heat and wattage loading of the motor from my understanding.


I ask this: do you think a 10t on 20v or a 5t on 10v would have any startup differences assuming the cells and ESC can deliver the power? In my time I have messed mostly with gearing and voltage and kept wind count constant.


As for building the 3032, I was gonna fix the stator with 30min epoxy or green locktite. The 3032 isn't something I want to take apart multiple times as the ring bearing is pressed in. My plan was to use 24awg wire most likely, I have a 5lb spool of it. Another thing we could mess with is magnet count and arrangement. Probably want to stick with dLRK or 12 slot /16 pole ABCx4 construction for direct drive.

Yes, the larger AWG wire will have a stronger magnetic field because of what? Total Power output as far as watts goes, depends alot on the total resistence of the winding. What affects this? Total wire size used,(multiple strands even), and length of the run.

If you try a Wye Termination winding, just remember total run length is about twice that of the Delta. The thing that intrigues me about it is, it is pulling on 8 magnets at a time instead of 4. This gives a torque bonus at the expense of kv. That's why I was suggesting using fewer turns on each pole.

"I ask this: do you think a 10t on 20v or a 5t on 10v would have any startup differences assuming the cells and ESC can deliver the power?"

I think idealy they would start the same if the strand count was such to make the resistence equal. The 5T would make more heat and draw twice the amps. The 10t would run cooler and be more efficient.

I looked for the Green Loctite at a local "O Reilly" Auto parts store. They had the Permatex brand. Come to find out, Permatex Green isn't exactly the same as the Loctite Green, because it's medium strength. Where can I find the Loctite Green?

I do believe there is a magnet/winding configuration that will work better than these "out of the box" Delta Outrunners. I hope you find it.

[sikeston34m]

I just did a run with 6S1P A123. I forgot to change the low voltage cutout though. With the LVC set at 3.0, the run lasted 11 minutes.

Performance is good. Temps are well in check. The Batteries got up to 120, but the ESC and the Motor remained cool. ESC at 97, Motor at 95 degrees.

A123 with only 1P, the voltage seems to sag ALOT under a load.

I'm gonna try 5S1P 4000mah Lipo next.

[johnrobholmes]

I have the permatex green, didn't realize it was medium penetrating. I will probably stick with epoxy then. Only place I know that carries loctite brand would be online retailers.


The conversion from Wye to Delta is 1.7 winds, so a 10 turn Delta is equivalent to a 10/1.7 turn Wye - almost 6 turns. This keeps kv constant. The conversion from a 10 turn D at 980kv to a 6 turn Y is as follows: [10T/1.7=5.88T] [980kv x (5.88T/6T)] = 961kv with a 6T Y termination. Substituting the 6 for any other wind count will give kv with Y termination.

Looks like the 3032 with a 6Y on 4s lipo will be pushing it pretty hard. 15k rpm, don't know how well the ring bearing will take it.


One thing I didn't think of for startup is the length of wire and the inductance on a coil. The ESC will sense a higher strand count coil better, so maybe this could cause lower kv motors to start up better. Not a product of motor torque as much as the ESCs increased ability to see a higher wind motors position? The issue with total motor power always gets me when thinking of startup. To me any 1000watt motor should start up the same unless the wind count is on the extreme end of things. Probably not the most accurate assumption.

[johnrobholmes]

Oh yes, the scorpion stators are keyed. If you had the means to mill a keyway into the bearing tube you could easily have a removable stator.

[sikeston34m]

Originally Posted by johnrobholmes

I have the permatex green, didn't realize it was medium penetrating. I will probably stick with epoxy then. Only place I know that carries loctite brand would be online retailers.


The conversion from Wye to Delta is 1.7 winds, so a 10 turn Delta is equivalent to a 10/1.7 turn Wye - almost 6 turns. This keeps kv constant. The conversion from a 10 turn D at 980kv to a 6 turn Y is as follows: [10T/1.7=5.88T] [980kv x (5.88T/6T)] = 961kv with a 6T Y termination. Substituting the 6 for any other wind count will give kv with Y termination.

Looks like the 3032 with a 6Y on 4s lipo will be pushing it pretty hard. 15k rpm, don't know how well the ring bearing will take it.


One thing I didn't think of for startup is the length of wire and the inductance on a coil. The ESC will sense a higher strand count coil better, so maybe this could cause lower kv motors to start up better. Not a product of motor torque as much as the ESCs increased ability to see a higher wind motors position? The issue with total motor power always gets me when thinking of startup. To me any 1000watt motor should start up the same unless the wind count is on the extreme end of things. Probably not the most accurate assumption.

I ran the 3032/10 in an E maxx. It was running pretty warm. It would start good and had great acceleration though. The 3032/10 is 823kv. You might want to back down from the 980kv some.

[sikeston34m]

The 5S1P 4000mah run lasted a little less than 20 minutes. These are older 10C cells. I've ran them pretty hard all summer in the E maxx, so I doubt they are quite putting out 4000mah anymore. I bought these batteries in Feb.

Battery temps are 120 degrees. Motor is at 100 degrees and the ESC is 115 degrees. All still well within range.

The 5S Lipo setup runs exactly like the 6S1P A123 setup. I couldn't really tell any difference as far as performance goes.

I'll try 6S 4000mah Lipo next. We should see some real gains then.