Will RC brushless motors work with a crystalyte controller?

Just curious. They're brushless motors, so I'd think... so? Or maybe the crystalyte and related controllers don't have a high enough switching frequency for the Kv of RC motors?

I know the amp limit would be appallingly low for the hungrier motors, but that wouldn't be a problem with the right heat dissipation, would it?

Most RC motors don't have hall sensors, so you'd be limited to a pedal first kind of controller or you'd have to install hall sensors. Other than that, it should work fine.

Ok, I take it you're referring to outrunners specifically? Well, if you weren't, that's the kind I meant.(Although, inrunners have the same problem, don't they?)

If it's true that most RC airplane motors don't have sensors, how are RC airplanes with outrunners started? I swear I've seen some on youtube that just start without manual startup procedures.

Sensorless controllers start the motor with complex start software. They send a predetermined startup pulse sequence to the motor and look for the tiniest back EMF and go from there. They operate in open loop for a very short time (under a second). Once the ESC sees a good back EMF signal, it closes the loop and operates by solid back EMF.

Matt

Thanks for the explanation, recumpence. I suspected it used some sort of "guess start" type of algorithm... now why don't they put that in the Crystalyte's sensorless controllers to avoid the water-related problems of the sensored controller? Eh, it seems like the Chinese don't believe that these electric contraptions will be used in the rain.

Anyways, I was testing out my drive system by "kick starting" it, literally(I was trying to kick the back wheel to make it go faster). Even though I got Motor RPM speeds around 1500 RPM as the Cycle Analyst reported, it didn't seem to start it. So I brought out the belt sander and started revving up the back wheel in a continuous manner and it worked! If my 200Kv motor's nominal Kv rating is to be believed(Hobby city states it's within 10%), the fact it didn't lose track until about 500 RPM suggests that it only needed a back-EMF voltage of 2.5 V to start. As I started scaling the throttle, it seems like the cycle analyst gradually decreased its speed reading when it past ~2200 RPM, and then lost it completely and reported "0.0 mph" at around 3000 RPM. The motor seemed to work flawlessly and the belt system+motor made this eery low-pitched whining sound at around 1000 RPM and increased in pitch as the RPM increased.(I also attached a make-shift roller using an aluminum spacer to lift the belt to clear the make-shift wooden mount that I used to mount the motor, and man, did that make a racket. I think I'm just going to eliminate a few support bolts and cut off the offending area.)

Hi!

Yeah ! The Kelly and Crystalyte controllers are a lot less expensive for the amp rating vs a r/c brushless controller.
So how about adding the hall sensors and a timing mechanism to the r/c brushless motor?
All you would need is a small magnetic hub with the same number of poles attached with the hall sensors inside.
You could also vary the timing for greater performance.

Just a thought,

rcpi

rcpi said:

Hi!

Yeah ! The Kelly and Crystalyte controllers are a lot less expensive for the amp rating vs a r/c brushless controller.
So how about adding the hall sensors and a timing mechanism to the r/c brushless motor?
All you would need is a small magnetic hub with the same number of poles attached with the hall sensors inside.
You could also vary the timing for greater performance.

Just a thought,

rcpi

Click to expand...

I know it's been brought up before, but I'm just waiting for one of the electronics guru's around here to show us how to cannibalize a mouse or something as cheap to DIY an optical sensor that emulates the hall sensor output. With the right know how, wouldn't it be as easy as putting properly spaced marking on the bell housing or drive shaft, and 1 or 3 optical sensors?

John

Optical sensors hook up much like hall sensors. All you need are 3 sensors and an encoder disc. Making the disc would be the hard part.

You can do a separate magnetic encoder wheel that uses hall sensors too.

I think the easiest way would be to locate hall sensors near the edge of the rotor as close as possible to the edges of the magnets. If they are oriented properly, they should switch when the gap between magnets passes them. You might be able to use 'back iron' on them so they can be mounted at an angle.

One of our motor experts might be able to tell us the proper phase angle between them based on the number of rotor/stator poles.

Hi !

I am new to this forum. But do have a working e-bike. Used a K-Mart Mongoose mountain bike, crystalyte brute hub motor and 48v controller. Then added a Foxx Power 48v 20amp LiFePo4 battery system. Am looking for a more efficient motor setup by using the gears on the bike, or a Di Vinci gearless hub hooked up to a large r/c brushless motor.

I also fly model airplanes and helicopters, both gas and electric. Also have a few gas and electric r/c 4x4 monster trucks like the HPI Savage and the “T” and “E” Maxx. Am experienced in the r/c brushless motors and controllers.

My Raptor 50 and 90 size helicopters use a magnetic pickup for the engines rpm limiter.
They also sell an optical device too. I noticed you can buy all of those components at radio shack or this other place called “All electronics”

I have a small machine shop and make a lot of my helicopter parts. It would not be too hard to make a test setup with the hall sensors or the optical ones. I do have a small 300w brushless motor collecting dust. But it is only rated for 14.8 volts. Would the 48v Crystalyte controller work on 15 or 20 volts? Just as a test? Or do they have a low voltage cut off built in them. Hmm, maybe hook up the 300w brushless motor on 48v and just take it real easy on the throttle. I don’t care if the motor gets fried, it is a very old used one anyway. But I do not want to fry my Crystalyte controller !

Any thoughts would be appreciated. If it sounds like a go, I can build and run a test immediately.

rcpi

Thought I'd report my experiences with using the Turnigy C6374-200 motor with the crystalyte controller(It's the 200 Kv HXT motor found at hobbycity.com.). So far, it seems like the motor starts rumbling and vibrating wildly while drawing the max current limit nearly half the time, and I suspect it might be the controller as it appears I'm the only one with this problem with their RC motor and I also happen to be the only one using a pedal-first crystalyte controller with their RC motor. It doesn't do this except when I'm riding it in the real world; In very unrealistic testing(the only load is the wheel and drive-train, not a rider riding on top of it), it appears to work perfectly.

Hi !

Did you have a hall sensor setup with that motor?
It won’t run properly without the hall sensors.

I had taken my Crystalyte hub apart and noticed the armature had slanted windings.
The poles where the windings are ? They are not straight, but slanted so 3 poles can be across each magnet on the stator. Not sure if all sensored brushless motors are built that way.
Looks like that kind of a design can create a lot of low speed torque.

Anyway, I am thinking of stretching my bike at the rear and mounting the crystalyte hub in the frame.
Then run it as a separate motor and be able to use the bikes gearing to help with efficiency.
That way if I take off in first gear the motor will not use as much current.
Also it would be able to climb steep hills with high motor efficiency.
By keeping the motor rpms at a higher rate, it should run with a lot more efficiency.
If that setups works, then the NuVinci gearless transmission hub would be even better!
There are no gears, just a very smooth transition thru the ratios.

rcpi

rcpi said:

Hi !

Did you have a hall sensor setup with that motor?
It won’t run properly without the hall sensors.

Click to expand...

swbluto said:

I also happen to be the only one using a pedal-first crystalyte controller with their RC motor

Click to expand...

The pedal-first controller I have had the current limited to 10 amps. It does this as no specific speed or set of speeds, and this behavior doesn't seem to be specifically related to the terrain(It did this even over very smooth road). The sets of speeds this happened was between ~500 RPM and ~2000 RPM, the min and max speed I was traveling at(~4-16 mph).

Fechter thought a pedal-first would work without modification and it does for about half the time, but the other half of the time it just rumbles and vibrates and makes a "growling" like sound, if you can imagine a motor growling. I think it might be losing sync with the motor or something. Do you think a sensored controller with the sensors installed in the motor would eliminate this problem?

Sure !

I would think the r/c motor on a sensor type controller would definitely need hall sensors installed.
The r/c brushless controllers have a feedback circuit that controls the timing of the 3 phases.
They can sense everything the motor is doing. Most r/c controllers have 3 choices of motor timing.
My Jazz Kontronik controller has an auto adjust timing circuit.

If someone was willing to send me a r/c brushless motor that could handle 48 volts, I would be willing to make the hall sensor setup and test it. Whether it works or not I would send the motor and the sensor parts back to you. It would let me test the theory without having to buy a motor and also let whoever get the parts made at no cost. If it worked out, it would be a huge benefit to both of us.

I would not modify the motor other than possibly putting a small flat on the output shaft.
The sensor would be an external setup attached to the output shaft and the mounting bolts of the motor casing. The timing disk would mount on the output shaft or to the pulley or sprocket you are using. The motor shaft would need a flat put on it so the timing wheel wont slip.

If there are any others out there interested, just contact me.

I live in Naperville Illinos. (near Chicago)

rcpi

I would think one is really better off to run a rc designed controller simply because of the volt amp differences. Though I know a crystalite controller can be modded to handle some more power than stock it seems like they have a max of 40 amps at 72Volts and that controller sells for 229.99 on electric riders website. Castle Creations sells the HV110a RC brushless controller which is a 50volt 110 amp controller that is also $229.99 unless you're getting a deal. If you add it up you get 2880 Watts with the crystalite and 5500 Watts with the Castle Creations. In this case the Castle is a much better deal delivering twice the power while being 1/3 of the size and weight of the other controller.

Also brushless outrunners are made to run at lower voltages I think the highest I've seen is around 50volts which means the crystalite controller is gonna top out at more like 2000Watts. The RC motors love current because they are designed for lower voltages, the motor that I was using was designed to handle a max of 65Amps, but I can tell you that it was willing to pull more than that.

Lastly you'll have to add hall sensors to the rc motor if you want it to run with the crystalite controller. Though halls are not expensive it's not really worth the time in my opinion. The bright side being if you buy a good sensorless rc speed controller it will work with almost any motor. Mine will turn my transmagnetic 800Watt sensored 110K/V motor just as well as my 380K/V brushless outrunner.

rcpi:

I'd be greatly interested in your experiment.

I have a BOB trailer which I've been meaning to drive with a motor. In a flush of newbie excitement, without considering the controller options, I ordered an outrunner (HXT 80-85B which has a nicely manageable 170Kv) and other components to gear it down including a #25 final drive without a freewheel so that I could use braking/regen to control the trailer.

Upon reading more about the Phoenix controllers, it looks like braking is best left turned off. And of course, as discussed here, none of the other BLDC controllers (like the Kelly ones) support the "sensorless" mode.

So, my options are AFAIK:

1. get a new high-rpm brushed motor (like the Magmotor, S28-150) and then get a regen-controller like the 4QD or Kelly ones,
2. change my final drive to use a freewheel, forget about motor-braking, and just go with the Phoenix controllers,
3. (and this is news), Kelly is supposedly working on a sensorless controller which should be ready in 2 months,
4. hope for a Hail Mary in terms of retrofitting hall sensors onto an outrunner.

I should mention that I am using a front-wheel brake disk hub for my trailer's single wheel, and attaching a 80T sprocket to the disk-mount, which is why motor-braking (with or without regen) appeals to me.

fyi: from, The Perfect Ebike motor

CNCAddict said:

-outrunners can't be sealed effectively and have good cooling at the same time
-Inrunners have a higher natural frequency in the rotor dynamics so they are much less susceptible to damaging vibrations no matter what the rpm
-It's impossible to add an encoder to an outrunner without a complex mounting system that's prone to failure

Click to expand...

So, it looks like the encoder idea is doomed.