Anyone Successfully Used a RC Style ESC with Hub Motor??

[Danny Mayes]

Hi all,

Has anyone out there successfully used an RC style ESC like a Castle HV series with a brushless Hub motor???

My reason for asking is i am planing to build a powered trailer for a pram and one of my intentions is to start getting experience with the Castle ESC for a RC build down the track.

I understand that the Castle HV ESC will blow with any current going back into it so a hub with internal freewheel is critical. This is what i am having trouble finding...

I need brushless, geared (because my top speed will only be 10km/h) and freewheel front hub with disk break ability. I looked through the "definitive hub" thread and discovered the Cute and Bafang motors which look ideal but can someone confirm that whilst coasting there is no current being generated by the motor i.e. the motor is not spinning?

Any help is greatly appreciated.

Regards,

Danny

 

[neptronix]

Yeah... people seem to be going the opposite direction, aka using eBike controllers on RC motors now as ESCs are not reliable for our duty in the slightest.

 

[Danny Mayes]

Thanks Neptronix,

Yeah they are...

Only thing is my system will be 500w max so even the hv40 will only be running at 25%.

I want the programability of that controller and the data logging. I don't know if normal EV controllers can match it's programability but either way if i can make it work with the HV40 it would much more suit my purpose...

I am looking at the Q100 350W - http://www.bmsbattery.com/front-dri...nt-driving-brushless-hub-motor-for-ebike.html

If i can establish whether it generates current whilst coasting or not then i think i am half way there

You got to admit the RC ESC's are damn elegant solutions.

D

 

[neptronix]

I believe one of the big problems with RC ESCs is that they don't have amp limiting.
Hub motors need amp limiting, big time. Especially geared hub motors which aren't designed to handle a lot of amps in the first place.

The maximum amps for that Q100 are quite low. 15 amps i think?

You would be better off with a 6FET infineon; it would have amp limiting and be far more effecient, and better.. more reliable.

Infineon controllers are programmable via USB.
Also, celllog8's can do some recording of the battery drain if that's what you're looking for.

If you are looking for cheap, cell_man has a 350w kit that may do it for you.
The controllers are like a pound.. not programmable... but 17a from the factory.

 

[Danny Mayes]

Thanks for that. i appreciate it. If i don't go this way i will look into the 6FET infineon and the celllog8's.

Well the Castle ESC do have current limiting as well as low voltage cut off (either soft or hard). You can tweak the timing, advancing or retarding it and it will log the voltage and current draw as well as ripple on your supply. Also you can adjust the throttle and program for soft start.

You can see why it is i want to use it. All that programability in such a small package...

My wife will be mostly using it with our bub in the pram so i want to be able to fine tune it for smooth running as much as possible.

I have sent and got replies to a few emails from BMSbattery. Jake has been very helpful so far but haven't heard anything back since i asked if it will in fact generate current back whilst coasting...

D

 

[neptronix]

I was not aware that the castle creations had amp limiting. I have heard numerous stories of eBike guys blowing those up with RC motors.

If a freewheeling hub motor generates any current at all while freewheeling, it is going to be an extremely low amount if any; for example.. if the clutch mechanism is not working correctly due to age, abuse, or a machining fault, it is going to do a bit of regenerative braking. I've had a geared hub motor do this to me before... it had a lot of mileage on it and somehow it had a tiny bit of drag.

BTW, li-ghtcycle blew an ESC by using partial throttle for a long period of time.

 

[Danny Mayes]

Ahh cool, Yeah that's the info i am looking for.

Yeah Mat and those crazy cats are blowing them up all the time. I have followed a lot of those threads closely and its mostly always due to over current, over voltage, too much ripple on the supply or current going back into them from the motor acting as a generator.

Interesting... I may just need to buy the hub motor and see. I can easy spin it manually and measure what it generates easy enough.

Either way by what you are saying, after a period of time what it is regenerating may increase.

I could just put a high power diode in series with the power wires to the motor. I guess this would solve all this anyway. I'm just not sure if it is that easy. May be someone with better electrical knowledge could enlighten me...

D

 

[neptronix]

Ahh cool, Yeah that's the info i am looking for.

Yeah Mat and those crazy cats are blowing them up all the time. I have followed a lot of those threads closely and its mostly always due to over current, over voltage, too much ripple on the supply or current going back into them from the motor acting as a generator.

That's about right. That and just; they are not built to do peak current for a long period of time. Think of their intended application; RC flight. The ESC gets plenty of hot air removed from it, at a high altitude where it is often cooler. I think also with RC flight, you blow a ton of amps getting into the air, then once you're in the air, you use quite a bit less.

Whereas we will be climbing a hill for quite a long time, at low speeds..

Another issue is that ESCs limit your voltage potential. Are you okay with 12s ( 4.2v/lipo ) max? Because i don't know of one that can handle any more than that.

Interesting... I may just need to buy the hub motor and see. I can easy spin it manually and measure what it generates easy enough.

Either way by what you are saying, after a period of time what it is regenerating may increase.

I could just put a high power diode in series with the power wires to the motor. I guess this would solve all this anyway. I'm just not sure if it is that easy. May be someone with better electrical knowledge could enlighten me...

D

Surely a slightly dragging hub motor will not generate even a fraction of what the RC motor generates.
Mind you, i have not made any measurements.. that is an educated guess.
It is like the difference of a slightly dragging brake and a fully engaged one.. how bout that

 

[Danny Mayes]

That's about right. That and just; they are not built to do peak current for a long period of time. Think of their intended application; RC flight. The ESC gets plenty of hot air removed from it, at a high altitude where it is often cooler. I think also with RC flight, you blow a ton of amps getting into the air, then once you're in the air, you use quite a bit less.

Whereas we will be climbing a hill for quite a long time, at low speeds..

Yeah that sounds accurate But like i said I will be putting around at 10km/hr max so i think 500w system peak will be more than enough and that's still a quarter of what the HV40 will do constant.

Another issue is that ESCs limit your voltage potential. Are you okay with 12s ( 4.2v/lipo ) max? Because i don't know of one that can handle any more than that.

Yeah that is what i would like to run and more than enough. I will probably start out at 6s and see what current draw i am getting...

Surely a slightly dragging hub motor will not generate even a fraction of what the RC motor generates.
Mind you, i have not made any measurements.. that is an educated guess.
It is like the difference of a slightly dragging brake and a fully engaged one.. how bout that

Yeah, good point. I wonder how much current they can handle back into them, I guess they could handle a little but really i got no idea. I don't want to find out the hard way if you know what i mean :?

I think i would just go with the diode to be safe... But still would like to hear from anyone if they have pulled this off.

With the ESC protected from regen current i can't see any reason for it not working but still even the RC guys have problems with some RC motors...

 

[Ypedal]

I think the Diode thing will not work for you because the controller needs to sense back EMF to get started without hall sensors....

I have not yet blown up my HV110 ( on an RC motor ) , but i have noticed that when running partial throttle the sucker gets hot, but at full throttle it stays cool ( but the motor however.. gets REALY hot !! lol ) ..

going very slow at partial throttle is best done with hall sensored controller...

Johnrobholmes has done it using a hub motor, might want to ask him about it .

 

[Hillhater]

....I need brushless, geared (because my top speed will only be 10km/h)

..I assume you realise that even a geared hub motor wont run any slower (rpm/volt) than a DD hub. ?
IE:- your max operating speed ..10 kph.. will be determined by the wheel diameter and voltage...not the internal gearing.

 

[liveforphysics]

A hubmotor is a MUCH MUCH lighter load on an RC controller than most any of the large RC motors.

In some cases, like a 9c hub vs the big turnigy 130kv motor, the RC motor is literally more than 10x more load on the controller.

 

[Danny Mayes]

Thanks for the input guys.

I think the Diode thing will not work for you because the controller needs to sense back EMF to get started without hall sensors....

Isn't that what the 3rd wire is for? The diode would just go on the two power wires to the motor and i would leave the sensing wire connected as normal. Actually only one diode would be necessary.

Or do EV sensorless only use 2 wires and use the same 2 for sensing?? If this is the case then damn, it won't work.

going very slow at partial throttle is best done with hall sensored controller...

Yeah, well, this is what i'll be doing. The Q100 350w has halls too (i think, i better double check, the 250w did) so if i do find problems at lower speed i can convert to a sensored
controller.

Johnrobholmes has done it using a hub motor, might want to ask him about it .

Great, thanks Ypedal, i will.

..I assume you realise that even a geared hub motor wont run any slower (rpm/volt) than a DD hub. ?
IE:- your max operating speed ..10 kph.. will be determined by the wheel diameter and voltage...not the internal gearing.

Yeah i do realise this. My thinking is a geared's stator will be rotating faster for the same wheel speed and therefore having the motor cruising in a more efficient state.I guess it is a function of how it is wired but considering i am going to be running it at probably half speed anyway i thought it would help. Another benefit is moves towards reducing the likely hood of problems above, regarding running sensorless at lower speed as the frequency of pulsing is multiplied by the gearing ratio...

On BMSbattery you input what wheel diameter when purchasing the hub. I assume they wire it different for whatever diameter you are running. I will specify for a 28" but actually run a 12" to get my top speed right down and torque up...

A hubmotor is a MUCH MUCH lighter load on an RC controller than most any of the large RC motors.

In some cases, like a 9c hub vs the big turnigy 130kv motor, the RC motor is literally more than 10x more load on the controller.

Yeah, thanks for the input. I assumed as much, well at least it occurs that way form the outside looking in. This is exactly why i think they are perfect for the application. I really don't have any concerns at all about the HV40 handling a 350w hub. Its a 2000w controller.

D

 

[Danny Mayes]

I think the Diode thing will not work for you because the controller needs to sense back EMF to get started without hall sensors....

hrmm, i am trying to find info on ESC's now. No luck yet.

Because i just thought, are the motors 3 phase and that's what the 3 wires are on BLDC motors?? and yeah it uses back emf to determine switching frequency.

I initialy thought it was 2 power wires and a sensing wire...

:?

 

[Danny Mayes]

OK so that makes sense, they are 3 phase...

Just as you said Ypedal, the diodes will not work.

I just placed and order for the Q100 350w. Jack assures me that it will not generate any current backwards so it should work. We will see

 

[magudaman]

Unless something has change the current limiting on the Castle Creation controllers it is very very crude. It has a settings like high medium and low. From what I was told from castle a long time ago they just measure the voltage drop across the fets to get a very rough current estimate. If and when the controller hits the current limiter it just basically shuts down and then kicks back on.

The standard hall sensored controllers limit the current by ramping back but not shutting down the throttle completely.