Bafang hall sensor failure - go sensorless ?

Hi all

I had 2 out of the 3 hall sensor failed and now I am wondering if I should replace the hall sensors or buy a sensorless controller. I'd rather buy a sensorless controller really rather than opening and replacing the hall sensors but I've read most sensorless controllers don't start the bafang smoothly .. there is a clutch( hammer ) noise. Is there a controller that won't do this ( but not being soft start ) ? Which one would you recommend ? Is clutching(hammer) noise only when you start the motor from dead start ? Because some people report this noise not only when they start.. Is it something to worry about ? Where could I buy the hall sensors if I would like to replace them ?

Thanks !

why do you think the hall sensors failed? usually the only thing that kills them is shorting out when the motor tears out of the fork and they short out or get tons of water inside the hub with direct drive motors.

you may wanna doublecheck, i still have a few i can sell, but it is a bitch to repair so make sure they are dead first and why. if it is from rain, you may not get very far without fixing that first.

Some folks say the ecrazyman (Shenzen) or the Aotema (Wilderness Energy) sensorless controllers work well with the Bafang however I am dubious about that. The dual mode controller I have from ecitypower/bmsbattery did not work to my satisfaction on my freewheeling geared motors so when a hall sensor went out on my Bafang after 3,000 miles I locked up the clutch so it would not freewheel and have used it sensorless since that time. With the clutch locked up all it takes is the slightest forward movement for a perfect start.

http://endless-sphere.com/forums/viewtopic.php?f=4&t=10458&start=45#p212576


-R

Well I measured the voltage . Only one of them is going 0.5-4.5v the other is 0.5 and the other is 2v ?! I think I measured them correctly... There was a problem with my hall sensor connection and one wire wasn't wired perfectly so sometimes I had to move the hall cable to make the motor work and suddently the motor stopped working...

So the sensorless controller doesnt work that good with the bafang .. Should I order a new bafang , buy the sensorless controller or get some hall sensors and fix it.. ? I want to freewheel so locking the freewheel is not an option. Any sensorless controller that works ok with the bafang except keywin's and aotema ?

Hmm...

mer said:

So the sensorless controller doesnt work that good with the bafang .. Should I order a new bafang , buy the sensorless controller or get some hall sensors and fix it.. ? I want to freewheel so locking the freewheel is not an option. Any sensorless controller that works ok with the bafang except keywin's and aotema ?

Hmm...

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Yep been there, done that, it’s a dilema alright. :? The way the hall sensors are installed on the Bafang I couldn't see how I was going to replace the defective one on my motor but if you can repair it that's definitely the cheapest solution. I'm on the throttle 90% of the time to some degree so having the wheel freewheel isn't a big deal. With the clutch locked up the resistance is still less than a direct drive motor. I'd like to see more data on freewheeling Bafangs used with the other sensorless controllers available so for selfish reasons I'd say try one of them however they may not work to your satisfaction so you'd be back to square one. Replacing the motor is of course the most expensive and time consuming if you have to rebuild the wheel. When My Bafang hall first went out I was fortunate enough to have another motor core lying around (a 24V unit) which slid right into the case so I didn't have to mess with a wheel rebuild. When I locked the clutch on the original failed 36V motor I slid the 24V core out and slid the old one back in. Good luck with whichever solution you go with.

-R

Are you saying, moving the cable makes or breaks the hall to work? It seems more like a broken wire as it goes thru the axle, as I had. I asked Kewin for the sensoless and it worked but as listed it did hammer the clutch and it did it each time the throttle was off and back on. I replaced the cable and it was fine for a while and now I had to replace 1 sensor. Yeah it's tough but doable. Take it apart check the wires before you check the sensors funtion. Good luck, take your time and you can do it.
Dan

DAND214 said:

Are you saying, moving the cable makes or breaks the hall to work? It seems more like a broken wire as it goes thru the axle, as I had. I asked Kewin for the sensoless and it worked but as listed it did hammer the clutch and it did it each time the throttle was off and back on. I replaced the cable and it was fine for a while and now I had to replace 1 sensor. Yeah it's tough but doable. Take it apart check the wires before you check the sensors funtion. Good luck, take your time and you can do it.
Dan

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I agree totally with Dan, Fixing it right as it was designed for is the best solution. There are alot of threads here that describe wire replacement on hub motors. Hammering the freewheel with a sensorless controller will eventually break the motor.
Without the freewheel there will be substantial drag from the motor when just pedaling with no assist.
Even if you disconnect the phase wires when you have a failure, you still have to drive a planetary gearset while moving on pedal power with Russell's locked freewheel.
The bafang is small and lightweight but all the benefits of a geared hub are lost with a locked freewheel.
There is absolutely no drag from a direct drive hub such as the 9Continent with the phase wires disconnected.

Affliction said:

Without the freewheel there will be substantial drag from the motor when just pedaling with no assist.
Even if you disconnect the phase wires when you have a failure, you still have to drive a planetary gearset while moving on pedal power with Russell's locked freewheel.
The bafang is small and lightweight but all the benefits of a geared hub are lost with a locked freewheel.
There is absolutely no drag from a direct drive hub such as the 9Continent with the phase wires disconnected.

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Yes there is resistance from my Bafang with a locked up clutch but as I remember it IS LESS than the cogging torque from a 9C motor. I don't have my 9C laced to a rim right now so I can't compare it against the locked Bafang however someone else can if they like by running one up to 20 mph (no load) then release the throttle and time how long it takes to stop spinning. My locked up Bafang takes 8 seconds to stop from 20 mph where it used to take about 50. On the road since I use the throttle 90% of the time there was only an opportunity to freewheel 10% of the time anyway so the ability for the wheel to freewheel was only a marginal advantage at best.

As I said previously the cheapest route would be to fix the hall sensor but if that can't be done then sensorless operation can make use of an otherwise worthless motor. Once someone chooses to run sensorless then they can keep the clutch freewheeling and possibly get satisfactory results however locking the clutch insures much better sensorless performance. This may not be something anyone else wants to do but it's definitely an option and it works very well for me. It's also apparent that Bafang recognizes hall failures as a problem since they now offer two motors without halls. Finally at least one manufacturer, Fusin, has chosen to offer a non-freewheeling geared motor however I have not seen a report yet from anyone using one.

-R

Russell said:

Yes there is resistance from my Bafang with a locked up clutch but as I remember it IS LESS than the cogging torque from a 9C motor.

-R

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Do you not listen? My previous post referred to the phase wires being unplugged! How do you achieve cogging torque from open phase leads?
The planetary gearset of the bafang will drag alot more than a direct drive hub with the phase leads unplugged!
Now lets set the record straight! If you have cogging torque of any kind, then you have an improper motor/controller application!
The motor timing to the controller is wrong! I heard alot about "cogging torque" but it is all BULLSHIT!
If your motor resists at all, even in pulses, then the timing is off! If you can reprogram like the infineon then all is good.
I've had this "cogging effect" by using mix match motors to controllers. tHIS IS NOT NORMAL FOR AN E-BIKE!
If you have any cogging whatsoever then your setup is wrong and you are losing speed and effientcy.

Affliction said:

Do you not listen? My previous post referred to the phase wires being unplugged! How do you achieve cogging torque from open phase leads?

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People do not disconnect and reconnect the phase wires to their direct drive motors when they ride their bikes, though I doubt it decreases the resistance of a direct drive motor compared to one left connected to a controller unless that controller is defective. Frankly I remember my 9C being just as difficult to spin without being connected to any electronics.

Affliction said:

The planetary gearset of the bafang will drag alot more than a direct drive hub with the phase leads unplugged!
Now lets set the record straight! If you have cogging torque of any kind, then you have an improper motor/controller application!

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Forget about the comparison between a direct drive phase wires being connected or not. As I suggested if someone wants to see if their direct drive motor offers more resistance than a locked Bafang then all they need to do is throttle up to 20 mph, release, and time how long it takes to stop. My Bafang with a locked clutch takes 8 seconds to stop from 20 mph on the test stand.

Affliction said:

The motor timing to the controller is wrong! I heard alot about "cogging torque" but it is all BULLSHIT!
If your motor resists at all, even in pulses, then the timing is off! If you can reprogram like the infineon then all is good.
I've had this "cogging effect" by using mix match motors to controllers. tHIS IS NOT NORMAL FOR AN E-BIKE!
If you have any cogging whatsoever then your setup is wrong and you are losing speed and effientcy.

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Yeah everybody else is wrong and you are right there is no cogging torque with a direct drive hub motor


-R

Russell said:

Yeah everybody else is wrong and you are right there is no cogging torque with a direct drive hub motor
-R

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Ohh you simple fool
If your phase timing is off you get cogging; just like if you roll the wheel backwards but not as severe.
You think cogging is normal? :lol: :lol:
I have absolutely no cogging with my setup and I can smoothly accelerate from a dead stop.
There is no 'judder' or 'miss' on my motors.
So YES! there is No cogging torque on direct drive hub motors providing you have the phase timing matched to the hub motor!

Forget about the comparison between a direct drive phase wires being connected or not. As I suggested if someone wants to see if their direct drive motor offers more resistance than a locked Bafang then all they need to do is throttle up to 20 mph, release, and time how long it takes to stop. My Bafang with a locked clutch takes 8 seconds to stop from 20 mph on the test stand.

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The geared weight of the spinning components is what keeps this spinning so long.
No load means absolutely shit for how a hub motor performs.

Affliction said:

Russell said:

Yeah everybody else is wrong and you are right there is no cogging torque with a direct drive hub motor
-R

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Ohh you simple fool
If your phase timing is off you get cogging; just like if you roll the wheel backwards but not as severe.
You think cogging is normal? :lol: :lol:
I have absolutely no cogging with my setup and I can smoothly accelerate from a dead stop.
There is no 'judder' or 'miss' on my motors.
So YES! there is No cogging torque on direct drive hub motors providing you have the phase timing matched to the hub motor!

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Apparently you don't understand the term "cogging torque" as I used it. Cogging torque is ever present in a direct drive motor since it's due to the interaction of the magnets and windings. Spin your motor by hand and that resistance is what I'm referring to as "cogging torque". So I will just refer to what I am talking about as "resistance" and repeat that the "resistance" of my Bafang with the locked freewheel is less than a direct drive hub motor. Again, spin your motor up to 20 mph and see how long it takes to stop.

from ebikes.ca

A third property that is important to characterizing a permanent magnet motor is the torque needed to simply turn the shaft. This is often called the cogging or drag torque and results from both the strong forces between the iron poles on the rotor and the magnets, and the induced eddy currents caused by the moving magnetic field. On direct drive hub motors, this torque is quite substantial, between 0.3 to 1 N-m, and it increases with the motor speed. Proper engineering and tight manufacturing tolerances can reduce this torque, but it is always a lot higher in permanent magnet motors with iron poles than any other type of machine.

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-R

Affliction...OBVIOUSLY nobody experiences cogging torque when they are accelerating. Its when the dd motor is acting as generator and resists forward motion when the throttle is dropped to nothing and reverse EMF is produced.

I experience it on all my motors including combinations of start immediate, pedal first crystalyte, and Hightekbikes Aotema controllers with Crystalyte and 9C motors. Perhaps "cogging torque" is a rather widely used misnomer for this resistance experienced with every DD motor.

And I'm happy to refer to it as "cogging torque" if everyone else calls it that. It's got nothing to do with missing, juddering or anything like that, like with messed halls or lack of sync. Russel is obviously referring to the lack of freewheeling freedom experienced when a dd motor "pushes back" as the juice is de-supplied from a moving bike. Good luck finding a dd motor that freewheels like a geared.

Perhaps it is unfortunate that this legitimate phenomenon has been dubbed "cogging torque" - whatever. i guess that makes everyone using this term a "poor fool" as well. Do you have to be so confrontational?

now if you are "renaming" cogging to another meaning then you are skirting the issue.
"Cogging" is a rough transition of one motor phase to the other, there is no other meaning.
Quoting E-bikes.ca? are you kidding? I have proven their asumptions wrong in the past! They are not gods! they are just like you and me on the cusp of e-bikes!

freewheeling freedom experienced when a dd motor "pushes back" as the juice is de-supplied from a moving bike

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YUP! mis-timed hall sensors! You just proved my point! Reverse regen currents are only produced from mistimed setups.
One bad hall sensor will cause a cogging effect as well.
You guys really think this is normal? My bike coasts with absolutely no resistance from the hubs.
Regen is achieved by retiming the controller to resist back emf and push it to the battery.

Affliction said:

The bafang is small and lightweight but all the benefits of a geared hub are lost with a locked freewheel.
There is absolutely no drag from a direct drive hub such as the 9Continent with the phase wires disconnected.

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Affliction said:

The geared weight of the spinning components is what keeps this spinning so long.

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All of these statements are simply incorrect. Locking up the clutch on a geared motor does nothing to take away the MAIN benefits of a geared hub motor which are lightness, small size and excellent torque. It does take away the benefit of the wheel being able to freewheel when not under power. This benefit however is minimal if a person uses the throttle much of the time since when under power the clutch is engaged. So for someone who uses the motor infrequently not having the freewheeling ability means more than someone who uses the throttle most of the time. With a sensorless controller having the locked clutch is a big advantage since the geared motor can start and restart from zero throttle just like a direct drive motor.

The weight of the spinning components has something to do with how long a wheel spins however I have a regular bike wheel which will spin seemingly forever and it is very light. Of course a spin-down test has nothing to do with motor performance however it IS an indicator of drag and that's all I was getting at. When the Bafang's clutch wasn't locked it would take 50 seconds to spin down from 20 mph and now with the clutch locked it takes 8 seconds. This shows that the drag has indeed increased as of course you would expect however if you conduct the same test with any direct drive motor I'm sure it will spin-down quickly too. If it spins down more quickly than 8 seconds then it's a good bet it's because of more drag. On the road under power neither amounts to much. I can feel the drag of the gears and motor when not under power but it's less than my 9C and the locked clutch makes sensorless operation MUCH better and allows me to continue to use the Bafang to power my bike rather than as a doorstop :wink: .

-R

A hub motor with the phase leads disconected is a NO-load condition. You can create all the back emf you want but it all goes nowhere and is not used so no load is introduced. This rides like a normal bike. All the stuff about cogging on ebikes.ca is all scientific and of very minimal effect in the real world. You guys read it like it's the bible
If you complain about cogging then there is something wrong with your setup.
E-bikes should be smooth on or off the throttle.

Well, I'll continue to use the term "cogging torque" if everyone else except you is, if it helps to make conversation globally comprehensible. And most folks don't use it to refer to Hall problems - what's the point of that if its mostly experienced on sensorless controllers? And not on acceleration either.

I need a sensorless controller here in Victoria, due to the rain, and the amount of cogging torque experienced with various types of sensorless controllers is of great interest, having given up on Hall's entirely due to two motor failures. And I experience it on all of my combinations of 9C and crystalyte motors with Aotema and crystalyte pedal first controllers - least on the 9C. So yes - it does exist, and it is a problem. What would you call it ?

"The rough feeling on deceleration experienced with a direct drive motor on throttle reduction on a bike driven in a wet environment that can't use Halls?"

Affliction said:

A hub motor with the phase leads disconected is a NO-load condition. You can create all the back emf you want but it all goes nowhere and is not used so no load is introduced. This rides like a normal bike. All the stuff about cogging on ebikes.ca is all scientific and of very minimal effect in the real world. You guys read it like it's the bible
If you complain about cogging then there is something wrong with your setup.
E-bikes should be smooth on or off the throttle.

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Affliction,

I will agree with you that when the phase leads are disconnected there is an ELECTRICAL no-load condition however the cogging torque is something that’s always there.

A demonstration is in order:

Simply go up to your bike and spin your direct drive motor wheel by hand....I'll wait....

OK did you feel that resistance?

Now do you have a regular bike wheel to spin or can you remember how freely they will spin and spin and spin?

Yeah you betcha there's a big difference ain't there!

Now on the road that additional drag which 99% of the regulars on this board either call "cogging torque" or recognize the term as that inherent resistance can feel like a lot or a little depending on the motor and what you're used to. Under power that drag is meaningless but while pedaling without power it IS noticeable. If that's something we can't agree on then we are at an impasse.


-R

chvidgov.bc.ca said:

Well, I'll continue to use the term "cogging torque" if everyone else except you is, if it helps to make conversation globally comprehensible. And most folks don't use it to refer to Hall problems - what's the point of that if its mostly experienced on sensorless controllers? And not on acceleration either.

I need a sensorless controller here in Victoria, due to the rain, and the amount of cogging torque experienced with various types of sensorless controllers is of great interest, having given up on Hall's entirely due to two motor failures. And I experience it on all of my combinations of 9C and crystalyte motors with Aotema and crystalyte pedal first controllers - least on the 9C. So yes - it does exist, and it is a problem. What would you call it ?

"The rough feeling on deceleration experienced with a direct drive motor on throttle reduction on a bike driven in a wet environment that can't use Halls?"

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Oh no now don't start using "cogging torque" to describe the action of sensorless controllers

Actually I don't know what the appropriate name for the effect of a sensorless controller trying to start a motor from a dead stop is but I call it "hammering". With my dual-mode controller starting either my direct drive or freewheeling motors from a complete stop can trigger the hammering. From a dead stop the controller simply doesn't know where the motor is but it fires the phases in some kind of order trying to get the motor to move so it can read the back voltage and figure it out. With a freewheeling motor this hammering can occur even when under way because the motor stops spinning whenever the throttle is released which causes the controller to lose the position and it has to restart it again when the throttle is once again activated. I found this to be a royal pain so when a hall sensor went out on my Bafang I ripped out the hall wiring and locked up the clutch so now whenever the front wheel is moving the motor is turning. Now all it takes is the slightest forward movement for the sensorless controller to take off smoothly. I'd still like to find a sensorless controller that would work perfectly with a freewheeling geared motor but I'm not at all certain that's possible. As sensorless operation gains popularity I'm sure there will be more controller choices available.


-R

Russell said:

Affliction,

I will agree with you that when the phase leads are disconnected there is an ELECTRICAL no-load condition however the cogging torque is something that’s always there.

A demonstration is in order:

Simply go up to your bike and spin your direct drive motor wheel by hand....I'll wait....
OK did you feel that resistance?
Now do you have a regular bike wheel to spin or can you remember how freely they will spin and spin and spin?
Yeah you betcha there's a big difference ain't there!
Now on the road that additional drag which 99% of the regulars on this board either call "cogging torque" or recognize the term as that inherent resistance can feel like a lot or a little depending on the motor and what you're used to. Under power that drag is meaningless but while pedaling without power it IS noticeable. If that's something we can't agree on then we are at an impasse.
-R

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You'll wait EH?> The drag is minimal. With my controller powered it was alot less. It spun like a regular bike wheel.
No throttle, just spun it by hand. When I disconnected the phase wires, it spun freely just like it was powered on the controller.
If you are peddaling a dual hub bike really fast down a hill with the phase wires disconnected you might notice something.
The speeds of pedalling a heavy bike are nowhere near enough to generate sufficient voltage to have any noticible effect.
"Cogging" implies a noticible 'bumping' while the wheel turns. If this term is not acurate then it needs to be changed.
With my controllers conected, it takes alot of energy to pedal it with the battery off. When I disconnect the phase plugs it flies!
I can pedal my bike no problem with all my electric gear installed.

while pedaling without power it IS noticeable. If that's something we can't agree on then we are at an impasse.

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Ya! my bike weighs a ton! I'm discounting your claims because it didn't peddal well to begin with when i bought it!
I bought it for the heavy frame and components. and this has nothing to do with cogging torque.

Cogging torque of electrical motors is the torque due to the interaction between the permanent magnets of the rotor and the stator slots of a Permanent Magnet (PM) machine. It is also known as detent or 'no-current' torque. Cogging torque is an undesirable component for the operation of such a motor. It is especially prominent at lower speeds, with the symptom of jerkiness

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frock ALL YOU GUYS!
Bullshitting to try and make a point!
I was right all along!
Proper controller timing will fix it all.

Heh Heh, yer both right , and both wrong some. But it's entertaining 8)

Some dd motors cog a lot , some hardly at all. This is with no controller connected. How many different kinds of motor have you owned affliction?

If all I ever owned was my aotema, I'd think cogging was a myth too. With my 5304, it's no myth. Even within a specific motor type, it varies. I do belive Justin has seen a few more motors than most folks.

A controller mismatch can make things really suck. That is definitely true.

Russel, I wasn't referring to starting the motor! I was referring to stopping the motor. My Crystalyte and 9C are generally smooth on takeoff, excepting the occasionally "hammering" on the Aotema controller I use on the Crystalyte. The roughness/"push back" of the motors I only experience on a rapid drop to a no current throttle state when I am near the no load speed. There is noticeable continuous unvariable resistance from the motor - a general roughness too. To me the hammering is some sort of issue with synchronization only felt on startup.

Not sure what your issue is called chiv, but it's not cogging. I suppose I'd call it stutter.

Oh dear, our common language spinning out of its gyre - "The best lack all conviction, while the worst / Are full of passionate intensity".