Brushless Motor stutter and loosing torque?

[magudaman]

I have a ecrazyman 70a controller running on a 16s pack into a BMC 1000w motor from the superkids. When accelerating or under heavy load the motor stutters and loose torque almost like the timing is getting off. I have tried a different hall and phase configuration that works but it does the same thing. Here is a short video so you can hear the motor problem.


[youtube]2coxgPFCKQA[/youtube]



Any ideas of what is happening? I was thinking maybe interference in the hall sensor lines? Is the motor being over saturated? The motor wires are undersized like 14ga too but this is my extra vehicle so I didn't think it would be an issue, maybe that creates lots of magnetic field creating interference?

 

[RallySTX]

Judging from the vid, I couldn't hardly hear anything wrong. Just a slight warble to the whine. I thought the bike accelerated well. Ride it and then check the wireing for hot spots. Do either the controller or motor get hot? Perhaps one of Leyns diagnostic devices might help.http://endless-sphere.com/forums/viewtopic.php?f=31&t=20413
Brian L.

 

[magudaman]

Thanks Brian for the response and I should order one of those for as much as I am dealing with brushless motors. It is tough to hear the motor over the chain all all but the sound I am specifically talking about is from the 4 to 8 second point in the video. It is like the controller wont even feed it full power while that wobble or noise is happening possibly creating the drop in torque. It seems to be amplified while twisting full throttle and can be avoid if you accelerate slowly enough. The torque also doesn't seem as linear as the old motor that was on this controller. All around I am disappointed in the torque of this motor so far, especially since I increased the reduction ratio so my top speed is now at 23mph.

 

[RallySTX]

I see what's going on, you are useing an outdrive with a 70 amp controller with 60 volts worth of A123. I would want a Cycle Analyst onboard, or a Tournagy voltmeter at least. Something like that could tell you what the load is doing to your batteries. I think you may be bounceing off the limits of the batteries and the controller as well. 10 ah worth of cells isn't very much either. I suspect you are dragging the batteries down to the low cutoff of the controller under load. I would want at least 20 ah of batteries to reduce voltage sag, and something to give power data while in use. Now, I'm a newb, I have no experience with outdrives, and there is a section on motor tech that you might want to check out. They most likely can help you more.
Brian L.

 

[magudaman]

I see what's going on, you are useing an outdrive with a 70 amp controller with 60 volts worth of A123. I would want a Cycle Analyst onboard, or a Tournagy voltmeter at least. Something like that could tell you what the load is doing to your batteries. I think you may be bounceing off the limits of the batteries and the controller as well. 10 ah worth of cells isn't very much either. I suspect you are dragging the batteries down to the low cutoff of the controller under load. I would want at least 20 ah of batteries to reduce voltage sag, and something to give power data while in use. Now, I'm a newb, I have no experience with outdrives, and there is a section on motor tech that you might want to check out. They most likely can help you more.
Brian L.

Well really it is internally an outrunner with a case around it but not an RC motor, more of a large escooter motor. So it is sensored from the factory. And I am powering it with about 53v nominal 20ah of Lifepo4 and a peak of 70a coming out of the electric bike controller. The motor that was in this bike before would consume peaks of about 80a off this same system with no issues. My onboard cycle analyst doesn't recording the voltage dipping too low since my controller cuttoff is below my BMS shut down point. I thought this was more of a controller timing issue than the motor issue and that was why posted in the ebike technical. I appreciate the ideas!

 

[RallySTX]

I sujested the outdrive section just to increase your feedback, I had no trouble with where your post started. I had no idea you had a CA, most include that in their sig. You said in your original post that you are useing 16s of unspecified cells. The only chemistry you list is in your sig. If you really need help, GIVE US THE FULL STORY! You also need to pay a bit more attention to your own business thread. I can only cover for you so often. When the stutter occurs, if it's related to the battery BMS cutting the power, the display ought to see that. You're welcome!
Brian L.

 

[Bluefang]

I have the same problem with a modified 12fet controller, a sudden drop in torque. Mines worse as if i am sitting on the bike it wont move me at all, this is from a bike that originally would almost try and throw me off the back, i ended up changing everything in the motor, halls phase wires etc and trying a different controller(300W 6fet) which almost had the same effect so i put it down to been the hub motor. Bought a whole new hub motor kit, tried installing my modified controller and same problem, almost like the controller suddenly has a really low current restriction but this all happened while i was ridding the bike and i have since reprogrammed the controller a few times. Now running a 9C kit on the bike, but i would love to figure out why the other system stutters so much.

Have a read thru the thread i had, pretty sure they are similar problems http://endless-sphere.com/forums/viewtopic.php?f=30&t=24804

 

[magudaman]

I have the same problem with a modified 12fet controller, a sudden drop in torque. Mines worse as if i am sitting on the bike it wont move me at all, this is from a bike that originally would almost try and throw me off the back, i ended up changing everything in the motor, halls phase wires etc and trying a different controller(300W 6fet) which almost had the same effect so i put it down to been the hub motor. Bought a whole new hub motor kit, tried installing my modified controller and same problem, almost like the controller suddenly has a really low current restriction but this all happened while i was ridding the bike and i have since reprogrammed the controller a few times. Now running a 9C kit on the bike, but i would love to figure out why the other system stutters so much.

Have a read thru the thread i had, pretty sure they are similar problems http://endless-sphere.com/forums/viewtopic.php?f=30&t=24804

Well that sounds like a pretty serious. I am wondering of these new fancy digital controller are having issues with certain motors. I wish I still had one of my old cystalyte controllers to test that and see if it works.

Well I tried that different hall configuration all soldered up and no such luck. At full throttle, low speed(<15mph) with load the controller will no let the current go over about 25 amps. Once the I hit around 15 mph still full throttle the motor feels smoother and the current jumps up to 50 amps and the torque feel adequate. I am thinking about picking up a 30 amp controller cheap and trying that out.