Wheel Hop/Vibration With Front Hub

[The Mighty Volt]

Hi again

Just wanted to upload a few videos of a recurring "problem" with my front hub {Sensorless Aetoma, 36v 20Ah rated ductape Lifepo}.

I understand that sensorless motors prefer, though do not demand, a rolling start.

Today, I went out for a proper cruise, and drew 12Ah out of the 20AH rated pack.

Towards the end of this run, during which the motor had behaved impeccably, I began to encounter a disturbing pattern of vibration when attempting to accelerate from a low speed. This chugging vibration was actually quite disconcerting, and was amplified by moderate increases in the grade of the road I was travelling on.

At speed, and going downhill, It would pan out and disappear fully even at full throttle. But as soon as I hit the next hill, even hard pedaling in a high gear resulted in chugging, even with gentle throttle.

I could best describe it as the e-bike equivalent of axle-hop that solid-axle RWD muscle cars experience. Its like the wheel is hopping itself off the ground rather than rolling forward.

Again, this seems more prevalent at the very end run than at the beginning, and is more prevalent going up hills and during sudden application of stress to the motor/controller/battery.

The nuts are not loose! I checked and double checked.

http://www.youtube.com/watch?v=7ybGrFYqfnM&feature=channel

http://www.youtube.com/watch?v=vvAPVqiZX1E&feature=channel

Specifically, keep your ears open for a vibrating/metallic sound when the wheel IS NOT spinning. I have applied little throttle and pinned the bike with my weight to simulate hill climbing/stress.

 

[dogman dan]

Any wires rubbing tires? loose connector? Sounds like a phase wire problem, or god forbid, the controller is going bad.

The motor, when stalled, may try to run backwards if forward can't happen. That may be what we see on the video's. BTW, stalling it like that may be a good way to blow the controller.

You may just have low voltage on the battery if the problem is worse at the end of a ride. That chattering does seem a lot like what I got when I tried to run the motor on 28v. So you might look at your pack voltage at the end of a ride and see if it's low.

In any case, the aotema motor , or any other motor, will chatter some when overloaded. But you shouldn't be hearing a lot of it just because you ride up a hill, so I think you do have something wrong, either with the controller or low battery voltage.

 

[The Mighty Volt]

Any wires rubbing tires? loose connector? Sounds like a phase wire problem, or god forbid, the controller is going bad.

Nah......nothing like that. One thing it could be is a combination of a weakening battery with the lack of weight that comes down on the front forks going uphill.

 

[TMaster]

Maybe you have a bad cell in the pack and when the pack is charged up the good cells are strong enough to compensate. Take about 5 to 10Ah out of the pack and check each cell with a meter individually. Don't short anything.

I'm leaning more towards a battery problem since it seems to run fine through half the first part of the pack. But I don't have much experience with these controllers yet.

The tests in the video; was the pack discharged some already, or was it fresh off the charge?

 

[The Mighty Volt]

Maybe you have a bad cell in the pack and when the pack is charged up the good cells are strong enough to compensate. Take about 5 to 10Ah out of the pack and check each cell with a meter individually. Don't short anything.

I'm leaning more towards a battery problem since it seems to run fine through half the first part of the pack. But I don't have much experience with these controllers yet.

The tests in the video; was the pack discharged some already, or was it fresh off the charge?

Hi all and thanks for helping!

@ TMaster: yes, the pack was quite discharged, well over 50%, in those videos.

The funny thing is that I took her out for a spin an hour ago and it was grand. It still had the old shudder going up the hill though. On the straight, flat and smooth as you like.

I am leaning towards what dogman said: when the motor is quite slow or under load, I may stall it momentarily, then it gets confused and stalls.

I will keep monitoring it.

Thanks again fellas. 8) 8)

 

[johnrobholmes]

Sensorless cannot always deal with dropping voltage under load. It can cause sync issues. Do you have another controller to test? A weak battery could also be the culprit, causing a large voltage ripple that wreaks havoc on sensorless commutation.

 

[The Mighty Volt]

Sensorless cannot always deal with dropping voltage under load. It can cause sync issues. Do you have another controller to test? A weak battery could also be the culprit, causing a large voltage ripple that wreaks havoc on sensorless commutation.

There was one other thing which came to mind....the other day, in a car park, a guy intimated that he wanted to park where I had stopped, so I rolled forward and floored the throttle and got this terrible response from the motor......it just stalled and went "innnnnnnnnnnngggggggg" ...........I am beginning to think that the sensorless motor hates being strained, period.

It doesn't mind work...it just hates being strained. It doesn't like being asked to work hard suddenly, or asked to work hard over a distance when the battery is dying. It's a pity, as it is such a peach in normal circumstances. I guess it just isn't, well, it isn't an X5 :lol: :lol:

I have checked those nuts like a paranoid squirrel.......they are on tighter than my own.

 

[dogman dan]

I think you have a battery issue, on the other threads I see you have the V power stuff from cammy cc. Now that I put 1+1 together, I take back what I said on the battery section thread about running a new motor on the same battery. You may have some dead cells in there, and then the remaining ones can't handle the amp load when you push the motor hard. It's only drawing about 22 amps, but with voltage drop, the controller starts to act up.

From the other threads, I get the feeling you are also simply expecting more out of a middle wattage motor than you will ever get. This motor will climb moderate hills just fine, but of course not at the same speed. I put 2500 miles on my aotema with a ping 36v 20 ah battery, and never got a lot of shudder out of my motor, climbing a 7% hill a mile long everyday.

There is still the possibility that you have a nicked wire where they leave the axle, but that is likely to blow the controller if that is the case. After that, I'd be suspecting the cheezy bullet connectors to the motor. A weak connection there would produce the same symptoms and you could never know it since it's sealed in rubber.

See if you can rig a voltmeter so you can monitor battery voltage when you climb a hill. If below 36v, there's your problem. If the battery is not sagging, then replace the motor connectors, and look inside the controller for a possible bad connection there where the phase wires are soldered.

I think you may be more happy with this motor if you have it working right, and quite possibly a better battery is the fix. Bummer you spent so much on v power batteries. Seems like there are lots of posts about them having spotty quality but the price lure is irresistable.

 

[The Mighty Volt]

I think you have a battery issue, on the other threads I see you have the V power stuff from cammy cc. Now that I put 1+1 together, I take back what I said on the battery section thread about running a new motor on the same battery. You may have some dead cells in there, and then the remaining ones can't handle the amp load when you push the motor hard. It's only drawing about 22 amps, but with voltage drop, the controller starts to act up.

From the other threads, I get the feeling you are also simply expecting more out of a middle wattage motor than you will ever get. This motor will climb moderate hills just fine, but of course not at the same speed. I put 2500 miles on my aotema with a ping 36v 20 ah battery, and never got a lot of shudder out of my motor, climbing a 7% hill a mile long everyday.

There is still the possibility that you have a nicked wire where they leave the axle, but that is likely to blow the controller if that is the case. After that, I'd be suspecting the cheezy bullet connectors to the motor. A weak connection there would produce the same symptoms and you could never know it since it's sealed in rubber.

See if you can rig a voltmeter so you can monitor battery voltage when you climb a hill. If below 36v, there's your problem. If the battery is not sagging, then replace the motor connectors, and look inside the controller for a possible bad connection there where the phase wires are soldered.

I think you may be more happy with this motor if you have it working right, and quite possibly a better battery is the fix. Bummer you spent so much on v power batteries. Seems like there are lots of posts about them having spotty quality but the price lure is irresistable.

Hey dogman, thanks as ever for your input.

The Watts-Up is recording a minimum voltage {Vm} of around 33.92v.

That said, current resting voltage is over 38v.

One issue I did notice is that when I arrived home, my controller had a solid RED L.E.D........this is definitely not correct, as it is supposed to flash a green L.E.D too.

I will need to consult my documentation to explain that.

Yes, you are correct, I am trying to drag too much out of the battery and the motor. Time for either a 5303+ or a Currie set up.

 

[dogman dan]

33v might be low enough to cause some shitty performance. My ping 36v has never been below 40v resting, and that's after the bms has tripped when the pack was 100% depleted. Resting voltage is 44 when charged, and 46 hot off the charger. It seems odd to me your bms doesn't trip long before the motor starts to run crappy.

Does your charger even put out 45v? If not that could be part of the problem.

 

[The Mighty Volt]

33v might be low enough to cause some shitty performance. My ping 36v has never been below 40v resting, and that's after the bms has tripped when the pack was 100% depleted. Resting voltage is 44 when charged, and 46 hot off the charger. It seems odd to me your bms doesn't trip long before the motor starts to run crappy.

Does your charger even put out 45v? If not that could be part of the problem.

Charger puts out 45.54v

Also, I can provide some figures for how the battery has been charging:

TIME Voltage
2140h 37.97


2223h 40.22v

2300h 40.37v

2310h 40.43v

2330h 40.55v

2340h 40.62v

2345h 40.68v

0010h 40.92

0015h 40.96

0016h 40.96

0030h 41.01v

0034h 42.26v

0036h 43.00v
43.11v
43.20v
43.27v
43.32v


0037h 43.52v
43.71v

0042h 44.95v
44.96v
44.97v
44.97v

0043h 44.98v
44.99v
45.00v
45.01v
45.02v
45.03v

And there is more where that came from. I dont know if the above is proof or symptomatic of very much, I would welcome any opinion on it. Cheers.