Troubleshooting help : 5kW hub motor internal noise issue-> sabvoton error lock

[nclsfr]

Hello Endless Sphere amazing community,

Started my electric bike journey about 4 years ago and now invoking your precious help so hopefully I can figure out what got wrong with my 5kW hub motor.

"hub motor is virtually maintenance free" they said... well... virtually maybe. In reality it seems it is not, really

A bit of context, the frame came from Luna Cycle and the rest of the kit came from Chinese vendor ncyclebike you can find here: http://www.powerfulelectricbike.com/aboutus.html

Of course I have customized along the way, added LED front & back lights + horn signal, a shimano floating disk at the front, mudguards, dual temperature sensors for outside temperature and internal steel case battery temperature, quadlock...

I have also built my own 20s6p battery pack with Liitokala 26650 cells and smart BMS from IC GOGOGO, this was quite a challenge but definitively worth it and the ability to monitor all parameters of the battery and levels of each cells is very nice

The bike brought me great joy and I was planning to use it on a regular basis for my 10 km commute to work with the summer coming back, but unfortunately came this new problem...

Here is a video link of the actual "knocking noise" problem: https://www.youtube.com/watch?v=fmOPAhFkbnk

All kind of advice and experience on similar issues will be very welcomed so hopefully I can fix this in the most cost effective and efficient manner.

You can hear the noise that is repeating on each rotation of the wheel, with a very loud occurrence of that sound at 1:19 in the video.

This is big trouble because besides the annoying noise this is making it is also preventing the smooth rotation of the wheel, creating some inconsistent drag and even in some cases leading to an "overCurrent" error at my sabovoton 72080 controler.

When this happens the controller gets locked and I have to turn off and on the keylock switch so the throttle is working again.

For some reasons this is mostly happening at slow speed, maybe it has something to do with centrifugal force, also at higher speed the noise of the motor might be covering the noise of that noise.

I suspect something inside the hub motor got damaged but no clue what, maybe magnets, bearings, bent axis or something else ?
I have checked a couple videos how to open such an hub motor and it looks quite tough, also I kinda lack the proper tools...

I have also noticed my wheel got now quite wobbly as well and this was definitively not the case when I received it about 4 years ago.

I supposed it happened over time but I have never use the bike off road and traveled only about 1200 km so the wheel as been treated quite respectfully and I was expecting to do much more kilometers on that..

The wobble seems to come from the axis and not the spokes but I am not sure, in any cases I would like to do something about it because I suspect all of these issues might be linked

What do you think ?

Please help a fellow ebiker from Brussels Belgium!

ps: stay home, stay safe & build bikes (until we can go out again to ride) :wink:

 

[amberwolf]

the first question is, exactly what happened just before the problem began? if it was a sudden start to the problem, there is probably a specific cause that can be found easier by knowing what happened just before then.


the wobbliness of the wheel could be a separate issue, or related.


if the wobbliness is caused by spokes growing loose (common because of too-large spokes being used with rims that can't take that tension, so the rim cracks or deforms around the nipple holes, loosening the spokes), then it's probably unrelated to the internal noise, and would just need a new rim and the correct spokes for that rim (both in length and thickness), and relace the motor into a new wheel.

if the wobbliness is caused by bearings wearing out in the motor, then they are probably related. or if it's caused by the actual axle wearing out inside the bearing id hole (i have one motor this has happened to).


the video sound actually almost sounds like it is in the rim instead of the motor. if so, then there could be a nipple fallen off a spoke into the wheel, or just the head of a nipple sheared off rattling around in there. either of those should be evident at the rim-spoke end, as the nipple will either be missing or probably easy to turn by hand (they should not be turnable without a spoke wrench).


it could also be something inside the motor itself--when bearings fail by chipping then they may make loud banging sounds as the balls run over the chips.

 

[nclsfr]

Hello, great thanks for your quick feedbacks

I checked all the nipples and spokes, besides 1 or 2 nipples which appear to be superficially corroded, none of them are missing nor can be turned by hand and all of them seem to be pretty tightly attached to the rim

To be fair this noise problem began quite some time ago, I cannot exactly remember when but it has been for at least 1 year

Since it was only an intermittent noise pretty much unnoticeable above 30km/h and a non-functional issue (it was not causing trouble with the spinning nor sabvoton lock / electric issue) I didn't bother much... but you could say I have been warned and this was only a matter of time...

I was discussing today with a local Belgium company https://cachera.be/ which is unfortunately not able to manage repairs on such "big" motors, they told me an electric problem is almost never caused by a deformed rim or loose spokes, which I guess makes sense.

If this is true then it seems the only way forward would be to open this beast of a motor...

In parallel I am still waiting answer from ncyclebike vendor, hopefully they will come up with some kind of solution

I think at this step I should consider some options to replace this hub motor wheel by a similar or another one, would you have any recommendations for that ?

I really like the crazy amount of torque so I am afraid 3000w might be a bad downgrade choice.. Also I don't want to be bothered by derailleur and I'm pretty happy with my single speed so I understand I would need spacers right ?

I have now seen some even larger hub motors wheels on AliExpress labelled at 8000w or even crazy 12000w but the price is quite steep, also not sure I would make sense with only 80A Sabvoton and also weight will be even worst

Other important information and major incentive for me to upgrade the complete controller + motor setup would be the ability to achieve a wheelie which I was sadly never able to do with my current setup (maybe it would be possible but I didn't want to risk it and mess around too much with the sabvoton parameters)

Then if I must buy another hub motor wheel I would consider if possible to buy from more reliable and closer vendor located in Europe, in case a similar issue happens again so hopefully I can get some help and support directly from the vendor

Please let me know what do you think and if you have any references for the above, many thanks again for the help

 

[amberwolf]

if you don't need the power for more than moments at a time, you can put quite a lot of power thru a hubmotor for very short periods, usually up to several times their "ratings" (which are for continous operation limits).


that said, your best bet to figure out some of what you want is to go to http://ebikes.ca/simulator , read the entire page so you know what everything is and how to use it, and then play with different systems, or variations of a single system, to learn which kinds of changes will be better at giving you what you want, and how much power you will actually need to do what you want, etc.

part of this is so you can try different windings of the same motor, but with the same controller and battery and bike/etc., and see if the torque goes up or down, and then vary with the controller current limit or battery voltage, etc., and see how much it goes up.

to find out how much torque you need (in n-m) to wheelie, you can find the equations for leverage / etc needed to calculate based on the wheel diameter and the lever arm length (from center of wheel to center of mass of bike), the torque needed to rotate the arm the amount you need it to (how high a wheelie).

then you can use the simulator to find out which system type would give you more torque for less equipment so you can find the cheapest way to do what you want. (it won't have prices or anything, and most likely you'll need to use the "custom" options in the various dropdowns to input your ratings, but it will give you limits to apply to your searches for parts.)


at the moment, i'd guess that qsmotor's qs205 would probably do what you're after, but i don't know which winding. people have safely put several times it's "3kw" power limit into it without damaging it (though it's possible to do so--i have one i bought with both axle ends broken off at the bearings that was at least tested at a few times it's power rating).

regardless of motor you choose, you'll probably have to change the controller for more phase current, and possibly the battery for more voltage/current, depending on exactly what you want

 

[amberwolf]

I was discussing today with a local Belgium company https://cachera.be/ which is unfortunately not able to manage repairs on such "big" motors, they told me an electric problem is almost never caused by a deformed rim or loose spokes, which I guess makes sense.

it shouldn't. but... if it's causing enough distorted loading on the axle, the bearings could wear adn then the rotor doesnt' stay aligned with the stator, which could cause current-flow changes that the controller may have problems with.


the problem could be magnets coming loose inside the motor from overheating (or even just from inadequate glue).

the problem could be a hall signal problem--a broken wire anywhere in the path from inside motor to inside controller, taht vibrations of the right type cuase to disconnect/reconnect. or an electronics failure in a sensor itself, or the controller itself.

could just be a wiring problem; poor connection between motor and controller, or wiring damage at the axle exit, etc.

 

[nclsfr]

Hello, sharing last update, apologies for the late feedbacks

In short : I am now waiting ncyclebike vendor to ship new hub motor wheel with laced rim and new tire so I can replace it all

Tried to fix it without luck, after all investigations and cleaning vendor told me he finally suspected an issue with the bearings

Vendor proposed to send me new bearings but I didn't accept because I am not very confident I can properly do the job to replace them

The disassembly of the non-drive side of the hub seems like a very big trouble with the wires going through the axle and I have also spotted other damages so I don't really trust this wheel anymore and prefer to replace it all

Below the pictures of the process I went through to open the hub as this might serve for future reference

https://www.dropbox.com/sh/h1qkhfu17ey7w7l/AABchcoJS-hSa9hB1EXKYcj-a?dl=0

Still wondering about the defects / damages that can be seen in the pictures, any ideas about it ?

Do you think it would still worth it to replace the bearings if I can get my hands on some new or better ones ?