Q128C Cutting out since knocked / bent connectors

Hi, i've done around 100 miles so far on my q128c set up and its been flawless. Today however whilst fixing a puncture I knocked the connecters (don't ask) and a few of them bent slightly.

It still fits in the connector slots correctly and initially everything seemed alright.

However every so often it would just loose 100% of power and PAS / throttle would provide 0 watts of power. The display still worked and everything, but when pushing the throttle I would get a spinning icon where the temperature displays. I have seen this icon before but it was because the connectors weren't pushed in far enough.

However, turning the system on and off when cycling would allow the power to work as normal.

Any ideas on this / is it broken connectors?

Are you talking about the 9-pin mini connector?
It sounds like one or more of the phase pins has broken down inside the connector molding.
Unfortunately, the "male" part of the connector runs in to the motor so there are two options to ck the 'continuity", neither great.
You could remove the cover on the motor and ck each wire from the pin at the connector to where it attaches to the PC board at the other end w/ a multimeter(ohms).
Or, you could try and access the individual wires inside the bundle somewhere between the connector and the motor. W/ normal wires, an old trick would be to carefully strip some of the outer sheathing off and push a sewing needle into each sm wire to connect one of the multimeter's leads too. But these wires are different. I think they are hardened steel or something and the insulation is more of a coating than a sheathing. If the pin trick doesn't work, one would have to remove several inches of the outer insulation so each sm. wire could pulled away and some of it's coating could be removed(using a lighter).
If I though it was a Hall sensor wire, I would say you could try a Hall sensor test which is a different tack. Buy I think it's phase wire(the bigger ones).
Or just cut out the connector and hope that's the problem.
But replacing the connector can be an issue as well.
The 9-pin connectors come from China and are included in the "kits" and are not always avail. here in the States. Ebike CA and Luna cycle have carried them at times, but I'm not sure about now.
Any way you go you are looking at a PITA job.
BTW, ebikes are subject to the Murphy's Law of flat tires. The harder it is to get the wheel on and off, the more likely you are to get a flat. Look into "flat resistant"(flat guard) tires.

lovelock wrote;

Hey, thanks for the lengthy response on my post about a potential broken connection on the q128c.

I'm eyeing up a new project but this time want to go for a single speed conversion. Do you know much about the q128h? I've really enjoyed the smooth and quietness of the 'c' so would like to stick with the q series.

A few questions for you (I hope you don't mind):

- Is the Q128H the correct motor for a single speed?
- Its a 800watt rated motor vs the 500w of the 'c', I currently have a 20a controller from PSW power, do you think a 12s from BMS Battery would also be suitable due to the extra it could output? I have a decent battery that can supply 30a continuous so 25a of the 12s shouldn't be an issue.

Thanks in advance, Craig.

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There are single speed gears(called "fixies") available, but I have never looked at them closely because the smallest tooth count is a useless 16 T. You can do what I'm currently doing. My shift cable went bad here in a sm. beach town in Mex and I simply leave the chain on the smallest gear. You can remove the shifter/cable and and adjust the derailleur stop screws to make sure the wheel is centered on the gear. Of course, you want the cassette to have an 11T sm. gear. There are cassettes that have a replacement sm gear available for when it wears out, but they are expensive. I simply buy a cheap 11T-25T cassette and replace the whole thing. It's not the "cleanest" look, but it's the only way I know how to do it.
Motor ratings are only guides to what they can handle. it's the controller and pack that dicate the system power and going from a "C" to an "H" will not increase that.
If you follow my single speed advice and can fix the cable on the motor you have now, you do not need another motor. Take the money saved and buy quality flat guard tires.
Be advised, The "H" takes a free wheel, not a cassette and you will have to buy an 11T-??T free wheel from DNP Enoch. They are pricey at $40 to $50.

motomech said:

lovelock wrote;

There are single speed gears(called "fixies") available, but I have never looked at them closely because the smallest tooth count is a useless 16 T. You can do what I'm currently doing. My shift cable went bad here in a sm. beach town in Mex and I simply leave the chain on the smallest gear. You can remove the shifter/cable and and adjust the derailleur stop screws to make sure the wheel is centered on the gear. Of course, you want the cassette to have an 11T sm. gear. There are cassettes that have a replacement sm gear available for when it wears out, but they are expensive. I simply buy a cheap 11T-25T cassette and replace the whole thing. It's not the "cleanest" look, but it's the only way I know how to do it.
Motor ratings are only guides to what they can handle. it's the controller and pack that dicate the system power and going from a "C" to an "H" will not increase that.
If you follow my single speed advice and can fix the cable on the motor you have now, you do not need another motor. Take the money saved and buy quality flat guard tires.
Be advised, The "H" takes a free wheel, not a cassette and you will have to buy an 11T-??T free wheel from DNP Enoch. They are pricey at $40 to $50.

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Thanks again! If it turns out that I can't fix the issues with the connections on the q128c, can I buy another and replace the internals without getting the hub relaced onto a new motor?

The parts stockpiling begins, welcome to the World of Ebike building
If you want, we can go over how to open that motor. What makes it difficult to unscrew the cover is that the act of pedaling the bike tends to tighten it.
Also, if you order anything from BMS Battery, add a couple of 9-pin connectors for repair of the Q128C and for a spare.
I always suggest folks stock up on the little stuff(torque arms, spoke wrenches, left-hand throttles, etc)that are cheap, but expensive or hard to find over here.

motomech said:

The parts stockpiling begins, welcome to the World of Ebike building
If you want, we can go over how to open that motor. What makes it difficult to unscrew the cover is that the act of pedaling the bike tends to tighten it.
Also, if you order anything from BMS Battery, add a couple of 9-pin connectors for repair of the Q128C and for a spare.
I always suggest folks stock up on the little stuff(torque arms, spoke wrenches, left-hand throttles, etc)that are cheap, but expensive or hard to find over here.

Click to expand...

Interesting, I did see someone changing the internals when they had a faulty one and they used a special tool from BMS themselves.

If I was to purchase another hub and have it replaced, is there any other recommended rear hubs worth trying? I've enjoyed the q128c but the 22mph tops out very quickly and doesn't give you anything else when cycling faster.

My battery is a 48v 18ah from Insat International using decent batteries, my current controller is the 20a sine from PSW Power.

For reference, I also have the 201rpm 36v motor but ran at 48v. Will a 48v version ran at 328 be a bit faster? The hills around here aren't that steep but was told the 201 36v and 48v was the sweet point.

Yes, the motor "cores", once the covers are removed, are quite easy to swap out. In that way, you can use the built wheel you have now and just order a motor(no wheel) and save some on shipping.
In regards to motor speeds, I have found what works best for me is the standard formula of compromise, mid-speed motor(260 rpm rated @ 36 Volts) in a 26" whl. powered by 48 Volts.
One of the nice things about the Q128C, is there is a mid-speed avail., not the case w/ the Q100.
The 328 Q128C rating @ 48 Volts is the same thing as 260 @ 36 Volts.
Expect a top speed in the 23 to 25 mph range w/ little or no loss of climbing performance.

Just wanted to try and revive this thread before I make my big order of parts and a motor!

I’ve checked the pins and although some of them bent, they seem okay and not loose.

I decided to try a 6 mile ride to work to see if messing around had fixed anything! The outward journey wasn’t too bad, it cut out a handful of times but as usual the motor stated working again after a few seconds or I turned the power on and off

The return leg however was much worse and the motor was cutting out every few seconds.

Is there anything else for me to check / test before binning the motor?

In regards to cutting out, the display still works but the PAS and throttle don’t do anything.

Another quick update on this, I purchased a multimeter and decided to charge my battery a bit longer than normal.

It was 3/4 bars on the display so this time I left it overnight. Tested to show 54ish volts (I think).

I put it on my bike and had it up on a bike stand with the throttle tied down. I left it going for 10 minutes whilst wiggling every cable, bumping the bike around, moving the wheel, braking... everything! It didn't cut out once.

I've now just gone for a 3 miles ride without it cutting out, tested battery at it was at 52.8v so still plenty of charge.

I'm going to keep draining the battery and check its power when it first cuts out, unless it doesn't do it again!

Does this still sound like the phase wire?

EDIT: Just gone out for a 10 mile evening ride and had no issues what so ever. I gave it a good run, plenty of throttle etc but it ran fine.

Also checked the battery when I got home, after 14 miles its dropped to 52v so I think the battery isn't the issue.

The controller and all the wiring has so far been 'stuffed' into the seat bag. For these two rides the only difference is that I have taken all the excess wiring and cabled tied it out of the bag reducing stress on the connections and controller heat. I also have disconnected the power connections (Maplins yellow bullet connectors) to read voltage.

It might just be coincidence... but perhaps there was a wiring issue or something with the power connectors?