I'm stumped on replacing Ouxi V8 controller...

[Pylonflyer]

2023 Ouxi V8 20" Fat Bike 750Watt 48v - "Amazon Special"

Here's the story: Daughter's bike started to make a harmonic buzzing noise and loss of power after bumping into a friend's bike (kind of a mild T-bone accident, no one got hurt). Assumed it was mechanical issue, but it's looking more and more like a bad phase in the system after more testing. I think she may have over-amped something when she was power on into the other bike.

I tested the motor phase wires for burnt windings, and they seem to be within similar resistance. Pulled apart hub motor to check planetary gears, looks good. Smelled controller and tested the FETs, seemed ok but I'm not the best at diagnosing esc's. I'm pretty experienced with RC brushless motors and such, but these e-bikes are new territory for me besides building some scooters and e-skateboards over the years.

Took a chance assuming motor is fine, and ordered a new esc from v8fatbike.com based on their recommendations. They said my bike would be "V3" compatible (that's their terminology on controller versions see pic), and I got their "V8" controller which, on paper, is within the specs of the original model: V8S-500. Got the new controller and 95% of plugs and wires are the same, but there is an extra "alarm" 3-pin plug (see pic) that has 48v coming out, and the 9-pin motor plug is red inside vs black (original) (see pics at bottom).

Got everything plugged together and display comes up, lights come on, turn signals work, horn works.... but no throttle. Motor does nothing. I searched the interwebs for info, nothing helpful. Played around in Chat GPT for a long while and it said to "jump" the outer pins of the un-used alarm plug (see pic of jumper). Still nothing. Plugged the old esc back in and motor runs, but it's not healthy sounding.

Now I'm stumped. Can it be that the 9-pin motor order is not the same? Different sensor pin order? Or is the new controller not programmed for this motor? Emailed V8fatbike.com support and they said this controller should work. Are they totally inept in their own products? Highly probable but so am I.

Is anyone familiar with this motor/esc brand to where I may be missing a simple step in programming something in the display menu? Are these esc/motor combos not universal and I have to do a custom esc process? Get a universal esc (KT keeps popping up in my searches). Or, should I save myself gray hairs and stress and buy a drop-in 20" hub motor/esc combo from Bafang or something and just rewire the dang bike? The 48V battery is fine, btw.

Appreciate any guidance from gurus or fellow victims of this bike who have fixed something similar.


Original esc


New esc

extra "Alarm" plug, jumped outer pins per instruction

 

[amberwolf]

The most likely original fault is a wiring fault in the motor cable where it exits the axle. This can happen even if there is little or no visible damage to the cable jacket, as if the insulation on the inner wires is softer than the outer jacket, a pinch / cut can occur on that insulation inside the jacket that allows multiple wires to touch each ohter, even if it's only a high resistance connection, and that allows signals to interact that shouldn't.

Sometimes those are phase to phase, and can damage the controller's FETs, which usually (but not always) causes the motor to be unable to be operated by the controller, and with a direct (non geared) drive motor also greatly increases the drag from the motor when unpowered. (with a geared motor it only increases the drag when rolling it backwards). A well-protected controller may detect overcurrent and shutdown output before damage happens, but the system wont' operate the motor.

Sometimes those are signal-to-signal, just confusing the controller or causing it to go to sensorless mode, whcih with many dual-mode types means it now operates in square wave / trapezoidal mode instead of sine, so it's much noisier and has a hard time starting from a stop because of lack of sensor data.

Sometimes those are phase-to-signal, which can damage the motor itself, blowing up it's hall sensors, and damaging the controller, including killing hte MCU or the 5v system, potentially any throttle or PAS or other 5v accessories.



If any of those damages occured, then any parts not yet replaced could cause the system to not work with them correctly. There are tester units (see the various "ebike tester" and "motor tester" threads for info on various versions) you can get to verify operation of most simple parts.

If none of these damages occured, then you could just have a compatibilyt problem between the parts you've changed and hte originals. Without knowing what every wire on the new controller is supposed to be for, and what it expects for data and signals, and what hte old controller had for all those, it's tough to say whether they're intercompatible or not. The new controller seller might or might not have a clue, lots of sellers will tell you anything that gets you to buy their stuff, and once you pay them, it doens't matter to them anymore; they've got your money.

The most common problem is display/controller incompatibilty--E-HP has a thread about displays that has a lot fo links and info on what has been found so far about that, but there are hundreds of thousands or more of controller designs, and probably at least thousands of display designs. Even a display that is externally identical to another may have different firmware on it that doesnt' work with anything but hte one controller it came with. Or a new controller may expect you to do specific button operations on the display, where the original one didn't, and that info may only be in the manual for the *display* that comes with that new controller, and not with the controller itself. It can be very trying to deal with.

To make matters even harder, no wiring is guaranteed to be the same, even for identical connectors, as there are no always-followed standards. There are common wiring choices that many places use because it can be cheaper to do that, but there is no guarantee that even the same manufacturer will build things the same way every time.



All that said...I'd first verify the motor cable is not damaged. Then verify all other cables are not damaged. No scuffs, bends, cuts, abrasions, etc. If the motor cable is damaged, fix that, reinsulating each wire individually, and retest with teh original controller, since that "works", and see if it gets better.

While doing the fixing, use a multimeter on continuity or ohms and test which pins on your motor connector go to each of the damaged wires. That can be used later if there is still a problem to see what to test next.

 

[Pylonflyer]

Thank you for the long response. Lots to think about. I didn't even know about those ebike motor/esc testers, thanks! I got one and discovered that my motor phases are good. However, the plugs on my esc are not even close to being easy to hook up to test. It has all the round-style pin connectors so alligator clips won't cut it.

 

[amberwolf]

There are thousands of round style pin connectors, so you'd need to be more specific. If you don't know the names, that's ok--just show good clear images of tehm and we can help identify them. If you're referring to the one like you show on the mtoor connector, that's probably a variation of the Julet / Higo Z910.

You can get "pigtails" that have bare wires at one end, or extension cables that you can cut in half to make your own, for all sorts of testing purposes and for using one device with a controller that has different connectors, etc.

 

[n00b]

2023 Ouxi V8 20" Fat Bike 750Watt 48v - "Amazon Special"

Here's the story: Daughter's bike started to make a harmonic buzzing noise and loss of power after bumping into a friend's bike (kind of a mild T-bone accident, no one got hurt). Assumed it was mechanical issue, but it's looking more and more like a bad phase in the system after more testing. I think she may have over-amped something when she was power on into the other bike.

I tested the motor phase wires for burnt windings, and they seem to be within similar resistance. Pulled apart hub motor to check planetary gears, looks good. Smelled controller and tested the FETs, seemed ok but I'm not the best at diagnosing esc's. I'm pretty experienced with RC brushless motors and such, but these e-bikes are new territory for me besides building some scooters and e-skateboards over the years.

Took a chance assuming motor is fine, and ordered a new esc from v8fatbike.com based on their recommendations. They said my bike would be "V3" compatible (that's their terminology on controller versions see pic), and I got their "V8" controller which, on paper, is within the specs of the original model: V8S-500. Got the new controller and 95% of plugs and wires are the same, but there is an extra "alarm" 3-pin plug (see pic) that has 48v coming out, and the 9-pin motor plug is red inside vs black (original) (see pics at bottom).

Got everything plugged together and display comes up, lights come on, turn signals work, horn works.... but no throttle. Motor does nothing. I searched the interwebs for info, nothing helpful. Played around in Chat GPT for a long while and it said to "jump" the outer pins of the un-used alarm plug (see pic of jumper). Still nothing. Plugged the old esc back in and motor runs, but it's not healthy sounding.

Now I'm stumped. Can it be that the 9-pin motor order is not the same? Different sensor pin order? Or is the new controller not programmed for this motor? Emailed V8fatbike.com support and they said this controller should work. Are they totally inept in their own products? Highly probable but so am I.

Is anyone familiar with this motor/esc brand to where I may be missing a simple step in programming something in the display menu? Are these esc/motor combos not universal and I have to do a custom esc process? Get a universal esc (KT keeps popping up in my searches). Or, should I save myself gray hairs and stress and buy a drop-in 20" hub motor/esc combo from Bafang or something and just rewire the dang bike? The 48V battery is fine, btw.

Appreciate any guidance from gurus or fellow victims of this bike who have fixed something similar.

View attachment 380278
Original esc
View attachment 380277

New esc
View attachment 380280
extra "Alarm" plug, jumped outer pins per instruction
View attachment 380279
View attachment 380281View attachment 380282

I'd try a different throttle first, because that's what my latest issue and fix was.
Dry fittin' everything and no spin with throttle.
Several different controllers, couple different motors, same throttle, no spin, derp!
Hook up other throttle, works 1st go.
1 of those controllers might be bad anyway, but I'm ready to roll now!
I don't think that alarm stuff has to be hooked up for it to go.
Power and phases and throttle do.