Bafang BFSWX02 stutters then stops now nothing

[linter]

This is on an electric scooter. Used to run just fine, then became increasingly problematic, and now it'll stutter for a second when the throttle is turned, then nothing, and pretty much all nothing after that.

i have the same set up on a different scooter and it works fine. i've connected the bad scooter's throttle to the good scooter -- nothing, as well as used the good scooter's battery and controller -- again, nothing -- as well as used both the good's battery/controller and throttle, once again, nothing. in my mind, that narrows it down to the motor itself. any way for me to test the motor further, without opening it up? and if i do open it up, what might the likely culprit/s be?

thanks!

 

[vfr400]

What sort of connectors do you have on the controller? Can you show them?

 

[Nealh]

As vfr has said check the controller phase connections and if they look good (no sign of heat scorching or melting ), test the mosfets for an issue.

 

[linter]

see pix. the connectors all seem good,



in the pic above, everything on the working bike is hooked up to the bad one and i get the stutter, then nothing. if the issue was soley with the controller on the not-working craft, then the way you see it connected now should produce the desired result, right? that means it's either the pins on motor on the bad scooter or something internal. and the pins look okay, tho it's hard to say from the photos below.

if it's the motor, what's my next move?

 

[Nealh]

In that case then the halls need testing in the stuttering hub, if the connector at the controller from the motor cable is a moulded WP one, then one will have to make up/modify another moulded WP cable to connect in between to test the hall out puts.

 

[vfr400]

Moulded connectors are great until you need to test something. That's why I always recommend controllers with block connectors.

These are things that could be wrong with your system:
1. Motor connector not in far enough. It must go all the way to the marked line, not just in tight,
2. Damaged motor cable, especially where it comes out of the axle. Check that very carefully. This one is a strong possibility.
3. Faulty mosfets in the controller. You say you tried a controller that worked on another system, so this cause is not very likely. I won't tell you how to test these until all other possibilities have been exhausted.
4. Faulty hall sensors in the motor. That doesn't normally happen without some special cause. Maybe your motor connector wasn't in far enough, which broke a connection, which would make the motor over-heat, so that's a strong possibility.
5. Wire in the motor rubbed through because it wasn't routed correctly. I've seen this a couple of times, but it's pretty rare.

Unless the problem is with the motor cable you will need to test the motor connections and the hall sensors.

Test 1: Check continuity with a meter between each pair of the big three pins, which there should be between each pair, then check whether there's any continuity between each big pin and the motor casing, which there shouldn't be anything.

Test 2. Check the function of the hall sensors. There are three ways to do that.
2a. Open the controller so that you can get to where the hall wires are soldered.
2b. Open the motor so that you can get to where the hall wires are soldered.
3c. Get hold of a female motor connector from an old controller or motor cable. Expose all the wires and apply 5v to the red and black wires, which power the halls.
For each of those three tests, with the halls powered, check that you have 5v between red and black, then measure between each of blue, green and yellow, while you rotate the motor slowly backwards. You should see the 5v switching on and off.

 

[linter]

thank you both and i'll dig into this as time permits. firstly, i'll have to track down from how-to vids on youtube to help me through the process. i do have a meter but haven't used it for anything but checking AA battery strength and the like. even testing continuity will be new, so i'll need to educate myself along the way. again ... thanks!

 

[linter]

well, all i've managed to do so far is strip the head of *only* one screw while taking the top plate off the motor. the interior looks pretty clean, though the big wire looks a little wonky right down at the base. the pix kinda show that.

now ... what would my next step be?

vfr400 wrote: with the halls powered, check that you have 5v between red and black, then measure between each of blue, green and yellow, while you rotate the motor slowly backwards. You should see the 5v switching on and off.

is there a vid you know of that gives step by step to do this?

thanks!

 

[linter]

bought one of those cheapo testers and within minutes managed to fry the motor on the good bike. i'm going to take a nap now. damn it.

 

[vfr400]

bought one of those cheapo testers and within minutes managed to fry the motor on the good bike. i'm going to take a nap now. damn it.

You can't fry a motor with any sort of tester.

 

[linter]

i'm sure you're right, but introduce the potential for operator error and, in my case, anything is likely. meanwhile, leaving the formerly good scooter aside for the moment, the o.g. bad one does as you see on the video:

https://youtu.be/b7z-e5Us7HY

for testing, the scooter is upside down. spinning the wheel forward, the phase lights all come on at once. at rest, hall blue light is out, while H green and yellow are solid lit. a slow spin of the wheel get solid yellow, with blue and green alternating.

thoughts? suggestions?

Thanks!

 

[vfr400]

Your yellow hall sensor isn't switching. You need to find out why - connection issue, damaged cable or blown sensor.

 

[linter]

okay, thanks. which of those is the easiest to check (and least likely for me to make things worse)?

meanwhile, if you've got a moment, here are two pix of tester hooked up to the formerly good bike. don't know what i did but i surely did something. fast spin gets all three appropriate lights going at once. as to the halls, the first photo is with no movement. only the blue and green are lit. the second is with a bit of movement, and only the middle light goes and off. the first light stays solid, and yellow light isn't lit up at all ever.

wish i'd never started going down this rabbit hole and lived w/ the one good motor. (i have a disease like MS and these scooters are one of the only ways i can walk my dog.)

as with the other scooter, when this one is hooked up to the battery and throttle, it does one or two jerks forward, then stops completely. dang. double dang. dang dang.





btw / the motor cable has a white wire among the many but there's no equivalent white wire on the tester, so i haven't hooked it up to anything. don't know what that might mean ....

 

[vfr400]

okay, thanks. which of those is the easiest to check (and least likely for me to make things worse)?

meanwhile, if you've got a moment, here are two pix of tester hooked up to the formerly good bike. don't know what i did but i surely did something. fast spin gets all three appropriate lights going at once. as to the halls, the first photo is with no movement. only the blue and green are lit. the second is with a bit of movement, and only the middle light goes and off. the first light stays solid, and yellow light isn't lit up at all ever.

wish i'd never started going down this rabbit hole and lived w/ the one good motor. (i have a disease like MS and these scooters are one of the only ways i can walk my dog.)

as with the other scooter, when this one is hooked up to the battery and throttle, it does one or two jerks forward, then stops completely. dang. double dang. dang dang.

View attachment 42134

View attachment 42133

btw / the motor cable has a white wire among the many but there's no equivalent white wire on the tester, so i haven't hooked it up to anything. don't know what that might mean ....

To use the tester, you connect it up, switch it on, then turn the motor backwards slowly. The hall lights should flash in sequence and so should the phase lights underneath. When the motor is stationary, you can get any pattern of hall lights depending where the motor stops relative to the magnets.

The motor phases generate their own power, so will probably flash even when the tester is switched off. the halls use 5v provided by the tester.

There's no way you can damage anything with the tester because it only gives 5v, which isn't enough to kill the halls no matter how you connect them. The only way you could damage anything is if you connected a phase wire to a hall wire, then spun the motor, but that's normally impossible because of the connectors.

 

[linter]

in both cases, i am spinning the wheel backwards to test. in both cases, the phase lights do not move in sequence but rather light up all at once. the hall lights are as i've said. with movement:

1/ bad scooter (BS): blue and green alternate, while yellow just stays lit.
2/ new bad scooter (NBS): blue stays lit, green goes on and off, yellow isn't lit at all.

any further thoughts or suggestions?

 

[vfr400]

then turn the motor backwards slowly.

Did you let the phase wires touch the hall wires while spinning the 2nd motor?

 

[linter]

not that i know of. just went and did tested again, making sure nothing touched = same result.

or are you saying that if i did touch em, that might explain why the motor no longer works? if so, yes, sadly, that's possible.

 

[linter]

on the BS (the og one), i turned on the tester and went to the circuit board w/ my multimeter. put red on the lil 5V blob of solder as seen in the pic below, then the black on HA (nothing), HB (3.18) and HC (4.99). i'd assume HA is the yellow hall wire. from this, can we conclude that the hall itself is bad or are there still other possibilities?

 

[vfr400]

The signals are dynamic. You're testing to see whether the halls switch on and off. You can't test anything with a stationary motor. Secondly, you measure voltages from ground, not from 5v.

 

[linter]

man o man. okay, at this point, i guess i'm going to see if i can find some local help, before i do more damage. thanks again for your input!